It was a herb that inspired the development of the first of the NSAIDs. White willow (Salix alba) is a herb traditionally used for pain relief and reducing fever (3). It contains flavonoids, tannins and salicylates; with the salicylate salicin considered to be the key active constituent (4). The discovery of salicylates from white willow and meadowsweet (Filipendula ulmaria) and their pain-relieving activity led to the development of acetylsalicylic acid (aspirin). 

White willow extract has been found to inhibit COX enzymes, tumour necrosis factor-α (TNF-α) and NFκB (5), all of which are involved in inflammatory pathways. Much lower levels of salicylates are provided by effective therapeutic doses of white willow than are administered when taking aspirin, which means that fewer of the gastrointestinal side effects seen with aspirin are experienced (5).

It also suggests that constituents other than salicin are involved in the beneficial effect seen. Evidence suggests that white willow may be effective for treating lower back pain, and one study found that a standardised extract containing 120–210 mg of salicin was equivalent to the NSAID rofecoxib (6).

A study of 96 students with primary dysmenorrhoea (painful periods) found that 750 mg of mefenamic acid was less effective than 400mg of white willow (containing 240mg of salicin) at reducing pain, as measured using a visual analogue scale (7).

Turmeric (Curcuma longa) has been well researched for pain, particularly to treat knee osteoarthritis. It impacts on inflammatory markers interleukin-6 (IL-6) and TNF-α, and has been found to downregulate pain receptor expression (8); indicating a more complex mechanism of action than NSAIDs. 

A meta-review of turmeric systematic review found there to be moderate GRADE evidence for the use of turmeric to relieve pain and improve symptoms of osteoarthritis (8). GRADE is a tool to systematically assess the quality or certainty of evidence in clinical research. 

One study of 144 patients with knee osteoarthritis found that 1 g of a bioavailable turmeric extract was as effective as paracetamol at reducing pain over six weeks, while achieving greater decreases in inflammatory markers C-reactive protein (CRP) and TNF- α (9).

Another study of 367 patients showed that 1.5 g of turmeric extract was as effective as 1.2 g ibuprofen but with fewer gastrointestinal side effects when taken for four weeks by adults with knee osteoarthritis (10).

The measurement of inflammatory markers is one way to objectively determine whether an intervention is likely to be having an effect on the processes involved with pain and inflammation. So, the reduction of CRP and TNF-α by turmeric was a positive sign that it was having an impact on the cause of the pain, rather than providing a placebo effect or simply improving overall wellbeing.

Prostaglandins are short-acting signalling molecules that are involved in inflammatory responses. They are synthesised by COX enzymes and inhibiting their production by COX is a key mechanism of action of aspirin and NSAIDs. A study of 60 patients with knee osteoarthritis demonstrated that both NSAID naproxen and a supplement containing turmeric, ginger and black pepper inhibited prostaglandin E₂ (PGE₂) with no significant difference (11).

Fennel (Foeniculum vulgare) has also been proposed to alleviate pain by lowering prostaglandin levels. Two meta-analyses have both concluded that fennel oil or capsules is equivalent to conventional drug therapies such as the NSAID mefenamic acid at treating dysmenorrhoea (12,13).

The holistic and “nudge”-like approach of herbal medicine that aims to address health challenges over the long-term may not seem at first to be the most suitable way to address pain. The urgent feeling and discomfort experienced when we are in pain stimulates the desire for fast-acting solutions. 

A randomized-controlled trial in 88 healthy adults with acute musculoskeletal pain found that those who took 1g of a black seed oil (Nigella sativa), turmeric and frankincense (Boswellia serrata) extract had pain relief comparable to paracetamol within an average of one hour (14). 

There is also evidence that topically applied pain-relieving herbs like chilli (Capsicum spp.), rosemary (Salvia rosmarinus) and lavender (Lavandula angustifolia) can act quickly (15).

Due to the difficulties in achieving results when treating pain, multiple drugs are often combined to provide a more effective outcome. The addition of herbal anti-inflammatories to standard therapy may also be a good approach. 

A study of 140 patients with knee osteoarthritis found that 1 g of a curcuminoid complex combined with 100 mg of the NSAID diclofenac daily for 28 days was more effective than the diclofenac alone. Pain and quality of life were improved and the number of rescue analgesics needed for uncontrolled pain were lower in those taking the curcuminoid complex. There were also fewer adverse effects and less need for treatment of acid reflux with H2 blockers in the curcuminoid group (16).

In women with primary dysmenorrhoea, there is an increase in release of prostaglandins, particularly PGE₂. A standard treatment is the NSAID mefenamic acid. One study of 150 female students found that combining 250 mg of mefenamic acid with 500 mg of turmeric powder daily for five days around the start of menstruation led to significant reduction in pain compared with either treatment alone (17).  

Some herbs work via similar mechanisms to common pain-relieving medication such as NSAIDs. In many cases, they have been demonstrated to be as effective as standard painkillers, but with fewer side effects and, in some cases, they may mitigate the side effects produced by NSAIDs. This may be due to the complexity and synergy from multiple different phytochemicals in one herb.

Additionally, the holistic approach used in herbal medicine will aim to address the factors that have caused or are prolonging the increased inflammation in the first place and work towards fully resolving the underlying pathology.

1. NICE. How do analgesics work? Clinical Knowledge Summaries. 2025. Accessed March 25, 2026. https://cks.nice.org.uk/topics/analgesia-mild-to-moderate-pain/background-information/mode-of-action/
2. Gunaydin C, Bilge SS. Effects of nonsteroidal anti-inflammatory drugs at the molecular level. Eurasian J Med. 2018;50(2):116–121. https://doi.org/10.5152/eurasianjmed.2018.0010
3. Committee on Herbal Medicinal Products (HMPC). Final European Union herbal monograph on Salix [various species including S. purpurea L., S. daphnoides Vill., S. fragilis L.], cortex. European Medicines Agency; 2017. EMA/HMPC/80630/2016-Corr. Accessed April 23, 2026. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-salix-various-species-including-s-purpurea-l-s-daphnoides-vill-s-fragilis-l-cortex_en.pdf
4. Matyjaszczyk E, Schumann R. Risk assessment of white willow (Salix alba) in food. EFSA J. 2018;16(Suppl 1):e16081. https://doi.org/10.2903/j.efsa.2018.e16081
5. Heinrich M, Barnes J, Prieto-Garcia JM, Gibbons S, Williamson EM. Fundamentals of Pharmacognosy and Phytotherapy. 4th ed. Elsevier; 2023.
6. Oltean H, Robbins C, van Tulder MW, Berman BM, Bombardier C, Gagnier JJ. Herbal medicine for low-back pain. Cochrane Database Syst Rev. 2014;2014(12):CD004504. https://doi.org/10.1002/14651858.CD004504.pub4
7. Raisi Dehkordi Z, Rafieian-Kopaei M, Hosseini-Baharanchi FS. A double-blind controlled crossover study to investigate the efficacy of salix extract on primary dysmenorrhea. Complement Ther Med. 2019;44:102–109. https://doi.org/10.1016/j.ctim.2019.04.002
8. Rolfe V, Mackonochie M, Mills S, MacLennan E. Turmeric/curcumin and health outcomes: a meta-review of systematic reviews. Eur J Integr Med. 2020;40:101252. https://doi.org/10.1016/j.eujim.2020.101252
9. Singhal S, Hasan N, Nirmal K, et al. Bioavailable turmeric extract for knee osteoarthritis: a randomized, non-inferiority trial versus paracetamol. Trials. 2021;22(1):105. https://doi.org/10.1186/s13063-021-05053-7
10. Kuptniratsaikul V, Dajpratham P, Taechaarpornkul W, et al. Efficacy and safety of Curcuma domestica extracts compared with ibuprofen in patients with knee osteoarthritis: a multicenter study. Clin Interv Aging. 2014;9:451–458. https://doi.org/10.2147/CIA.S58535
11. Heidari-Beni M, Moravejolahkami AR, Gorgian P, Askari G, Tarrahi MJ, Bahreini-Esfahani N. Herbal formulation “turmeric extract, black pepper, and ginger” versus naproxen for chronic knee osteoarthritis: a randomized, double-blind, controlled clinical trial. Phytother Res. 2020;34(8):2067–2073. https://doi.org/10.1002/ptr.6671
12. Lee HW, Ang L, Lee MS, Alimoradi Z, Kim E. Fennel for reducing pain in primary dysmenorrhea: a systematic review and meta-analysis of randomized controlled trials. Nutrients. 2020;12(11):3438. https://doi.org/10.3390/nu12113438
13. Shahrahmani H, Ghazanfarpour M, Shahrahmani N, Abdi F, Sewell RDE, Rafieian-Kopaei M. Effect of fennel on primary dysmenorrhea: a systematic review and meta-analysis. J Complement Integr Med. 2021;18(2):261–269. https://doi.org/10.1515/jcim-2019-0212
14. Rudrappa GH, Chakravarthi PT, Benny IR. Efficacy of high-dissolution turmeric-sesame formulation for pain relief in adult subjects with acute musculoskeletal pain compared to acetaminophen: a randomized controlled study. Medicine (Baltimore). 2020;99(28):e20373. https://doi.org/10.1097/MD.0000000000020373
15. Barnett H. Pain relief: 5 analgesic herbs for external application. Herbal Reality. 2023. Accessed April 23, 2026. https://www.herbalreality.com/health-lifestyle/mobility-fitness/5-herbs-instead-painkillers/
16. Shep D, Khanwelkar C, Gade P, Karad S. Efficacy and safety of combination of curcuminoid complex and diclofenac versus diclofenac in knee osteoarthritis: a randomized trial. Medicine (Baltimore). 2020;99(16):e19723. https://doi.org/10.1097/MD.0000000000019723
17. Hesami S, Kavianpour M, Rashidi Nooshabadi M, Yousefi M, Lalooha F, Khadem Haghighian H. Randomized, double-blind, placebo-controlled clinical trial studying the effects of turmeric in combination with mefenamic acid in patients with primary dysmenorrhoea. J Gynecol Obstet Hum Reprod. 2021;50(4):101840. https://doi.org/10.1016/j.jogoh.2020.101840

Historically, herbal dosing was developed through empirical trial, observation, experience and long-term use. Effective doses, preferred formulations and the knowledge of optimal remedies was passed through the generations (1).

Traditional texts often describe dosing in experiential terms, such as a glass or handful, or an amount tolerated. While these measures may appear imprecise from a modern or conventional perspective, they reflect a responsive approach to medicine — trial and error.

Doses were often adjusted according to the strength of the herb and individual’s response over time. Sometimes doses may have to be adjusted according to the strength and purity of a batch of herbs, as differences in harvesting, drying, storage and processing can impact the strength of the actives. The importance of feedback and adjustment of doses was a valuable part of traditional practice (2).

Plant and formulation factors 

The characteristics of the herb itself must be considered when determining an appropriate dose. Herbs differ widely in their strength, safety profile and therapeutic range; these differences directly inform how they should be used (3). Nutritive herbs such as nettle (Urtica dioica) or dandelion (Taraxacum officinale) are rich in minerals and phytochemicals which are often used in generous doses over extended periods of time for their vast medicinal benefits ranging from anti-inflammatory to blood tonic effects (4,5).

In contrast, aromatic and bitter herbs tend to act more immediately on digestion, circulation and the nervous system and may produce noticeable effects at relatively small doses. For example, peppermint (Mentha x piperita, M. arvensis) stimulates taste receptors and digestive reflexes; even modest amounts can have carminative effects and stimulate gut motility (6).

Similarly, aromatic nervines such as lavender (Lavandula angustifolia) or lemon balm (Melissa officinalis) can have calming effects at relatively low doses (7). Some herbs have a narrow safety profile therefore require great precision and clinical judgement when dosing. Lily of the valley (Convallaria majalis) a cardiotonic can be highly toxic even in small over-doses (8). Hence, careful dosing, appropriate training and awareness of contraindications is so important.

Today, for most people dosing from raw or unprocessed material may be confusing. Telling someone to take a pinch of a powdered herb can lead to significant dosing variability, as a pinch can range on average from 0.3 g to 0.6 g. This variability could lead to double the dose which could have adverse effects rather than a therapeutic benefit. Therefore, quantifying a pinch as a definitive value (e.g., “a pinch is 0.3 g”) makes dosing reproducible, and standardises the process.

When using leaves in preparations (i.e. add two leaves) this can also have inconsistent dosing effects. The variable size, condition and stage of maturity of the leaf can also impact the efficacy of dosing. Furthermore, dried and fresh material will have different effects; dried material may be more concentrated, and the composition of bioactive compounds may have changed (i.e., essential oils may evaporate during drying). All these factors can impact the effective dosing of herbals (2,9,10,11).

Even among commonly used herbs, factors such as duration of use, interactions and individual sensitivity must be considered. For these reasons, effective dosing relies on familiarity with both traditional dosages and contemporary safety data, allowing herbs to be used confidently and appropriately.

Individual factors 

Determining an appropriate dose always begins with the person. Age, gender, body composition, digestive capacity, liver and kidney function, comorbidities and individual sensitivity all influence how someone may respond. A healthy adult with good digestion may require and safely tolerate a higher therapeutic dose to achieve a clinical effect.

In contrast, an older or frail adult, a child, or someone with comorbidities may only tolerate lower doses and respond better when doses are gradually introduced and increased. Response to doses also varies depending on individuals’ experiences as some people may respond to very small doses, particularly with aromatic, bitter or nervine herbs; while others can tolerate larger doses before any clinical response is seen.

Effective dosing, therefore, relies not on standardised quantities alone, but on careful assessment of the individual’s capacity to receive, process and respond to herbal medicines (12).

The nature of the condition being treated is equally important when determining dose. Acute and relatively minor health conditions often respond best to higher or more frequent dosing over a short period of time, with the aim of supporting the body through a transient physiological challenge.

For example, in the early stages of an upper respiratory tract infection (i.e., cold/flu), herbs such as elderberry (Sambucus nigra) or echinacea (Echinacea purpurea) may be taken as tinctures or infusions regularly to support immune and inflammatory responses, soothing symptoms and reducing recovery time.

Acute musculoskeletal pain (i.e., sprain/strain or minor injury) may respond well to short-term internal use of anti-inflammatory herbs such as turmeric (Curcuma longa) alongside topical applications of arnica (Arnica montana) or rosemary (Salvia rosmarinus) (7,12).

On the other hand, chronic conditions usually require low to moderate doses taken consistently over a longer period. Chronic digestive disorders, hormonal imbalances or stress-related conditions often respond better to sustained doses that work gradually with underlying physiological patterns rather than attempting rapid relief of symptoms.

The use of ashwagandha (Withania somnifera) for reducing stress and anxiety can take up-to two weeks before a clinical effect is observed, as the adaptogen regulates cortisol and other hormones (13). When managing on-going or chronic conditions high doses may be poorly tolerated and unnecessary, therefore a “low and slow approach” would allow for cumulative effects and monitoring to take place (14).

Most conventional pharmaceutical medicines have standard formula and doses. There is a comprehensive pharmacopeia which makes production scalable and reproducible. Aspirin is an example of a synthetic medicine (originally isolated from willow (Salix alba)) whereby a single active compound (acetylsalicylic acid) was identified, and chemically synthesised (15).

The therapeutic effects are evidence based with randomised controlled trials (RCTs) to validate the efficacy. For most herbal medicines, there is often not a single isolated compound responsible for the therapeutic effects. Instead, herbal medicines are a complex mixture with many active constituents.

The mixture of compounds are known to work synergistically to have a therapeutic effect; hence, isolating a single compound would not be as therapeutically beneficial (16). For this reason, dosing is rarely about achieving a precise milligram quantity of one active ingredient. Instead, it involves establishing an effective therapeutic relationship between the plant, the preparation and the person taking it.

Finally, the form of preparation has a significant impact on dosing. Teas and decoctions favour water-soluble constituents and are often taken in larger volumes. Powders and capsules rely on digestion and absorption and may therefore require higher quantities to achieve an effect.

Tinctures are more concentrated and allow for flexible, incremental dosing. Herbal dosing tends to operate within broader therapeutic ranges than pharmaceutical drugs, allowing for a greater degree of flexibility and individualisation. The dose is shaped not only by pharmacology, but also by constitution, strength, sensitivity and condition treated (11).

In practice, standardising dosing of herbals is best approached using clearly defined therapeutic ranges rather than fixed doses. Replacing ambiguity in dosing by eyeballing, using a cupful or a few drops/leaves, by standard measures such as volumes for liquids (i.e., millilitre for tinctures) and weights for solids (i.e., gram for dried herbs), can improve dosing. Where reputable suppliers have preparations available with clear strength and doses these may be a preferred option to use. 

It is important to regularly review an individual’s response to herbals, and educate them of the signs of efficacy, intolerance and adverse effects so that dosing can be refined over time. One of the strengths of herbal medicine is that it is responsive. Signs that a dose may be too low include a lack of change to symptoms, after an appropriate trial period, or progress which prematurely stalls.

On the other hand, signs that a dose may be too high may include digestive discomfort, headache, nausea or exacerbation of symptoms. Hence, herbal dosing is a dynamic process. Ongoing observation, communication with practitioners and adjustments are integral to safe and effective herbal practice (17).

There is no single answer to the question of how much is enough when it comes to herbal dosing. Effective dosing emerges from the relationship between plant, preparation and individuals, informed by knowledge, use and experience of the person and practitioners.

1. Bhamra SK, Slater A, Howard C, Heinrich M, Johnson MRD. Health care professionals’ personal and professional views of herbal medicines in the United Kingdom. Phytotherapy Research. 2019;33(9):2360-2368. https://doi.org/10.1002/ptr.6418 
2. Kofi Busia. Herbal medicine dosage standardisation. Journal of herbal medicine. 2024;46:100889-100889. https://doi.org/10.1016/j.hermed.2024.100889 
3. Jürges G, Sahi V, Rios Rodriguez D, et al. Product authenticity versus globalisation—The Tulsi case. Aravanopoulos FA, ed. PLOS ONE. 2018;13(11):e0207763. https://doi.org/10.1371/journal.pone.0207763 
4. Devkota HP, Paudel KR, Khanal S, et al. Stinging Nettle (Urtica dioica L.): Nutritional Composition, Bioactive Compounds, and Food Functional Properties. Molecules. 2022;27(16):5219. https://doi.org/10.3390/molecules27165219 
5. Kania-Dobrowolska M, Baraniak J. Dandelion (Taraxacum officinale L.) as a Source of Biologically Active Compounds Supporting the Therapy of Co-Existing Diseases in Metabolic Syndrome. Foods. 2022;11(18):2858. https://doi.org/10.3390/foods11182858 
6. Hirata M, Fornari Laurindo L, Dogani Rodrigues V, et al. Investigating the Health Potential of Mentha Species Against Gastrointestinal Disorders—A Systematic Review of Clinical Evidence. Pharmaceuticals. 2025;18(5):693. https://doi.org/10.3390/ph18050693 
7. Chevallier A. Herbal Remedies. DK Pub.; 2007.
8. Currie GM, Wheat JM, Kiat H. Pharmacokinetic Considerations for Digoxin in Older People. The Open Cardiovascular Medicine Journal. 2011;5(1):130-135. https://doi.org/10.2174/1874192401105010130 
9. Nakra S, Tripathy S, Srivastav PP. Drying as a preservation strategy for medicinal plants: Physicochemical and functional outcomes for food and human health. Phytomedicine Plus. 2025;5(2):100762. https://doi.org/10.1016/j.phyplu.2025.100762 
10. Bhamra SK. Investigating the Use and Identity of Traditional Herbal Remedies amongst South Asian Communities Using Surveys and Biomolecular Techniques. Published thesis (PhD). 2016.
11. Wilde M. Doses and Measures. Napiers. Published August 3, 2021. Accessed January 14, 2026. https://napiers.net/blogs/news/doses-and-measures 
12. Tyson RJ, Park CC, Powell JR, et al. Precision Dosing Priority Criteria: Drug, Disease, and Patient Population Variables. Frontiers in Pharmacology. 2020;11. https://doi.org/10.3389/fphar.2020.00420 
13. Fuladi S, Emami SA, Mohammadpour AH, Karimani A, Manteghi AA, Sahebkar A. Assessment of Withania somnifera root extract efficacy in patients with generalized anxiety disorder: A randomized double-blind placebo-controlled trial. Current Clinical Pharmacology. 2020;15. https://doi.org/10.2174/1574884715666200413120413 
14. Frost R, Bhamra SK, Heinrich M. Herbal Products and Antidepressants: A Safe Combination or a Risky Mix? Phytotherapy Research. Published online January 13, 2026. https://doi.org/10.1002/ptr.70173 
15. Mahdi JG, Mahdi AJ, Mahdi AJ, Bowen ID. The Historical Analysis of Aspirin discovery, Its Relation to the Willow Tree and Antiproliferative and Anticancer Potential. Cell Proliferation. 2006;39(2):147-155. https://doi.org/10.1111/j.1365-2184.2006.00377.x 
16. Efferth T, Koch E. Complex Interactions between Phytochemicals. The Multi-Target Therapeutic Concept of Phytotherapy. Current Drug Targets. 2011;12(1):122-132. https://doi.org/10.2174/138945011793591626 
17. Bhamra SK. The revival of herbal medicines. Prescriber. 2024;35(6):13-16. https://doi.org/10.1002/psb.2157 

Constituents are often described as water-soluble, alcohol-soluble, or oil-soluble. But solubility behaves more like a continuum. A constituent may be somewhere on the spectrum of sparingly to highly soluble in any given solvent. Rather than asking “is this constituent water-soluble?” the question becomes, “from this herbal matrix, how soluble is this constituent in water, at this temperature, and using this extraction method?”

This is why changing the solvent and extraction method can change the focus and function of a herbal medicine. A standard infusion emphasises constituents that dissolve readily in hot water. Are these the constituents (and associated actions) that we desire in a particular medicine? A tincture made with a given menstruum extracts a different spectrum of constituents from the same herb. Which constituents will we focus on when we adjust the ethanol percentage of the menstruum? An infused oil of that herb will capture yet a different spectrum of constituents, therefore featuring different actions and energetics than the infusion or tincture.

The main influence on solubility is polarity — a property arising from a molecule’s electron distribution. If this distribution is unbalanced (i.e., there is internal charge separation) we have a polar compound. If the distribution is perfectly balanced, we have a nonpolar molecule. And, as with solubility, polarity is a spectrum. Any phytochemical or solvent falls somewhere along the continuum.

The key to solubility is matching the polarity of the solvent to the polarity of the constituents we desire to extract. The old aphorism “like extracts like” applies: higher-polarity solvents (like water) focus on higher-polarity constituents, while lower-polarity solvents (like fixed oils) favour lower-polarity constituents.

Relative polarity of solvents

If you think of water as being 100% polar, then glycerin would be about 81% as polar as water. Pure ethanol would be about 65% as polar as water. These solvents are close enough that they will intermix with each other. Each of these solvents targets a particular group of constituents but there is overlap in what they will extract. Fixed oils and carbon dioxide (CO₂) extract lower-polarity constituents don’t easily mix with water, vinegar, glycerol or ethanol.

Solvent / menstruum	Relative polarity
Water	1.00
Vinegar (like water but also acidic)	~ 1
Glycerin (glycerol)	0.81
Ethanol (100%)	0.65
Olive and other fixed oils	~ 0
Carbon dioxide (CO₂)	~ 0

A tincture is made with a hydroethanolic solvent system (menstruum) containing both mid-polarity ethanol and high-polarity water. By adjusting the ethanol (EtOH) percentage, we are tuning the overall polarity of the menstruum. More EtOH in the menstruum → lower polarity; less EtOH → higher polarity. This is one reason tinctures are so versatile — by choosing the right EtOH–water ratio, we design the menstruum to selectively extract constituents by polarity matching. In other words, menstruum composition strongly influences the phytochemical profile of the resulting tincture (1,5).

Hydroethanolic solvents

“K” is one way to quantify polarity. Since water is highly polar and ethanol (EtOH) is moderately polar, mixing them together in different proportions will create a menstruum with a specific polarity. The higher the % EtOH, the lower the polarity of the hydroethanolic solvent system (menstruum). We tincture different herbs with different % EtOH to match the polarity of the constituents we want to extract from those herbs.

EtOH / Water	~ K	EtOH / Water	~ K
100% water	80	60% EtOH	47
10% EtOH / 90% H2O	74.5	70% EtOH	41.5
20% EtOH	69	80% EtOH	36
30% EtOH	63.5	90% EtOH	30.5
40% EtOH	58	95% EtOH	27.8
50% EtOH	52.5	100% EtOH	25

In herbal pharmacy, “yield” indicates the amount of finished tincture collected. But from a phytochemical perspective, “yield” usually refers to the concentration of a constituent in the product. A high constituent yield is often but not always better. For example, an extraction rich in astringent tannins may be more appropriate in some cases (surface inflammation, excessive secretion) and less appropriate in others (dry conditions, sensitive digestive mucosa). What matters is whether the preparation delivers the appropriate concentration of the desired spectrum of constituents for a particular therapeutic application.

Polarity is central, but several additional factors can influence the concentration of constituents in our extractions:

Temperature

Heat is a kind of kinetic energy that physically increases the extraction of most constituents. At the same time, some kinds of constituents are sensitive and will degrade with excessive heat. We learn to choose the optimal temperature for an extraction solvent, and to apply heat for the right period of time (e.g., infusion vs. decoction).

Time

Longer contact between solvent and herb generally enhances extraction up to a point, but the optimal time is influenced by factors including plant matrix, surface area, agitation, constituent class, and type of preparation.

Surface area

Chopping, grinding, or powdering increases surface area of the plant matrix, facilitating solvent–constituent contact and enhancing extraction. Very fine powders, however, can complicate filtration.

Agitation

Shaking or stirring increases kinetic jostling between solvent and constituents, usually accelerating extraction and constituent yield.

Pressure

Increasing pressure (e.g., in a tightly closed canning jar or electric pressure cooker) usually enhances extraction.

Plant matrix

Constituents may extract somewhat differently depending on how they are packaged within plant tissues. Delicate structures like flowers yield their constituents more readily than tough structures like seed coats or root barks. Cellular structure and co-constituents such as mucilages, tannins, and resins can also alter extractability.

Taken together, these variables should be considered as part of the extraction method; they help explain why preparations of the same herb in the same solvent can be noticeably different. The combination of botanical quality, solvent, and extraction method largely determines constituent yield and product quality.

Water

Water excels for higher-polarity constituents such as mucilages, polysaccharides, sugars, and some kinds of glycosides. It is the preferred solvent for making teas, infusions, and decoctions. Hot water almost always works better than cold water.

Hydroethanolic solvent systems (menstrua)

Lower % EtOH generally favours more polar compounds; higher % EtOH extracts lower-polarity constituents. Rather than a single “correct” percentage for each herb, it’s more accurate to think in ranges that can be adjusted to extract particular constituent families. Depending on your menstruum composition, you can create multiple different medicines from a single herb.

Glycerin and honey

Glycerin is a viscous and polar solvent, often used when alcohol is not desired. It can extract many water-soluble constituents along with a moderate concentration of aromatics, though it is generally less efficient than ethanol for lower-polarity constituents. However, its extraction spectrum can be increased considerably by employing heat, pressure, and agitation. As a solvent, honey behaves similarly to glycerin.

Vinegar

Vinegar is an acidic aqueous solvent. Acidity can change the solubility of certain constituents, particularly alkaloids, by shifting them into more water-soluble ionic forms (1,4). Traditional vinegars and oxymels (made by combining infused vinegars and honeys) offer versatile, alcohol-free alternatives to hydroethanolic tinctures or glycerites.

Fixed oils

Botanical oils such as olive, safflower, or coconut are both therapeutic substances and low-polarity solvents. Herb-infused oils feature low-polarity, lipophilic constituents including many terpenoids and some phenolics, making them valuable for topical preparations. Culinary preparations such as infused ghee or vinegar-and-oil salad dressings can also double as herbal products. Oils are generally unsuitable solvents for mineral salts and polar constituents including mucilages and glycosides.

Supercritical carbon dioxide

Supercritical carbon dioxide (CO₂) extraction is sometimes used for low-polarity constituents (e.g., gingerols from ginger (Zingiber officinale) curcuminoids from turmeric (Curcuma longa), cannabinoids from hemp (Cannabis sativa)). This modern method uses high-pressure, low-temperature conditions, with the advantage that CO₂ leaves no solvent residue in the finished product. CO₂ extracts are good at preserving the characteristic flavours and aromas of herbs. They are especially suitable for use in highly concentrated formulas delivered in capsules. (2)

Betalains are the vivid, water-soluble pigments responsible for red-violet and yellow-orange colours in plants such as beetroot (Beta vulgaris) and prickly pear (Opuntia ficus-indica) fruit, as well as edible greens including red orach (Atriplex hortensis var. rubra) and purslane (Portulaca oleracea). These medicinal food-herbs (and their betalains) have antioxidant, anti-inflammatory, and broad-spectrum bioprotective effects. (3)

Betalains are highly polar. This predicts several practical outcomes:

• They extract readily into water and other higher-polarity solvents such as lower % EtOH menstrua. Betalain extraction decreases as EtOH percentage increases.
• Glycerin and honey can be suitable solvents, especially when gently warmed to decrease their viscosity.
• Vinegar (which is mostly water) is a good solvent for betalains.
• Betalains are not lipophilic; they do not extract well into fixed oils.

As another example, echinacea (Echinacea spp.) contain several important groups of constituents — immunomodulating polysaccharides (IP), alkamides, and polyphenols including phenolic acids and flavonoid glycosides. Each group has a characteristic polarity range (4). IP are quite polar and most soluble in hot water; alkamides have moderate polarity and favour 50–60% EtOH menstrua; and the polyphenols are mid- to higher-polarity constituents that extract fairly well with both hot water and lower % EtOH. 

Since all these constituents are bioactive, which solvent is “best”? We could bypass this question by delivering a dose of the tincture in a water-based extract like an infusion or decoction!

1. Lee JE, Jayakody JTM, Kim JI, et al. The influence of solvent choice on the extraction of bioactive compounds from Asteraceae: a comparative review. Foods. 2024;13(19):3151. https://doi.org/10.3390/foods13193151 
2. Uwineza PA, Waśkiewicz A. Recent advances in supercritical fluid extraction of natural bioactive compounds from natural plant materials. Molecules. 2020;25(17):3847. https://doi.org/10.3390/molecules25173847 
3. Sadowska-Bartosz I, Bartosz G. Biological properties and applications of betalains. Molecules. 2021;26(9):2520. https://doi.org/10.3390/molecules26092520 
4. Petrova A, Ognyanov M, Petkova N, Denev P. Phytochemical characterization of purple coneflower roots (Echinacea purpurea (L.) Moench.) and their extracts. Molecules. 2023;28(9):3956. https://www.mdpi.com/1420-3049/28/9/3956 
5. Ganora L. Herbal Constituents: Foundations of Phytochemistry. 2nd ed. Louisville, CO: HerbalChem Press; 2021. https://www.herbalconstituents.com/book 

Research into medicinal plants can be broadly split into two approaches. The first focuses on traditional and ethnobotanical uses of plants, which includes studies looking at plant use in specific geographical areas. The second covers use of plants in drug discovery, mechanistic in vivo and in vitro studies, and clinical studies assessing the effectiveness of herbal medicines (1).

Common themes for herbal research over the last ten years include: 

• The benefits of herbs to treat obesity, cancer, cardiovascular disease and infectious diseases
• Conservation and sustainability
• The interplay between the gut microbiome and phytochemicals
• Polyphenols and cardiovascular or cognitive health
• The use of formulations such as nanotechnology to improve bioavailability and efficacy

While the use of plants for health is truly global, the majority of research into medicinal plants is carried out in China and India, followed by Iran, Brazil, USA, South Korea, and Pakistan (1,2). 

Government funding, as well as the acceptance of Traditional Chinese Medicine (TCM) within the Chinese healthcare system has contributed to the large amount of herbal research produced there. India has also emerged as a global leader, since the launch of The World Health Organization (WHO) Global Traditional Medicine Centre there in 2022. Supported by the Government of India, this has the aim of advancing herbal research and enabling the ability of member states to conduct research that can address evidence gaps in the safety and efficacy of traditional medicine. 

The WHO’s 10-year global traditional medicine strategy was published at the end of October 2025. One of its key aims is to “integrate safe and evidence-based traditional and complementary medicine services within national and local health systems as appropriate, particularly at the level of primary health care” (3). Its first strategic objective is to strengthen the evidence base for traditional, complementary and integrative medicine (TCIM) through innovative research and digital tools, while encouraging collaboration between scientists and traditional practitioners. The location of the research centre in India is likely to consolidate India as one of the main countries contributing to herbal research globally.

Non-communicable diseases, such as obesity, diabetes, cancer, chronic respiratory disease and cardiovascular disease are responsible for the vast majority of deaths globally and are due to a combination of genetic, environmental and behavioural factors (4). Due to the magnitude of the problem, they are a big focus for research in all areas, and this is no different for herbal research. In cardiovascular research, China is again a key contributor (5).

TCM has been found to effectively reduce hypertension and blood lipid levels, improve outcomes in patients with type 2 diabetes, and relieve angina or reduce cardiovascular events (6).

The COVID-19 pandemic was a stimulus for research into the antiviral properties of herbs, as people focused on improving their immunity and looked into the possibility of herbal remedies for a viral disease with no known treatment. There is no treatment or vaccine for most viruses, and this need has provided an opening for herbal remedies.

A review of trends in global antiviral herbal research identified some key TCM herbs to treat COVID-19. These included liquorice (Glycyrrhiza glabra), Japanese honeysuckle (Lonicera japonica), baikal skullcap (Scutellaria baicalensis), ma huang (Ephedra sinica), weeping forsythia (Forsythia suspensa), Korean mint (Agastache rugosa), astragalus (Astragalus membranaceus), and poria (Poria cocos) (7).

Other areas of interest identified in this review include herbs for hepatitis B and C, respiratory syncytial virus, HIV, herpes simplex virus and influenza, those that support the immune system and the mechanisms of action of specific phytochemicals such as quercetin, andrographolide, luteolin, artemisinin and kaempferol. Nanoparticle formulations and essential oils also show promise, as well as technologies such as network pharmacology and molecular docking studies to virtually screen active ingredients (7). 

Metabolomics is a branch of research that analyses the complete range of metabolites in a biological system. The chemical complexity of plants means that this type of research is useful when analysing both plants and their impact on the body. Chemical analytical techniques are used to produce a unique “fingerprint” of all the metabolites in a sample. Raman and infrared spectroscopy, and liquid chromatography-mass spectrometry have been used for years, but newer technologies, such as mass spectrometry imaging and ambient ionisation techniques are rapidly increasing the ways to analyse samples.

The newer techniques allow measurement and determination of the chemicals present in dried herbs or herbal capsules containing multiple different plants without the need to extract the chemicals first (8). This means that samples can be tested for adulteration and likely effectiveness rapidly and throughout the supply chain. Metabolomics can be used to assess adulteration and contamination in quality control, as well as investigating the mechanism of action and to identify biomarkers of efficacy.

Screening herbal samples, extracts and mixtures of herbs enables the identification of all the compounds present. This can then be combined with computational analysis to match the chemical structures of compounds in a herb with proteins that they are likely to bind to. The biological processes that mix of compounds is likely to impact on can be determined and the pharmacology of a herb can be predicted. This field of research is known as network pharmacology and is increasingly being used to identify or justify specific uses of herbs or herbal formulations.

Network pharmacology integrates large datasets of information from phytochemistry analysis and biological assays to predict how a herb or mixture of herbs might work in the body by connecting up the network of active constituents from the herb with potential targets in the body (9,10). The field of research developed in the early 2000s from a desire to explain how complex formulae in Chinese medicine could be having an effect in the body (9). This approach reflects a paradigm shift from viewing drugs as single-target molecules to recognising the synergistic complexity of herbal formulations. 

Another innovation has been the use of nanoparticle formulations to improve bioavailability and stability, while reducing toxicity (11). Nanoparticles were first discovered as a natural occurrence during the preparation of herbal products, such as decoctions. The natural formation of vesicles and particles when plants are traditionally prepared is thought to contribute to the synergy effect seen when a whole plant extract is more effective than the main bioactive phytochemical extracted from a plant (12). Artificial nanoparticle technology is now being used to improve the efficacy of single phytochemicals that are known to have targeted efficacy in vitro, but which aren’t very bioavailable — for example, curcuminoids from turmeric root. 

The dual pressures of climate change and increasing popularity of certain herbal medicines, has led to difficulties in sourcing some herbs, with increasing numbers being added to at-risk lists (13). A changing climate, and subsequent environmental conditions, alters the levels of active compounds in the plants (14). In response, organisations such as the American Botanical Council (ABC) have launched initiatives to share information about sustainability challenges and promote responsible sourcing.

A key barrier to herbal research, as with many types of research, is money. Who funds research and why helps to define the field. This is why most clinical trials are carried out on standardised and trademarked extracts of herbal preparations produced by supplement companies and manufacturers. This has been particularly true for turmeric (Curcuma longa) and ashwagandha (Withania somnifera). 

An interesting development this year has been the launch of a trademarked extract of shatavari (Asparagus racemosus) by Ixoreal, the company behind the ashwagandha extract KSM-66. Despite centuries of use in Ayurvedic medicine for women’s health, shatavari has been relatively under-researched to date. The BioActivEx research group at University of Exeter has addressed this gap with a series of clinical studies funded initially by Pukka Herbs, showing benefits for muscle strength in older women (15,16,17). Additional studies have been published on the use of shatavari for perimenpausal symptoms, alone (18,19) and in combination with ashwagandha (20), as well as for the traditional use to support breastfeeding (21).

The gut microbiome

In line with the general increasing awareness of the importance of the gut microbiome, there has also been a flurry of new herbal research into the interplay between the gut microbiota and phytochemicals. How herbs affect the microbiome and how the microbiome affects the metabolism and bioavailability of herbs are both topics that have received attention.

While 60% of the variation in drug metabolism between individuals is due to genetics, there is a significant contribution from the gut microbes. Bacteria in the gut play a part in how plant chemicals are broken down and absorbed into the body. This will consequently have an impact on the efficacy and the toxicity of a herb (22). The presence or absence of specific microbes in the gut is likely to contribute to why herbs are more effective for some people than others.  

Plant chemicals such as polyphenols are well documented to impact the gut microbiome. Some phytochemicals have a prebiotic effect, promoting the growth and survival of beneficial microbes, while others may have an antibacterial effect on less desirable species (23). 

Herbal medicines have the potential to contribute to some of the key challenges to improving health. It will take more coordinated efforts globally to ensure that the herbal research is meaningful and can impact as many people as possible.

1. Salmerón-Manzano E, Garrido-Cardenas JA, Manzano-Agugliaro F. Worldwide Research Trends on Medicinal Plants. Int J Environ Res Public Health. 2020;17(10):3376. Published 2020 May 12. https://doi.org/10.3390/ijerph17103376 
2. El Allaoui H, El Ahmadi K, El Abdouni A, Dira I, El Bastrioui M, Bouhrim M, Eto B, Shahat AA, Herqash RN, Haboubi K. Trends and Insights in Medicinal Plant Extract Research: A Ten-Year Bibliometric and Visualization Study. Horticulturae. 2024; 10(11):1163. https://doi.org/10.3390/horticulturae10111163
3. WHO. Global Traditional Medicine Strategy 2025-2034. 2025. https://iris.who.int/server/api/core/bitstreams/cf37a4ad-4d27-4244-a7ee-001de39841ee/content 
4. WHO. Noncommunicable diseases. Fact sheet. 2025b. https://www.who.int/news-room/fact-sheets/detail/noncommunicable-diseases 
5. Chen Y, Li WW, Bi SL, et al. Visualizing research trends and identifying hotspots of herbal components for treating cardiovascular diseases: A bibliometric analysis from 2000 to 2023. Medicine (Baltimore). 2024;103(6):e35047. https://doi.org/10.1097/MD.0000000000035047 
6. Hao P, Jiang F, Cheng J, Ma L, Zhang Y, Zhao Y. Traditional Chinese Medicine for Cardiovascular Disease: Evidence and Potential Mechanisms. J Am Coll Cardiol. 2017;69(24):2952-2966. https://doi.org/10.1016/j.jacc.2017.04.041 
7. Hu L, Wang C, Zhang Y. Hotspots and trends in global antiviral herbal basic research: A visualization analysis. Eur J Integrative Med 2024. 102419.
8. Alum EU, Manjula VS, Uti DE, et al. Metabolomics-Driven Standardization of Herbal Medicine: Advances, Applications, and Sustainability Considerations. Natural Product Communications. 2025;20(8). https://doi.org/10.1177/1934578X251367650
9. Yuan Z, Pan Y, Leng T, et al. Progress and Prospects of Research Ideas and Methods in the Network Pharmacology of Traditional Chinese Medicine. J Pharm Pharm Sci. 2022;25:218-226. doi:10.18433/jpps32911
10. Zhao L, Zhang H, Li N, et al. Network pharmacology, a promising approach to reveal the pharmacology mechanism of Chinese medicine formula. J Ethnopharmacol. 2023;309:116306. doi:10.1016/j.jep.2023.116306
11. Ai S, Li Y, Zheng H, et al. Collision of herbal medicine and nanotechnology: a bibliometric analysis of herbal nanoparticles from 2004 to 2023. J Nanobiotechnol 2024 22:140. https://doi.org/10.1186/s12951-024-02426- 
12. Li J, Zhang YL, Jin T, et al. Advanced Pharmaceutical Nanotechnologies Applied for Chinese Herbal Medicines. Adv Sci (Weinh). 2025;12(31):e00167. doi:10.1002/advs.202500167 
13. Mykhailenko O, Jalil B, McGaw LJ, Echeverría J, Takubessi M, Heinrich M. Climate change and the sustainable use of medicinal plants: a call for “new” research strategies. Front Pharmacol. 2025;15:1496792. Published 2025 Feb 3. doi:10.3389/fphar.2024.1496792
14. Alum EU. Climate change and its impact on the bioactive compound profile of medicinal plants: implications for global health. Plant Signal Behav. 2024;19(1):2419683. doi:10.1080/15592324.2024.2419683
15. Greed E, Pritchard J, Struszczak L, et al. Shatavari supplementation during eight weeks of resistance training increases training load, enhances skeletal muscle contractility and alters the skeletal muscle proteome in older women. Front Nutr. 2025;11:1498674. Published 2025 Jan 6. doi:10.3389/fnut.2024.1498674
16. O’Leary MF, Jackman SR, Sabou VR, et al. Shatavari Supplementation in Postmenopausal Women Improves Handgrip Strength and Increases Vastus lateralis Myosin Regulatory Light Chain Phosphorylation but Does Not Alter Markers of Bone Turnover. Nutrients. 2021;13(12):4282. Published 2021 Nov 27. doi:10.3390/nu13124282
17. O’Leary MF, Jackman SR, Bowtell JL. Shatavari supplementation in postmenopausal women alters the skeletal muscle proteome and pathways involved in training adaptation. Eur J Nutr. 2024;63(3):869-879. doi:10.1007/s00394-023-03310-w
18. Gudise VS, Dasari MP, Kuricheti SSK. Efficacy and Safety of Shatavari Root Extract for the Management of Menopausal Symptoms: A Double-Blind, Multicenter, Randomized Controlled Trial. Cureus. 2024;16(4):e57879. Published 2024 Apr 8. doi:10.7759/cureus.57879
19. Yadav P, Yadav S, Vedururu SS, Kumari G. A Standardized Asparagus Racemosus Root Extract Improves Hormonal Balance and Menstrual Health and Reduces Vasomotor Symptoms in Perimenopausal Women: A Randomized, Double-Blind, Placebo-Controlled Study. J Am Nutr Assoc. 2025;44(8):754-764. doi:10.1080/27697061.2025.2510474
20. Pingali U, Nutalapati C, Wang Y. Ashwagandha and Shatavari Extracts Dose-Dependently Reduce Menopause Symptoms, Vascular Dysfunction, and Bone Resorption in Postmenopausal Women: A Randomized, Double-Blind, Placebo-Controlled Study. J Menopausal Med. 2025;31(1):21-34. doi:10.6118/jmm.24025
21. Ajgaonkar A, Debnath T, Bhatnagar S, Debnath K, Langade J. Shatavari (Asparagus racemosus Willd) root extract for postpartum lactation: A randomised, double-blind, placebo-controlled study. J Obstet Gynaecol. 2025;45(1):2564168. doi:10.1080/01443615.2025.2564168
22. Lim DW, Wang JH. Gut Microbiome: The Interplay of an “Invisible Organ” with Herbal Medicine and Its Derived Compounds in Chronic Metabolic Disorders. Int J Environ Res Public Health. 2022;19(20):13076. Published 2022 Oct 11. doi:10.3390/ijerph192013076
23. Guan Y, Tang G, Li L, et al. Herbal medicine and gut microbiota: exploring untapped therapeutic potential in neurodegenerative disease management. Arch Pharm Res. 2024;47(2):146-164. doi:10.1007/s12272-023-01484-9

I entered the world of research because I often felt that the quality of research in herbal medicine was questionable by many. To dig in deep, during my Master’s degree, I conducted the quality assessment of the COVID-19 clinical trial using Ayurveda intervention and compared it to the COVID-19 clinical trial using non-Ayurveda intervention, including conventional medicine (majority).

We found out that there was a difference between Ayurveda and non-Ayurveda trials. Initially the results favoured Ayurveda trials, so we conducted a sub-group analysis. The subgroup analysis could not establish the difference in the quality between two groups. 

After the completion of my degree, we conducted a next stage study to assess the characteristics and reporting of traditional medicine including Ayurveda and traditional Chinese medicine and compared it with conventional medicine. We found out the traditional medicine trials were less likely to report the results than conventional medicine.

We have also conducted a pilot study on fibromyalgia participants who were offered group therapies and weekly one-to-one sessions of Ayurvedic lifestyle intervention and noticed a significant improvement in pain and quality of life. 

My next project will be around cancer, and we are still at the proposal stage.

Plants and fungi play a crucial role in both serious and non-serious health conditions. Because they are in their natural form, the human body is likely to adapt and respond to them more easily. It is very unfortunate that not enough scientific evidence is available to prove this point. While some does exist, definitely more is required. However, to give an idea, I can give an example of traditional medicine Ayurveda.

The 5000 year old classical textbook of Ayurveda talks about both curable and non-curable disease. From nausea and vomiting to cancer, you name the condition and you can find a co-relation in those books. In the management of every condition they talk about suitable herbs. The book even talks about emergency health conditions like poisoning. The number of trials conducted that demonostrate positive results regarding herbal efficacy during COVID-19 signifies that this area is worth exploring. So, I believe more robust scientific work is needed to validate the relevance of ancient wisdom in the modern world.

Coming from both backgrounds and while working with experts in research and experts in traditional or herbal medicine, I have noticed a disconnect between the experts in these two areas. A lack of comprehension between these two worlds has troubled me. There are only a few people who are or who choose to train in both the areas. I feel that basic training on both should be offered to see better results. However, this isn’t the biggest challenge, but a lack of funding.

Lack of funds in this area contributes to the majority of challenges. Neither it supports the ones who are already working in the system, nor tempting others who would join. Research in herbal medicine is majorly an individual interest and this approach according to me is not sustainable. 

The above challenge leads to another. I have talked to a few researchers in herbal medicine who stopped researching because they did not feel that their work attracted enough attention or appreciation. So, often they prefer to focus on their practice, which gives them more fulfilment. I believe most of the challenges can be faced if there comes a body which regulates the funds in this area as well.

As a practitioner, I feel lack of awareness is a challenge. However, it does not bother me since there are many who are aware and there are many who through their experience find a way to connect with this science. One thing that is not a challenge for me but for the client is finding the right practitioner. I have seen a few clients who almost lost their hope in herbal medicine before meeting me. I think more information should be given to the clients on how to choose the one who has the expertise to work with them.

The answer is both yes and no.

We know that the absence of evidence does not mean evidence of absence. So, I have seen both the segments. Ones who are intrigued by this area and wish to work to contribute in generating the evidence. While there are also some who are very much occupied by the conventional medicine parameters. They judge traditional medicine on the same parameter, which gives out a sense of bias.

According to me, different streams of medicines work on different modes of action. Hence, they should not be compared under the same parameters.

An integrative approach is the need of the hour. The concept has been introduced to us for quite some time. However, we are yet to see it flourishing in practice. Both conventional medicine and herbal medicine should work hand in hand. One can offer what the other requires. So, instead of fighting over evidence, more contribution is needed to work towards building the evidence.

I come from India, so herbs have been a chief part of our kitchen. It is very important to know the basic properties of the herbs you are using. This ancient kitchen wisdom has been transferred from generation to generation.

Unfortunately, there has been a gap or some misinformation in recent years in the name of modernisation, which have negatively interfered with regular household practices. Therefore, clearer information on the kitchen herbs or even herbs required for health conditions should be shared with the masses. Herbal Reality is already doing this good deed and I appreciate the work done in making this information accessible.

As a phytochemist, I work predominantly on the extraction, isolation and characterisation of natural bioactive compounds from plants. I use different methods of extraction to yield the highest possible quantities of biologically active (i.e. anti-oxidant, anti-inflammatory, antiproliferative) molecules.

In addition, I perform semi-synthetic synthesis reactions to functionalise the natural parent molecules in an attempt to increase their activity, such as introducing aromatic ring moieties.

Lastly, I carry out a series of biological assays to assess the novel derivatives’ bioactivity, for example, in cancer cell lines, and then prepare the hit molecules into nanoformulations to improve drug solubility and deliverability.

Natural compounds are structurally diverse and complex molecules, which means they can have multiple drug targets and an array of biological activities. This means that natural compounds and extracts can often have synergistic effects. In fact, around 70% of the worlds’ chemotherapeutic drugs are either based on a natural compound or a structurally similar analogue.

Nature provides scaffolds of these structurally complex molecules that have phenomenal activity in cancer cell lines and, in my opinion, were the backbone to chemotherapy research. We have also seen the importance and effectiveness of using natural products as an adjunct to standard chemotherapeutic drugs. So, it is of utmost importance that natural product research for cancer therapy continues. 

Natural product chemistry is certainly not always straightforward! Plants contain hundreds of molecules and extracting the one you want can be a complicated and time-consuming process, not to mention large quantities of solvents are usually required for the extraction and separating (chromatographic) processes.

In addition, for every kilo of dried plant material used, sometimes only a few grams (or even milligrams!) of the desired compound can be obtained, making the process arduous and tedious. 

Plants can definitely be misunderstood, perhaps because they have been less studied/explored with a scientific lens. However, I do believe the landscape is changing. I also believe that in a world that has been heavily influenced by industrialisation, herbal medicine can sometimes be viewed as an archaic and irrelevant practice.

I suppose some scientists believe that moving from natural drugs to synthetic pharmaceuticals is progress and that the only way is forward. But from what I see in the scientific community (at least in my small world!), many scientists are acknowledging the benefits of having both practices (herbal and pharma) as part of the medical system.

Herbal medicine has been (and continues to be in many developing countries) the primary healthcare system and foundation to medical care. The importance of herbal medicines to medicine is categorically and undeniably significant. In countries where allopathic medicine is too expensive or unavailable, herbal medicine is used and accepted by the population.

In addition to this, in more developed countries, a return to a more “natural” way of living has spiked the curiosity of the general population to enquire and use more herbal medicines, as they recognise the benefits of herbal medicines (including fewer adverse effects and synergistic properties) when compared to synthetic medicines.

As for the future, as long as we can safeguard and protect the natural fauna and flora of this planet, herbal medicines could provide the answers and solutions to many of the ailments of our current society.

Herbal medicines often have a better safety profile when compared to allopathic (that’s not to say that all natural products/plants are safe, since plants contain toxic compounds – it’s all about the dosage really!). However, this does mean that plants are fantastic to use against “everyday illness” such as common colds, flu and sore throat and, perhaps more importantly, herbal medicines are much more suitable for preventative healthcare, something that the allopathic medical system is not geared towards — modern medicine has been more focused on treatment rather than prevention.

The ethnopharmacology collection has been given a particular emphasis. One of the most pressing medical needs currently is to counteract antibiotic drug resistance. We have decided with this collection to gather plants which have both a long-term traditional use, and also modern history of scientific research in this area of medicine.

Although many are used in Chinese herbal medicine, the list includes plants from other herbal traditions. Some of the most important and hardy herbs are grouped together in a dedicated outside display bed and others are in other areas of the botanic garden. More tender herbs will be kept in the relevant zone of the greenhouse complex.

Anti-bacterial/parasitic/cancer herbs

• Reynoutria japonica (hu zhang)
• Phellodendron japonica (huang bai)
• Mahonia fortunei (gong lao mu)
• Berberis vulgaris (berberis)
• Rheum palmatum (da huang)
• Salvia officinalis (sage)
• Salvia rosmarinus (rosemary)
• Thymus vulgaris (thyme)
• Melaleuca alternifolia (tea tree)
• Tanacetum vulgare (feverfew)
• Glycyrrhiza glabra (gan cao)
• Artemisia annua (qing hao)
• Isatis tinctorium (da qing ye/ ban lan gen)
• Nigella sativa (nigella seed)
• Scutellaria baicalensis (huang qin)
• Dryopteris crassirhizoma (guang zhong)
• Reynoutria multiflora (he shou wu)
• Morus alba (sang ye, sang bai pi, sang zhi, sang shen)
• Zingiber officinale (sheng jiang)
• Cinnamomum vernum (cinnamon)
• Curcuma longa (jiang huang)
• Geranium strictipes
• Arctostaphylos uva ursi (bearberry)
• Andrographis paniculata (andrographis)
• Pelargonium sidoides
• Coptis chinensis (huang lian)

Immune tonics (adaptogens)

• Astragaulus propquuinqus (syn membranaceus ) (huang qi)
• Schisandra chinensis (wu wei zi)
• Panax quinquefolius (xi yang shen)

Interpretation of such a complex subject is a much bigger challenge than simply explaining Chinese medicine as in the case of the ‘use class’ display. It has to be easily explained by the garden tour guides and also needs to satisfy the requirements for a leading university for accurate statements based on scientific validation.

I have decided that the best approach is to isolate a few fundamental principles with examples. The background can then be enlarged through articles on the website which can be kept up to date with research papers when needed.

Around 40% of approved drugs during the last 30 years are derived from plants (4). Some studies have also indicated that of 122 plant derived drugs, 80% of their use in modern medicine was related to the same medical application used in the original traditional medicine (5).

Herb plants from China and the far east are one of the richest regions for drug prospectors today (2,7). China has over 30,000 species of plant, of which 3000 have been claimed to have specific traditional medicinal use. The process of finding and testing the chemicals is a long and expensive process and funding has reduced considerably in developing new drugs from natural materials (1). However, there are several which show potential to assist with drug resistance (1,3).

In 1967 the Vietnamese army asked China to assist with persistent malaria in the troops. Herbs were sourced from traditional herbal medical texts. These texts are known as the ‘Ben Cao’ and are a major resource as documented records of herbal use for over 2000 years (6,8).

They represent a long-term human clinical trial but without the control required by scientific RCT (random controlled trials). Traditional herbs which have been used for malaria symptoms were screened. The most effective was the herb Artemisia annua (qing hao) which first appeared in the Shen Nong Ben Cao written around 150AD. This led to the discovery of the drug artemisinin, as the main active anti-malarial component.

The sesquiterpene lactone (9,10,12) drug artemisinin has a unique and highly unstable structure due to the double bond trioxane group shown at the bottom of the molecule.

The effect of the trioxane bond is to oxidise iron to form toxic free radicals. The malaria parasite Plasmodium vivax survives by digesting the host’s haemoglobin. It is more sensitive to the free radicals than the human host cells and hence the parasite is killed, and the malaria halted. The drug also attacks in a second way at the same time to disrupt the DNA of the parasite. Artemisinin has also been found to kill the liver fluke parasite responsible for schistosomiasis which is second only to malaria as a parasitic killer in the tropics (16,17).

The effect on cancer cells is also interesting. Some cancer cells are also high in iron and are also damaged by the iron oxidising effects of artemisinin. Because artemisinin is so unstable, it proved very difficult and expensive to synthesise as a drug. New strains of Artemisia annua were cultivated with 20 times the content of artemisinin.

Genetically modified yeast has also been developed, which manufacture the drug, making it less dependent on the plant source (13). It is often forgotten that chemical synthesis of drugs is an important factor in the conservation of the original wild herb plants which would otherwise be over-exploited.

As this was a new method of attack compared to the quinine drug, artemisinin was able to provide an effective treatment for the problem of drug resistance which had developed with quinine drugs and had fewer side effects compared to piperaquine alone. Initially the mortality rate was 30% lower compared to treatment with quinine (14,15).

Artemisinin is a very fast acting drug with a half-life of 1 hour, hence it is best used with a slow release drug to combat the parasite and prevent resistance. WHO guidelines now state that it should not be used on its own for this reason (18). Despite its initial dramatic Artemisia annua effect, drug resistance to artemisinin is becoming apparent (20). Adaptation is occurring.

There is no doubt that concentrated artemisinin as a drug is a more powerful antimicrobial than the herb. Artemisinin as a drug however, is not exactly the same as Artemisia annua the herb.

Artemisia annua also contains many other chemicals including the anti-inflammatory scopoletin, which could explain its ability to reduce fever. One of these other chemicals is a methylated flavonoid which increases the action of the artemisinin, although it does not actually kill the parasite itself. Could these play a part in its action in preventing drug resistance to artemisinin?

A single herb plant has manufactured many chemicals which have evolved to enable growth and reproduction and to protect themselves from environmental stress. Plants have an immune system which can react within seconds to a predator to protect them from being eaten or resist disease pathogens such as virus or bacteria. As these pathogens have evolved new methods of attack, so the plant has manufactured new chemicals. But they also retain the old chemical defences creating a historical armoury and ability to act in several ways at the same time.

Bacteria and other pathogens that attack humans are not that different in structure than those that attack plants. They have similar cell walls and use similar methods to attack. Hence it is not surprising that they can also work for human pathogens.

One drug that has attracted research is the alkaloid berberine. This is a chemical found in many herbs used in most traditional medicine systems for treating infection and also the underlying inflammation. Examples include Phellodendron amurense, Coptis chinensis, Mahonia species, and Berberis species.

Isolated berberine alkaloids in pure form do have antimicrobial activity. When there are only a few bacteria they secrete a chemical that attracts other bacteria. However, when the bacterial colony reaches a certain size, they produce a different chemical which causes them to secrete a slimy biofilm over the entire bacterial colony.

This alteration in response to bacterial population numbers is known as quorum sensing. Berberine is thought to destroy the biofilm protection defences by the bacteria. Berberine can also weaken the bacterial cell wall and enter the bacteria causing more damage. The bacteria have evolved a mechanism known as an ‘efflux pump’ which literally pumps the berberine back out. As a counter strategy the plant produces another chemical (5 methoxyhydnocarpin) which inhibits the action of the efflux pump.

One of the reasons that penicillin was so effective for so long was that it contains two lines of attack on the pathogen. When we subject a pathogen to a single attack, it is relatively easy for it to evolve a response.

A simple attack promotes a simple evolutionary defence and drug resistance can develop more quickly. This may explain why plants have often developed diverse chemical strategies. These may include chemicals which can attack in more than one way, or a group of chemicals which can launch a complex attack or increase the action of each other.

The ability for a mixture of chemicals to have a greater effect than ether on its own is termed synergy. We can see this in all the examples given but I would suggest that synergy is central to the action of all herbs and it is what distinguishes the action of a drug from that of a herb.

Synergy has been observed where a herb or extracted chemical from a herb is given at the same time as an antibiotic drug which has ceased to become effective as in drug resistance. The combination can be more powerful than either the herb alone or the antibiotic (38-47).

The root of Scutellaria baicalensis (huang qin) is a traditional Chinese herb that has been used for at least 200 years as a herb in the damp heat class (6,7,8).

From a western perspective it has been employed for reducing fever, treating hepatitis and for infection in the lungs, bowel and bladder. The main active component has been isolated as the polyphenolic flavonoid drug baicalein. Phenolic compounds are often used as antimicrobial compounds (3).

Recently attention has been turned on the ability of baicalein to kill cancer cells. Drugs used in the treatment of cancer are also becoming less effective due to drug resistance by cancer cells (4-52). Baicalein as a drug has shown potent activity against pancreatic cancer cells, which are by nature fiercely resistant to cell death (21-24).

It also has few side effects which is a bonus when treating this disease. The mechanism of action on cancer cells is multi layered. In this case 3 mechanisms have been found. It appears to decrease the ability of the cancer cells to produce a protein which enables the cancer cell to evade cell death.

All cells, including cancer cells, have a programme which causes the cell to die. This is called apoptosis. Baicalein is causing this apoptosis programme to be triggered in the cancer cell. Finally, baicalein inhibits the fat metabolism pathway that enables proliferation of the cancer cells. In other words, this appears to be a highly sophisticated multi action weapon developed by the plant. Plants also suffer from cancer diseases.

Baicalein is also only 1 of 50 flavonoids in the plant which act more effectively if used together as opposed to a single drug extract (25-27). A whole extract of Scutellaria baicalensis has been demonstrated to resensitise drug resistant MRSA bacteria to become susceptible again to conventional antibiotic (26-31).

The use of complex whole herb extracts at the same time as a lower dose of strong antibiotic drugs is a novel approach to antibiotic resistance. Synergy research has become a new development in the pharmaceutical industry so we may see a new approach developing in the future (38,39,40).

All the above examples are focused on killing parasites. This is a natural way of approaching the problem. The battle between pathogens and host is as old as cellular life evolved and drug resistance is not a new event. The creation of concentrated antibiotics drugs has been a true life saver and the search for new antibiotic drugs with new strategies of attack will continue as it has done in plants.

However, if a person is weak then it is just as important to regulate the host immune system.

Herbal medicine does not have the same power to deal with acute infection, but it does have a potential role in long-term balancing of the immune system. Within the Chinese materia medica there are herbs which are traditionally used to strengthen the immune system.

One key herb is Astragalus propinquus (huang qi). Over 100 chemicals have been isolated from this herb including polysaccharides, flavonoids and saponins (7). Most attention with respect to immunity has centered on the effects of the saponins which are steroidal in form.

Unbalanced immunity can be deficient leading to a lack of response. However, it can also be excessive causing allergies, autoimmune diseases or chronic inflammation. The pharmacology of Astragalus has yet to be studied in any real detail but there is some evidence that in vitro, these saponins promote B cell proliferation and antibody production.

Whilst it may appear that Astragalus does have some components in the form of steroidal saponins, which have effects similar to or are synergistic with the drug interferon (7) which triggers immune responses, as a whole herb it has demonstrated an ability to control chronic bowel inflammation from an overactive immune response (54,55).

Astragalus membranaceus belongs to a class of herbs which are considered to be adaptogenic. This means they have the ability to help the body adapt to stress, which includes attack by a pathogen.

The action of adaptogens is complex but thought to work in general through the hormone mechanism by regulation of cortisone and adrenal function (53).

Plants also have a well developed hormonal system, and the structure of hormones across plants, insects and man is similar. It is interesting to note that the chemistry of these steroidal compounds in astragalus, which is in the plant family of Fabaceae, are similar to other key adaptogenic herbs in an unrelated family. Panax ginseng (ren shen) and Eleutherococcus gracilistylus (wu jia pi) in Araliaceae also contain steroidal based glycosides.

Panax ginseng (ren shen) has been studied in more depth and it appears that there are 2 main groups of steroidal glycosides at work. The first are the triol gingenosides (Rg1) which stimulate the body and the other are the diol gingenosides (Rb1) which are sedating and calming.

The action of these on the body is considered to be via the hypothalamus and adrenal glands (56). Contradictory actions within a single herb are not uncommon and this may be how they can regulate. This is also seen in sugar regulation where the whole extract of Panax will reduce blood sugar levels in hyperglycaemia but raise it in hypoglycaemia. They are more homeostatic in action than simply synergistic.

What can we gain from this type of analysis? With the combined knowledge of traditional herbal experience and modern scientific precision we can learn from plants which have been working on the problem of drug resistance for millions of years longer than humans.

More insight on TCM and the gardens in Bristol are shared on the RCHM youtube channel.

General references

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31. Fujita M, Shiota S, Kuroda T et al. Remarkable Synergies between Baicalein and Tetracycline, and Baicalein and β-Lactams against Methicillin-ResistantStaphylococcus aureus. Microbiol Immunol. 2005;49(4):391-396. doi:10.1111/j.1348-0421.2005.tb03732.x
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35. Stermitz F, Lorenz P, Tawara J, Zenewicz L, Lewis K. Synergy in a medicinal plant: Antimicrobial action of berberine potentiated by 5′-methoxyhydnocarpin, a multidrug pump inhibitor. Proceedings of the National Academy of Sciences. 2000;97(4):1433-1437. doi:10.1073/pnas.030540597
36. Stermitz F, Beeson T, Mueller P, Hsiang J, Lewis K. Staphylococcus aureus MDR efflux pump inhibitors from a Berberis and a Mahonia (sensu strictu) species. Biochem Syst Ecol. 2001;29(8):793-798. doi:10.1016/s0305-1978(01)00025-4
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41. Yang Z, Wang B, Yang X, Wang Q, Ran L. The synergistic activity of antibiotics combined with eight traditional Chinese medicines against two different strains of Staphylococcus aureus. Colloids and Surfaces B: Biointerfaces. 2005;41(2-3):79-81. doi:10.1016/j.colsurfb.2004.10.033
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The two main benefits of researching herbs and herbal medicine are to gain greater understanding of what, how and why something works, and to provide evidence that reassures other healthcare professionals and members of the public of the safety and efficacy of herbs. Gaining wider recognition and understanding of the power of herbs and herbal practice requires us to be able to connect the current scientific environment with what we know from traditional medicine. Choosing the best ways to research herbs, however, can be a challenge.

There are problems with the current methods of research in biomedicine, and not just for herbs. The tools currently used to support evidence-based medicine were designed to investigate the efficacy of single compounds and the research field assumed that there were such things as magic bullets for every disease.

Clinical trial methods that were developed to measure the effects from single compounds will always be lacking as a method to investigate the complex and subtle effects of plants, or indeed, the effect of any medicine in a complex human interacting with a complex world.

A clinical trial can tell you how a specific intervention might impact a population on average, but won’t necessarily have much to say about how a herbal consultation will impact on an individual.

There are encouraging examples of studies that have compared personalised treatment from a herbalist with control groups for conditions such as menopause, osteoarthritis, urinary tract infections and upper respiratory tract infections (1,2,3,4). In the majority of these studies, herbal practitioners were involved in the design or execution of the research. Historically, doctors have been involved in research into what works in their clinics, so perhaps this is something that herbalists should be considering.

Some practitioners or supporters of herbal medicine argue that viewing it via the biomedical lens is inappropriate or detracts from its meaning and that the traditional use of herbs over hundreds of years provides adequate evidence to justify their efficacy and safety. There will always be value in traditional and empirical knowledge that can’t be “proved” by modern science. However, there are benefits from research that go beyond simply confirming what we think we already know.

Research can help us to confirm our instincts about how traditionally used herbs might be beneficial for modern diseases. We can extrapolate from our deep understanding of historical use and the characteristics of herbs to see how they might be beneficial for these more modern health problems. Research can confirm our suspicions about how certain herbs might be working.

Obesity and metabolic disorders are more of a problem now than a few hundred years ago and cinnamon is proving to be a valuable herb for addressing this (5,6). But, when we look to traditional knowledge, this is a relatively modern use. Many older herbals only mention cinnamon with reference to its use as a flavouring. Mary Seacole discusses using it to treat cholera in her autobiography of 1857 (7), and in 1931, M Grieve listed the uses of cinnamon as a carminative, astringent, stimulant and antiseptic for vomiting and diarrhoea (8).

It is only in more modern times that its use to help regulate blood sugar levels has been documented. Since one of the first clinical studies looking at benefits of cinnamon for those with diabetes was published in 2003 (9), the majority of research now published about cinnamon focuses on this pressing area of importance. The stories of how plants are used evolves as human culture does. Traditional medicine is not static and should be reinventing itself as the world around us changes.

Science research is a reflection of the important questions that society has. Scientists do not work in a vacuum, but get ideas about what to research from the world they see around themselves, as well as the people who will fund their work.

Greater numbers of people researching the benefits of herbal medicine or simply the benefits of herbs and other plants reflects an increase in the feeling that nature got it right. Herbal medicine is associated with nature and gentleness – two values that many of those who seek to use it are aligned with.

The way that herbalism is practised, with a focus on empowerment and the responsibility of our clients to be aware of nutrition, lifestyle and how they can best manage their own health would certainly benefit modern healthcare systems that involve minimal contact time with a physician and pill prescriptions rather than advice.

As research into herbal medicine grows and those who appreciate the benefits of herbalism are involved more in academic fields, knowledge can be transferred both ways.

Herbalists are the best people to demonstrate the power of herbs, so we need to be involved in the scientific process that society has to investigate the world and add to knowledge.

The way that science is communicated is changing. The internet means that everyone can easily access the latest research findings, or discuss them in online forums with others. You can have an opinion on science whether you are a scientist or not. This will also have an impact on what science is carried out.

Whether a research paper gets traction on social media is now a factor in how much it is cited and can have a positive impact on which areas get attention and funding. The popularity of herbal medicine with large sections of society will increase the likelihood that herbal research is interesting enough to be invested in.

Confidence in an area of science develops as a result of coherent approaches to research questions, standardised methods and consistent, reproducible results.

The various approaches to herbal science by researchers from many different disciplines means that consensus has been harder to come by, but this is improving. For acceptance of herbal medicine by practitioners of modern biomedicine, an evidence base built on randomised clinical trials is needed. The World Health Organization has published guidance for clinical evaluation of herbal medicines, which is a good start (10).

The key factor needed for more well-designed research studies into how society can benefit most from herbs is funding. Without the money and power of the pharmaceutical industry, research carried out by herbalists working within universities or studies by companies who sell herbal products and have an interest in the field has been the main driver. Organisations, universities and private companies funding relevant and well-designed research is welcome and necessary, but for maximum impact, collaborations of researchers and herbalists working together will help this exciting, developing field of research.

1. Green J, Denham A, Ingram J, Hawkey S, Greenwood R. Treatment of menopausal symptoms by qualified herbal practitioners: a prospective, randomized controlled trial. Fam Pract. 2007 Oct;24(5):468-74.
2. Hamblin L, Laird A, Parkes E, Walker AF. Improved arthritic knee health in a pilot RCT of phytotherapy. J R Soc Promot Health. 2008 Sep;128(5):255-62.
3. Flower A, Harman K, Lewith G, Moore M, Bishop FL, Stuart B, Lampert N. Standardised Chinese herbal treatment delivered by GPs compared with individualised treatment administered by practitioners of Chinese herbal medicine for women with recurrent urinary tract infections (RUTI): study protocol for a randomised controlled trial. Trials. 2016 Jul 27;17:358.
4. Wong W, Lam CL, Fong DY. Treatment effectiveness of two Chinese herbal medicine formulae in upper respiratory tract infections–a randomized double-blind placebo-controlled trial. Fam Pract. 2012 Dec;29(6):643-52.
5. Mousavi SM, Rahmani J, Kord-Varkaneh H, Sheikhi A, Larijani B, Esmaillzadeh A. Cinnamon supplementation positively affects obesity: A systematic review and dose-response meta-analysis of randomized controlled trials. Clin Nutr. 2020 Jan;39(1):123-133.
6. Davis PA, Yokoyama W. Cinnamon intake lowers fasting blood glucose: meta-analysis. J Med Food. 2011 Sep;14(9):884-9.
7. Seacole M. Wonderful Adventures of Mrs Seacole in Many Lands. 1857. James Blackwood.
8. Grieve M. A Modern Herbal. 1978. Peregrine Books. Middlesex; England. P.202.
9. Khan A, Safdar M, Ali Khan MM, Khattak KN, Anderson RA. Cinnamon improves glucose and lipids of people with type 2 diabetes. Diabetes Care. 2003 Dec;26(12):3215-8.
10. World Health Organization. General Guidelines for Methodologies on Research and Evaluation of Traditional Medicine. Geneva: World Health Organization; 2000. WHO/EDM/TRM/2000.1.

Over the course of my field work, aiming to observe the harvesting of medicinal plants at the “right times” for production of pharmacopoeial quality herbs, done in the “right ways” for sustainable resource management and trade, I can state that, in recent decades, predictability of harvest periods has become uncertain in some regions of the world. In some locations there has been notable fluctuation from year-to-year.

Anecdotally, plant harvesters have shared their observations of the changing climate, uncertainties of harvest times and yields, as these factors directly impact livelihoods and rural economies.

I have also observed some impacts of extreme weather on herb quality (e.g., stunted growth, lower yield, lower essential oil content) but also on the ability to even harvest herbs in some years due to, for example, torrential rains, flash flooding, and landslides (or conversely no monsoon at all). Changing or fluctuating growing seasons can also impact whether, or not, there will be sufficient labor available at harvest time.

In rural communities, where some villagers make some – or all – of their household income harvesting medicinal plants for trade, different herbs or mushrooms are targeted for harvesting in different months based on traditional ecological knowledge (TEK). Labor was traditionally organized accordingly. Climatic unpredictability may be impacting such TEK.

But these statements come only from my experiences and observations. The accumulated analyses of competent researchers worldwide are contributing to a growing body of scientific literature, that carries with it, I believe, urgency.

While shifting flowering and fruiting phenology (1,2), and altered phenological synchrony between plants and pollinators (3), is observable, measurable, and documented, less is known about changes that may be occurring in the composition and content of phytochemicals, so-called secondary metabolites, and phytonutrients where much of the medicinal properties lie (4,5,6).

Mismatches between plant and pollinator populations may lead to extinction of a plant species and/or its pollinator (7), especially in ecoregions of high endemism.

Plants are either adapting to changing weather patterns, and to the narrowing of suitable habitat, and/or are migrating to more suitable habitat areas (8). Or, if unable to adapt or migrate rapidly enough, some species may face a threat of extinction (9).

Endemic plants with a limited geographic distribution may be the most vulnerable (7). However, in their recent paper on endemism hotspots, Harrison and Noss (2017) concluded “Current knowledge suggests that centres of endemism will remain relatively climatically buffered in the future, with the important caveat that absolute levels of climatic change and species losses in these regions may still be large.”(10)

To inform species conservation strategies as well as the development of suitable agro-techniques for the successful cultivation of threatened wild medicinal plants, of a reproducible therapeutic quality, research on habitat range and secondary metabolites production under different climate models is still in its infancy.” (7,11) Not enough is known, yet.

Abiotic plant stresses such as elevated atmospheric carbon dioxide (CO₂), temperature and precipitation extremes, and changes in ultraviolet radiation exposure, among others, impact  phenology, physiology, and phytochemistry, which, in turn, could also impact a plant’s chemical defences against biotic stresses such as attacks by pathogens and insect herbivores (12).

Changes in phytochemical composition whether due to abiotic or biotic stressors, or both, could also have relevant implications for coevolutionary plant and pollinator interactions (13).

And it is not only insect herbivores. Arboreal folivores, such as the native Australian koala bear (up-listed from ‘vulnerable’ to an ‘endangered’ species in February 2022) (14), coevolved with eucalyptus trees, having a specialist diet, limited mainly to eucalyptus leaves (15).

Due to increasingly frequent extreme heatwaves and droughts, the koala may not be able to rely on eucalyptus leaf moisture for hydration, and, in the future, may need supplemental sources of water for survival (16). The leaves and distilled essential oil of the leaves and terminal branchlets harvested from Eucalyptus globulus trees, endemic to Victoria and Tasmania, Australia (17), are used in traditional medicines (18).¹⁸ Changes in a medicinal plant’s content and composition, if significant, “could” also impact posology and pharmacological action(s) (19).

Ghazghazi et al (2022), in their recent study on the effect of drought stress on physio-biochemical traits and secondary metabolites production in Pinus halepensis, the leaves of which are used in traditional medicines of the Mediterranean region state: “The capability of plants to respond to abiotic stress is associated with their plasticity as well as the adaptableness of plant traits to fluctuating bioclimatic conditions.”(20) According to the VILLUM Research Center for Plant Plasticity:

“Plant plasticity refers to a plant’s ability to adapt to and cope with changes in its environment. In contrast to animals, which are able to actively move away to avoid challenges such as predators or a changing climate, plants have acquired the ability to biosynthesize an unprecedented array of structurally complex bioactive natural compounds with specialized roles in order to cope with environmental challenges.” (21)

In a systematic review of papers published from 2015 to 2020, that analyzed climate change impacts on secondary metabolite production and accumulation in medicinal plants, Pant et al (2021) reported that impacts from environmental factors such as changes in temperature, elevated CO₂, elevated ozone, UV light, and drought were not only species-specific but different variables were associated with adverse impacts on plant growth and yield, as well as significant increases or decreases in secondary metabolite content (22).

Most of the following examples from the current literature concern medicinal plants used in China. This is not an intentional focus on traditional Chinese medicine (TCM), but rather an observation that much of the published climate change scenario research involving medicinal plants, that I have seen or have paid attention to, is focused on habitat suitability and quality of herbal drugs used in TCM. That is not to say that similar research is not being carried out involving medicinal plants of other regions – it is.

Using MaxEnt (maximum entropy) modelling, Zhan et al (2022) evaluated and predicted the distribution area of Panax notoginseng (san qi) under future climate scenarios, as well as the relationship between total saponins content (about 90% are ginsenosides) and habitat suitability.

They predict a gradual decrease in suitable habitat area with migration towards high-altitude areas of central-eastern Yunnan province, and decreased ginsenoside content in future highly suitable habitat areas for this species (8).

Also using MaxEnt ecological niche modeling, Shi et al (2022) predict a sharp decline in suitable habitat for Meconopsis punicea (hong hua lü rong hao) by 2050, with a likely upward migration to inhabit a narrower elevational range in the Qinghai-Tibet Plateau.

Other studies found the luteolin content of a related species Meconopsis quintuplinervia (wu mai lü rong hao) to be significantly impacted by changes in altitude. While these researchers predict that the secondary metabolites content will change as the distribution area shrinks and changes in altitude in the coming decade, no specific predictions in content levels or impacts on therapeutic use are made (23).

In a similar study on Gentiana rigescens (dian long dan), Shen et al (2021) predict that current highly suitable habitats in southwest China will turn into lowly suitable habitats or unsuitable habitat for this species. In their 2050 and 2070 models, migration to high elevations is predicted with an increased accumulation of bioactive constituents, i.e., iridoids including loganic acid, swertiamarin, and sweroside, showing a correlation between altitude and iridoid concentration (24).

Using ArcGIS (geographic information system mapping software) with MaxEnt, Yan et al (2020) predict that, by the 2050s, the unsuitable habitat areas for Gentiana macrophylla (qin jiao) in China would increase by 11.92% under the moderate greenhouse gas emissions/climate scenario, concurrently with significant losses of suitable habitat. Furthermore, an accelerated speed of fragmentation of most of the suitable habitat area for this species is predicted, threatening reproduction and long-term survival (25).

Using fuzzy theory and a MaxEnt model, Guo et al (2016) predicted the future distribution range of Schisandra sphenanthera (nan wu wei zi) in the Qinling mountains, under three different climate change scenarios, for the periods 2020s, 2050s and 2080s, as well as determining any associations with synthesis and accumulation of schisantherin A in the fruits with various climatic variables.

The Pharmacopoeia of the People’s Republic of China requires that dried S. sphenanthera fruits contain not less than 0.20% schisantherin A, while the Hong Kong Chinese Materia Medica Standards require that the dried fruits contain not less than 0.67% of the total content of schisandrin A and schisantherin A.

This study predicted that under the three future climate scenarios, the habitats of pharmacopoeial quality S. sphenanthera fruits will continue to decrease towards near extinction; suggesting that, at least in this specific study area in the Qinling mountains, highly suitable habitat areas for S. sphenanthera may disappear if the annual mean temperature begins to exceed 20 ºC and/or if the annual precipitation level should exceed 1,200 mm (26).

For some species, the suitable habitat area may expand with climate change. That is the case, according to Wang et al (2022) for Artemisia annua (qing hao), used in TCM but also the only plant source of the antimalarial drug substance artemisinin. In this study, the future suitable habitat for A. annua is projected to expand inland, perhaps significantly, although the effects of increasing temperatures differ in different time periods.

However, the authors raise uncertainty as to whether the expansion of A. annua habitat area will be beneficial, or not, to its medicinal value in terms of the content and yield of artemisinin secondary metabolites. For this reason, these researchers suggest implementing a system of protecting genetic resource reserves and experimental cultivation bases within the geographic origin areas of the species, particularly areas where the wild populations possess higher artemisinin content such as Sichuan, Guangxi, Guizhou, and Yunnan (27).

In traditional herbal medicine, safe and effective formulation and dosage can be based, in part, on accumulated knowledge, stemming from the clinical observations of many generations of practitioners, often monographed in the pharmacopoeias and formularies of the codified systems of traditional medicine.

Traditional pharmacopoeias generally describe the identification, composition, properties, and quality of each herbal drug based on an assessment of representative materials that have been observed to be effective for their intended traditional uses. In this way, traditional medicine is informed by local or traditional ecological knowledge (TEK) and traditional medical knowledge (TMK).

If, by the year 2050, or the year 2070, or the year 2100 (young herbalists reading this should still be around!), certain medicinal herbs have adapted or migrated and survived the predicted changes – but, in doing so, their composition and content have significantly changed, by comparison to their ancestors described in the traditional medicine literature, TEK and TMK will also necessarily evolve.

Traditional medicine is not stagnant, not stuck in time. It is reasonable to predict that medical herbalists will continue to be keen observers of nature and adjust formulations and dosage, if need be, in response to the changing environment, changes in herbal drug content, and patient response to herbal drug preparations.

Scientists have developed elaborate climate models, indeed useful to help predict changes in suitable habitat areas, and whether the plants and pollinators can or will migrate together, in time to survive, and whether different plants will respond differently in terms of secondary metabolite production.

Increasing uncertainty of continued access to certain medicinal plants, of traditional origins and qualities, may, however, cause the practice of herbal medicine to also adapt and change.

The full extent of impacts of the climate crisis on availability and quality of medicinal plants in general cannot be known at this point. Assumptions and variables, from any region, that could exhibit a global impact on climate predictions, are adjusted each time new data is published.

For example, while a study published in January 2019, in the journal Proceedings of the National Academy of Sciences, showed that Greenland’s ice was melting far more rapidly than scientists previously thought, (28) in February 2022, University of Cambridge scientists subsequently reported an unprecedented melt rate of the Greenland Ice Sheet that would change sea level rise projections, AGAIN (29). What happens in Greenland, doesn’t stay in Greenland.

1. Kharouba HM, Ehrlén J, Gelman A, et al. Global shifts in the phenological synchrony of species interactions over recent decades. Proc Natl Acad Sci U S A. 2018;115(20):5211-5216. doi:10.1073/pnas.1714511115
2. Vâtcă S, Gâdea S, Vâtcă A, Stoian V. Research trends in ecophysiology of medicinal plants. Hop and Medicinal Plants. 2020;28(1-2):178-188.
3. Wang C, Tang Y, Chen J. Plant phenological synchrony increases under rapid within-spring warming. Scientific Reports. 2016;6. doi:10.1038/srep25460
4. AbdElgawad H, Peshev D, Zinta G, van den Ende W, Janssens IA, Asard H. Climate extreme effects on the chemical composition of temperate grassland species under ambient and elevated CO2: A comparison of fructan and non-fructan accumulators. PLoS ONE. 2014;9(3). doi:10.1371/journal.pone.0092044
5. Zhang C, Yang D, Liang Z, et al. Climatic factors control the geospatial distribution of active ingredients in Salvia miltiorrhiza Bunge in China. Scientific Reports. 2019;9(1). doi:10.1038/s41598-018-36729-x
6. Gairola S, Mohd Shariff N, Bhatt A, Prakash Kala C. Influence of climate change on production of secondary chemicals in high altitude medicinal plants: Issues needs immediate attention. Journal of Medicinal Plants Research. 2010;4(18):1825-1829. doi:10.5897/JMPR10.354
7. Guru A, Saha P, Kumar V, Hidangmayum A, Dwivedi P. Medicinal Plants in India: Impact on Biodiversity, Pharmaceutical Industries and Production Chain Due to Climate Change. In: Arya A, Patel VS, Agrawal M, Murthy CN, Bhatt B, Padate G, eds. Environmental Pollution, Climate Change and Altered Lifestyle during COVID. Daya Publishing House; 2022.
8. Zhan P, Wang F, Xia P, et al. Assessment of suitable cultivation region for Panax notoginseng under different climatic conditions using MaxEnt model and high-performance liquid chromatography in China. Industrial Crops and Products. 2022;176. doi:10.1016/j.indcrop.2021.114416
9. Kougioumoutzis K, Papanikolaou A, Kokkoris IP, Strid A, Dimopoulos P, Panitsa M. Climate change impacts and extinction risk assessment of Nepeta representatives (Lamiaceae) in Greece. Sustainability. 2022;14(7):4269. doi:10.3390/su14074269
10. Harrison S, Noss R. Endemism hotspots are linked to stable climatic refugia. Annals of Botany. 2017;119(2):207-214. doi:10.1093/aob/mcw248
11. Harish BS, Dandin SB, Umesha K, Pallavi HM. Impact of Climate Change on Medicinal Plants – A Review.  5th World Ayurveda Congress 2012, Bhopal, Madhya Pradesh, India. 7-10 Dec 2012.
12. Bidart-Bouzat MG, Imeh-Nathaniel A. Global change effects on plant chemical defenses against insect herbivores. Journal of Integrative Plant Biology. 2008;50(11):1339-1354. doi:10.1111/j.1744-7909.2008.00751.x
13. Jamieson MA, Burkle LA, Manson JS, Runyon JB, Trowbridge AM, Zientek J. Global change effects on plant–insect interactions: the role of phytochemistry. Current Opinion in Insect Science. 2017;23:70-80. doi:10.1016/j.cois.2017.07.009
14. Department of Agriculture Water and the Environment. Increased protection for koalas. The Hon Sussan Ley MP Minister for the Environment Media Releases. Published online February 11, 2022.
15. Reckless HJ, Murray M, Crowther MS. A review of climatic change as a determinant of the viability of koala populations. Wildlife Research. 2017;44(6-7):458-470. doi:10.1071/WR16163
16. Mella VSA, McArthur C, Krockenberger MB, Frend R, Crowther MS. Needing a drink: Rainfall and temperature drive the use of free water by a threatened arboreal folivore. PLoS ONE. 2019;14(5). doi:10.1371/journal.pone.0216964
17. Fensham R, Collingwood T, Laffineur B. Eucalyptus globulus. The IUCN Red List of Threatened Species 2019 eT61912929A61912931. Published online 2019.
18. Committee on Herbal Medicinal Products (HMPC). Community Herbal Monograph on Eucalyptus globulus Labill., Folium. European Medicines Agency; 2013.
19. Applequist WL, Brinckmann JA, Cunningham AB, et al. Scientists warning on climate change and medicinal plants. Planta Medica. 2020;86(1). doi:10.1055/a-1041-3406
20. Ghazghazi H, Riahi L, Yangui I, Messaoud C, Rzigui T, Nasr Z. Effect of drought stress on physio-biochemical traits and secondary metabolites production in the woody species Pinus halepensis Mill. at a juvenile development stage. Journal of Sustainable Forestry. Published online 2022. doi:10.1080/10549811.2022.2048263
21. VILLUM Research Center for Plant Plasticity. What is Plant Plasticity? University of Copenhagen, https://plantplasticity.ku.dk/what_is_sb/.
22. Pant P, Pandey S, Dall’Acqua S. The influence of environmental conditions on secondary metabolites in medicinal plants: A literature review. Chemistry and Biodiversity. 2021;18(11). doi:10.1002/cbdv.202100345
23. Shi N, Naudiyal N, Wang J, et al. Assessing the impact of climate change on potential distribution of Meconopsis punicea and Its influence on ecosystem services supply in the southeastern margin of Qinghai-Tibet Plateau. Frontiers in Plant Science. 2022;12. doi:10.3389/fpls.2021.830119
24. Shen T, Yu H, Wang YZ. Assessing the impacts of climate change and habitat suitability on the distribution and quality of medicinal plant using multiple information integration: Take Gentiana rigescens as an example. Ecological Indicators. 2021;123. doi:10.1016/j.ecolind.2021.107376
25. Yan H, He J, Zhao Y, Zhang L, Zhu C, Wu D. Gentiana macrophylla response to climate change and vulnerability evaluation in China. Global Ecology and Conservation. 2020;22. doi:10.1016/j.gecco.2020.e00948
26. Guo Y, Wei H, Lu C, Gao B, Gu W. Predictions of potential geographical distribution and quality of Schisandra sphenanthera under climate change. PeerJ. 2016;2016(10). doi:10.7717/peerj.2554
27. Wang D, Shi C, Alamgir K, et al. Global assessment of the distribution and conservation status of a key medicinal plant (Artemisia annua L.): The roles of climate and anthropogenic activities. Science of the Total Environment. 2022;821. doi:10.1016/j.scitotenv.2022.153378
28. Bevis M, Harig C, Khan SA, et al. Accelerating changes in ice mass within Greenland, and the ice sheet’s sensitivity to atmospheric forcing. Proc Natl Acad Sci U S A. 2019;116(6):1934-1939. doi:10.1073/pnas.1806562116
29. Brackley P. ‘Unprecedented’ melt rate at Greenland Ice Sheet found by University of Cambridge scientists could change sea level rise projections. Cambridge Independent. Published online February 25, 2022.

It was once thought that the brain and central nervous system (CNS) were largely protected by the ‘blood-brain barrier’ from immunological, inflammatory and infective processes in the wider body, and indeed from many medicines and plant constituents. This view now needs to be amended.

Systemic inflammation or immune disease can disrupt this barrier, to provoke inflammatory processes within the CNS, with secondary complications there including protein aggregations, oxidative stress and disturbed mitochondrial function.

This ‘neuroinflammation’ is now understood as the major factor in neurodegenerative diseases like Alzheimer’s, Parkinson’s, ALS and multiple sclerosis (1,2). It is also seen as contributing to mental diseases such as schizophrenia, clinical depression and bipolar disorder, (3) and increasingly to so far unexplained conditions like post-viral syndromes (including long Covid (4,5)) ME and other chronic fatigue syndromes (6) and fibromyalgia (7).

The prospect of finding remedies that could modulate such inflammatory processes is only just emerging from the laboratory, with all the attendant caveats, and there are few human studies yet published. However the weight of evidence for plant interventions has been building, (8,9,10) to such an extent now that there is a huge incentive for herbal practitioners and nutritional therapists to develop new approaches to the management of some of the most pressing problems of modern times (11).

Before we look at some of these prospects, it will be important to explore some of the mechanisms that are emerging as central to these conditions. They are changing much of what we learnt in school! There is a wide range of accessible scientific papers cited for further reading.

Neuroinflammation is the subject of increasing academic, medical and psychiatric attention (12). It is defined as an inflammatory response within the brain or spinal cord. Like other inflammation it is initially beneficial, removing harmful metabolites, inhibiting pathogens and promoting repair, but if persistent can lead to neurodegeneration(13).

Key agents of this response include resident support cells (the ‘glia’: microglia and macroglia), endothelial cells at the blood-brain barrier, and immune cells migrating from the rest of the body.

These cells can be ‘activated’ to generate a raft of inflammatory agents such as IL-1β (strongly associated with major depressive disorders as well as fatigue [14]), IL-6, IL-8, IL-33, TNF-α, CCL2, MMPs, substance P, reactive oxygen species, histamine and proteases, PAR-2, and NF-kB (15).

In a process referred to as ‘immunoexcitotoxicity’ these inflammatory agents can in turn excite glutamate receptors to increase reactive oxygen species/reactive nitrogen species, lipid peroxidation products, and prostaglandin activation, which then leads to dendritic retraction, synaptic injury, damage to microtubules, and mitochondrial suppression (16).

Increasing evidence indicates that it is mitochondrial dysfunction, involving alterations in mitochondrial respiratory enzyme activities, oxidative stress, disrupted cell wall permeabilty, and enhanced apoptosis, that plays a particularly significant role in neuropathophysiological processes  (17).

A key mechanism in preventing neuroinflammatory damage has emerged. There is increasing data on the pivotal role of one of the most powerful innate antioxidant mechanisms in the cell, Nrf2 (nuclear factor erythroid 2 related factor 2), against inflammatory processes in neurodegenerative disorders. 

The ‘Nrf2/ARE’ (Nrf2 bound to an antioxidant responsive element) signalling pathway has shown upregulation of antioxidant genes, inhibition of microglia-mediated inflammation, and improved mitochondrial function in neurodegenerative diseases (18). As will be seen below, polyphenols and other plant constituents are likely to protect against neurodegeneration through Nrf2 activation (19).

Microglia are the main neuroinflammatory agents. They are the primary immune cells throughout the brain and CNS and comprise between 5-15% of the central nervous tissue population. Core functions include

• primary immune surveillance and other monitoring of the CNS environment;
• physiological housekeeping e.g migrating to injured sites, remodelling synapses, and maintaining myelin homeostasis; (20)
• macrophage-like protection against injurious stimuli such as pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), including with the production of inflammatory cytokines and chemokines.

Microglia develop in the embryo as a variety of macrophage, but then migrate to the emerging nervous system (which they help to shape [21]) and thereafter their turnover appears to be wholly within the CNS. Turnover rates are low and this could account to susceptibility to the effects of age, (22) injury or stress (22).

Note that microglia are not to be confused with ‘macroglia’, notably astrocyctes, large star-shaped cells originating alongside neurons from neuroblastic tissue, and with complex supporting roles, including having profuse interactions with neuronal dendrites and synapses (perhaps millions per astrocyte).

Astrocytes themselves however can become excited by activated microglia (via TNF-α-mediated increase in ATP secretion or activation with toll-like receptor (TLR) ligands (24)) and in turn can stimulate greater neurotransmitter activity. This observation is significant because pathological activation of microglia and alteration of neurotransmission are both early symptoms of most brain diseases.

Microglia vary considerably in their responses, with initial differentiation between ‘good’ and ‘bad’ types (26) now elaborated by the awareness that many different phenotypes and behaviours are present (27,28), complicating therapeutic interventions like anti-inflammatory drugs (29).

In health the relationship between neurons and microglia is mutually positive: healthy neurons produce calming agents, eg fractalkine, that prevent inappropriate microglial activation (30), while inactivated microglia generate neurotrophic agents such as brain-derived neurotrophic factor (BDNF) that are important for example in recovery from ischaemic stroke (31). The interactions are also dynamic and intimate. Microglial responses depend closely on neuronal activity (32) and include ‘pruning’ or ‘stripping’ of superfluous or dysfunctional synapses (33).

However following injury or disruption, especially with the inflammatory elements noted above, the resting spider-shaped microglia responsible for surveillance change to the amoeboid appearance associated with their activated state, and kick off production of interleukins and other cytokines, as well as a cascade of astrocytic activations.

Allowing for the complexities in microglial phenotypes referred to earlier there is no doubt that there is a polarisation of microglial activation

1. to an M1 phenotype by exposure to inflammatory lipopolysaccharides (LPS) or IFN-γ, leading to the expression of pro-inflammatory cytokines notably IL-1β , or
2. to an M2 phenotype following exposure to IL-4/IL-13, for resolution of inflammation and tissue repair mediated by TGF-β, IL-4 or IL-10. (34)

Factors that lead to M1-activation of microglia are likely to be central to neuroinflammatory disease. On the other hand therapeutic strategies that could favour M2 anti-inflammatory activation of microglia hold much therapeutic promise (35).

The blood-brain barrier (BBB) is a highly specialized physical and biochemical barrier that separates the CNS from the peripheral circulation and is critical in maintaining its microenvironment. BBB disruption is implicated in a wide range of CNS pathologies including stroke, Alzheimer’s, multiple sclerosis, Parkinson’s and epilepsy.

Normal BBB protection is accomplished by specialized endothelial features:

1. Tight junction protein complexes lock adjacent endothelial cell cytoskeletons with transmembrane proteins such as claudins, occludin, tricellulin and junctional adhesion molecules (JAMs).
2. CNS endothelial cells express primary active transporters such as P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and multidrug resistance proteins (MRPs) that restrict the ability of many substances to access brain parenchyma (36).
3.  Disturbance in at least one of these transporters (P-gp) is often implicated in neuroinflammatory conditions (37). However, as this is expressed on the luminal surface of the cerebral blood vessels it provides an opportunity for blood-borne agents to affect BBB performance. St John’s wort has been suggested as having a benefit at this mechanism (38).

A key to understanding the BBB is to appreciate that it needs to be dynamic and adaptable to circumstances. There is a circulatory imperative: the brain requires constant high levels of glucose and oxygen as it has no stores itself. This requires that the brain microvasculature rapidly responds to environmental changes to match blood flow to brain metabolic demands, while still protecting the brain environment from threats. As well as core nutrients this barrier needs to allow for selective passage of immune cells as required (39).

All this can only be done through coordinated cell activities, an insight that has given rise to the concept of a ‘neurovascular unit’ (40), a symbiosis of between endothelial cells, microvascular support cells (pericytes), glial cells, and neurons as well as extracellular components.

Of the glial cells the astrocytes, which cover the vast majority of blood vessel surfaces in the CNS, are known to have significant effect in supporting BBB integrity (41), in association with pericytes that also coat the blood vessels. It is the microglia again which appear to have particular influence on BBB responsiveness (43): many migrate to blood vessels walls as ‘perivascular microglia’ to monitor BBB integrity and the influx of blood solutes into brain parenchyma (44).

The anti-inflammatory M2 activation of microglia is also associated with this protective activity (45). On the other hand microglia activated to the M1 phenotype by vascular exposure to pathophysiological stressors are likely to cause inflammatory damage to the BBB (46).

The implications for brain health in BBB breakdown are likely to be critical. Early consequences include cognitive dysfunction (47). Microvascular injury with BBB dysfunction and reduced cerebral blood flow has been cited as directly prompting the classic beta-amyloid protein accumulation in Alzheimer’s disease (48).

There is increasing evidence that the gut microbiome and other aspects of gut health can play a critical part in the aetiology of neuroinflammatory conditions (49). Gut microbial dysbiosis leads to the secretion of amyloid and of lipopolysaccharides (LPS), which both disturb gastrointestinal permeability and the blood-brain barrier.

Amyloids (e.g. curli, tau, amyloid-beta, α-syn, and prion) derived from pro-inflammatory gut bacteria such as E.coli and species of Streptococcus, Staphylococcus, Salmonella, Mycobacteria, Klebsiella, Citrobacter, and Bacillus have been reported as initiating factors for the abnormal aggregation of amyloid-beta (Aβ) peptide in Alzheimer’s (50). Innate Aβ peptide production may actually be part of a healthy immune response against pathogenic microbes (51).

However, bacterial amyloid mimics Aβ; through toll-like receptor TLR2 activation  and pro-inflammatory mediator production (52) this can seed and elicit misfolding and aggregation of Aβ peptide, followed by microglial cell activation (53). Amyloidosis is confirmed as associated with higher gut levels of pro-inflammatory bacteria and lower anti-inflammatory bacteria (54).

Perhaps even more important for herbal therapeutics, M1 activation of microglia is also associated with the presence of bacterial lipopolysaccharide (LPS) absorbed from the gut (55,56). We shall see later that this is an obvious therapeutic target in managing neuroinflammation, and will also see more evidence of this in looking at depression.

Clearly there is a case in neuroinflammatory disorders for working on the gut environment. As one reviewer has noted: “consumption of prebiotics, probiotics, and synbiotics restored cognition … through gut-brain axis, leading to improved hippocampal plasticity, brain mitochondrial function, and decreased microglial activation” (57).

It is a reliable assumption in clinical practice that the most likely pressures in any chronic inflammatory condition in the body arise from the gut, and this is likely to apply too to all the problems of neuroinflammation that we have been describing. Finding ways to reduce the absorption of inflammatory agents and stealth pathogens, and to ameliorate immunological disturbances at the gut wall will always be a core role for the herbal practitioner. Supporting a healthy microbiome is emerging as the most important focus here and we explore the therapeutic prospects of working here in a separate piece in Herbal Reality.

Depression is increasingly viewed as an inflammatory disorder mediated by microglia (58), even being termed a ‘microgliopathy’ (59). It has been demonstrated that depressed patients present neuroinflammatory alterations, including changes in T-cell population (60),  and have high blood levels of inflammatory cytokines (with levels of IL-1β, IL-10, and TNF-α correlated to depression severity, and IL-8 inversely so) (61). Levels of TSPO, a marker of microglial activation as measured by positron emission tomography (PET) scans, are elevated in the brains of those suffering major depressive episodes (62).

Depression is also strongly linked to infections, especially viral infections (63). These are likely related to microglial activation (64).

Interestingly for the herbal strategist, and restating the point above, provocations to depression can be linked also to a leaky gut wall: to high raised IgA/IgM responses to lipopolysaccharides (LPS) from Gram-negative gut bacteria (65,66).

LPS are used in research to generate depressive behaviour, (67) and their depressant effects have been confirmed in human studies (68). Manipulations of the gut microbiota (and even vaccines) have been postulated as ways to prevent or treat depression (69).

It is however interesting to note that vulnerability to inflammatory factors appears to be modified by pre-existing socio-behavioural factors. A placebo-controlled study in 115 healthy adults of the effects of an infusion of gut derived LPS (in this case an endotoxin from E. coli), showed that expected increases in proinflammatory cytokines and subsequent depressed mood were moderated by baseline levels of perceived stress, sensitivity to social disconnection, and the severity of symptoms of anxiety and depression.

These background factors were associated with increased activation of pro-inflammatory transcription control pathways (e.g. NF-κB) in response to endotoxin (70). In other words, inflammatory causes of depression do not act in isolation from other prevailing factors.

The obvious fatigue that follows infections as well as inflammatory and immunological diseases has been linked to increased levels of pro-inflammatory cytokines. These include IL-1, IL-6, TNF-α and IFNα; activation of the TLR Cycle by pathogen-associated and damage-associated molecular patterns (‘PAMPs’ and ‘DAMPs’), altered glutaminergic and dopaminergic neurotransmission, mitochondrial dysfunctions, and oxidative stress-induced defects in the sodium-potassium pump (71).

In various laboratory models viral infection has been demonstrated as able to increase blood brain barrier permeability,  microglia/macrophage activation through Toll-like receptor 3 (TLR3) signalling, and upregulation of the serotonin transporter in astrocytes so reducing extracellular serotonin (5-HT) levels (72).

There have been further suggestions that chronic fatigue syndromes can have autoimmune origins, with increased immune activity against 5-HT, associated with activation of immuno-inflammatory pathways and bacterial translocation (73).

Methodological limitations so far hamper firm conclusion’s but activation of microglia and astrocytes is increasingly considered a leading factor in the case of chronic fatigue syndrome (74).

It is becoming clear that unhealthy modern lifestyles are contributing to neuroinflammatory disorders (75). The obverse of that is that there are many positive dietary measures that could be adopted, (76,77) and in particular the prospects for the use of spices, (78) herbs and dietary plants in modulating neuroinflammation are increasingly promising (79,80,81,82,83,84).

There is the real prospect that plants may turn out to be better agents at reducing neuroinflammatory damage than new anti-inflammatory medicines. They have the huge advantage that most can be safely consumed over many months and years, forming part of the diet as well as in a herbal regime. Below are some of the more interesting subjects of current research, many published just before this article was written and certainly to be seen in increasing volume in the future.

Polyphenols

Polyphenols exert numerous biological effects likely to help protect the ‘neurovascular unit’, including anti-aggregatory platelet activity, the vasodilatory effects of nitric oxide generation, free radical scavenging properties, and acting on the signalling cascades implicated in endothelial apoptosis. Such benefits have been identified for protection against stroke damage (85), and even in reducing later protein aggregate formation in Alzheimer’s and Parkinson’s diseases (86,87).

Various protective functions have been identified for flavonoids (88,89,90,91,92). In the case of cocoa polyphenols these have also been associated with their role in modulating intestinal immunity (93). Other promising remedies with high polyphenol content include turmeric, rosemary, green tea, red grapes and ginkgo, outlined below.

Turmeric (Curcuma longa)

Turmeric’s prominent polyphenol complex curcumin has been shown to reduce levels of TLR4 and its downstream effectors including NF-κB, IRF3, MyD88, and TIRF that are associated with stimulated astrocytes (94), and to have a wide range of potential neuroprotective properties (95). However the very poor absorption of curcumin across the blood-brain barrier on top of its core absorption problems across the gut wall means that much laboratory research on the role of naturally-presented curcumin in nerve tissue should be discounted in clinical practice (96).

There are some promising leads for a readily absorbed turmeric constituent ar-turmerone (97). However a more promising mechanism is the capacity of turmeric and curcumin to reduce the absorption of inflammatory bacterial LPS from the gut (98,99,100). As has already been noted in this article, bacterial LPS is a potent factor in neuroinflammation and this may turn out to be the most exciting mechanism for benefits of turmeric in alleviating neuroinflammation.

Rosemary (Rosmarinus officinalis)

Rosemary leaves contain two diterpenes, carnosic acid and carnosol, which account for most of its observed antioxidant, anti-inflammatory, and anti-carcinogenic activities in the laboratory. They also demonstrate neuroprotective effects and reduction in neuroinflammatory activity in both in vitro and in vivo, in some cases more intensely than resveratrol or sulforaphane (see below) (101).

Rosemary also includes caffeic acid and its ester rosmarinic acid as important bioactive constituents. Rosmarinic acid demonstrates neuroprotective effects in different models of neuroinflammation and neurodegeneration, as well as chemical-induced neurotoxicity and oxidative stress (102).

Green tea (Camellia sinensis) and EGCG

As well as high polyphenol content the most prominent constituents in green tea research are the catechins, especially epigallocatechin-3-gallate (EGCG). These have been shown to have a wide range of neuroprotective benefits across many models including in clinical studies, and justifies the value of probably both green and black teas as the most widely consumed fluids around the world (103,104,105,106,107,108,109).

Ginkgo (Ginkgo biloba)

A standardised ginkgo leaf extract (EGb761) was shown to reverse microglial activation and release of inflammatory agents caused by interference to CNS circulation (110), to significantly inhibit astrocyte activation after ischaemic stroke (111), to have stabilising effects on LPS-activated microglia in vitro (112), and to reduce other neuroinflammatory activity (113).

One of ginkgo’s terpene lactones, ginkgolide B, has demonstrated neuroprotective effects in several models of neurological diseases (114), including in reducing the deposition of protein plaques (115). Although these are laboratory studies using specific derivatives of ginkgo leaf they point to promising effects in managing the microvascular elements of neurological disease in humans.

Red grapes, red wine and resveratrol

Resveratrol, a stilbene polyphenol found in many plant species, and notably red grape skins and seeds, is actually capable of crossing the blood-brain barrier and has been found, at least in part (116), to have multiple biological properties, including attenuating mitochondrial dysfunction (117), preventing neurological disorders, reducing neuroinflammatory processes, inhibiting apoptosis (118,119), reducing microglial activation (120), and stabilising astrocyte activity (121).

Most interestingly, in relation to the specific neuroinflammatory processes associated with liver damage (hepatic encephalopathy), the neurological benefits of resveratrol could be mediated by changes to the gut microbiota (122).

Broccoli and sulforaphane

Sulforaphane is an active constituent in various species of brassica and is provided in broccoli seed sprouts supplements. It is a prominent activator of Nrf2 (nuclear factor erythroid 2 related factor 2 – outlined above). In the CNS sulforaphane has shown protective potential against a wide range of neuropathies via promotion of neurogenesis or inhibition of oxidative stress and neuroinflammation (123,124).

Ginger (Zingiber officinalis)

Ginger is a common food ingredient that looks another promising component of an anti-neuroinflammatory regime (125,126,127). As with turmeric, there are prospects that some of these effects may be mediated via changes in the gut microbiota (128). There are studies that implicate both shogaols (129,130) and gingerols (131) in these benefits.

Cinnamon (Cinnamomum spp)

Extract of cinnamon and cinnaldehyde inhibit abnormal protein plaque formations in a number of models, have effects against multiple oxidative stress and pro-inflammatory pathways, modulate endothelial functions and attenuate vascular cell adhesion molecules (132). Cinnamic acid has been shown to help shift microglial activation to the M2 phenotype (133).

There are also pointers to neuroprotective effects for other herbs (134):

• Ashwagandha (Withania somnifera) has been shown to have a range of effects reducing LPS-induced neuroinflammation (135), and ameliorated neurotoxic complications of high fat diets (137).
• Brahmi (Bacopa monnieri) inhibits the release of inflammatory cytokines from microglial cells and inhibits enzymes associated with inflammation in the brain (137), as well as other activities consistent with protection against neurodegenerative diseases (128).
• Saffron (Crocus sativa) is showing evidence of inhibiting amyloid-beta aggregation, preventing plaque and neurofibrillary tangle formation, and in other ways reducing neuroinflammation (139).

Wu wei zi – Chinese magnolia berry (Schisandra chinensis)

Prominent constituents of this important TCM remedy are dibenzocyclooctadiene lignans such as schisandrins: various studies have reported that the crude extracts and the isolated pure lignan components effectively protect the neuronal cell damage (140).

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Monoamine oxidases (MAOs) are a family of enzymes* found in the brain, gut, liver and other tissues; they catalyse the oxidation and inactivation of monoamine neurotransmitters, including serotonin, noradrenaline and dopamine, which are important in the regulation of mood.

There are two kinds of MAO: MAO-A and MAO-B. MAO-A is found primarily in the intestine and in the regions of the brain that have serotonin, norepinephrine, dopamine and tyramine substrates; MAO-B is found primarily in platelets and in the regions of the brain that are rich in dopaminergic neurons.

The function of MAO inhibition was discovered in 1958 (22). Drugs that suppress MAO-A in the brain have been used as anti-depressants since then. These drugs remain far longer in the system than plant-based sources.

MAO inhibitors (MAOIs) inhibit the MAO enzyme, thereby allowing serotonin, norepinephrine and dopamine to accumulate in the synapse (5). Mood changes induced by MAOIs can also be aphrodisiac, and the plants considered below are sometimes used for that purpose in various cultures around the world.

* Oxidases are enzymes that utilize molecular oxygen as acceptor, and convert phenolic substances to quinones.

Around seventy plants are now known to contain monoamine oxidase inhibitors (MAOIs) (3).* The list of plants known to contain chemicals that have this function augments nearly annually. Below, we consider nine plants that contain MAOIs (22).**

Two of the plants, Syrian rue and yagé, are used mainly for psychoactive effects. Passion flower, nutmeg, liquorice and fragrant ginger contain MAOIs, though they are used primarily as food and in folk medicine, rather than for inebriation. The other three plants discussed (caltrop, cowhage and heart-leaved moonseed), are used mainly in Āyurvedic medical treatments and for aphrodisiac purposes.

* Ott (1994:73–75) lists sixty-seven plants in nineteen botanical families with MAO-inhibiting ß-carbolines.

** Other commonly used plants that have MAOI properties, to varying degrees, include betel nut (Areca catechu) and yohimbe (Pausinytalia johimbe) [MAO-A inhibitors]; kava (Piper methysticum), olives (Olea europaea) [MAOI-B inhibitors]; black pepper (Piper nigrum), long pepper (Piper longum) cannabis (Cannabis sativa), cocoa (Theobroma cacao), coffee (Coffea arabica, Coffea canephora), golden root (Rhodiola rosea), tobacco [MOA-A and MAO-B]. See Psychonautwiki 2021.

One of the MAOI plants that has a very long history of use is Syrian/mountain/ wild rue (Peganum harmala) (35). This plant belongs to the Zygophyllaceae botanical family and is known as harmal/harmel (in Arabic) or as isphand/isfand/spand/sipand more widely in the Middle-East and Asia.

In Egypt it is known as besata (‘Plant of Bes’) and in Morocco as mejnenna, which means ‘what makes your crazy/possessed’*. It is probably the MAOI plant most widely used for its psychoactive, aphrodisiac and medicinal properties.

In Iran and neighbouring regions, the seeds of Syrian rue are still used for apotropaic purposes, and as an aphrodisiac—sometimes in the form of an extracted oil—by Turks, Moroccans, Tunisians and others (35). The shamans of Hunza, in the mountains of northern Pakistan, inhale the vapours of rue, which they call supándur, to ‘call the spirits’ during their trance (9,35). The inhalation of thick smoke from burning seeds is also mentioned in classical Persian poetry (35).

The angular, reddish brown seeds of rue are usually boiled before being crushed, producing a reddish extrusion, which is used as a traditional dye for cloth and carpets. The seeds contain almost equal quantities of the alkaloids harmine, harmaline, and tetrahydroharmine (THH), which are ß-carboline derivatives, all belonging to a class of compounds that act as monoamine oxidase inhibitors (MAOI). The effects of harmine, harmaline and tetrahydroharmine are similar but not identical.

Effects of harmaline

In a pioneering study, Naranjo conducted psychotherapeutic sessions with thirty volunteers in 1964 to test the effects of harmaline (9). The drug is described by Naranjo as ‘oneirophrenic’ (dream-inducing). It induces a state of relaxation and a tendency to withdraw from the environment, to keep eyes closed, and to want all sounds to be kept to a minimum (20). It lowers blood pressure and may also induce sleep.

Naranjo found the benefit of harmaline to lie primarily in allowing psychotherapeutic access to unconscious processes and imagery. Although not strictly a psychedelic, in large doses rue can produce semi-psychedelic visionary experience, though accompanied by nausea and vomiting (20).

* There is archaeological evidence from the Caucasus region of its use, probably as an intoxicant that was burnt and inhaled, which dates from the 5^th millennium BCE (Sherratt 1995:30). In the 3^rd millennium BCE, rue appears in a Mesopotamian cuneiform text as šibbaratu, in a section on poisoning (Scurlock 2014:636). Around 2,000 years ago, the Copts in Egypt used rue primarily as a medicine to treat skin diseases, worms and ‘sick testicles’ (Manniche 199:145). Rue was well known to physicians in the classical Greco-Roman world.

Pliny the Elder (23–79 CE) considered rue (ruta) to be among the chief medicinal plants, with numerous applications, and also as one of the main ingredients of antidotes to poisoning (Natural History 20.153). Dioscorides (c. 30–90 CE) records several, similar applications to those of Pliny, and notes that the wild or mountain varieties are referred to as moly by Cappadocians and others (De Materia Medica 3.51–54) (2000:423–428).

The Banisteriopsis caapi vine, which is in the Malpighiacea botanical family, grows principally in the Amazon region of South America, where it is usually known as yagé; it is also cultivated these days in several countries in South America and in other tropical regions, such as Hawaii. It is another rich source of MAOIs, though as a percentage of volume it is not quite as rich as in Syrian rue. Some varieties of the vine also contain traces of DMT and 5-MeO-DMT (see below).

The vine is used alone for its psychoactive effects by some groups, such as the Tukano in north-west Amazonia. It is macerated and left to stand in cold water, which is then drunk (1,6,12,13,51). Other groups, such as the Matsigenka tribe of the Manu region of Peru, boil the vine until it attains a honey-like consistency; sometimes tobacco or other plants are added. From the 1960s onwards they began to add Psychotria viridis (usually known as chacruna), which contains NN-dimethyl tryptamine (DMT), which produces a psychedelic effect (1,19,22,25,40,52).

The formula comprising the Banisteriopsis caapi vine and Psychotria viridis, plus additional booster/moderator plants is the basis of the psychedelic/entheogenic concoction known as ayahuasca, a powerful psychedelic concoction.Torres (38) maintains that although some tryptamine-containing plants have been in use in South America since 2000 BCE, there is no evidence for use of the Banisteriopsis caapi vine for making ayahuasca before the initial contact with Europeans, c.1550–1650.

Ayahuasca analogues

Even though plants containing MAOIs are psychoactive on their own, one of the functions of MAOIs is that if taken together with a plant containing tryptamine alkaloids, such as psilocybin mushrooms or NN-dimethyl tryptamine (DMT), then the psychedelic effects of the tryptamines are augmented (45). Ott lists sixty-two plants with one or more of nineteen psychedelic/entheogenic tryptamines (52).

If a plant containing the tryptamine DMT is consumed orally it has no effect unless a plant containing MAOI is consumed at the same time. The MAOI effect permits the DMT to be activated and potentially induce powerful psychedelic/entheogenic effects for approximately two to four hours.

Because many plants contain either MAOIs or DMT it is possible to make analogues of ayahuasca from many kinds of plants (22), though not all plants are suitable as they may also contain toxins. It should also be noted that the use of MAOIs can be dangerous, even fatal (3,4).

It is impossible to know when humans first made use of plants that acted as analogues of ayahuasca. In the modern era, the scientific discovery of the chemistry of the entheogenic effects of the combination of DMT with an MAOI is attributed to the research of Holmstedt and Lindgren, which was published in 1967 (32); but in 1955 William Burroughs had already alerted the great botanist Richard Schultes to the importance of the importance of the combination of Psychotria viridis and the Banisteriopsis caapi vine, to produce the ‘fireworks’ of the yagé experience (23,25,27,24), which information Schultes presented at a conference in Los Angeles in 1967 (2).*

Nevertheless, apart from a few isolated reports, it was not until the 1980s that a significant body of research began to be published on ayahuasca analogues (sometimes referred to as ‘anahuasca’) (15,41).**

One of the consequences of the diffusion of this information, partly as a consequence of the widespread use of the internet since the 1990s, is a global trend—albeit conducted by a small number of people—to experiment with combinations of various kinds of tryptamines, such as psilocybin mushrooms and Mimosa tenuiflora (containing DMT), with other plants, such as Syrian rue, which contain MAOIs. Samorini (2019) has coined the term ‘X-huasca’ for these novel combinations.***

* Lees (2016:108–112). See also St John (2015:20–34) for a comprehensive account of Burroughs’ engagement with DMT.

** Notable amongst publications that have contributed to a wider understanding of this phenomenon are those of McKenna et al. (1984a; 1984b); Gracie and Zarkov (1985); Ott (1994; 1996a; 1996b; 1997b; 1999), Rätsch (2005) [1998]:716–720; DeKorne et al. (2002) [2000], and Keeper of the Trout (2002 [1993–2001]; 2004a [1998–2001]; 2004b [1997]). See, particularly, Ott (1994).

*** Turner (1994:62–72) also reports on the potentiating effect of rue with other psychedelics; Ott (1994:65) notes how β-carbolines can enhance the effects of peyote. See also Clark (2020:147–163; 2021:18–29).

The genus Passifloraceae contains twelve genera and around 600 species (51,22,3,4), which are evergreen, climbing vines, most of which are tropical plants native to Central and South America.

Since the 18^th century, many varieties have been cultivated worldwide. In pre-Columbian times, Indians used the plant as food, for medicine and as a sedative. The fruits can be particularly delicious. Mild, sedative teas are traditionally made in Amazonia made from several varieties of passionflower; in European folk medicine the plant is also prescribed for this effect and also as an aphrodisiac, hence the name ‘passion flower’.

Ott lists fifteen species of passion flower, including Passiflora incarnata, that contain MAOIs (46). Harman is by far the most widespread MAO-inhibiting ß-carboline in passion flower (22).

The roots of Passiflora involucrata are used in the region of Iquitos in Peru as a constituent of an ayahuasca analogue. Research indicates that the main active constituents of passion flower are C-glycosylflavones, apigenine and luteoline. Smoking passion flower also engenders psychoactive effects, producing a mild, cannabis-like high (22).

Gracie and Zarkov report on bioassays of extractions from Syrian rue, Banisteriopsis caapi and Passiflora incarnata (33). These plants, as expected, significantly potentiated the effects of tryptamines, including DMT, LSD and psilocybin mushrooms. Interestingly, DMT, 5-MeO-DMT, psilocybine and psilocine, besides their effects as tryptamines (which can engender a psychedelic effect) also on their own have MAO inhibition properties (10).

The nutmeg tree (Myristica fragrans) is originally from southeast Asia, where it is commonly used as a spice in cooking and also as an aphrodisiac and a medicine (24). The main chemical in nutmeg with MAOI properties is myristicin (34).

In India, nutmeg, known as jāyphal in Hindi, besides being a commonly used spice, is often found in multi-plant Āyurvedic aphrodisiac formulas.

In this capacity, the nut itself is sometimes used separately from the hairy covering of the nut, known as jāypatti or jāvitrī, which is used for making the spice known as mace. Nutmeg was used in Europe in the Middle-Ages as an aphrodisiac. However, consuming large amounts of nutmeg can be poisonous.

Used since at least 500 BCE, the Scythians are said to have introduced the sweet root to the Greeks. Liquorice is in the Leguminosae/Fabaceae botanical family and has some aphrodisiac effect (24).

Continuous use can lower metabolism, decrease thyroid function, and deplete potassium. Some varieties of liquorice (Glycyrrhiza glabra/inflata/uralensis) contain chemicals that have MAOI properties, which are still incompletely understood (34).

Another commonly used plant, which is rich in MAO inhibitors, is galangal / aromatic ginger (Kaempferia galangal). It is native to South and South-East Asia and is used in Asian cuisine (52).

Tribulus terrestris, known as caltrop, puncture vine, cathead, and as gokṣura in Sanskrit, is another plant containing MAOIs (21), in the form of harmine etc. It is commonly used in Indian Āyurvedic aphrodisiac formulas and also used by people hoping to increase athletic performance (22). It is a fruit-producing plant in the Zygophyllaceae botanical family that grows widely in the Mediterranean region, South Asia and South Africa.

Mucuna pruriens, usually known as cowhage or Bengal velvet bean, contains not only MAOIs but also DMT and 5-MeO-DMT in trace amounts (43). This plant, in the Fabaceae botanical family, is known in Sanskrit as kappicacchu or ātmaguptā; it also features commonly in Āyurvedic aphrodisiac formulas. It is also used in Āyurveda to treat Parkinson’s disease, as the plant also contains L-DOPA, a psychoactive chemical which is nowadays manufactured in pure form to treat the disease. In Indian folk medicine the plant is also used to treat snakebite.

Tinospora cordifolia (Sanskrit guḍuci/madhuparṇi/soma/amṛta, Hindi giloy, heart-leaved moonseed) contains jatorrhizine, berberine and plamatine, all of which, individually, act as MAOIs (both MAOI-A and MAOI-B. This plant has several Āyurvedic medical applications, including use for diabetes and as an anti-inflammatory (43), and is also a common constituent of multi-plant aphrodisiac formulas.

Plants containing chemicals that inhibit MAO activity have a long history of use by humans in many cultures for their psychoactive and aphrodisiac effects. Although the chemistry of the plants discussed in this article is now well understood, there is still more to be discovered about how these chemicals effect the brain and nervous system.

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Critics of herbal medicine sometimes lead the public to believe that they should avoid herbal remedies because there is a lack of evidence about the safety or efficacy of medicinal herbs. They often resort to the somewhat exhausted mantra that “just because something is natural does not mean it is safe” (2,3,14,28).

This is on the face of it an accurate assessment, but it may also be a half-truth. It could equally be suggested that because something is natural it is more likely to be safe (due to its longevity of use without incident for example) rather than something which is unnatural, such as a synthetic drug made in a laboratory with all its inherent risks and unwanted side effects.

Indeed, it is because of the latter that the general public often seek a ‘natural alternative’ in the first place.

The general longevity of use in traditional practice over many centuries suggests the vast majority of herbal medicines when used appropriately by practicing herbalists are as safe as fruit and vegetables (indeed many of them are fruits and vegetables), with only a few stronger herbs employed in limited dosages.

Part of the problem is that some researchers chose to ignore the existence of the professional herbalist who is trained to flag any potential contraindications which might assuage at least some of the perennial concerns they raise. Instead, some prefer to put across their conflated concerns of an unsuspecting public stepping into the mire, and rather than suggest that the public consults with a professional herbalist; they play on fears and generate uncertainty (13,16). The objective of this type of criticism is to create a sense of doubt in the public eye, but is it all just smoke and mirrors?

While it’s true to say that some herbs such as Atropa belladonna are dangerous in the wrong hands, access to such plants is legally controlled and these herbs are unavailable to the general public. And while unsuspecting amateurs harvesting from incorrectly-identified species in the wild may cause problems for themselves, such misadventure is not in any way connected to professional herbal medicine.

By and large, the majority of herbs used by herbal practitioners are tried and true over long periods of time. A small selection of herbal medicines may be considered more medicinally “potent”, but the discerning herbal practitioner uses restricted doses and fixed durations of use for such herbal preparations and is trained to be aware of any potential toxicity.

The deconstruction of semantics aside, we are still left with the question – is there a lack of evidence for herbal medicine? In order to put this question into context, we might begin by examining the term “evidence” itself. Critics of herbal medicine believe that herbal medicine can only be understood through certain types of evidence.

In a court of law the defendant or prosecution presents corroborating evidence for particular statements to establish the foundations of their arguments. This corroborating evidence may come from diverse sources. The origins of evidence are less important than the strength of such evidence to convince a judge and jury. But what if the judge demanded that only evidence gathered from the City of London could be considered, even if the events around the case occurred outside the City of London? You would be correct to think that such a hypothetical situation would be ludicrous.

The term evidence-based medicine (EBM) became popular in the 1990s (31). It presents the case that all medical interventions should be “evidence-based”, with the double-blinded randomised controlled trial (RCT) considered the gold standard in clinical research. Systematic reviews and meta-analyses of RCTs (peer review) became the pinnacle of the new evidence hierarchy.

The clinician could then use this information to best inform their clinical judgement. However, evidenced-based medicine in this particular reading has a number of confounders and inconsistencies. Firstly, it implies that there was no evidence before EBM or if there was it was circumstantial (coming from outside the City of London in our earlier hypothetical scenario).

Secondly, it implies that evidence can only be assessed in a certain way and that this evidence is better than other types of evidence such as expert opinion. The imposing hierarchy of EBM is summarised in Figure 1 below:

On first glance it seems odd to put expert opinion at the bottom of the pyramid and place systematic reviews at the top. The concept of defining evidence in this way may well be a noble attempt to eliminate bias from influencing clinical decision making, but this itself is predicated upon the erroneous belief that bias can be completely eliminated. It seems more likely that bias may only be limited through these processes but only in carefully controlled laboratory conditions (creating internal validity) which unfortunately have little connection to what happens in the real world (lacking external validity).

The RCT is a methodology which is used in testing the efficacy of new drugs, treatments and health care services. The use of RCT research is considered highly effective by its supporters because it is thought to minimise allocation bias (Nunan, Heneghan and Spencer, 2018).

The significant characteristic of RCTs is that trials usually include a control experiment alongside the main treatment. These are known as placebo-controlled studies. They are used in comparing changes recorded in the active treatment group in order to ascertain that the placebo group that was not included in the treatment does not react in a similar manner. This serves the purpose of proving whether the active treatment actually had an impact on the active study group.  In this way it can be established whether or not a new drug is superior to placebo. But how do you establish a placebo?

Comparing a drug to a placebo in an RCT sometimes implies that the placebo effect has a fixed value, say 30%, so the new drug must be equal to or greater than placebo in terms of safety and effectiveness and yet placebo effects may be greater or lesser than 30% depending on many factors. For example, there may be more than one placebo effect depending on the circumstances, so placebo controls may actually potentially increase bias in some cases (9).

But let’s assume in a double blind randomised controlled trial that a new drug is found to be greater than placebo and no major adverse reactions are recorded. The trial and methodology should then be independently replicated and a statistically similar result would be expected. Replication trials should mimic the methodology of the original trial, and statistically similar results would either validate the original study or bring it into question. When we speak of gold standards, this extra layer of scrutiny would help to strengthen the clinical trial process. In turn systematic reviews and meta-analyses might include replication trials as specific inclusion criteria.

What if the RCTs are not independently replicated? The results may be unreliable, and the primary research data would be flawed? What if researchers later conducting a meta-analysis only include certain RCTs (some of which may be flawed) and not others (which may not be flawed) in a peer review? In that case secondary and tertiary research could also be flawed, casting shadows over the whole process.

What of researcher conflicts of interest; study cohorts which are not representative of the general public; unrealistic sample size; lack of preclinical screening for participants; use of unrealistic dosages or durations of use; and statistical bias? There are many problems with such a rigid methodology, if full checks and balances are not put in place.

Professor John Ioannidis put this into stark perspective with his highly influential paper Why Most Published Research Findings are False, which has become the most cited research paper of all time (19). Ioannidis argues that due to a lack of replication trials, statistical incongruence and the initial “truth” of a research question, most research may be false. If Ioannidis is correct, could this culture of false or erroneous data account for increasing iatrogenic events which now sees modern medicine as a leading cause of death in annual all-cause mortality statistics? (22) This would imply that there is a crisis in the current EBM paradigm.

On the other hand, expert opinion at the bottom of the EBM pyramid (Figure 1) might be in need of a paradigmatic reappraisal. Imagine a physician who has seen thousands of patients and developed successful healing strategies over many years in real world situations. Would it be advisable to value their expert opinion above the results of a potentially flawed clinical trial?

David Sackett, nominated by his peers as the “Father of EBM” for his pioneering work, describes EBM as an amalgam of the best systematic research, expert opinion and the patient’s rights and choices (29). If we follow Sackett’s description, we see a tripartite approach, not a single approach that favours filtered over unfiltered information but a multifaceted approach which values systematic research alongside expert opinion, and importantly brings in the vital component of patient experience and opinion.

Patient-centred care has become a popular term in modern medical parlance, and yet many patients do not feel satisfied by the care they receive under the current medical model. Patient satisfaction is an important and commonly used indicator for measuring quality of care. Disempowerment of the patient may occur because of long waiting times; the all too brief consultation process where empathy does not occur and where key information can be missed; but also because of side-effects and/or a lack of efficacy of prescribed medications and procedures (17).

Taking these comments into consideration, there are problems and obstacles within the current paradigm of EBM. We must also consider how useful this methodology is to herbal medicine in particular?

The RCT process is designed for pharmaceutical drugs within a reductionist paradigm, where a candidate drug with a single therapeutic target is examined. Clearly, the multi-constituent nature of herbs (with multiple therapeutic targets) does not fit easily into this model. Some researchers have tried, occasionally successfully, to put herbs through such scrutiny, but the cost and time involved may hardly be worth the effort, especially when it is often not reflective of or does not contribute to an understanding of the practice of herbal medicine.

Could the RCT process be reconfigured in such a way so as to examine the protocol a herbalist uses in clinical practice for a particular condition, and compared with an orthodox treatment, rather than testing a single herb or constituent against an imagined placebo? Might this provide evidence of the efficacy and safety of herbal medicine if it is designed to reflect actual practice?

Systematic research can be useful provided it is relevant to herbal practice. Where it is not relevant to practice it may be considered as “background information”. The danger of an obsessive approach to EBM and a paradigm enthralled to scientism is that it may also eclipse other important strands of evidence.

What if the playing field is levelled and we consider other strands of evidence equally and without imposing an EBM-like hierarchy? I propose an “evidence house” model for herbal medicine research on egalitarian lines, where each room yields key information which can establish a foundation of evidence upon which to build. In contemplating this approach I decided that I would examine those stems of evidence upon which I have drawn for practical information and which have since informed my practice and led to successful outcomes for my patients.

While some information offers very basic clues, my approach here is not be overly concerned with the initial ‘strength’ of the data, but rather whether or not these clues may in time provide practical, safe and effective outcomes in clinical practice through comparison and consolidation of other multiple strands of data.

I am alert to the potential weaknesses in such a model in a reductionist sense but I stress that a perceived deficiency in one room may be supported by strengths in another and that it is a combined or holistic approach that might provide the best evidence for herbal medicine. For example, a traditional practice may provide the original clue on how to use a particular herb or treat a certain condition.

On its own, this reference to a traditional use may be unsatisfactory but what if the clue is supported by evidence from one or more of the other rooms in the evidence house? And what if the original clue is not supported?

The six “rooms” for building the proposed evidence house are as follows.

1. Tradition
2. Folklore
3. Organoleptics
4. Phytochemistry
5. Systematic Research
6. Empiricism

Imagine an architect’s blueprint of a ground floor in which all 6 rooms share a “hallway”, meaning that they connect or integrate with each other holistically in the evidence “house”. Each has, or could be considered as having, various strengths and weaknesses and there may be ways of evaluating each of these for “structural integrity” and creating better insulation in time as the model is developed through further research.

All of these rooms alone have yielded clues which in time have led to practical results in my clinical practice, and this is the main criteria upon which I will draw in presenting this model. Some rooms have helped more than others but I reiterate that the room itself is not hierarchically more important as a singular evidence base.

What is important is how one room connects to the other rooms and how the collective gathering of information from multiple rooms leads to an evidence base for safe and effective health outcomes. This approach combines quantitative and qualitative data and both objective and subjective viewpoints. Let us consider each room as if we are viewing the house.

From the beginning of my dedication to herbal medicine, I learned from a tradition. By tradition I mean historical texts which were not lay commentaries but rather, practical guides written by professional practitioners intended as the furtherance of knowledge. These herbals were textbooks in schools of medicine across the world until relatively recent times, written by learned physicians and based on their own experiences and observations.

This differentiates tradition from folklore (the “room next door”) because it is based on the experiences of practitioners whose vocation in life was dedicated to the healing profession. These early physicians, in the cases of Dioscorides or Avicenna for example, were also well-travelled and drew upon other traditions outside of their locality, comparing and contrasting, amalgamating or rejecting different aspects of information and practice over long periods of time.

Their written wisdom is then passed down the generations to new students and apprentices who continue the tradition. In the case of the aforementioned authors, this process may occur over several centuries. Such authors, then, are not only important to herbalists but to the history of medicine itself.

Over the passage of time, we find new herbals appearing; sometimes blindly or lazily following the classic authors without scrutiny; sometimes challenging concepts or contributing new wisdom. The corpus of herbals is actually immense but it is possible to look at certain authors whose significance and contributions were such that they become historical beacons. It is possible to trace the use of a single herb over the centuries by giving precedence to such classical texts in the Western Herbal Tradition to show continuity of medicinal uses along with fresh approaches and scholarly commentary. Such a process has been neatly established by herbalists already (32).

One of the confounders in this approach discussed by these authors is the identification of a plant. Different common names, incomplete descriptions or poorly drawn figures may be misrepresentative of a plant when comparing one author with another in historical texts and cause dilemmas of identification and for tracing continuity, at least until the times of Linnaeus and the development of the standard Latin binomial classification of genus and species.

Such a pitfall has also been negotiated by a number of scholars such as Beck (6)in the case of Dioscorides, or (1) in the case of Avicenna, and is no longer as big of a problem problem in modern times with international acceptance of Latin binomial classification. In fact there is a research project at Kew Gardens being conducted to solve this very issue. A researcher can now chart the history of a plant’s medicinal uses over thousands of years.

Importantly, the use of what herbalists refer to as “energetics” is also a crucial and fundamental aspect of herbal medicine tradition because its application, irrespective of the herb or herbs used, is still pertinent today. This is all the more relevant because it is precisely this heuristic tool of energetics that allows for individualised protocols within a holistic paradigm. Compare a bespoke strategy such as this with the apparent one size fits all approach of allopathic medicine.

Energetic differentiation establishes principle qualities of disease using basic concepts such as hot, cold, dry or damp and variations thereof. Similarly, a herb or herbal formula can also be categorised as hot, cold, dry or damp or variations thereof. Part of the practitioner’s traditional role is to access the patient and decide which of these categories best relates to the patient’s symptoms in terms of having an excess or a deficiency of these basic qualities.

A patient could be too cold or too hot, but they could also be cold and dry, hot and dry, or hot and damp (but not cold and hot, or dry and damp. which are mutually incompatible). These conditions can progress and change so that someone who starts off too hot can become too cold in time. The practitioner must use pattern recognition to deduce the initial imbalance as well as the progress of that imbalance.

Once recognised through good case taking and diagnostic examination the physician uses herbs in a treatment of opposites, according to the appropriate action of the herbs. In rudimentary terms, the “strength” of the herbal protocol would also be surmised from the stage of disease progression as well as the patient’s individual predicament by using a system of degrees.

A person with the common cold may feel cold and shivery or hot and sweaty. This would require a different approach in each case. Compare this to allopathic medicine where there is no differentiation and both patients may receive the same antibiotic treatment. The traditional holistic approach does not end here.

The patient is also given adjunct advice whose remit is to challenge the potential causes of their condition, thereby treating both causes and symptoms in a holistic root and branch approach. In the Hippocratic school of thought, for example, we find reference to the 6 non-naturals – six areas of life over which the patient has some influence and which ultimately affects their health.

The non-naturals include fresh air; motion and rest; sleeping and waking; food and drink; excretion and detoxification and the passions/ emotions. Incorrect diet and lifestyle choices may lead to contra-naturals, or symptoms, in the Hippocratic model. In a sense then, traditional herbal medicine is not so much a system of healthcare as the practice of ‘life-care’.

This basic view of herbal tradition describes fundamental principles which are as valid today as they were in centuries past. By researching a herb in classic texts at various junctures in time, the researcher discovers uses, preparations, specific indications, energetics, dosages (though not always), contraindications, synergies with other herbs and other practical information developed over immense periods of time. This tried and true information can be applied practically, and it is a route by which many first find themselves intrigued by the possibilities of medicinal plants.

Although folklore is certainly a part of Tradition in its wider sense, it can also be treated separately. While the herbal Tradition can be discussed in terms of herbal medicine as a vocation and a profession, there are also myths and legends particularly in rural areas where local people (folk) carry on ancient oral traditions about the local use of plants (lore).

Such lore is often dismissed as archaic, superstitious or at best anecdotal but such accusations belie a partiality. Common people often filter their understanding of the world through the lens of local customs, beliefs and religions which create cultural meaning and identity. In dismissing folklore, one may also be dismissing the entire culture that goes with it!

A modern reader wanting to understand such a culture from an ethnobotanical perspective might embrace local customs, beliefs and religions as a means to set the scene for a wider cultural understanding within which such customs evolve.

For example, a piece of lore might call for the use of a herb for a particular condition but this may be accompanied by prayers, songs or magic rituals which the modern reader may feel is out of time or incongruent  within the current scientific paradigm. Therefore because of this “superstitious” misunderstanding of folk tradition in general, any suggestion of a folk cure being effective is often dismissed.

The American linguist Kenneth Pike saw a similar discrepancy in the anthropological sciences. He coined the terms Emic and Etic in his seminal 1967 text Language in Relation to a Unified Theory of the Structure of Human Behaviour to describe the difference between looking at the worldview of another through your own cultural lens to “establish an objective, scientific approach to the study of culture” (Etic) and looking at it within the context of “grasping the world according to one’s interlocutors’ particular points of view” (Emic). Emic assumes the role of “native perspective”; Etic the role of an “arm’s length” approach (27).

However, some scholars have begun to compare ancient descriptions with modern interpretations. This is an instance of taking a clue from one room and supporting it with clues from another. For example, researchers compared Ginger (Zingiber officinale) in Persian folk medicine with indications from contemporary research, concluding that modern uses of Ginger confirmed the traditional folk uses of Ginger. The research also revealed that there were other properties from traditional folk use which have yet to be elucidated in a modern context thereby offering more new clues for medicine (21).

In order to consider folklore as an evidence base I refer to my original criteria – does it yield practical information which can lead to safe and successful clinical outcomes? Ethnobotany is the study of human relationships to plants. A study of this subject may yield useful information when assuming an Emic approach, using Pike’s descriptors. This does not mean such a study is without its own inherent problems.

There may be discrepancies with the correct botanical identification of the plant in question if it is known by a local name which cannot easily be equated to its modern binomial taxonomy. There may be an absence of cultural context in regards to the customs and rituals which may accompany it. There may also be a dilution of the original practice over the generations. These confounders do not prevent the discovery of practical information.

For example, researchers considered a number of plants from 10^th century Anglo-Saxon texts for their potential use as antimicrobials. In the study, several preparations of Agrimonia eupatoria, Arctium minus and Potentilla reptans were screened for antimicrobial activity against gram-positive and gram negative bacteria (Watkins, Pendry, Sanchew-Madina and Corcoran, 2012).

The texts examined had previously been considered as having “little or no value to medical understanding” (8). The authors cross-referenced from several translations of the Anglo-Saxon texts to negotiate potential confounders and keep close to the original clinical indications. All plants demonstrated antibacterial efficacy and the authors concluded Anglo-Saxon texts may be a good source for rediscovering plants lost to current herbal practice (34).

An ethnobotanical study of Allen & Hatfield’s Medicinal Plants in Folk Tradition: An Ethnobotany of Britain and Ireland (2004) which has been gathered from multiple sources including the work of the Irish Folk Commission based on oral tradition, concluded that many of the plants studied may be potential sources for new therapies (10).

Ethnobotany is unfortunately an area of concern where indigenous information is stolen to discover interesting compounds for novel drug discovery. The term ‘biopiracy’ is sometimes used to describe this theft of cultural intellectual property from native cultures (4) If used respectfully, it offers data which can be cross-referenced with other ethnobotanical uses in other parts of the world, much like historical research of traditional use in established herbals, and provides clues which can be filtered through other rooms.

The term organoleptics refers to the use of the senses to acquire information. The skills of the wine taster or the perfumer who can detect and describe multiple flavours or scents are well known to modern culture. In the history of herbal medicine we also find reference to a concept known as the Doctrine of Signatures which infers that the shape of a plant or plant part may resemble a part of the body and so it must be intended for healing that part, by the signature of God. However, this may be an oversimplification.

The shape may be important, but so too is the taste of the herb, the scent of the herb, its colour, its texture, its location and so on. Rather than fixating on shape alone, information may be gathered and consolidated from multiple sensory experiences. For example, a sweet-tasting plant may reveal the presence of polysaccharides or a salty taste might reveal the presence of mineral salts such as magnesium and potassium. A bitter taste may reveal the presence of alkaloids. An aromatic scent might reveal the presence of terpenes. A yellow colour may indicate a connection to the liver; a red colour may indicate a connection to the heart and so on.

Philippus Theopastrus Bombastus Von Hohenheim (1493-1541) also known as Paracelsus wrote his famous comments on signatures in the text Supreme Mysteries of Nature (1656).

Jacob Boehme (1575-1624) wrote Signatua Re-rum (The Signatures of All Things) which was a contemporary work. TheGiambattista Della Porta (1535-1615) text Phytognomonica (1588) is even earlier, and mention must also be made of William Cole (1626-1662) and his book The Art of Simpling (1656) which serve as early works in regards to organoleptics, however these concepts and methods are much older than the 16^th century!

They developed independently across centuries in multiple cultural centres – Europe, China, America, India and Africa (12)). Many ancient tribes discovered the medical properties of plants in manners such as this, gaining empirical data from sensory information. The concept of entrainment with plants does not literally mean “talking to plants” but implies the tacit gathering of information between two living beings through sensory engagement.

Spending time in the company of plants is what Aristotle would call “learning by doing”. Developing the senses in this way may take years to learn but in time allows one to elucidate constituents and also to intuit from other information to create tacit patterns of association that can only come from direct encounters.

Modern research also confirms organoleptics.  De Medeiros et al., 2015 found significant associations between both taste and therapeutic indications (p<0.001); and smell and therapeutic indications (p<0.0001). (23) provide evidence for a highly significant association between the organoleptic properties of plants and the use of these species as medicine. Geck et al., 2017 show that organoleptics guide the choices of the therapeutic actions of medicinal plants.

Organoleptics is something of an art form but with careful practice, the novice can gain useful information of a practical nature, but for some this may take decades. However, initial clues from inspecting a plant, no matter how strange they may seem at first, can be compared with clues from other rooms.

It may seem tangential to consider phytochemistry as a singular source of evidence; however the effects of a plant’s primary and secondary constituents are now largely established in terms of their effects on the body. Taking an unfamiliar plant and researching its chemical composition allows a fundamental understanding of what a plant might do medicinally, once its phytochemistry can be elucidated.

This information can be found in research databases and with practice via organoleptic techniques. In the absence of historical record or clinical trials, knowing a plant’s phytochemistry can provide an understanding of both therapeutic qualities and potential cautions if toxic constituents are present.

Phytochemical analysis such as high performance liquid chromatography (HPLC) involves both qualitative and quantitative analysis of plant chemistry. While qualitative analysis is concerned with the presence or absence of a compound, quantitative analysis accounts for the quantity or the concentration of the compound present in the plant sample (15).

Several phytochemical databases already exist such as Phytochem and Duke’s, documenting qualitative and quantitative levels of primary and secondary compounds in plants. Considerable research has been done into singular constituents.

For example, alkaloids are now known to have a notable physiological effect on the body in general because they have a structural relationship with neurotransmitters such as dopamine or acetylcholine (33). Another family of phytochemicals, flavonoids, are similarly well documented and some constituents such as the polyphenolic compound quercetin have demonstrated antioxidant, antifungal, anti-carcinogenic, hepatoprotective, and cytotoxic activity (5).

When working with an unfamiliar plant, perhaps one which has little historical information or research, information as to its potential medical uses can be gained by knowing the range of secondary metabolites present and whether they are water soluble (hydrophilic) or fat soluble (lipophyllic) which would inform of the most appropriate solvent to use for crude extraction, depending on the intended actions.

One confounder, and perhaps the bane of this approach, is to see one constituent as having more importance than other constituents (much like the question if one type of evidence is superior to another). This is reductionism at work where value is placed on a single compound and medicines are standardised to meet very specific levels of this compound because it has been previously found to have a certain effect in cell lines for example.

The original medicine is thus modified, and may be considered a phytopharmaceutical. A case in point here may be Ginkgo biloba leaf, which does not have a long history in herbal medicine but systematic research has tended to use standardised extracts in past research and so some promote the standardised extracts accordingly. But, is there more to Ginkgo than gingkoflavones?

Plants generate compounds in the wild to deter pests and diseases or in reaction to its overall environment. The traditional use of a herbal medicine has been the use of the whole herb, plant part or crude extract where there will be seasonal and locational variability in constituents.

A plant’s medicinal actions occur when a combination of phytochemicals interacts with the epithelium on ingestion. It is the combination of actions, not one action in particular, that creates the healing effect. Indeed, when singular compounds are extracted side effects may ensue because a compound may be toxic or non-toxic depending on the presence of other constituents.

Phytochemistry can help to corroborate ancient uses in the absence of systematic research. Organoleptics can help to identify constituents and effects in a similar way. This is a good example of how the interrelationship between each room helps to improve the overall structure of the evidence house.

Modern forms of research such as double blind randomized controlled trials are not wholly applicable to herbal medicine because of their reductionist philosophical underpinning. A standard trial tends to investigate the effects of one compound on one molecular target. This is unsuitable because herbal preparations contain multiple constituents with multiple molecular targets. I have already discussed some other inherent problems earlier.

However, clinical trials can be designed in such a way so as to evaluate the herbalist “package” (the in depth consultation, the bespoke formula and tailored advice) and its effects on a particular health condition.

For example, a pilot study (n=45) was conducted by herbal practitioners to assess the effectiveness of professional herbal practice in the treatment of menopausal symptoms. All participants completed the study.

The treatment group (n=15) demonstrated a statistically and clinically significant reduction in menopausal symptoms compared to controls (n=30). Reduction in symptoms for the treated group was 9.05 points greater than that for the control group, CI 5.08-13.03, as were changes in vasomotor scores (mean 1.81, CI 1.00-2.62). Libido increased (mean 0.69, CI 0.38-0.99) in the group receiving herbal treatment (18).

Another study (n=120) into the alleviation of menopausal symptoms used a herbal formula containing Chamomilla recutita, Foeniculum vulgare and Crocus sativa (25). The formula was tested against placebo in different dosages in a randomized triple blind study.

After 12 weeks of daily treatment there were significant improvements in physical, psychological and urogenital domains in group B who had taken a dose of 1000 mg, 120 mg, 60 mg of the aforementioned herbs in drop form, whereas improvements in symptoms were less significant in the other dosage groups (Madhavian, Najmabadi, Hosseinzadeh, Mirziaean, Aval and Esmaeeli, 2019).

Such a trial is informative about dosage as well as the particular herbs that could be used to treat menopause. Bringing a greater emphasis to qualitative approaches helps to unpack other aspects of the herbal package, such as patient centred care through empathy and the length of time herbalist consultations typically afford (11).

Studies such as these are appropriate because they inform about herbal practice. Other studies which, for example, utilise a single isolated compound on a susceptible inbred animal at unrealistic doses are being geared towards the development of pharmaceutical drugs and have no bearing on actual practice. Unfortunately, background information such as this is sometimes used to justify or refute usage.

Qualitative studies, for example using questionnaires to access patient perceptions may also be valuable. Mixed-method research which utilises both quantitative and qualitative disciplines may also yield useful information, but the main criterion for any systematic research applies here – does it ultimately inform about herbal practice?

If we consider the EBM pyramid in its current form as a hierarchy of evidence, we may ask who decides which type of evidence is superior and which type of evidence is inferior, and what criteria are used to make these distinctions? On first glance it appears that these distinctions are made through an epistemological bias which favours one type of knowledge above another. It seems ironic that what we consider to be “expert opinion” is ranked at the very bottom of the EBM pyramid.

The term “expert” can also be misleading because it suggests complete knowledge of a subject which is not possible, but what is implied by EBM is that knowledge gained through empiricism is somehow inferior to knowledge gained from rationalism and quantitative data. The relegation of empirical knowledge in this way reveals an epistemological bias which may undervalue traditional herbal medicine (20).

Empiricism is the theory of knowledge which claims that most or all our knowledge is obtained through sensory experience over time, rather than through rational deduction (24). Therefore knowledge gained a priori is considered by empiricists to be inferior to knowledge gained a posteri in philosophical terms. Practitioners of traditional herbal medicine gained knowledge over the ages largely through empiricism. It is only with the development of reductionist philosophy, such as the mechanisation of the body as promoted by Descartes and the scientific method as espoused by Bacon that rationalism became prominent and increasingly dominant as a philosophical paradigm.

However, in herbal medicine empiricism always tends to the individualisation of treatment. Conversely, in reductionist medicine the individual patient is labelled with a disease (machine with broken part) and the emphasis is on more universal treatment protocols. Nonetheless a consequence of this approach may be to confound the concept of patient centred care within the current reading of EBM.

A holistic approach considers that a body is an interconnected whole with multiple influences that can affect any particular part. A “broken part” may therefore not be at fault in and of itself, nor are things always down to genetic “bad luck” (though of course with some conditions this is inevitable).

Rather illness is often caused by an ongoing homeostatic imbalance in one or more systems of the body. To focus solely on the perceived “broken part” misses this wider reality. It can also be argued that most diseases are consequences of poor diet and lifestyle choices (30).

To focus on “broken parts” as being self-responsible confirms rational medicine’s place as a system for a masking of symptoms rather than a removal of causes, and so confutes the perception of patient centred care by neglecting the bigger picture.

Rational philosophy contends that empiricism is subjective and that different observers may have different interpretations of the same object. The rationalists argue that elimination of bias, at least insofar as this is possible, helps to remove the doubt that may be caused by these conflicting views. Yet, by disengaging with causative factors and avoiding a holistic approach, the patient is not wholly treated, leaving room for error.

It is argued that a better approach may therefore be a combination of rationalism and empiricism as practiced by the 2^nd century Roman physician Galen (35). Indeed, central to the argument for an “evidence house” for herbal medicine is that we draw on multiple sources of evidence without preference.

What has become known as ‘practice-based evidence’ places greater emphasis on the experiential approach where the practitioner gains knowledge by working directly with patients rather than theorising about them. The practitioner learns over time what does or doesn’t work in real world conditions. After treating a number of patients with the same condition or similar symptoms, the practitioner learns to understand the triggers and drivers which lead to a particular imbalance.

In time the practitioner also notices that the same herbs or herbal combinations and particular adjunct advice may often be indicated for this condition. This empirical knowledge is therefore an important evidence base that is generated over time. It is the foundation upon which many of our classic herbals were written. The case-series which documents the herbal treatment of a condition in multiple patients is an evidence base that can be developed from such empirical data.

Practice-based evidence also bears some hallmarks of a long term clinical trial. Recently, researchers examined what are referred to as N=1 trials which incorporate much of the rigour of clinical trials, but are designed for individual patients. Individualising treatment interventions and outcomes in research designs is consistent with the movement towards patient-cantered care, according to the authors (7).

A more inclusive approach to evidence also encapsulates qualitative data from patient observations and narratives, creating space for involvement and therefore patient empowerment.

To ascertain evidence for the safety and efficacy of herbal medicines by systematic research alone is in and of itself a limited and limiting process. Such reductionism is inconsistent with the holistic paradigm of herbal medicine.

However, one form of research and evidence can be complimentary to another. A double blind randomised clinical trial may back up a historical use described in a classic herbal for example (26).  An ethnobotanical use may provide hypothesis for clinical research and so on.

Part of the problem with contemporary research into herbal medicine though is the focus on singular constituents perceived as active ingredients rather than the vocational practice of herbal medicine itself and what it has to offer. While the study of phytochemistry provides insight it is best served by focusing on the matrix of compounds rather than a singular compound. It can also help give weight to historical observations or folk practices.

In this more complex assessment of herbal medicine, we may be better served by drawing on a holistic perspective. The evidence house offers multiple rooms of information which connect into each other to form a whole foundation.

Each room may lead the researcher to practical information which can deliver successful outcomes, although each room taken alone has its own pros and cons. Information from one room can go some way to offsetting the limitations of another room in a complimentary manner. This prevents epistemological tensions and allows for a greater appreciation of traditional herbal medicine.

Further research could be done into each room and a potential weighting, the strength or weakness of evidence, could be quantified for each room but this may be a slip towards reductionism. Rather, a researcher might consider that where there is an obvious weakness in one room, there may be strengths in other rooms.

Drawing on all of these areas, and perhaps others not mentioned here, answers the question on how to access the safety and efficacy of a herbal medicine while attempting to avoid the clash of incongruent paradigms.

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Echinacea (Echinacea spp., Asteraceae)

Preparations made from aerial and root parts of echinacea, mainly E. angustifolia and E. purpurea, are popular and scientifically supported options for the prevention and treatment of the common cold. Echinacea extracts contain a mixture of compounds with cytokine-suppressing and -inducing effects, suggesting that echinacea extracts and alkaloids may be useful for treating allergic and inflammatory responses.

Echinacea extracts have also demonstrated immunosuppressive effects, which may be beneficial in COVID-19 patients where the inflammatory response is exacerbated. The risk of herb-drug interactions with echinacea is deemed low.

Elderberry (Sambucus nigra, Adoxaceae)

Elderberry juice has long been used as a diaphoretic in the treatment of the common cold. It also has immunomodulatory properties. Elderberry extracts have shown antiviral effects against influenza virus A and B in vitro and in human clinical trials. Despite these promising results, they cannot be extrapolated to suggest a positive effect in patients with COVID-19 as there are no scientific data available. The available evidence suggests there is a low risk of adverse effects when using elderberry before SARS-CoV-2 infection or in the early stages of infection.

South African geranium (SAG; Pelargonium sidoides, Geraniaceae)

SAG roots and rhizomes possess immunostimulant activity as assessed in several in vitro models. More than 30 clinical trials have been conducted with an SAG extract (Eps 7630^®; Umckaloabo^®; Dr. Willmar Schwabe GmbH & Co. KG; Karlsruhe, Germany) in the treatment of acute respiratory tract infections. The promising antiviral effects and strong safety profile of the extract warrant further clinical investigation.

Medicinal mushrooms and fungal preparations

Medicinal fungi are an expanding area of research, with oyster mushroom (Pleurotus ostreatus, Pleurotaceae); Ganoderma spp. (Ganodermataceae), chaga (Inonotus obliquus, Hymenochaetaceae); caterpillar fungus (Ophiocordyceps sinensis, Ophiocordycipitaceae); and maitake (hen-of-the-woods; Grifola frondosa, Meripilaceae) drawing the most interest.

Other mushrooms have been clinically studied with focuses on the treatment of cancers, immunological diseases, and immune-adjuvant therapy. Clinical and animal studies have demonstrated that the bioactive polysaccharides or polysaccharide-protein complex from medicinal fungi enhance innate and cell-mediated immune responses. Data with chemically well-defined fungal ingredients in COVID-19 patients are needed to evaluate whether specific fungi could be beneficial.

Adaptogens are natural compounds that increase the body’s adaptability, resilience, and survival in nonspecific ways. While more than 100 medicinal plants have been identified to possess apoptogenic activity, only a few have been shown to exhibit multitarget effects on the neuroendocrine-immune system.

These include andrographis (Andrographis paniculata, Acanthaceae), eleuthero (Eleutherococcus senticosus, Araliaceae), ginseng (Panax spp., Zingiberaceae), rhodiola (Rhodiola rosea, Crassulaceae), schisandra (Schisandra chinensis, Schisandraceae) and ashwagandha (Withania somnifera, Solanaceae).

In addition to affecting the immune response, the ability of these adaptogens to alleviate stress-induced mental and behavioral disorders is relevant as these conditions have increased due to the COVID-19 pandemic.

Licorice (Glycyrrhiza spp., Fabaceae)

Licorice spp., primarily Glycyrrhiza glabra, G. inflata, and G. uralensis, root contains bioactive compounds that possess anti-inflammatory and antiviral effects. β-Glycyrrhetinic acid, a metabolite of one of these components, may enhance the activity of hydrocortisone, suggesting that the coadministration may have a therapeutic effect in inflammatory lung diseases. More studies are needed to gain new insights on the potential role of licorice or its components in the treatment of COVID-19.

Turmeric (Curcuma longa, Zingiberaceae)

Curcumin, the main bioactive component of turmeric, has demonstrated activity against a variety of viruses by interfering with critical steps of the viral replication cycle. Curcumin also blocks cytokine release, which has translated to clinical improvements in animal models of diseases where a cytokine storm affects morbidity and mortality outcomes. Taken together, curcumin may theoretically be of benefit in COVID-19 pathophysiology and clinical manifestations.

Frankincense (Boswellia spp., Burseraceae)

Frankincense inhibits inflammation through the cyclooxygenase (COX) pathway. Most studies have reported moderate anti-inflammatory efficacy with frankincense as a mono-product and in combinations with other herbs, suggesting its use as a promising approach for the treatment of COVID-19-related inflammatory complications.

Salicylate drugs of botanical origin

A range of herbs contain salicylic acid derivatives. These include 

• Willow spp. Salicaceae
• meadowsweet (Filipendula ulmaria, Rosaceae)
• Birch (Betula spp., esp. Betula lenta, Betulaceae)
• Wintergreen (Gaultheria procumbens, Ericaceae) oil

While preparations derived from these botanicals are often used externally, there is no evidence for negative side effects in the context of COVID-19.

There exists no evidence that the immunomodulating herbs discussed here would exacerbate a cytokine storm, and herb-drug interactions are not expected.

Botanical drugs and supplements continue to gain interest from researchers as potential therapeutic agents for SARS-CoV-2 drug development. Still, research exploring the mechanisms of action and efficacy of these herbs in the content of SARS-CoV-2 exposure is needed. In either case, despite the lack of strong clinical data to support active recommendations, the current evidence suggests these botanicals are safe enough to permit use by the public with the appropriate caution.

The authors declare no conflicts of interest.

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Polypharmacy, which can be defined as a patient being on 5 or more medicines is becoming increasingly common, especially amongst those who are 65 or older. This has arisen due to the increased use of preventative medication, and the increasing burden of chronic disease due to both longevity and the western lifestyle.

Research and guidelines have focused on single diseases resulting in patients with more than one illness being started on multiple medications, all individually indicated but in combination resulting in polypharmacy.

Some patients are prescribed 10 or even 15 medications and often experience marked side effects such as dizziness, indigestion, bowel problems, fatigue and falls. These patients have their symptoms controlled but they often do not have a good quality of life and don’t feel well.

In the UK between 2008 and 2015 the number of hospital admissions directly related to drug side effects increased by 53.4%, from 60,055 in 2008-2009 to 92,114 in 2014-2015. Every year in Europe an estimated 8.6 million unplanned hospital admissions occur as a result of drug side effects and in the US the harm resulting from medication errors is estimated at $42 billion dollars per annum (2).

Herbal medicines have an important role to play in reducing the drug burden of the population, especially when used alongside lifestyle changes, and the deprescribing of unnecessary medication. The targeted use of herbal medicines may also help to reduce the drugs bill, adverse drug reactions and encourage self-help.

Herbal medicine and humanity have enjoyed a close symbiotic relationship for millennium and today there are approximately 21,000 different plants used worldwide.

Some plant medicines are very potent with their therapeutic action coming from a relatively small number of powerful phytochemicals and have often formed the basis for drug development for example foxglove (Digitalis pupurea) and digitalis for heart failure and heart rate control, and belladonna (Atropa belladonna) and associated alkaloids as inhalers in chronic obstructive pulmonary disease.

However, many plant medicines represent a more complex range of actions containing 100s of potentially active principles which work in synergy, with it often being difficult to reliably isolate the “active” ingredient. These herbal medicines are well suited to the management of more complex illnesses as they are themselves inherently complex, whilst at the same time being biologically close to us, having evolved within the natural world. Herbal medicines at this end of the spectrum have a low side effect profile, and provided they are of good quality and attention is given to potential drug herb interactions are safe.

The evidence base for herbal medicine varies from Level I evidence where a plant has had enough research to allow for a systematic review of randomised controlled trials to Level IV evidence where the knowledge of the plant is based on experience and expert consensus (3). The majority of herbal medicine evidence is empirical being at Level IV, which is seen conventionally as having a lower level of validity when compared with Level I evidence.

However, the empirical basis of herbal medicine is particularly powerful as it spans centuries as opposed to decades and is also often cross cultural. A significant number of national guidelines such as NICE guidelines are partially based on Level IV expert consensus and so this can be considered an acceptable level of evidence, especially considering the low side effect profile of most plant medicines.

Diabetes and in particular Type 2 Diabetes mellitus is becoming a major health issue with an 80.1% increase in the prescribing of diabetic medication in the UK in the decade leading up to 2017, the overall cost of diabetes medication in 2016-17 being £983.7 million (4).

Herbal medicine has a role to play in diabetes with there being 400 herbal medicines which are believed to help diabetes (5).  

Plant medicines which have demonstrated an effect on diabetes in human clinical trials are Gymnema (Gymnema sylvestre) a herbal medicine used traditionally in Ayurvedic medicine (6), fenugreek (Trigonella Foenun-graecum) which has been used in the Middle East and India (7) and cinnamon (Cinnamomum zeylanicum) (8), all of which have beneficial effects on blood glucose levels.

Recent research into type 2 diabetes has also shown that a calorie restricted diet of 800 calories a day for a period of 3-5 months reversed diabetes in 46% (9), and it is likely that the addition of herbal medicines such as Gymnema, Fenugreek and Cinnamon would potentiate the effectiveness of diet in the treatment of type 2 diabetes.

Viral upper respiratory tract infections such as coughs, colds and ear infections are a common reason for patients to attend general practice, with time and patient pressures sometimes leading to unnecessary antibiotic prescribing. This increases the risk of antimicrobial resistance with there being a direct link between the amount of antibiotics prescribed in a community and antibiotic resistance.

It has been estimated that increasing antibiotic resistance could lead to 10 million deaths a year worldwide by 2050, with an estimated 25,000 people dying in Europe each year as a result of antibiotic resistant infections such as MRSA and E. Coli. (10).

The increased education of the public, GPs and Nurse Prescribers in the use of herbal medicines for the self-care of viral infections could lead to reduced antibiotic prescribing, with the use of herbal medicines such as Elderberry (Sambucus nigra fructus) in the treatment of viral upper respiratory tract symptoms including fever, nasal congestion, and headache (11).

In addition, there is evidence that Echinacea (Echinacea angustifolia/purpurea) can be used in the treatment and prevention of colds (12) and Andrographis (Andrographis paniculata) in reducing the symptoms of upper respiratory tract infections (13).

Mental health problems are increasingly prevalent in the UK population with antidepressants representing the biggest increase in prescription items in 2016. 64.7 million prescriptions for antidepressants were issued in 2015-16, with 3.7 million more anti-depressants being dispensed in 2016 than the previous year, and in 2015 anti-depressants cost the NHS £780,000 a day (1).

Herbal medicines have been used for mental health problems for centuries and can play an important role along with lifestyle changes, and psychological therapies in mild and moderate depression.

St John’s wort (Hypericum perforatum) has a high level of evidence (Level 1) with one meta-analysis of 29 trials showing it to be as effective as antidepressants in mild and moderate depression, and more effective than placebo in major depression, with fewer side effects than conventional antidepressants (14).

A 2017 meta-analysis of 27 clinical trials came to similar conclusions when comparing St John’s wort to Selective Serotonin Reuptake Inhibitors (SSRIs) such as citalopram (15). St John’s Wort however does need to be used with attention to the other medication which the patient is taking due to its potential interaction with medications such as the contraceptive pill and warfarin.

Rhodiola (Rhodiola rosea) has also been shown to effect depression (16) and is thought to have adaptogenic effects helping the immune and endocrine system to adjust to stress. Herbal medicines can also be helpful in anxiety with 21 plants having human clinical trial evidence of efficacy such as chamomile (Matricaria recutita), skullcap (Scutellaria lateriflora), passionflower (Passiflora incarnata), and ashwagandha (Withania somnifera) (17).

Ashwagandha has been shown to improve anxiety and stress compared to placebo (18) and the potential for adaptogenic herbal medicines such as ashwagandha and rhodiola along with others such as reishi (Ganoderma lucidum) to help reduce the adverse effects of stress is unique to herbal medicine and highly significant considering the prevalence of stress in the community. The humble chamomile tea (Matricaria recutita) is available from most food stores has been shown to reduce anxiety scores and is a good example of a readily available herbal medicine with significant self-care potential (19).

There can be no doubt that herbal medicines alongside the use of lifestyle medicine and the deprescribing of medications which are no longer indicated can play a critical role in healthcare and reducing a patient’s medication burden. Plant medicines can also play an important part in patient self-care, and the management of stress and mental health problems, as well as in preventative medicine.

There is an urgent need for better education of both the public and frontline health care professionals into the possible benefits of plant medicines, as well as more appropriate research into the use of herbal medicines, especially those which are commonly used by practitioners with good empirical effect but which have not attracted research.

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17. Sarris J. McIntyre E. Camfield DA. Plant-Based Medicines for Anxiety Disorders, Part 2: A Review of Clinical Studies with Supporting Preclinical Evidence. CNS drugs, 2013-08-01, Vol.27 (8), p.675-675
18. Pratt MA, Nanavati KB. et al. An alternative treatment for anxiety: a systematic review of human trial results reported for the Ayurvedic herb ashwagandha (Withania somnifera). Journal of Alternative and Complementary Medicine 2014 Dec;20(12):901-8
19. Keefe JR. Mao JJ. Soeller I. Li QS. Amsterdam JD. Short-term open-label chamomile (Matricaria chamomilla L.) therapy of moderate to severe generalized anxiety disorder. Phytomedicine (Stuttgart), 2016-12-15, Vol.23 (14), p.1699-1705

This focus on the quality of each remedy was elaborated in the second flowering of Galenic medicine in the 9^th-11^th centuries, still widely practised throughout the Islamic world as Unani/Tibb (‘unani’ is the Arabic word for Greek).  Islamic medicine also pays more respect to the qualities of individual herbs than to formulations, Physicians are expected to understand intimately the nature of each remedy, its natural habitat, its specific energy pattern, actions, indications, specific relationships to the organs, duration of action, toxicity and contraindications, types of preparation, dosage, administration and antidotes.

Interestingly the settler traditions of North America in the 19^th century rediscovered Galenic principles themselves. The pioneer Samuel Thomson credited his espousal of heating remedies in fever management not only to native American traditions like the sweat lodge and use of cayenne, but to earlier Greek-Roman concepts. In his widely popular 1835 book ‘New guide to health; or the botanic family physician’ Thomson also espoused vitalistic principles similar to those of Ayurveda and also naturopathy.

1. Health follows from obeying natural laws
2. Disease is an obstruction or diminution of vital energy
3. Disease is caused by violation of natural laws such as:
   • hereditary (violation by forefathers)
   • lack or excess of exercise
   • sudden temperature changes
   • wrong diet and over-eating
   • poisons and pollutants
   • injury
4. Symptoms, such as fever, are due to the effect of the disease and are not the disease itself
5. Disease has only one basic type of cure – to remove obstructions or restore vital energy using substances that act in harmony with natural laws and the vital energy
6. In doing so one or more of the following effects should be accomplished:
   • relaxation
   • contraction
   • stimulation
   • soothing
   • nourishing
   • neutralisation

However neither Thomson, nor his more sophisticated successors in the North American Eclectic and Physiomedical traditions, developed substantial formulation protocols. They did develop deep insights into the vital actions of each herb and so produced the most elaborate materia medicas of the modern age, but like Galen and the Islamic physicians before them clearly kept their focus on the individual remedy. There are formulae in all their books, but it seems these were less important than their role in eastern classic texts.

So discussing Western herbal formulation is much more difficult than the relatively clear descriptions in Chinese and Ayurvedic medicine. Over the course of the last few centuries, largely due to the meteoric rise of allopathic medicine along with various forms of discrimination against Herbal Medicine, much of the traditional language has morphed into modern scientific terminology.

The closing of Eclectic schools in America in the early 20^th Century, and the removal of Physiomedicalism from herbal education in the UK in the late 1970s, shut the doors on the more formal inclusion of vitalism in herbal training. In the face of various legal threats to practice and coupled with the pressure to ‘modernise’ the profession and promote ‘phytotherapy’ as the modus operandi, much of the framework and language of vitalistic thinking has been obscured.

In spite of its modern appearance phytotherapy can still be seen as the end of a cultural line through western history. The benefits of the phytotherapeutic approach to our understanding as herbalists are of course priceless, however an innate lure to the naturalistic means this cultural void has been filled by a somewhat disconnected approach to herbal pharmacology; some phytochemistry, some science, part Galenical, part Physiomedicalist, part Thomsonian, part Eclectic and probably ‘part’ a few other things depending on the herbalist’s training and experience.

This over-emphasis on molecular herbalism risks leading western practitioners away from differential prescription based on a comprehensively clear set of principles. How do we decide on using Melissa or Scutellaria or Taraxacum or Arctium in a clearly logical and vitalistic manner without a common diagnostic framework that is appropriate to how herbs work? In modern times we have been forced down the anti-inflammatory, antispasmodic, generally-anti route and in doing so diminished our collective autonomy.

Do we borrow from Asian traditions, tap into our Celtic past, use our intuition, or justify it all based on 1 out of the 1000s of the chemicals in the plant?

On a more positive note however, if Western practitioners follow the Galenic ideal they formulate from scratch with each patient, starting with a clean sheet of paper and building up an individual blend from a deep insight into the personality of each remedy and their assessment of the needs to the patient in front of them.

There has been much work by eminent herbalists and schools to develop the principles of our herbal traditions into a more cohesive form; Michael Tierra, Anne McIntyre, Graeme Tobyn, Thomas Garran, Jim McDonald to just mention a few have all written useful work integrating different modalities of Western, Ayurvedic, Chinese traditions.

Whether its using the Eclectic’s focus on tissue states (hot-cold/wet-dry/tense-relaxed), or re-birthing Galenical energetics, even some education on the levels of strength of each herb a la Culpepper, there is reflection across the community as to how we answer this cultural question about our identity in a world dominated by a primarily reductionist approach. We would do well to hold close Hippocrates’s advice that “Its more important to understand what sort of person has a disease than what disease a person has.”

That being said, the inherent functionality of the plants, and the very practical approach taken by the Western herbal tradition, means a wealth of information about each species is known. Out of all the herbal traditions, Western Herbal Medicine has perhaps most successfully coupled historical knowledge with phyto- and biochemical approaches, leading to a respected place in many communities and some healthcare systems.

Although some may debate whether the use of a single plant solely based on a disease name is really ‘herbal medicine’, nonetheless, in Germany for example, phytomedicine is widely dispensed alongside allopathic medicines. And the vast increase in high quality research made possible because of this understanding of phyto- and biochemistry is taking the profession to new heights of interaction with the forefront of medicine.

Generally speaking, like its Galenic, Islamic and North American precedents, modern Western Herbal Medicine categorises therapeutic groups of plants by effects on physiology. Often these ‘actions’ are related not only to the system they influence (e.g. expectorants, nervines) but also the class of phytochemical constituents they contain (e.g mucilages, tannins).

Whilst the contribution of Western herbalism to understanding how plants work cannot be underestimated – and new research into the interaction of herbs and the microbiome is revealing startling new insights – this action orientated approach is useful for categorising herbs but it takes you away from seeing the quality with which that activity may work. What a herb ‘does’ is not who that herb ‘is’.

To understand ‘how’ a herb initiates change in a given person you need to understand the character of the person and the herb; Valerian (Valeriana officinalis) and Skullcap (Scutellaria lateriflora) are two very different type of nervines and only knowledge of the traditional uses and doses, the guidance of a good teacher, knowing the vitalistic qualities and direct experience can really help to differentiate.

As the fortunate recipients of the wisdom of our ancestors, much of the differential selection of the best herbs for certain conditions has already been done. Of course, all herbs have more than one ‘action’ and experience has distilled these into their main activity (often described as primary and secondary actions). Further to the active nature of the herb, herbs are designated effective differentiators; Aromatic, Astringent, Bitters, Demulcents, Relaxants, Stimulants. So you can have aromatic nervines, bitter nervines etc. Today, secondary activities are often medicalised terms; anti-bacterial, anti-inflammatory etc.

Excellent summaries by Simon Mills & Kerry Bone, David Hoffman, Jill Stansbury are worth exploring further. Also take a look at the References and Biography further down.

Taking Ulcerative Colitis as an example and drawing from David Hoffman’s Medical Herbalism text as an example of a formula for IBS:

• Bayberry (Myrica cerifera) – 2 parts
• Mugwort (Artemisia vulgaris) – 1 part
• Chamomile (Matricaria recutica) – 1 part
• Wild Yam (Dioscorea villosa) – 1 part
• Peppermint (Mentha piperita) – 1 part
• Valerian (Valeriana officinalis) – 1 part

5ml of a tincture 3x/day. A carminative tea also prescribed.

Action	Herb	Function
Astringent	Bayberry (Myrica cerifera)	Stops diarrhoea, reduces mucus
Bitter	Mugwort (Artemisia vulgaris), Chamomile (Matricaria recutica)	Stimulates digestive secretions
Anti-inflammatory	Wild Yam (Dioscorea villosa), Chamomile (Matricaria recutica)	Reduce localised inflammation
Carminative	Chamomile (Matricaria recutica), Peppermint (Mentha piperita)	Smooth transition of gas
Anti-spasmodic	Wild Yam (Dioscorea villosa), Chamomile (Matricaria recutica), Peppermint (Mentha piperita)	Stop cramping
Vulnerary	Chamomile (Matricaria recutica)	Stops bleeding, damage to intestinal lining
Nervine	Valerian (Valeriana officinalis)	Treats underlying stress and stress from diarrhoea

Adaptogens are strengthening herbs that help us adapt to stress by interacting with the endocrine system. They help normalise metabolism and nourish the tissues. Examples include Licorice (Glycyrrhiza glabra), Ashwagandha root (Withania somnifera), Rhodiola root (Rhodiola rosea) and Ginseng root (Panax ginseng)

Alteratives are herbs that ‘alter’ the condition in a tissue by eliminating metabolic waste via the liver, large intestine, lungs, lymphatic system, skin and kidneys. Examples include Burdock root (Arctium lappa), Dandelion root (Taraxacum officinalis), Cleavers (Galium aparine), Poke (Phytolacca decandra) and Nettle leaf (Urtica dioica).

Amphoterics are herbs that bring balance to different organs, tissues and systems by regulating hyper and hypo functioning. Amphoterics create harmony. Examples include Licorice root (Glycyrrhiza glabra), Oatstraw flowering tops (Avena sativa), Hawthorn berry (Crataegus oxycanthoides).

Analgesic: These are medications that are applied internally or externally to reduce pain, Many of them work by depressing the functions of the central nervous system, Examples of effective analgesics include Jamaican Dogwood (Piscidia erythrina), Pasqueflower (Anenome pulsatilla), California Poppy (Eschscholzia californica), Corydalis (Corydalis yanghusuo) and Wild Lettuce (Lactuca virosa). Topically, Aconite (Aconitum napellus) and Cayenne (Capsicum minimum) are powerful anodynes.

Antimicrobials are herbs that interfere with the proliferation and life-cycle of microbes; bacteria, fungi, and viruses. Examples include Thyme leaf (Thymus vulgaris), Echinacea (Echinacea species), Elderberry (Sambucus nigra).

Aphrodisiac herbs are those that nourish, build and stimulate sexual desire and potency. Examples include Saffron (Crocus sativa) and Ashwagandha root (Withania somnifera).

Astringents: This group of herbs contain tannins that act to precipitate proteins and draw tissues together, tightening and toning them to reduce secretions and discharge. Astringents also tend to stop bleeding and can act on tissues with which there is no direct contact. Examples include Raspberry leaf (Rubus ideaus), Lady’s Mantle leaf (Alchemilla vulgaris), Agrimony leaf (Agrimonia eupatoria), Shepherd’s Purse leaf (Capsella bursa-pastoris), Witch Hazel leaf (Hamamelis virginiana) and Yarrow leaf (Achillea millefolium).

Bitters stimulate digestion by enhancing digestive secretion and peristaltic movements of the gut. They act via a reflex from the taste buds to the brain then through the vagus nerve to whole digestive system. Often these herbs are combined with warming digestives to balance the cold nature of bitters. Examples include Artichoke leaf (Cynara scolymus), Gentian root (Gentiana lutea), Wormwood leaf (Artemisia absinthium), Oregon Grape root (Mahonia aquifolium), Goldenseal root (Hydrastis canadensis)

Cardiotonics: These are herbs that bring order and strength to the cardiovascular system. speed up or slow down the heart as needed. Examples include Hawthorn berry and leaf (Crataegus oxycanthoides), Motherwort leaf (Leonurus cardiaca), Lily of the Valley leaf (Convalleria majalis), Garlic bulb (Allium sativum), Lime flower (Tilia platyphyllos), Mistletoe leaf and berry (Viscum album).

Carminative herbs are high in essential oils and help ease digestion by relieving gas, spasms and cramps. Examples include Aniseed (Pimpinella anisum), Fennel seed (Foeniculum vulgare) and Peppermint leaf (Mentha piperita).

Cholagogues and choleretics: Cholagogues promote the production of bile in the liver. A cholereticis a type of cholagogue that promotes the release of bile from the gall bladder into the duodenum. Cholagogues have an alterative and laxative effect. Cholagogues are contra-indicated if there is acute liver failure, obstructive jaundice, painful gallstones or cholecystitis. Examples include Celandine leaf (Chelidonium majus), Barberry root (Berberis vulgaris), Dandelion root and leaf (Taraxacum officinalis root), and Blue Flag root (Iris versicolor).

Demulcents are soothing mucilaginous and silky herbs that can be taken internally to soothe and protect damaged or inflamed tissue. Examples include Slippery elm bark (Ulmus rubra), Marshmallow root (Althea officinalis) and Limeflower (Tilia cordata).

Diaphoretics are herbs that cause sweating by increasing circulation in the periphary of the body. Usually used to help to relieve fevers some examples are Yarrow aerial parts (Achillea millefolium), Elder flowers (Sambucus niger), Ginger root (Zingiber officinalis).

Diuretics are herbs that stimulate the flow of urine, and help remove fluids from the body. Common examples are Dandelion leaf (Taraxacum officinalis), Burdock root (Arctium lappa) and Corn silk (Zea mays).

Emmenagogues are herbs that stimulate and promote menstruation. Examples include Marigold flowers (Calendula officinalis) and Chaste Tree fruits (Vitex agnus-castus), Turmeric root (Curcuma longa).

Expectorants are herbs that assist the body in expelling mucus from the upper respiratory tract. Examples include Licorice root (Glycyrrhiza glabra), Elecampane root (Inula helenium) and Thyme leaf (Thymus vulgaris).

Galactagogues are herbs that encourage the flow of breastmilk. Examples include Fennel seed (Foeniculum vulgare), Celery seed (Apium graveolens) and Shatavari root (Asparagus racemosus).

Hepatics are herbs that generally support liver function by decongesting as well as supporting bile flow. Examples include Dandelion root (Taraxacum officinalis), Yellowdock root (Rumex crispus), Turmeric root (Curcuma longa).

Hypnotics and sedatives: These are medications that promote a deep and relaxing sleep. They may work through muscle relaxant properties, through the action of volatile oils on the limbic system, or through the presence of alkaloids that affect the central nervous system. Chamomile flowers (Matricaria recutita), Lime flower (Tilia platyphyllos), Lemon balm leaf (Melissa officinalis), Wood Betony aerial parts (Stachys betonica), Skullcap leaf (Scutelleria lateriflora), Wild Lettuce leaf (Lactuca virosa), Passionflower aerial parts (Passiflora incarnata), Ashwagandha root  (Withania somnifera) Valerian root (Valeriana officinalis), Corydalis root (Corydalis yanhusuo), California Poppy aerial parts (Eschscholzia californica).

Hypolipidemics: These herbs mildly reduce serum lipids, including triglycerides and cholesterol. Examples include Hawthorn berry and leaf (Crataegus oxycanthoides), Turmeric root (Curcuma longa), Guggulu resin (Commiphora mukul), Garlic bulb (Allium sativum), and Cayenne fruit (Capsicum annuum).

Hypotensives: These herbs act to reduce a high blood pressure by relaxing muscles or through a calming effect upon the central nervous system. Examples include Hawthorn berry and leaf (Crataegus oxycanthoides), Garlic bulb (Allium sativum), Lime flower (Tilia platyphyllos), Cramp bark (Viburnum opulus), Valerian root (Valeriana officinalis), Motherwort  leaf (Leonorus cardiaca) and Mistletoe leaf and berry (Viscum album).

Immunomodulants: These herbs restore balance to a dysfunctional immune system. These are often used in chronic autoimmunity. such as Crohn’s and multiple sclerosis. Many immunomodulants are adaptogens, and vice versa. Examples include Reishi mushroom (Ganoderma lucidum), Astragalus root (Astragalus membranaceus), Licorice root (Glycyrrhiza glabra), Siberian Ginseng root (Eleuthrococcus senticosus), Ashwagandha root (Withania somnifera) and Cordyceps (Cordyceps sinensis).

Immunostimulants: These herbs stimulate the immune system protecting against infection, including non-specific mechanisms, and the specific mechanisms of humoral and cell-mediated immunity. Many immunostimulants are antimicrobials and vice versa, and are used in both acute and chronic infection. Examples include Echinacea root and leaf (Echinacea spp.), Garlic bulb (Allium sativum), Myrrh resin (Commiphora myrrha), Thyme (Thymus vulgaris, Andrographis leaf (Andrographis paniculata),) and Wild Indigo (Baptisia tinctoria).

Laxative herbs are those that stimulate or promote bowel movements. There are different types of herbs; gentle aperients, like Dandelion root (taraxacum officinalis), that have a mild effect; bulk-forming laxatives, like Flaxseed (Linum usitatissimum), that increase the water and bulk of the stool; stimulant laxatives is Senna leaf (Senna alexandria) that invigorate the muscles of the lower bowel to create a stronger motion. 

Nervines are herbs that soothe the nervous system and have a calming effect on the emotions. Examples include Oatstraw flowering tops (Avena sativa), passionflower (Passiflora incarnata), Lavender (Lavandula officinalis), St. John’s Wort (Hypericum perforatum), Rosemary leaf (Rosmarinus officinalis), and Gotu Kola leaf (Centella asiatica).

Rubefacients: When applied externally these herbs cause a mild local irritation and draw blood to the area through capillary dilation. Rubefacients are used to enhance blood supply to localized areas to remove congestion and promote healing. Examples include Cayenne fruit (Capsicum minimum), Mustard seed (Brassica spp.), Ginger root (Zingiber officinalis), and Peppermint leaf (Mentha piperita oil)

Sialogogues: These are medications that stimulate production of saliva to treat dry mouth, poor digestion, receding gums and infection including Prickly Ash bark (Zanthoxylum americanum), Echinacea root (Echinacea spp) and Spilanthes flower (Spilanthes acmella).

Tonics is a slightly controversial term as it seems to apply to herbs that bring tone to an organ or tissue. It is also used to refer to herbs that help the whole system to function better acting as general energy boosters. Examples of herbs that bvring tone to the tissues are the astringent Goldenseal (Hydrastis canadensis) and Ground Ivy (Glechoma hederacea). Those that bring energy are Cacao (Theobroma cacao), Oatstraw flowering tops (Avena sativa) and Ashwagandha root (Withania somnifera).

Vulneraries: These are wound-healing herbs used internally and externally. Astringent herbs such as Witch Hazel (Hamamelis virginiana) and Shepherd’s Purse leaf (Capsella bursa-pastoris) directly stop bleeding and promote the formation of an eschar (scab). Mucilaginous herbs such as Plantain leaf (Plantago lanceolata) and Selfheal leaf (Prunella vulgaris) soothe inflammation. Some vulneraries are used internally to speed tissue healing, including Marigold flower (Calendula officinalis), Plantain leaf (Plantago lanceolata), Selfheal leaf (Prunella vulgaris), and Marshmallow root (Althaea officinalis).

And Western Herbalists and phytochemists have taken the chemical insights to whole new levels of expertise, allowing for deeply scientific view of the inner workings of how the herbs behave in and act on the body. This has led to a specific understanding of how some species work, greater safety and improved quality standards.

The Monographs in The British Pharmacopoeia (and Indian, Chinese, European, USA etc) list the levels of marker compounds denoting medicinal grade. A pharmacopoeia (a word from the Greek for ‘knowing medicines’) is an official reference text containing a collection of standards to assure the quality of the medicines you can get from a doctor or pharmacy. Many herbs are used as medicines and their medicinal standards are published in the pharmacopoeias:

Herb name	Food grade ISO 6571/1984	European Pharamocopoeia
Chamomile flowers	Min. 0.2% essential oil	0.4% essential oil Apigenin min. 0.25%
Fennel seed (sweet)	Min. 1% essential oil	Min. 2% essential oil (specifying that 80% of this must be anethole with a maximum of 10% estragole and 7.5% fenchone)
Peppermint leaf	Min. 0.6% essential oil	Cut leaf min. 0.9% essential oil Whole leaf min. 1.2% essential oil

The attention to safety with regards contaminants (microbiological, heavy metals, pesticides, pollutants, extraneous materials) as well as quality in terms of upper and lower limits of important compounds) has brought the practice of clinical herbalism into the highest standard of safe and effective healthcare.

Prescribing regulations

Please note that there are specific dispensary standards for blending herbs for individual use that must be followed by practitioners in the UK as a part of our commitment to safe and effective practice through self-regulation. Please refer to your Practitioner Association for the specifics.

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“There is nothing in the world which does not have therapeutic utility when applied in appropriate conditions and situations.” – Charaka Samhita Sutrasthana

The creation of Ayurvedic formulas is based on some fundamental herbal pharmacological principles that are all grouped together in what is known as the dravyaguna shastra – the treatise on the qualities of medicinal substances.

Over 6,000 species have been described in Ayurveda, though perhaps around 600 are in common use today. At its heart is a very simple idea that opposites balance each other (samanya-vishesha). And that the opposite is also true that ‘like increases like’.

Essentially it promotes the idea that substances with like qualities increase each other proportionally:

• Cinnamon and ginger = double spicy, very heating
• Neem and andrographis = double bitter, very cooling
• Those with opposing qualities balance each other: Cooling diets, lifestyles or herbs such as aloe vera remove hot inflammation, whilst heavy herbs like Ashwagandha balance lightness.

Below is a list of the different criteria that are used in Ayurveda to differentiate the potency of each herb that need to be considered when combining herbs:

• Taste (rasa): Sweet, sour, salty, pungent, bitter, astringent (Find more about tastes in our article The Six Tastes of Ayurveda)
• Effect on the metabolic thermal body (virya): Hot, cold and neutral; this category clarifies whether herbs warm you up or cool you down, if they stimulate or reduce the digestive fire, whether they are expansive or contractile by nature, whether they increase circulation or reduce it.

The quantity of impact is graded into degrees:

Degree of heat	Heating flavours
hot in the third degree (hottest)	Pungent (katu)
hot in the second degree	Sour (amla)
hot in the first degree	Salty (lavana)
Degree of cold	Cooling flavours
cold in the third degree (coldest)	Bitter (tikta)
cold in the second degree	Sweet (madhura)
cold in the first degree	Astringent (kashaya)

• Post-digestive effect (vipaka): How the taste of a natural substance changes after digestion and cooking, hence how it influences the doshas and physiology in the long-term. This rather unique interpretation primarily refers to the long-term effects on the fluids of the body and their impact on the bowels and fertility. Drying bitter and pungent herbs, like neem for example, are considered to reduce fertility if used long-term as they ‘dry’ the reproductive fluids.
• Effect on the digestion, fluid system and tissues in the body (guna): The herbs have qualities of light, heavy, unctuous, drying, penetrating and soft; e.g. Mint is light, shatavari is heavy, aloe vera is unctuous, cinnamon is drying.
• The unique properties of the plant (prabhava): This describes what the plant’s unique activities are above and beyond their energetics. For example, tulsi (Ocimum tenuiflorum) is classified as heating but it therapeutically helps to clear heat and reduce fever through diaphoresis. This means that whatever the causes of the fever Tulsi is indicated, along with other appropriate herbs, and this is its prabhava; jwarahara– the fever destroyer.
• Tropism (satmya): The affinity a plant has for a certain organ, tissue or channel (ashaya/dhatu/srotas); e.g. Garlic for the lungs, turmeric for the liver, brahmi for the brain.
• Constitutional (dosha): The effect of the herb on the constitution; i.e. whether it increases, decreases or balances the doshas.

These energetic descriptions of the herbs are all based on the different qualities of nature. To use an artistic metaphor, the theory of energetic pharmacology is the canvas; this is the basis. The herbs are the paints that the artist uses to paint a picture full of texture, depth, colour and clarity.

How the colours of the paints are blended depends on the artist’s interpretation of the scene in front of them, just as the energetic qualities of the herbs are merely guides along the path to finding the perfect formula for the patient. They are not absolutes. This is the stroke of the brush that gives the picture its unique quality. The interpretations of herbal energetics are flexible and depend on who is taking how much, of what and when.

As beauty is in the eye of the beholder, so herbal energetics are in the senses of the experiencer. The skill of the herbalist lies in uniting the theoretical framework of energetic pharmacology (dravyaguna), with the reality of the balanced or imbalanced physiological state of the patient (dosha prakriti and dosha vikriti). 

“Drugs act by virtue of their own nature and qualities at the proper time, in a given place, in appropriate conditions and situations; the effect produced is considered to be their action (karma); the factor responsible for the effect is their energy (virya); where they act is the place (adhisthan); when they act is the time (kala), how they act is the mode of action (upaya); what they accomplish is the achievement (phalam).” – Charaka Samhita Sutrasthana

Having arrived at an accurate Ayurvedic diagnosis the next step is to define the treatment plan. Treatment focuses on clearing out excess doshas, ama and malas and strengthening deficient dhatus, agni, prana, tejas and ojas. Ayurveda uses six main techniques to treat disease and create health:

• Reducing (langhana) where there is an excess. Purification (shodhana) or palliation (shamana) are prescribed for reducing any excess pathologies.
• Tonifying (brimhana) where there is deficiency. Sweet and nourishing tonics (rasayana) are given for building strength.
• Drying (rukshana) therapy is used to alleviate any excess fluids in the system. Herbs that are diuretic or remove mucus dry the system.
• Oleating (snehana) treatments moisturise dryness and give unctuousness to the tissues by using oily and demulcent substances.
• Sweating (svedana) therapy reduces coldness, heaviness, stiffness, ama and trapped heat in the body by using steam and diaphoretic herbs.
• Astringing (stambhana) therapy is used to slow the excessive flow of bodily fluids with tannin rich herbs.

When making a formula based on these techniques, you always focus on:

• Disease specific treatment (vyadhi pratyanika):– focus on mitigating the disease
• Dosa specific (dosa pratyanika):– focus on regulating predominant doshic pattern
• Dhatu specific (dhatu pratyanika):– focus on predominant tissue imbalance
• Digestionspecific (agni):– focus on digestive energy
• Clearing toxins (ama):– focus on cleansing with bitter and pungent herbs

And you may include solutions for:

• Removing obstacles: low digestive fire (mandaagni), blocked channels (srotorodha), undigested wastes/toxins (ama), inflammation (raktapitta, shotha), palliation (shamana), deep cleansing (shodhana)
• Increase mental clarity (sattvavajaya), nourishing the intellect (medhya varga)
• Increase circulation (rakta pravritti)
• Rejuvenate inherited strength (ojas), inner metabolic fire (tejas), life-force (prana), general tonic rejuvenation (rasayana)

Carrier herbs (anupana)

This is the idea that certain substances either act as catalysts or messengers to the main active herb and help carry them to certain parts of the body. The carriers are either mixed with or taken alongside the medicine. Known as an anupana they are the medium that carries the herbs to their intended destination and enhances or moderates their effect. Water (hot or cold), milk, ghee, oil, herb juices, sugar, salt and honey are all used as vehicles.

• Water when hot encourages digestive agni, clears toxic ama and reduces vata and kapha;
• Water when cold reduces pitta;
• Milk counteracts pitta and also encourages the nourishing effect of Ashwagandha (Withania somnifera) or Shatavari (Asparagus racemosus);
• Ghee carries the herbs deep into the tissues, nourishes the nervous and reproductive systems and it also has a catalytic (yogavahi) effect on the herbs that helps to potentise them;
• Aloe vera (Aloe barbadensis) carries herbs to all the tissues with a special affinity for the plasma, blood and reproductive tissues;
• Honey clears kapha due to its warming astringency and is often used with herbs that treat the lungs and congested mucus conditions. It stimulates the appetite and prevents excessive excretions. It acts as a catalytic yogavahi substance that enhances the activity of the herbs taken with it

The herbs ride on these carriers like the scent on the wind. Using an anupana can enhance the potency of a preparation as well as facilitating its journey to the intended destination.

Famous Ayurvedic formula such as Triphala, Trikatu and Kaishor guggul incorporate these principles. Kaishor Guggul is a classic preparation including Triphala, Trikatu and a range of other herbs for reducing pain and inflammation, with a focus on arthritis, gout and skin problems.

Preparing Kaishor Guggul

Dose: 2 pills 2-3x/day with warm water

Each 250mg pill contains:

Common name	Latin name	Dose
Haritaki	Terminnalia chebula	7.75mg
Bibhitaki	Terminalia bellirica	23.26mg
Amalaki	Phyllanthus officinalis	7.75mg
Guduchi	Tinospora cardifolia	11.63mg
Shunthi	Zinigber officinale	5.81mg
Marich	Piper nigrum	5.81mg
Pippali	Piper longum	5.81mg
Vidanga	Embelia ribes	5.81mg
Jaypala	Croton tiglium	0.73mg
Trivrut	Operculina turpenthum	0.73mg
Guggulu	Commiphora mukul (purified)	186.05mg

Triturated with the decoction of: Haritaki (Terminalia chebula), Bibhitaki (Terminalia bellirica), Amalaki (Phylanthus officinalis), Guduchi (Tinospora cordifolia)

• Guduchi has a powerful pitta reducing action that penetrates deeply into the tissues.
• Guggulu scrapes the pitta and vata toxins from the plasma, blood and muscle tissues.
• Triphala, vidanga and trivrut combine to clear inflammatory toxins and ama.
• Trikatu digests the toxins in the tissues and enkindles the tissue agni.

‘Kaishor’ indicates ‘youth’, hence it is used to prevent ageing and keep youth intact.

For the best results the Sarangadhara Samhita recommends that when using guggulu preparations one should avoid sour foods, penetrating foods, indigestion, excessive exercise, hot sun, alcohol and anger.

By learning the basic language of herbs, getting to know the herbs and, overtime, developing your intuition you can take these principles and mould them with your expertise using base formulae as building blocks and adjusting as appropriate for each individual case.

Also read “The Ayurvedic approach to digestive health and nutrition“.

Medicinal substances are classified according to groups that have different physiological actions. The Charaka Samhita lists 50 groups of ten herbs and the Bhavaprakasha Samhita has 24 such categories. These Ayurvedic pharmacological concepts offer deep insight into how herbs work to balance the doshas, dhatus, and malas. They tie together the concepts of taste (rasa), energetics (virya) and post-digestive effect (vipaka) as well as incorporating prabhava so that we can have a clear understanding of the primary action of the herb. The list below contains some of the most popular categories listed throughout the Ayurvedic literature.

• Abhishyandi: These substances block the channels and cause heaviness. The flow of rasa is hindered and stagnation occurs when too much of these substances are used. They are mainly unctuous and heavy in nature; eg. yoghurt obstructs the flow in the channels.
• Anuloma: These herbs help vayu to move in its appropriate direction. They are often mild aperients and help with flatulence and constipation. They are usually aromatic and carminative herbs, commonly from the Umbelliferacea family, such as Fennel seed (Foeniculum vulgare) or Ajmoda (Apium graveolens).
• Arsoghna: There are anti-haemorrhoidal remedies such as Chitrak (Plumbago zeylanicum) or Ginger (Zingiber officinale).
• Artava janana: Herbs promoting the menstrual flow such as Myrrh (Commiphora myrrha).
• Balya: This means strengthening and these herbs are tonics. They are usually heavy and filled with the earth element, like Bala (Sida cordifolia) or Ashwagandha (Withania somniferum).
• Bhedaniya: These are purgative herbs that forcibly expel the solid and liquid parts of faeces. Kutki (Picorrhiza kurroa) has this effect at a high dose.
• Brmhaniya: These are nourishing herbs that are full of the water element; e.g. Shatavari (Asparagus racemosus).
• Chaksushya: These herbs improve eyesight; e.g. Amalaki (Phyllanthus officinalis).
• Chhardi nigrahana: These are anti-emetic herbs such as fresh Ginger (Zingiber officinale recens), Pomegranate juice (Punica granatum) or Cardamom (Elettaria cardamomum).
• Chedana: These herbs actively draw out toxins by scratching them from the tissues; Guggul (Commiphora mukul), Shilajit (Asphaltum) and Black Pepper (Piper nigrum) all help to detoxify the deeper tissues.
• Daha prasamana: These herbs alleviate burning sensations in the body, such as Sandalwood (Santalum album) or Coriander (Coriandrum sativum).
• Dipaniya: These herbs enkindle the digestive fire. They indirectly digest ama. They are usually pungent, hot and dry; for example Long Pepper (Piper longum), Black Pepper (Piper nigrum) and Chitraka (Plumbago zeylanicum).
• Garbashaya: These herbs have an affinity for the uterus, such as Ashoka (Saraca indica) and Roses (Rosa centifolia).
• Grahi: These herbs dry the moisture of the body and of the wastes; Ginger (Zingiber officinale), Cumin (Cuminum cyminum).
• Hikka nigrahana: These herbs are anti-hiccough such as Clove (Syzygium aromaticum).
• Hridaya: These herbs have a tonic effect on the heart; Arjuna (Terminalia arjuna) and Ashwagandha (Withania somnifera).
• Jeevaniya: These herbs are life-giving and rejuvenative herbs such as Amalaki (Phyllanthus officinalis).
• Jwarahara: These are anti-pyretic herbs for stopping fevers including Musta (Cyperus rotundus) and Kalmegh (Andrographis paniculata).
• Kandughna: These are anti-pruritic herbs such as Peppermint (Mentha piperita), Turmeric (Curcuma longa) and Musta (Cyperus rotundus).
• Kanthya: These herbs are renowned for their affinity for the throat; for example Licorice (Glycyrrhiza glabra), Long Pepper (Piper longum).
• Kasahara: These are anti-tussive herbs such as Vasaka (Adhatoda vasaka) or Long Pepper (Piper longum).
• Krumighna: These herbs are specifically for removing parasites and worms; for example Neem (Azadiracta indica) or Kalmegh (Andrographis paniculata).
• Kushtaghna: These are herbs that treat skin diseases such as Neem (Azadiracta indica) or Manjishta (Rubia cordifolia).
• Lekhaniya: These herbs ‘scrape’ the waste residues out of the body by a drying action. They are usually bitter and pungent in flavour; for example Guggul (Commiphora mukul), Myrrh (Commiphora myrrha), Vacha (Acorus calamus), Turmeric (Curcuma longa), Triphala, Barley and Honey.
• Madakari: These are substances that cause intoxication, such as alcohol.
• Mutra sangrahaniya: These herbs reduce the flow of urine such as Bhallataka (Semecarpus anarcadium)
• Mutravirechana: These herbs are diuretics that increase the flow of urine, such as Gokshura (Tribulus terrestris) and Coriander (Coriandrum sativum).
• Nidrajnana: These herbs promote sound sleep; eg Tagarah (Valeriana wallichi), Ashwagandha (Withania somnifera)
• Pachana: These herbs directly ‘digest’ ama.  They do not necessarily stimulate digestion as well; e.g. Triphala.
• Praja sthapana: These herbs prevent miscarriage such as Ashoka (Saraca indica).
• Pramathi: These herbs remove the accumulated doshas from the dhatusand cells; e.g. Vacha (Acorus calamus) and Black Pepper (Piper nigrum).
• Purisha sangrahaniya: These are intestinal astringents that stop diarrhoea such as Bilva (Aegle marmelos).
• Rakta shodhana (rakta prasadana): These herbs specifically clean the blood and ‘alter’ its chemistry so that it does not cause inflammatory problems; for example Manjishta (Rubia cordifolia).
• Rechana: These herbs are cathartics. They forcibly expel faeces as semi-solid diarrhoea; e.g. Castor oil (Ricinis communis) or Rhubarb root (Rheum palmatum).
• Rasayani: These herbs rejuvenate the cells and extend life. They are anti-oxidants and also remove diseases; e.g. Guduchi (Tinospora cordifolia), Amalaki (Phyllanthus officinalis) and Haritaki (Terminalia chebula).
• Samjanasthapana: These herbs are used to restore consciousness; eg Vacha (Acorus calamus).
• Sandhaniya: These herbs heal broken bones and hasten the repair of broken bone tissue. Guggul (Commiphora mukul) is famous for this. Resins have a significant role here because resins in general are considered to relate to the blood part of plants just as the bark of trees is said to relate to bone tissue. The analogy is that just as resin heals the bark so it heals the bone. They also encourage circulation to flow to the wounded part of the body and hasten healing.
• Shamana: These are herbs that reduce the pathogenic level of a dosha to a more healthful level. The dosha is not expelled from the body, it is calmed. These are ‘palliative’ herbs; e.g. Guduchi (Tinospora cordifolia).
• Shirovirechan: These are herbs that clear the orifices of the head, also known as errhines. Such herbs are Vacha (Acorus calamus) or Cloves (Syzygium aromaticum).
• Shodhana: These herbs actually clear the excess doshas out of the body; e.g. Triphala, Castor oil (Ricinus communis) or Manjishta (Rubia cordifolia).
• Shonita sthapana: These are haemostatic herbs such as Manjishta (Rubia cordifolia).
• Shramshana: Herbs that are laxatives and clear faeces before complete digestion is complete; e.g. Trivrut (Operculina turpethum).
• Shula prasamana: These are anti-colic herbs that prevent intestinal spasms; for example Hingu (Ferula asafoetida) or Cumin (Cuminum cyminum).
• Shukrala: Herbs that increase semen and/or give force to its ejaculation; e.g. Amalaki (Phyllanthus officinalis), Aswagandha (Withania somnifera) and Shatavari (Asparagus racemosus).
• Shukra janana: These are sperm increasing herbs; for example Ashwagandha (Withania somnifera) and Safed Musali (Asparagus adcendens).
• Shukra shodhana: These herbs purify the sperm such as Gokshura (Tribulus terrestris).
• Snehopaga: These are moistening herbs such as Castor oil (Ricinis communis) or Tila/Sesame (Sesamum indicum).
• Stambhana: These are astringent herbs that are constipating, stop bleeding and are drying. They have the properties of vata and so increase it. Manjishta (Rubia cordifolia) is a renowned astringent that stops bleeding diseases.
• Stanya janana: These herbs can increase lactation; for example Fennel (Foeniculum vulgare) and Shatavari (Asparagus racemosus).
• Stanya shodhana: These herbs purify the breast milk such as Fennel (Foeniculum vulgare) and Musta (Cyperus rotundus).
• Sukshma: These herbs are penetrating herbs that can travel through the minutest channels, such as Salt, Neem oil (Azadiracta indica) and Gotu Kola (Hydrocotyle asiatica).
• Swasahara: These herbs prevent breathing difficulties such as Somalata (Ephedra vulgaris) and Vasaka (Adhatoda vasaka).
• Swedopaga: Herbs that induce sweating such as Vasaka (Adhatoda vasaka).
• Triptighna: These herbs are thirst quenching such as Amalaki (Phyllanthus officinalis).
• Udara prasamana: These are allergy treating herbs such as Pit shirish (Albizzia lebbek).
• Vajikarana: These are aphrodisiacs that increase sexual desire, strengthen the reproductive system and nourish shukra dhatu; for exampleKapikacchu (Mucuna pruriens), Ashwagandha (Withania somnifera).
• Vamana: These are emetic herbs. They work specifically on pitta and kapha that have accumulated in the stomach. They move upwards and outwards. High doses of Licorice (Glycyrrhiza glabra) are emetic as is Madanphala (Randia dumentorium).
• Varnya: These herbs benefit the complexion and skin lustre. Aloe vera (Aloe barbadensis), Sandalwood (Santalum album) or Rose water (Rosa centifolia).
• Vedana sthapana: These are analgesic herbs such as Cloves (Syzygium aromaticum) or Ashoka (Saraca indica).
• Vikasi: These herbs destroy the tone of the joints by loosening the ligaments; e.g. Betel nut (Areca catechu).
• Virechana: These herbs are purgatives that move downwards. They dissolve undigested foods and expel them; e.g. Haritaki (Terminalia chebula).
• Vishaghna: These are anti-toxin herbs that destroy ‘poison’ in the system; e.g. Neem (Azadiracta indica), Kutki (Picrorrhiza kurroa) and Sariva (Hemidismus indica).
• Vyavayi: These herbs spread everywhere in the body and are then digested; e.g. Ganja (Cannabis sativum) and Opium (Papaver somniferum).
• Yogavahi: These are catalyst herbs. When they are mixed with another herb they enhance its action; e.g. Ginger (Zingiber officinale), Honey and Ghee.

You can find all Ayurveda articles on our Insights page

• Ayurvedic Pharmacopoeia of India, Government of India, 2001, India
• Bartram, T, Encyclopedia of herbal medicine, Grace Publishers, 1995, UK
• Bensky, D and Gamble, A, Chinese herbal medicine: Materia medica, Eastland Press, 1989, USA
• Bensky, D and Gamble, A, Chinese herbal medicine: Formulas & Strategies  Eastland Press, 1993, USA
• Bhishagratna, K, Susruta Samhita, Chowkhamba Press, 1996, India
• Bone, K, Clinical applications of Ayurvedic and Chinese herbs, Phytotherapy Press, 1996, Australia
• Bone, K, A Clinical guide to blending liquid herbs, Churchill Livingstone, 2003, UK
• Bone, K and Mills S, The principles and practice of phytotherapy, 2^nd edition Churchill Livingstone, 2013, UK
• British Herbal Medicine Association, British Herbal Compendium, BHMA, Vols 1 and 2, 1992, 2006, UK
• British Herbal Medicine Association, British Herbal Pharmacopoeia. BHMA, 1983, UK
• Che, Chun-Tao & Wang, Zhi & Chow, Moses & Lam, Christopher. (2013). Herb-Herb Combination for Therapeutic Enhancement and Advancement: Theory, Practice and Future Perspectives. Molecules (Basel, Switzerland). 18. 5125-41. 10.3390/molecules18055125.
• Chen J and Chen T, Chinese medical herbology and pharmacology, Art of medicine press 2004, USA
• Dash, B, Fundamentals of Ayurvedic medicine, Konark Publishers, 1978, India
• Dash, B, Materia medica of Ayurveda, Jain Publishers, 1991, India
• Dash, B and Sharma, R, Charaka Samhita, Chowkhamba Press, 1996, India
• Dwarkanath, C,  Introduction to Kayachikitsa, Chaukhambha press, 1996, India
• Ganora, L, Herbal Constituents, Foundations of Phytochemistry, 2019, USA
• Gogte, V, Ayurvedic pharmacology and therapeutic uses of medicinal plants, Bhavan’s Book University, 2000, India
• Govind das Vicharita, Bhaishajya Ratnavali, Motilal Banarsidas, 1997, India
• Hoffman, D, Medical herbalism, The science and practice of herbal medicine, Healing Arts Press, 2003, USA
• Kaptchuk, T, The web that has no weaver: understanding Chinese medicine, Congdon and Weed, 1983, USA
• Lad, V,  Textbook of Ayurveda: Fundamental Principles, The Ayurvedic Press, 2002, India
• Lad, V,  Textbook of Ayurveda: General Principles of Management and Treatment, 2012, The Ayurvedic Press, 2002, India
• Maclean, W and Lyttleton, J, Clinical handbook of internal medicine, Volume 1& 2, University of Western Sydney, 2002, Australia
• Meulenbeld, G, The Madhava Nidana and its chief commentary: chapters 1-10, Leiden and Brill, 1974, Holland
• Meulenbeld, G, Reflectons on the basic concepts of Indian pharmacology, in studies on Indian medical history edited by G Meulenbeld and D Wujastyk, Forsten, 1987, Holland
• Meulenbeld, G,  A history of Sanskrit medical literature,  Egbert Forsten. 2001, Holland
• Mills, S, The essential book of herbal medicine, Penguin Arkana, 1991, UK
• Murthy, P, Sarangadhara Samhita, Chowkhamba Press, 2001, India
• Murthy, S, Vagbhata’s  Astanga Hridayam, Krishnadas Academy, 1991-1995, India
• Murthy, S, Madhava Nidana (Roga viniscaya) of Madhavakara, Chaukambha Orientalia, 1995, India
• Murthy, S, Sarangadhara Samhita, Chaukhamba Orientalia, 1995, India
• Murthy, S, Bhavaprakasha of Bhavamisra, Krishnadas Academy, 2001, India
• Nadkarni, A, Indian materia medica, Popular Prakashan, 1954, India
• Namjoshi, A et al, The Ayurvedic formulary of India,  Government of India Press, 1978, , India
• Paranjpe, P, Indian medicinal plants: forgotten healers, Chaukhamba Sanskrit Pratishthan, 2001, India
• Paranjpe, P, Ayurvedic medicine, the living tradition, a guide to Ayurvedic generic formulations Chaukhamba Sanskrit Pratishthan, 2003, India
• Rang, H, Dale, M, and Ritter, J, Pharmacology, Churchill Livingstone, 1999, UK
• Reddy, R, Bhaisajya kalpana vijnanam, Chaukhambha Sanskrit Bhavan, 2001, India
• Sexena, N, Yogaratnakara, Chaukhambha Orientalia, 1995, , India
• Sharma, P, Cakradatta: a treatise on the principles and practices of Ayurvedic medicine,  Chaukhamba Publishers, 1998, , India
• Svoboda, R, Prakruti: Your Ayurvedic constitution, Geocom, 1988, USA
• Svoboda, R, Ayurveda: life, health and longevity, Penguin/ Arkana, 1992, India
• Svoboda, R and Lade, A, Tao and Dharma, Lotus Press, 1995, USA
• Tierra, M, Planetary herbology, Lotus Press, 1992, USA
• Tillotson, A, The one earth herbal sourcebook, Twin Streams, 2001, USA
• Tirtha, S, The Ayurveda encyclopedia, Ayurvedic Centre Holistic Press, 1998, USA
• Trease and Evans, Pharmacognosy 16^th edition, Harcourt 2009, UK
• Tobyn, G, Culpepper’s medicine: a practice of holistic medicine, Element, 1997, UK
• Williamson, E, Major herbs of Ayurveda, Churchill Livingstone, 2002 (Williamson 1), UK
• Zhou, Xian & Seto, Sai Wang & Chang, Dennis & Kiat, Hosen & Razmovski-Naumovski, Valentina & Chan, Kelvin & Bensoussan, Alan. (2016). Synergistic Effects of Chinese Herbal Medicine: A Comprehensive Review of Methodology and Current Research. Frontiers in Pharmacology. 7. 201. 10.3389/fphar.2016.00201.

A herbal prescription is a blend of herbs ranging from 1 to over 50 herbs plus, though more commonly from around 6-12 herbs. These formulas are often prescribed as a powder, pill, water (tea or decoction) or alcohol extraction (tincture or extract). Depending on the client, the illness, and the herb(s), the dose can range from low milligram doses to 100g or more a day.

Today we understand this idea of formulation, of how combining species together brings greater efficacy and safety, through the idea of synergy which is another way of saying “The whole is more than the sum of its parts”. Synergy implies a reciprocally beneficial relationship where plants’ nutrients and phytochemicals potentiate and support one another yielding a therapeutically superior result beyond that of their individual effects.  It opens up to the ideas of creative emergence where something can materialise out of the complexity that would not have manifested otherwise.

Given our 10 million or so years of human evolution its no surprise that our human genes respond very well to a wide range of low dose natural phytochemicals. Just think, if there are 1000 compounds in a plant and as we used to sustain our diet from around 150 species of plants (compared with around 20 today) our human eco-system is familiar with around 150,000 plant molecules. In contrast to this, modern medicine’s high-dose, single-molecule medicine has no precedent in our evolutionary history.

Whilst a high dose of a drug may be valuable in an emergency, herbs are the medicines we evolved to use for our everyday health. Tradition and synergy prove they work best when used as whole herbs, or full-spectrum extracts, in blended formulae.

As alluded to above, synergy is coupled with diversity. More diversity leads to greater efficacy and safety.

Synergy is coupled with greater efficacy as a low dose of many compounds work together to enhance their effects; e.g. energetically Ginger and Black pepper when used together are more pungent than when used alone, and phytochemically, Berberine’s bacteria modulating effects are enhanced by Methyoxylated flavonolignans in Mahonia aquafolium, or the multiple compounds in Hypericum perforatum that have been attributed with neurological effects, are more effective taken together than alone.

And safer. Synergy is coupled with safety as it can also ameliorate potential toxicity of some compounds; many herbs, such as aconite or calamus are traditionally prepared with other herbs, such as licorice and/or ginger, to mitigate extremes.

A great summary of synergy in herbal medicine is here by Eric Yarnell : https://restorativemedicine.org/journal/synergy-in-herbal-medicines-part-1/

Also, valuable to read is Lisa Ganora’s Herbal Constituents, Foundations of Phytochemistry.

Whilst there are many insights from different cultures, my experience is rooted in the Ayurvedic, Chinese and Western herbal traditions and so we will explore those approaches to making a herbal formula.

You can find more articles on Herbal Medicine on our Herbalism page.

• Ayurvedic Pharmacopoeia of India, Government of India, 2001, India
• Bartram, T, Encyclopedia of herbal medicine, Grace Publishers, 1995, UK
• Bensky, D and Gamble, A, Chinese herbal medicine: Materia medica, Eastland Press, 1989, USA
• Bensky, D and Gamble, A, Chinese herbal medicine: Formulas & Strategies  Eastland Press, 1993, USA
• Bhishagratna, K, Susruta Samhita, Chowkhamba Press, 1996, India
• Bone, K, Clinical applications of Ayurvedic and Chinese herbs, Phytotherapy Press, 1996, Australia
• Bone, K, A Clinical guide to blending liquid herbs, Churchill Livingstone, 2003, UK
• Bone, K and Mills S, The principles and practice of phytotherapy, 2^nd edition Churchill Livingstone, 2013, UK
• British Herbal Medicine Association, British Herbal Compendium, BHMA, Vols 1 and 2, 1992, 2006, UK
• British Herbal Medicine Association, British Herbal Pharmacopoeia. BHMA, 1983, UK
• Che, Chun-Tao & Wang, Zhi & Chow, Moses & Lam, Christopher. (2013). Herb-Herb Combination for Therapeutic Enhancement and Advancement: Theory, Practice and Future Perspectives. Molecules (Basel, Switzerland). 18. 5125-41. 10.3390/molecules18055125.
• Chen J and Chen T, Chinese medical herbology and pharmacology, Art of medicine press 2004, USA
• Dash, B, Fundamentals of Ayurvedic medicine, Konark Publishers, 1978, India
• Dash, B, Materia medica of Ayurveda, Jain Publishers, 1991, India
• Dash, B and Sharma, R, Charaka Samhita, Chowkhamba Press, 1996, India
• Dwarkanath, C,  Introduction to Kayachikitsa, Chaukhambha press, 1996, India
• Ganora, L, Herbal Constituents, Foundations of Phytochemistry, 2019, USA
• Gogte, V, Ayurvedic pharmacology and therapeutic uses of medicinal plants, Bhavan’s Book University, 2000, India
• Govind das Vicharita, Bhaishajya Ratnavali, Motilal Banarsidas, 1997, India
• Hoffman, D, Medical herbalism, The science and practice of herbal medicine, Healing Arts Press, 2003, USA
• Kaptchuk, T, The web that has no weaver: understanding Chinese medicine, Congdon and Weed, 1983, USA
• Lad, V,  Textbook of Ayurveda: Fundamental Principles, The Ayurvedic Press, 2002, India
• Lad, V,  Textbook of Ayurveda: General Principles of Management and Treatment, 2012, The Ayurvedic Press, 2002, India
• Maclean, W and Lyttleton, J, Clinical handbook of internal medicine, Volume 1& 2, University of Western Sydney, 2002, Australia
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Pain is a normal neurological response to a real or impending injury aimed at triggering an appropriate conservational response. Chronic pain is defined as a pain that is perceived beyond the accepted time involved in tissue healing (approximately 3 months) (1).

Interestingly, when pain receptors (called nociceptors) which respond to chemical, thermal or mechanical changes get stimulated over a large period of time, the brain neurons responsible for pain processing become over-sensitive, reducing the overall pain threshold of the individual. This process is called central sensitisation and plays a crucial part in the development of chronic pain conditions (2).

Moreover, medical literature provides evidence of the complex multidimensionality of chronic pain conditions, meaning that the psychological, emotional, social and behavioural aspects of an individual’s life play a role in the dynamics related to pain perception (3).

Chronic inflammation and chronic pain go hand in hand: a prolonged and abnormal inflammatory response mediated by the immune system can lead over time to an increased sensitisation of pain receptors (31). Nutritional deficiencies, excess consumption of pro-inflammatory foods, sedentary lifestyle, exposure to pollutants, gut flora imbalance and inappropriate exercise can all contribute to the process of inflammation and hence chronic pain (32, 33, 34, 35).

Additionally, when the survival mechanism of the body is abnormally activated, stress hormones such as adrenaline, noradrenaline and cortisol change the homeostasis of the tissues, leading to detrimental consequences, such as a decrease in pain tolerance and increase in tissue degeneration. Moreover, the cognitive part of the brain under the influence of stress hormones is less capable to detach the focus from the pain stimulus, meaning that the more stressed the individual is, the more physical pain becomes a burden in his/her life (30).

In terms of epidemiological data, The Global Burden of Disease Study 2016 stated that chronic pain-related diseases are the leading cause of disability and disease burden globally (4). In the UK only, a survey from 2017 reported that 34% of adults in the UK are affected by some forms of chronic pain (5).

As chronic pain is a condition that has psychological, emotional and social aspects, disciplines specialised in addressing the different dimensions of pain perception management have become popular; therapies such as hypnosis, acupuncture, CBT and massage therapy (36). Despite the existence of these alternative ways to deal with pain, pharmaceuticals are still extremely popular and among them one of the most prescribed classes of drugs are opiates.

Opiates are a double edge sword: although they are effective at reducing the symptoms, the risk of developing a physiological addiction is dangerously high (7). In the USA the prescription opiates abuse is at such a critical level to be considered an epidemic: deaths related to prescription opiates in 2010 was double of 2002 while 70% of drug related deaths in 2019 was linked to opiates (roughly 50.000 individuals) (8,9). In the UK the situation is not as dramatic as overseas, but prescription (and illegal) opioid related deaths are on the rise (10).

The lack of a side effect-free solution for managing chronic pain is putting many individuals on their knees; nevertheless, an ever-growing number of people who persisted in the quest for an effective alternative treatment for their condition are finding a possible solution in a herbal medicine native to Southeast Asia.

Kratom (Mytragina speciosa) is a widely cultivated tropical tree belonging to the Rubiaceae botanical family and indigenous to Southeast Asia. kratom has been used for centuries by the indigenous people of Southeast Asia both as a stimulant and a sedative. There are three main varieties of kratom whose names are given by the colour of the veins: green, white and red. Green strain kratom is said to be more potent of the other two, but the evidence is only anecdotal (39).

Its leaves, which are usually chewed or consumed as tea or powder, contain psychoactive indole alkaloids which have shown to have a strong affinity with the opioid receptors in the central nervous system (11).  These psychoactive compounds are mitragynine (the most abundant), 7-OH-mitragynine (the most bioactive), speciociliatine and corynantheidine.

Most of the research has been conducted on mitragynine and 7-OH-Mitragynine, which appear to bind agonistically mainly to µ-, κ- and δ- opiate receptors, causing analgesia and euphoria. Interestingly, these molecules are structurally different from common opiates such as morphine and they have been called ‘atypical opiates’.

This denomination has been given to them because they act as opiate receptor agonists without triggering the potentially harmful side effect common to opiate drugs use such as respiratory depression, sedation and constipation; this process is thought to happen because kratom indole alkaloids do not activate β-arrestin, a protein linked to cascade activation of opiates side effects (13). Because of this unique selective property, kratom could have a therapeutic potential as an opiate drug substitute in the mitigation of withdrawal syndrome (14).

The first document on kratom as an opioid alternative was published in 1988 and it concludes by stating that kratom might be a successful substitute for methadone as a rehab strategy (15).

Following this study, experiments on mice confirmed that kratom alkaloids cause significantly lower addictive behaviors compared to morphine-addicted control groups (16), while individuals using kratom alongside other narcotics reported higher quality social life and improved management of withdrawal syndrome.

In addition, kratom users alongside opiates report longer abstinence periods (up to one year) and have remarkably less chances to develop an opiate addiction (17,18,19).

In one online survey from 2017 involving 2798 American kratom users, 91% of them selected ‘pain management’ as a reason for using the herb, while another survey from the same year conducted by the American Kratom Association on 2867 individuals showed that 48% of participants used kratom to relieve pain and 10% used it as an opioid drug substitute (20, 21). Although specific studies on kratom and chronic pain management are still limited, there is significant evidence showing it to be a safer remedy compared to synthetic opioids when used long-term.

Kratom leaves can be consumed in different ways: hot infusions, chewed (the traditional way in Southeast Asia) and smoked. Most people take it in forms of pills, capsules, extract or as a powder mixed with a beverage (37, 40). A unique characteristic of kratom is to be both a stimulant and sedative depending on the dosage.

A few grams of dried leaves, cause an excitatory response in the central nervous system, while larger doses (5+ g) give the opiate-like euphoria and sedation (12).  In terms of safety, the available literature is controversial; although its use poses a risk of overdosing a thousand times smaller than opiates (25, 26), kratom use has been associated with liver toxicity and withdrawal syndrome.

In a detailed report from 2020 on liver toxicity associated with kratom consumption the FDA flagged 25 individual cases related to the toxic effects of kratom on the hepatic system. 37% of the individuals concerned have taken 5g to 20g daily of kratom in a powdered form for an average of 21 days before starting to notice signs and symptoms of malaise, jaundice and dark urine.

Nevertheless, there is no information regarding the existence of pre-existing medical condition of the consumers, nor specific hepatotoxic mechanism have been identified in human and animal studies. It is postulated that some compounds other than mitragynine could be cytotoxic to hepatocytes although there is no clear evidence (38). 

On the other hand, other sources state that no cases of death have been confirmed to be caused by kratom alone and most of the fatalities associated with its intake also involved the clear overconsumption of other drugs. There are high chances then that the fatality cases signaled by the FDA and other organisations might be biased by inadequate postmortem toxicology data and testing protocols (25).

The symptomatic side effects of taking kratom are somewhat similar to the opiate ones; these include nausea, vomiting withdrawal symptoms such as hostility, aggression, aching of muscles and bones and insomnia with potential increase of tolerance to the herb (27, 28).

Nevertheless, these symptoms are exceptionally milder compared to opiates, presenting with less intensity, the onset within about 12 to 16 hours and a duration of 1 to 3 days (26). In addition, a survey conducted on 2798 kratom users showed that less than 10% of participants developed the aforementioned withdrawal symptoms after one or more years of use (18).

Due to lack of research, there is no accepted standard safe dosage of kratom powder or extract but it is widely accepted that long-term use of kratom leaves for treating chronic pain and opiates withdrawal is not recommended due to its potential for addiction and hepatotoxicity (26).

Nevertheless, short-term use of kratom leaf powder appears to be relatively safe; a survey involving more than 8000 individuals revealed that withdrawal symptoms are dose/frequency dependent and a dosage of 5g three times a day elicited the desired analgesic effects in most of the participants while causing severe side effects only in 0.65% of the population (40).

Kratom quality is also another important factor to consider; due to the restricted regulations about the marketing of kratom products, most of the available kratom on the UK market is likely to come from the dark web or other illicit channels of trade. These unregulated products are a potential threat as they are likely to not have been subjected to quality tests, might not give the desired effects or could even be harmful (41).

To safely consume kratom then only use it under the guidance of a qualified practitioner in countries where it is legal and subjected to quality controls; to start with a low dosage (no more than 15g a day) and to quit immediately if side effects start to appear.

The legal status of kratom varies from country to country. In Europe, for instance, it is legal in Belgium, Netherlands and Germany but illegal in Italy and Switzerland, while controlled In Denmark and Portugal. Even in the US different states have contradictory laws about kratom. In the UK, the 2016 Psychoactive Substance Act put a ban on all substances and herbs known to have psychotropic effects unless regulated. This turned kratom into an illegal substance and made it unavailable on the market (29).

This article evaluated the potential of Mitragyna speciosa, kratom leaves, as a substitute for opioid and opiate drugs in the management of chronic pain. Chronic pain is a condition which burdens both the individual and the medical system in most countries worldwide; commonly prescribed drugs for managing chronic pain are opioids and opiates, which effectively modulate the symptoms but cause undesirable side effects, cause addiction and increase the risk of death by overdose when used long-term

Mitragynine and 7-OH-Mitragynine, the predominant indole alkaloids in kratom leaves, act as opiate receptors agonist causing opiate-like euphoria, analgesia and sedation without depressing the respiratory system and posing a far lower risk of developing serious addiction and withdrawal symptoms.

Despite its potential therapeutic benefits, various studies report side effects from kratom use such as hepatotoxicity and withdrawal symptoms. In conclusion, even though kratom appears to be an effective but less harmful remedy to manage chronic pain when compared to opiate drugs, its prolonged use could also have a negative impact on human health. In order to allow kratom to be legally prescribed, further pharmacological investigations on its safety and toxicity are required.

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Psilocybin is a naturally occurring tryptamine alkaloid discovered within the hundred plus species of psychedelic mushrooms occurring in many of the temperate or tropical climates of the world. Most commonly referenced as being an isolated constituent within the fungi genus of Psilocybe (4), psilocybin is just one constituent within a cocktail of potent compounds found within psychoactive mushrooms. Other constituents found within the Psilocybe genus include the alkaloid psilocin and a range of beta-carbolines including harmane and harmine. Both of which are potent inhibitors of monoamine oxidase enzyme (5).

The average psilocybin content within the psilocybe species is about 1%. Meaning one gram of mushrooms provides approximately 10mg of psilocybin (6). A number of modern human trials using psilocybin to treat depression follow the guide of 20mg-30mg psilocybin per 70kg of human body weight (7).

Like many psychoactive compounds, psilocybin exerts its effect on the nervous system via the 5-HT2A receptor. This is the same receptor targeted by selective serotonin reuptake inhibitor (SSRI) anti-depressant drugs. The difference is that psilocybin works as an agonist of the receptor, thereby producing a different and a potentially much more profound psychoactive reaction than SSRI.

This much needed help is looking like it is found within one of nature’s most magical gifts, the humble psychedelic mushroom. In recent decades ethnobotanists have discovered that the use of mushrooms for religious, healing and divinatory experiences spans across multiple indigenous cultures. From a herbalist’s point of view, what unites all of the global distribution of psychedelic mushrooms is the collection of potent neuro-active metabolites that inhabit each mushroom. Psilocybin being one of these inherent metabolites of particular interest to scientists, researchers and psychiatry.

The traditional view taken by governments of the world is one of great caution and criminality when considering the cultivation, possession, consumption and/or prescription of psilocybin containing mushrooms. The majority of countries around the world have legislation that makes it illegal to pick, grow, possess and consume psilocybin containing mushrooms.

After many decades of protest by indigenous communities, scientists and organisations such as the Multi-disciplinary Association for Psychedelic Studies (MAPS) endlessly campaigning for the safe and legal use of psilocybin containing mushrooms we can now see a positive momentum of change across the western world.

In November 2019 the United States Food and Drug Administration granted the Usona Institute ‘Breakthrough Therapy’ designation to conduct clinical trials on the use of psilocybin for treating MDD [viii]. This phase 2 trial involving 80 participants is due to finish in Spring 2021 (9) with results most likely showing psilocybin can produce sustained and substantial decreases in symptoms of anxiety and depression.

These healing effects have been shown before in sporadic trials with some even reporting sustained improvements in depressive symptoms following a single high dose treatment of psilocybin at the 6 month follow-up for almost 80% of the participants involved (10).

In 2016 the Beckley Foundation, based in London (UK) published results from a trial that involved 12 patients with moderate to severe, treatment resistant depression (11). After prescribing two dosages (10mg and 25mg, seven days apart) in a supportive setting, 67% of patients were depression free one week after treatment.

42% were still in remission three months later. These results are revolutionary when compared to conventional pharmaceutical options. Similar research has also been explored with other plant based psychedelic treatments for depression such as Ayahuasca (12).

Given the current conventional medical paradigm of patenting medicines, the trials involving psilocybin for depression remains in this exploratory stage. It could be that in years to come as more evidence emerges on how therapeutic isolated psilocybin can be, that we see a global distribution of this treatment. This does however bring up the question as to how taking isolated psilocybin on its own as a patented medicine compares to using the whole mushroom as found in the wild or through cultivation. This is a debate that has gone on for many decades between herbalists, pharmacists and scientists. The discussion of reductionism versus holism.

Many users of psilocybin containing mushrooms consume the whole mushroom on its own without considering the legal situation or cost of attaining a pharmaceutical isolate of psilocybin. This is all with the backdrop of the growing movement towards drug decriminalisation moving through the world, particularly the U.S.

In November 2020 the state of Oregon went further than decriminalisation and became the first state in the U.S to pass legislation that legalised the medicinal use of psilocybin (13). At the moment this doesn’t mean that whole psilocybin containing mushrooms can be openly sold at dispensaries like cannabis is, but it does mean they are drafting proposals for how and which treatment centres can provide psilocybin for those who wish to explore this method of treatment. This may follow other examples around the world, such as Holland, where Psilocybin mushrooms in the form of truffles are offered as a tool for healing and self-development (14).

It is forecasted that as more research on psilocybin is produced and the evidence-base is enhanced, then it is inevitable that more parts of the world will follow the path that medicinal cannabis has taken. Fewer prosecutions and ‘turning a blind eye’ to decriminalisation, to legalisation for medical treatment, and finally to potential legal cultivation, possession and consumption.

It remains to be seen how this movement of research, science, recreational use and overall discussion will lead us to. Each individual country will decide on the path they decide to take but it finally feels like the healing role of our more misunderstood plant and fungi allies is finally being acknowledged.

1. Davis, A. K. Barrett, F. S. May, D. G. et al. (2020) Effects of Psilocybin-Assisted Therapy on Major Depressive Disorder – A Randomized Clinical Trial, JAMA Psychiatry, 10.1001/jamapsychiatry.2020.3285
2. Greenberg, P. E. Fournier, A. A. Sisitsky, T. Pike, C. T. Kessler, R. C. (2015) The Economic Burden of Adults with Major Depressive Disorder in the United States (2005 and 2010), Journal of Clinicla Psychiatry, Feb;76(2): p. 155-162.
3. Nemeroff, C. B. (2007) Prevalence and Management of Treatment-Resistant Depression, Journal of Clinical Psychiatry, 68 Suppl 8: p. 17-25.
4. Peredy, T. Bradford, H. (2014) Mushroom, Psilocybin, Encyclopaedia of Toxicology (Third Edition), p. 418-419.
5. Blei, F. Dorner, S. Fricke, J. Baldeweg, F. Trottman, F. Komor, A. Meyer, F. Hertwick, C. Hoffmeister, D. (2019) Simultaneous Production of Psilocybin and a Cocktail of β‐Carboline Monoamine Oxidase Inhibitors in “Magic” Mushrooms, Chemistry – A European Journal, Vol. 26 (3) p. 729.734.
6. https://psychedelicreview.com/chemical-composition-variability-in-magic-mushrooms/
7. https://newatlas.com/johns-hopkins-psilocybin-study-finds-optimum-beneficial-dosage/18981/
8. https://www.businesswire.com/news/home/20191122005452/en/FDA-grants-Breakthrough-Therapy-Designation-Usona-Institutes
9. https://usonaclinicaltrials.org/major-depressive-disorder-psilocybin-clinical-trial-psil201
10. Griffiths, R. R. Johnson, M. W. Carducci, M. A. et al. (2016) Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial, The Journal of Psychopharmacology, Dec;30(12): p. 1181-1197.
11. Carhart-Harris, R. L. Bolstridge, M. Rucker, J. Day, C. M. J. Erritzoe, D. Kaelen, M. et al. (2016) Psilocybin with psychological support for treatment-resistant depression: an open-label feasibility study, Lancet Psychiatry, May 17.
12. Jimenez-Garrido, D. F. Gomez-Sousa, M. Ona, G. Dos Santos, R. G. Hallak, J. E. C. Alcazar-Corcoles, M. A. Bouso, J. C. (2020) Effects of Ayahuasca on mental health and quality of life in naïve user: a longitudinal and cross-sectional study combination, Scientific Reports 10, 4075.
13. https://www.nytimes.com/interactive/2020/11/03/us/elections/results-oregon-measure-109-legalize-psilocybin.html
14. https://www.synthesisretreat.com

Essential oil compounds, such as carvacrol and thymol (the hot and spicy compound found in oregano and thyme), destroy the bacterial cell membrane rendering them inactive. Green tea also does this.

Epigallocatechin gallate (EGCG), a polyphenol in green tea,impedes the bacteria’s own enzymes that are released to deactivate antibiotic activity. Tannins also do this and Triphala, one of Ayurveda’s most famous formulas made from the fruits of amla, bibhitaki and haritaki, is often used in antimicrobial formulas.

This system, called the efflux pump, is designed to stop antibiotics entering the bacterial cell and is a major cause of drug resistance. Certain compounds in some herbs inhibit this pump, allowing the antibiotics to deactivate the microbe. Baicalen found in thyme and some Scutellaria species reverses MRSA resistance to ciproflaxin by inhibiting the bacteria’s efflux pump.

Quorum sensing is the bacteria’s own protective mechanism enabling it to rally against compounds that are toxic to it, for example, by creating defensive-matrix biofilms, that act as a inhibitory barriers. Cinnamon, cranberry, garlic, ginseng and propolis interfere with this process, breaking down the web and preventing the microbes adhering together as a powerful conglomerate.

Herbs such as clove, dill and tea tree oil interfere with microbial energy cycles thus weakening its life cycle and rendering the microbe useless.

By targeting viral proteins, herbs can disrupt the life cycle of the microbe and block the proliferation of the invading virus. Andrographis has been shown to do this with the cold sores caused by herpes simplex 1 as well as with various flu viruses. Elderberry has been shown to deactivate the neuraminidase enzyme released by eight strains of flu.

Herbs work independently to limit microbial advance as well as enhancing the effects of antibiotics when they are most needed. They work synergistically as a single plant and when used in multi-herb combinations. They also work collaboratively with pharmaceutical antibiotics.

As healthcare professionals face the daily onslaught of sore throats, sinus problems, urinary infections and superficial wounds, it begs the question of why we are so readily using antibiotics known to cause resistance when the history, tradition and science for using plants is so robust? This question is particularly urgent given that the big antibiotic guns are being disempowered by overuse rather than preserved for life-threatening situations.

The list of medicinal plants that can enhance immunity and protect from infection is extensive. Further to the above-mentioned species, some of the most favoured in modern herbal clinical practice, also available for over the counter (OTC)  use and with solid scientific backing, are andrographis (Andrographis paniculata), echinacea (Echinacea purpurea/angustifolia), elderberry (Sambucus nigra), neem (Azadirachta indica) and tulsi (Ocimum sanctum). Their potential for helping solve the current healthcare crisis of antibiotic resistance is enormous.

Here we have only really discussed the way herbs defend against an attack by bacteria, but the herbal paradigm also embraces the concept of strengthening immunity by galvanizing both innate and acquired immunity. Herbalists use immune modulators to treat the broader spectrum of autoimmune, inflammatory and proliferative disorders so prevalent in modern healthcare. Again, the multi-dimensional and synergistic impact of herbs interfaces with our health in the broadest possible sense; herbs help us adapt to our environment and enhance our response to it.

One of the most interesting ways that these plants, with their complex phytochemical components, appear to work is by interfacing with our microbiome in our gut. As many plant compounds are not actually absorbed into the blood stream, it appears that they initiate signalling through our own probiotic bacteria. Signalling is when herbs initiate a response within our own probiotic bacteria so that a chain reaction occurs from herb to bacteria to our physiology. This is even more of a reason to not disturb unnecessarily our intestinal gut bacteria with antibiotics and keep our microbiome intact by using natural plants to keep us at our best.

• A paper from the European Herbal and Traditional Medicine Practitioners Association (EHTPA) for the House of Commons Select Committee on Science and Technology’s antimicrobial resistance (AMR) inquiry.
• Coon JT, Ernst E. Andrographis paniculata in the treatment of upper respiratory tract infections: a systematic review of safety and efficacy. Planta Med. 2004 Apr;70(4):293-8. Review.
• Chan BC, Ip M, Lau CB, Lui SL, Jolivalt C, Ganem-Elbaz C, Li taudon M, Reiner NE, Gong H, See RH, Fung KP, Leung PC. Synergistic effects of baicalein with ciprofloxacin against NorA overexpressed methicillin-resistant Staphylococcus aureus (MRSA) and inhibition of MRSA pyruvate kinase. J Ethnopharmacol. 2011 Sep 1;137(1):767-73.
• Hemaiswarya S, Kruthiventi AK, Doble M. Synergism between natural products and antibiotics against infectious diseases. Phytomedicine. 2008 Aug;15(8):639-52.
• Mondal S, Varma S, Bamola VD, Naik SN, Mirdha BR, Padhi MM, Mehta N, Mahapatra SC. Double-blinded randomized controlled trial for immunomodulatory effects of Tulsi (Ocimum sanctum Linn.) leaf extract on healthy volunteers. J Ethnopharmacol. 2011 Jul 14;136(3):452-6.
• Poolsup N, Suthisisang C, Prathanturarug S, Asawamekin A, Chanchareon U. Andrographis paniculata in the symptomatic treatment of uncomplicated upper respiratory tract infection: systematic review of randomized controlled trials. J Clin Pharm Ther. 2004 Feb;29(1):37-45. Review.
• Ponnusamy K, Ramasamy M, Savarimuthu L, Paul raj MG. (2010). Indirubin potentiates ciprofloxacin activi ty in the NorA efflux pump of Staphylococcus aureus. Scandinavian Journal of Infectious Diseases. 42, (6-7) :500-505.
• Sharma SM, Anderson M, Schoop SR, Hudson JB. Bactericidal and anti -inflammatory properties of a s tandardi zed Echinacea extract (Echinaforce): dual actions agains t respi ratory bacteria. Phytomedicine. 2010 Jul ;17(8-9):563-8.
• Vanka A, Tandon S, Rao SR, et al. The effect of indigenous Neem ( Adirachta indica) mouth wash on Streptococcus mutans and lactobacilli growth. Indian J Dent Res. 2001;12:133-144.
• Wagner H, Ul rich-Merzenich G. Synergy research: approaching a new generation of phytopharmaceuticals. Phytomedicine. 2009 Mar;16(2-3):97-110. Review part 1.
• Zakay-Rones Z, Varsano N., Zlotnik M, Manor O., et al Inhibition of several strains of influenza virus in vitro and redution of symptoms by an elderberry extract (Sambucus nigra L.) during an outbreak of influenza B in Panama. Journal of Alternative and Complementary Medicine. 1995;1(4):361-369

The ‘gold standard’ measure of efficacy is the randomised double-blind controlled clinical trial (RCT). The remedy to be tested is given to a population of subjects on the same basis as a placebo or comparison medicine in a way that neither the subjects nor the investigators know who is getting which.

This is intended to reduce conscious and unconscious bias, and by careful matching of each comparison group, and choosing a large enough population, to eliminate other factors such as natural improvements in the condition, suggestion and expectations, that may affect outcome.

There are many arguments about the reliability of the RCT to all circumstances and conditions. It does not reflect individual experiences of illness, is less useful in complex, rare and long-term conditions and blinding is often hard to assure.

‘Publication bias’ results when authors and sponsors hold back on results that do not reflect their expectations and tends to skew reports towards those that are positive. RCTs are very demanding and methodological rigour is also not assured. Nevertheless there is no substitute for a good RCT if we want to get some measure of the independent activity of a remedy.

RCTs require complex organisational capacity, specialist statistical and other skills, are subject to intensive ethical scrutiny, and therefore are notoriously expensive. However there are increasing numbers of such studies being published for herbs.

There is no doubt however that the RCT inventory for herbs is patchy and usually not conclusive. The best way to consider the evidence base is to link it to the most substantial resource we do have: the many centuries of human experience.

We can claim really useful information by distilling out the vast store of historical and anthropological records for the use of herbs as medicines (the science of ethnopharmacology). We can note that there would have been little room for sentiment and idealism in the life-and-death situations that prevailed through most of history.

The herbal remedies that have floated to the top of popular reputation around the world will have been tried and tested in the most adverse conditions, as the only medicines available and without backup ambulances and hospital emergency rooms: if they did not work they would not have been continuously and widely used.

However without rigorous screening the record of traditional use can appear motley. Each community and even family will have its own favourites. The placebo effect of a cultural icon is very powerful: if everyone around you is convinced that the remedy will work then it likely will.  Assessing traditional reputations is only reliable if we take broad overviews of the multitude of local stories.

Fortunately we can do this. We can take anthropological records from around the world. We can discount one tradition as a local fashion; if we can find a similar use in two discrete locations that looks like something more substantial; three or more distinct uses becomes a much stronger lead.

Some of our most popular remedies, like green tea, liquorice, chamomile, dandelion, mint, ginger, turmeric, cinnamon and other spices, have all established global reputations by being rediscovered anew in many parts of the world.

Some of the regional high flyers have grown their reputation across many distinct regions in their own continents and have established themselves more widely as well.

• Andrographis, ashwagandha, gotu kola and shatavari from India
• Astragalus and ginseng from China
• Echinacea from North America

We can also go deeper and look at what emerge as universal core pharmaceutical principles of early medicine, applying the simplest of all technologies: taste, smell and other senses.

When animals encounter plants they use their senses to understand them. Taste and smell are the main judges of quality and safety. Humans inherited these same instincts and then elaborated them to construct basic pharmaceutical standards for evaluating their remedies.

All classical medical traditions, from India, China, Islam and Europe categorised their medicines by taste and sensory quality. Although the language and cultural meanings were different the core insights were astonishing consistent and we can distil simple principles that each of us can use today.

If you look at the descriptions of the herbs on this site you will see that we invite you to do what our ancestors did: taste the herb! This is often a striking revelation. From what is often a powerful simple sensory hit we can often feel for ourselves what our elders understood about these remedies.

The following presents commonly encountered impacts of herbal remedies and how they translate into modern descriptions of their effects when we consume them. Key phytochemical groups are in bold: these most clearly transfer sensory experiences into pharmacology and are like the Rosetta stone – they provide instant translation of multiple local traditions into modern language.

Aromatic flavour

An ‘aromatic’ remedy, high in volatile essential oils, was most often associated with calming and sometimes ‘warming’ the digestion. Most kitchen spices and herbs have this quality: they were used both as flavouring and to ease the digestion of sometimes challenging pre-industrial foods. Many aromatics are classed as ‘carminatives’ and are used to reduce colic, bloating and agitated digestion.

They also often feature in respiratory remedies for colds, chest and other airway infections. They are also classic calming inhalants and massage oils, and are the basis of aromatherapy for their mental benefits.

Astringent taste

The puckering, astringent taste you get with many plants (the most familiar is black tea after being stewed too long, or some red wines) is produced by complex polyphenols such as tannins. Tannins are used in concentrated form (e.g. from oak bark) to make leather from animal skins. The process of ‘tanning’ involves the coagulation of relatively fluid proteins in living tissues into tight clotted fibres (similar to the process of boiling an egg).

Tannins in effect turn exposed surfaces on the body into leather. In the case of the lining of mouth and upper digestive tract this is only temporary as new mucosa are replenished, but in the meantime can calm inflamed or irritated surfaces. In the case of open wounds tannins can be a life-saver – when strong (as in the bark of broadleaved trees like oak) they can seal a damaged surface.

One group of tannins, the reddish-brown ‘condensed tannins’ are classified as procyanidins, which can reduce inflammation and oxidative damage.

Bitter taste

Bitters are a very complex group of phytochemicals with one thing in common: they stimulate the bitter receptors in the mouth. They were some of the most valuable remedies in ancient medicine. They were experienced as stimulating appetite and switching on a wide range of key digestive functions, including increasing bile clearance from the liver (as bile is a key factor in bowel health this can now be translated into improving bowel functions and the microbiome).

Many of these reputations are being supported by new research on the role of bitter receptors in the mouth and elsewhere round the body.

Bitters were also seen as ‘cooling’ reducing the intensity of some fevers and inflammatory diseases.

Blue/purple colour

Any fruits with a blue-purple colouring contain high levels of the polyphenols known as anthocyanidins. These work:

1. On the walls of small blood vessels, helping to maintain capillary structure to reduce a key stage in inflammation, and improving the microcirculation to the tissues
2. To improve retinal function and vision
3. To support connective tissue repair around the body.

Hot/spicy taste

Traditional ‘hot’ or ‘heating’ remedies, often containing spice ingredients like capsaicin, the gingerols (ginger), piperine (black or long pepper), curcumin (turmeric) or the sulfurous isothiocyanates from mustard, horseradich or wasabi, generate warmth when taken. In modern times this might translate as thermogenic and circulatory stimulant effects.

There is evidence of improved tissue blood flow with such remedies: this would lead to a reduction in build-up of metabolites and tissue damage.
Heating remedies were used to counter the impact of cold, reducing any symptoms made worse in the cold. The proof of this effect is in the doing of it: the results are often almost immediate!

Mucilaginous quality

Mucilages are complex carbohydrate based plant constituents with a slimy or ‘unctuous’ feel especially when chewed or macerated in water. Their effect is due simply to their physical coating exposed surfaces. From prehistory they were most often used as wound remedies for their soothing and healing effects on damaged tissues.

Nowadays they are used more for these effects on the digestive lining, from the throat to the stomach, where they can relieve irritation and inflammation such as pharyngitis and gastritis. Some of the prominent mucilaginous remedies like slippery elm, aloe vera and the seaweeds can be used as physical buffers to reduce the harm and pain caused by reflux of excess stomach acid.

Mucilages are also widely used to reduce dry coughing. Here the effect seems to be by reflex through embryonic nerve connections: reduced signals from the upper digestive wall appear to translate as reduced activity of airway muscles and increased activity of airway mucus cells. Some seed mucilages, such as in psyllium seed, flaxseed (linseed) or guar bean survive digestion to provide bulking laxative effects in the bowel. These can also reduce rate of absorption of sugar and cholesterol

Resinous taste

Resins are most familiar as tacky discharges from pine trees (and as the substance in amber, and rosin for violin bows). They were most valued however as the basis of ancient commodities like frankincense and myrrh (two of the three gifts of the Three Wise Men to the baby Jesus) and getting access to their source was one benefit to Solomon for marrying the Queen of Sheba (now Ethiopia). Resins were the original antiseptic remedies, ground and applied as powders or pastes to wounds or inflamed tissues, and were also used for mummification.

With alcohol distillation it was found that they could be dissolved in 90% alcohol and in this form they remain a most powerful mouthwash and gargle, for infected sore throats and gum disease. They never attracted much early research interest because they permanently coat and damage expensive glassware! For use in the mouth, gums and throat they are best combined with concentrated licorice extracts to keep the resins in suspension and add extra soothing properties. It appears that they work both as local antiseptics and by stimulating white blood cell activity under the mucosal surface. They feel extremely effective!

Sharp taste

The sharp taste of some fruits, and almost all unripe fruits, as well as vinegar and fermented foods, is produced by weak acids (the taste is generated by H⁺ ions from acids stimulating the sour taste buds). Sour taste buds are hard-wired to generate immediate reflex responses elsewhere in the body. Anyone who likes the refreshing taste of lemon or other citrus in the morning will know that one reflex effect is increased saliva production.
Other effects are subjective rather than confirmed by research but there is a consistent view that they include increased digestive activity and contraction of the gallbladder.

Smell of hay

The familiar country odour of haymaking, of drying grass and other plants, is largely produced by coumarins (originally isolated from tonka beans – in French coumarou) and widely used in perfumery. They have strong antioxidant activity in the laboratory and likely effects in modulating inflammation. They were most often associated with plants used in stuffing mattresses and pillows to encourage sleep.

Soapiness

When extracted in water some plants cause a lather and are used for washing. This property is due to the presence of saponins (from the Latin for soap), which are plant steroids.

Plants that are rich in saponins keep appearing across the world as important gynaecological and adaptogenic remedies (examples are shatavari, ashwagandha, astragalus, brahmi, ginseng, eleutherococcus, liquorice, kava, wild yam, and several important Native North American women’s remedies). Given this striking association it has been speculated that these plant steroids may modulate steroids metabolism in the adrenal cortex, ovary, and testes. Saponins are discussed briefly in a similar context under the sweet taste below.

Other saponins are used for their detergent properties as cough remedies: examples are the primulas, soapwort, senega, and ivy leaf. These exert a minor irritant effect similar to that of emetics and induce a well-known expectorant response by reflex from the upper gut to the airways.

Sweet taste

In the days when most people never tasted sugar, ‘sweetness’ was associated with the taste of basic foods: that of cooked vegetables, cereals and meat. In other words sweet was the quality of nourishment, and ‘tonic’ remedies. Describing a remedy as sweet generally led to that remedy being used in convalescence or recovery from illness.

Interestingly, the plant constituents most often found in classic tonics like licorice, ginseng are plant steroids including saponins, which also have a sweet taste.

A key point about these sensory guides to the action of herbs is that they led to a quite different understanding of what a medicine does. In herbal tradition medicines were classified by what they did for the body rather than what diseases you used them for. Medicines were warming or cooling, drying or moistening; they moved variously through the body, they aided eliminations from various quarters, they tonified.

The aim in herbal treatment is to match the action of the medicine to the needs of each individual. It is critical in understanding the traditional evidence base to understand this distinction and to incorporate it into any practice-based judgment.

Even however taking a modern medical view, there are many other cases where scientific research can illuminate and validate traditional practices, and vice versa. The early use of salicylate-rich willow bark to reduce fever and inflammation, the widespread use of liquorice sticks as tooth brushes, the 3000-year use of psoralen-rich plants in the treatment of vitiligo in India, the use in ancient Egypt of a treatment for angina pectoris based on visnagin and khellin, the unusual traditional practices in the growth and preparation of kava for reducing anxiety: all have all been validated by modern research and lessons have been learnt.

Ethnopharmacological studies show countless examples where pharmacological activity can be demonstrated in traditional remedies and practices.

Such tie-ups are clearly interesting; in effect the early reputation provides “human bioassay data” as a basis for future research and an assurance of relative safety. By contrast modern medicinal research has to start with novel chemicals that have never been used by humans before, and most promising new leads fail for safety reasons.

The examples above suggest that being able to combine two or more incomplete data sources can provide useful pointers to benefit, especially as the calculations are bedded in longterm human use over centuries.

All such evidence is circumstantial until fully verified. However if you are looking for promising leads to help someone whose conditions are not otherwise being well managed, then you can do worse than apply that other law-court principle, “on the balance of probabilities”, and try out one of the established traditional herbal remedies described on this site.

Evidence-base for herbal practice

There are many robust sources of herbal evidence, with online libraries like PubMed (free), Embase and Scopus (subscription) providing updated clinical trial reports, systematic reviews and meta-analyses in real time. There are also a range of paid-for herb-specific literature review services such as ESCOP, Natural Standard, HerbMedPro, the American Herbal Pharmacopeia and other specialist services.

The following texts are useful resources for practitioners wishing to use the evidence base in support of their clinical application of herbal remedies:

• Barnes, J, Anderson L, Phillipson JD (2007)  Herbal Medicines 3^rd Edition. Pharmaceutical Press, London [leading pharmacy-oriented guide to the evidence]
• Bone K and Mills S (2013) Principles and Practice of Phytotherapy, 2^nd Edition. Churchill Livingstone/Elsevier. [standard evidence-based text used in herbal medicine courses]
• Mills, S and Bone K eds (2005) The Essential Guide to Herbal Safety. Churchill Livingstone/Elsevier [a pragmatic guide to real and imagined safety evidence]

Rigorous consensus reviews of efficacy and safety evidence for many herbs used in Europe as medicines are available free online from The European Medicines Agency

Traditional use information

There are few original resources for those starting out on a search of traditional uses of herbal remdies. The following are recommended as including original anthropological accounts of traditional use. The focus here is on how earlier traditions were articulated in modern times, particularly the 19th and 20th centuries, rather than going to pre-modern original texts. Serious scholars will go to major resources like the Wellcome Library for the History of Medicine in London, or pursue ethnopharmacological literature at various schools of pharmacy and universities around the world.

These texts are suggested as introductions to traditional use of plants in different cultures.

• British Herbal Medicine Association. (1983) The British Herbal Pharmacopoeia 1983. Bournemouth, England. [UK herbal practitioner practices up to the mid-20^th century]
• Dalby, A (2000) Dangerous tastes: the story of spices.British Museum Press, London. [fascinating story of the world spice traditions and trading histories]
• Kaptchuk, T.J. (1983) The Web that has no Weaver: Understanding Chinese Medicine. Congdon & Weed, New York. [the most accessible introduction to the therapeutic principles]
• Lassak EV. and McCarthy T. (1983) Australian Medicinal Plants. Methuen Australia
• MacDonald, C (1974) Medicines of the Maori. Collins, New Zealand. [a great example of traditional use uninfluenced by other cultures]
• Moerman D.E. (1998) Native American Ethnobotany. Timber Press, Portland, Oregon [the most comprehensive resource of indigenous North American tribal uses]
• Perry L.R. (1980) Medicinal Plants of East and Southeast Asia. The Massachusetts Institute of Technology Press. [an absolute classic resource  of Asian folk use]
• Pole, S (2013). Ayurvedic Medicine. Elsevier [a great modern review of this tradition for the modern world]
• Ullman, M. (1978) Islamic Medicine. Edinburgh University Press
• Unschuld, P.U. (1985) Medicine in China: A history of Ideas. University of California Press. [a masterful review of the context]
• Vogel V.J. (1970) American Indian Medicine. University of Oklahoma Press. [a classic review]