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Garlic is a potent antimicrobial and antioxidant medicine with an extensive amount of impressive research

Garlic

Allium sativum Amaryllidaceae

Garlic is a panacea for all the ills. It is an invaluable medicine for the treatment of cardiovascular diseases such as atherosclerosis, hypertension and hyperlipidaemia as well as having potent actions to support respiratory and digestive health.

Sustainability Status

Sustainability status

Not currently on risk lists but complete data may be missing on the status of the species. Read more about our sustainability guide.

Key benefits
  • Digestive health
  • Respiratory health
  • Hyperlipidaemic
  • Antioxidant
  • Hypotensive
  • Common cold
  • Atherosclerosis
  • How does it feel?

    Garlic is a well-known kitchen bulb that is used extensively around the world. Its hot, pungent or spicy taste sensation is loved by many and used in a wide variety of cuisines. Garlic can be used fresh, as a tincture or dried in capsule form.

    However, its powerful taste may not be desirable on its own, and so it is sometimes used as a herbal honey. The honey does not mask the taste but transforms or softens it as well as the slight burning sensation that is sometimes felt on taking it in its raw form.

    It is rarely used as an infusion. However it may also be made into a decocted stock or in a broth, for example with rice noodles along with miso other spices such as ginger.

  • What can I use it for?

    garlic Allium sativumGarlic is one of the most readily available kitchen remedies that is a medicine chest in its own right. It is a great example of a home remedy that is in fact extremely potent medicinally for a wide range of acute conditions. It can be used to support general health, particularly in the cardiovascular, digestive, respiratory and immune systems.

    Garlic has many desirable medicinal properties from improving microcirculation and blood quality, to providing anti-bacterial and antioxidant properties. Garlic also helps to regulate blood sugar and blood lipids as well as improve the structural health of the microcirculation (for example arteries and capillaries). It is an all round super food that can be used as part of the diet to support one’s systemic health.

    Garlic is a highly valuable home remedy for upper respiratory tract infections and catarrhal conditions. It has a powerful anti-bacterial effect due to the high levels of aromatic compounds in garlic. These aromatic qualities appear on the breath quickly after ingestion. This is because they travel directly to the air sacs (alveoli) in the lungs where they are then exhaled. These volatile oils cleanse the bronchioles and alveoli of the lungs.

    Garlic is therefore an excellent support for lung health. It can be used for colds, coughs and mild chest infections to help clear mucus in the lungs. It is also powerfully antioxidant and anti-inflammatory to the lung tissues whilst opening up the airways to improve lung function overall.

    Finally, garlic is an excellent prebiotic that increases intestinal microbiome diversity. It can be used for flatulence and indigestion whilst also supporting the digestive process and assimilation of nutrients. Its anti-bacterial activity means it can be helpful in the treatment of mild food poisoning and dysentery.

  • Into the heart of garlic

    garlic seedsIn Ayurvedic medicine there is a unique model and understanding of what each organ does and how they connect. Ayurveda has its own unique philosophy and understanding of bodily systems and herbal qualities (or energetics) that has been built up over thousands of years of observation.

    In Ayurveda, there are three doshas: vata, pitta and kapha. Their energies are believed to circulate in the body and govern physical, mental and emotional characteristics. They are described as follows; vata- controls basic bodily functions as well as the mind, pitta- which governs metabolism, digestion and hormones linked to appetite and finally, kapha – which is responsible for strength and stability, muscle growth, weight and the immune system.

    By the traditional Ayurvedic understanding, garlic is understood to have pungent, light and warming qualities. Its dosa effect is VK- P+ meaning that it reduces vata and kapha (congestion) and enhances pita. It is said to be an invaluable medicine for digestive fire (11) . Garlic penetrates all tissues and enhances vital energy where there is coldness or atrophy in the body.

    Garlic rejuvenates vata, encouraging the free flow of breath. In Ayurvedic medicine garlic is said to be generative of inward, inspiring energy that connects the mind, inspiration and breath, regulating mental functions and respiration (11).

    Garlic is a fantastic decongestant to use during bouts of the common cold. But its decongesting effects also work on a more systemic level by inducing diaphoresis and outward movement of stagnation and heat through the skin – a classic action of aromatic pungent herbs.

  • Traditional uses

    Many medicinal plants and plant preparations were found in the tombs of ancient Egyptian pharaohs. Garlic bulbs were found in the tomb of Tutankhamun. Hot water extracts from garlic bulbs mixed with honey were a European folk remedy for whooping cough and intestinal worms.

    In Pakistan, a garlic extract is traditionally taken orally for illness of the stomach, to treat coughs and reduce fever. In Nepal, East Asia and the Middle East, garlic has traditionally been used to treat fevers and a variety of illnesses associated with the digestive system and lungs (14).

  • Traditional actions

  • Traditional energetic actions

    Herbal energetics are the descriptions Herbalists have given to plants, mushrooms, lichens, foods, and some minerals based on the direct experience of how they taste, feel, and work in the body. All traditional health systems use these principles to explain how the environment we live in and absorb, impacts our health. Find out more about traditional energetic actions in our article “An introduction to herbal energetics“.

  • What practitioners say

    Cardiovascular system

    Garlic has a multitude of therapeutic effects in the circulatory system. It is used by herbalists in the treatment of high blood pressure, atherosclerosis and to improve overall cardiovascular health.

    Garlic is used as a supportive treatment for hypertension. It works via a relaxing effect on the endothelium that lines the capillary walls. It also dilates the blood vessels and is powerfully antioxidant and regenerative to the vascular structures (1) via enhanced capillary skin perfusion (4). These actions combined allow garlic to produce effective results for treating high blood pressure and is safe to use at home. However for serious conditions it is advisable to see a clinical herbalist rather than just rely on home herbalism.

    garlic plant and bulbs

    A number of antioxidant compounds in garlic are responsible for the positive effects that garlic has on the endothelium (namely allicin and its derivatives). Garlic also reduces cholesterol and blood lipid levels. It is these effects combined that explain garlic’s well-referenced use as a prophylactic treatment in atherosclerosis (1).

    Garlic’s effect on atherosclerosis can also be explained by its capacity to reduce lipid content in arterial cells and to prevent intracellular lipid accumulation as well as having a regenerative effect on the vascular tissue (10). Garlic is both preventative and causes regression of atherosclerosis. This is an example of how herbs work to create an effect through multiple actions, as a result of their diverse phytochemistry.

    Digestive system

    Garlic can be used for a number of conditions in the digestive system. It has many health promoting properties including the ability to modulate the gut microbiota by enriching beneficial gut bacteria.

    Garlic may be used for food poisoning or other infections in the digestive system due to its powerful antimicrobial actions and prebiotic activity. Garlic increases the beneficial Lactobacillus acidophilus bacteria. It has a unique selective action which means that it is able to remove pathogenic bacteria without affecting the natural microflora (11).

    Garlic is also anti-parasitic, and antifungal against Candida albicans. It would work well for either as part of an approach that addresses dietary sugars and allows for recovery from the gastrointestinal inflammation that often results from these infections.

    Respiratory system

    Garlics powerful volatile oils have a potent therapeutic effect on the lungs. The oils appear on the breath shortly after ingestion which shows how they are transported via the cardiovascular system into the lung tissue. Garlic increases arterial oxygen levels and alveolar-arterial oxygen (9).

    It is a herb that should be considered for use in chronic respiratory diseases and lung infections. Used correctly and as part of an integrated approach garlic is one of the most established plant medicines for tuberculosis (TB). Allicin acts as an immunomodulator in TB helping more protective T helper cells to respond whilst actively reducing the bacterial burden of Mycobacterium tuberculosis in the lungs (12,13).

    Metabolic

    Garlic is sometimes used by herbalists in the treatment of elevated blood lipid levels that are insufficiently controlled by diet (1). It is also a powerful antioxidant that improves cell function and regeneration via its free radical scavenging effects.

    Garlic increases the speed that red blood cells travel at, which results in vasodilation (widening) of pre-capillary arterioles. This increase in the diameter of the blood vessels results in an increased inflow of interstitial fluidity. Interstitial fluid is the fluid found around cells which helps bring oxygen and nutrients to the cells and to remove waste products from them. This makes garlic an essential medicine for any conditions that may require deep healing on a cellular level through improved micro-capillary function and cellular perfusion (3).

    External uses

    An infused oil of garlic may be used for fungal infections and ringworm, as well as for ear infections (11). A mild oil infusion is often all that is required. For ear infections simply place half a clove of garlic roughly chopped into around 10ml of olive oil for between 1 and 6 hours. The garlic can be removed or filtered out and the remaining oil may be applied into the ear canal at 1 single drop twice daily. The oil can also be applied around the ear externally. It is important to use sterile equipment when making such preparations so as not to introduce further infection into the ear.

  • Research

    garlic bulbsThere have been many studies on garlic and its medicinally active constituents. Research has well established a number of its actions as related to a compound called allicin. These properties are well confirmed through a significant body of in vitro studies that show a strong evidence base for garlic’s anti-atherogenic, lipid-lowering, antihypertensive, anti-aggregatory, endothelium-relaxing, vasodilatory and antioxidant effects (1).

    There is an extensive amount of research into the anti-lipid effects of garlic and its compounds. There are also a large number of double-blind controlled clinical studies in human subjects that show the efficacy of garlic for the treatment of high blood pressure some of which have been included below (1). A systematic review of studies carried out on garlic and its constituents confirms the extensive evidence for its uses to reduce the risk for cardiovascular diseases. The anti-tumor, anti-microbial effects and hypoglycaemic actions are also confirmed (2).

    Cardiovascular health

    An open study was carried out to assess the effects of 300-900 mg of standardised garlic powder (1.3% alliin) on elastic properties of the aorta. The study included 101 healthy volunteers between 50 – 80 years of age was carried out over a period at least 2 years. Compared to the results from an untreated control group, garlic intake reduced age-related increases in aortic stiffness. The most significant differences were observed in pulse wave velocity (a measure of arterial stiffness) and pressure-standardised elastic vascular resistance. The positive markers were more evident among the older subjects (1).

    Hypertension

    A systematic review was carried out on the medical literature to investigate the current evidence of garlic for the treatment of hypertension. A total of seven randomised, placebo-controlled trials were identified. This meta-analysis compared results of garlic’s efficacy against the placebo, revealing a significant lowering effect of garlic on both systolic and diastolic blood pressure with no adverse effects. The studies results suggest that garlic is a safe and effective approach for hypertension.

    The effect of garlic on blood pressure was evaluated in a meta-analysis of 8 studies. The analysis showed that in the subjects who were treated with garlic overall had benefit when compared to those who had placebo. The review concludes that garlic powder may have some clinical benefit in mild hypertension (3).

    Atherosclerosis

    A study which used serum taken from patients with coronary atherosclerosis 2 hours after ingestion of 300 mg of standardised garlic powder (1.3% alliin) was carried out, to asses the efficacy for treatment of atherosclerosis. The study used cultured and incubated smooth muscle cells with serum as a measure of outcome. Results showed garlic reduced total cell cholesterol to 19.3% (1).

    A systematic review was carried out to evaluate the effects of garlic on the risk factors of cardiovascular disease (CVD). Databases MEDLINE-PubMed; COCHRANE; EMBASE; and Google Scholar were searched. The studies included demonstrated a clear evidence base for the use of garlic to reduce blood pressure, waist circumference, body mass index, LDL-c, non-HDL-c, total cholesterol, triglycerides, and inflammatory markers. The studies also showed that garlic can improve cardiovascular parameters such as coronary artery calcium, microcirculation, epicardial and peri-aortic adipose tissue, post occlusive reactive hyperemia, low attenuation plaque, carotid intima-media thickness; and carotid intima-media thickness. The review concluded that garlic can be considered in the prevention and treatment of CVD risk factors (5).

    Myocardial infarction

    A 3-year randomised placebo controlled study was carried out to assess the efficacy of an oily garlic extract for the treatment of myocardial infarction. A total of 432 patients with a history of myocardial infarction were assigned to the study. 222 were given an oily extract of garlic and 210 subjects received a placebo daily, in addition to other necessary medication. Significant reductions in the non-fatal reinfarction rate (44%) and mortality (31%) were observed in patients taking the oily extract of garlic compared to the placebo group (6).

    Respiratory system

    A randomised, double-blind, placebo-controlled study was carried out to evaluate the efficacy of one of garlics primary compounds, allicin, for the prevention of the common cold. The study group of 146 volunteers were split into two groups and given a daily dose of 180 mg of stabilised allicin or placebo for 12 weeks. There were significantly fewer occurrences of the common cold in the garlic group (24) than in the placebo group (65). In the placebo group, subjects experienced a significantly longer occurrence of symptoms (5.01 days) compared to the garlic group (1.52 days) and there were fewer days of illness in the garlic group (n=111) compared with the placebo group (n=366) (7).

    In a randomised, placebo-controlled study 41 patients suffering from hepatopulmonary syndrome which is an uncommon secondary condition that affects the lungs of people with advanced liver disease. The effect of garlic oil capsules (21 participants) was compared to placebo (20 participants) over a period of 9 to 18 months. Each garlic capsule contained 250 mg oil. After 9 months, a significant increase in baseline arterial oxygen level was observed. The increase on the garlic group was 24.66% whereas the placebo group showed only 7.37%. There was also a significant decrease in the alveolar-arterial oxygen gradient in the garlic group (28.35%) compared to placebo (10.73%) The arterial oxygen level and alveolar-arterial oxygen level were also significantly higher in the garlic group compared to the placebo group whose results actually came in significantly lower. Two of 21 patients in the garlic group and 7 of 20 patients in the placebo group died during the follow-up period of up to 18 months (9).

  • Did you know?

    The common name garlic is derived from the Old English word garleac which translates as “spear leek,” making reference to the lanceolate shape of the plant’s cloves.

Additional information

  • Botanical description

    Garlic (Allium sativum) is a species of bulbous flowering plant in the genus Allium. Its close relatives include the onion, shallot, leek and chive. Garlic is a perennial flowering plant growing from a bulb. It has a tall, erect flowering stem that grows up to 1 metre. The leaf blade is flat, linear, solid, and approximately wide, with an acute apex. The pink to purple flowers grow from upright stalks between July to September (Northern Hemisphere).

    The bulb is odoriferous and contains outer layers of thin sheathing leaves surrounding an inner sheath that encloses the clove. The bulb usually consists of 10 to 20 cloves that are asymmetric in shape (cloves at the centre may be less symmetrical). It produces hermaphrodite flowers. It is pollinated by bees, butterflies, moths, and other insects.

  • Common names

    • Spear leek
    • Camphor of the poor
    • Clove of garlic
    • Cultivated garlic
    • Nectar of the Gods
    • Rocambole
    • Rustic treacle
    • Serpent garlic
    • Stinking rose
  • Safety

    Garlic is safe to use during lactation. It is regarded as generally safe taken as food, although it should be avoided at medicinal doses during pregnancy due to its stimulating nature (11).

    The below interactions and contraindications are generally understood to be of limited evidence and are based on single case reports. However, if taking medications for any below mentioned serious and ongoing health conditions it is worth consulting a medical herbalist before taking garlic in medical doses. You can find a clinical herbalist in our resources section.

  • Interactions

    Caution is sometimes advised to those taking blood thinning medications. This caution relates to one case report in which an increased International Normalized Ratio (INR) was observed in 2 patients on warfarin and in one patient on fluindione who had used garlic products.

    One single case report relating to 1 patient has also led to caution in the use of garlic for those taking medications to lower blood pressure (such as lisinopril) (1). It is therefore advised to consult with a professional medical herbalist before taking garlic if taking any of the above medications.

  • Contraindications

    Caution is advised with regard to surgical operations due to some case reports with prolonged or increased bleeding. Garlic should be avoided for 10 days prior to surgical operations (11).

  • Preparation

  • Dosage

    Tincture (1:3 in 45%): Take between 1 – 6ml daily.

    Fresh:  Take between 1- 3 cloves per day for therapeutic effects.

    Dried: Take between 6 – 15g of dried garlic per day for therapeutic effects.

    For the treatment of more severe conditions; i.e. prophylaxis of atherosclerosis or treatment of elevated blood lipid levels and hypertension adults must take the equivalent of 6-10 mg of alliin (approx. 3-5 mg of allicin) daily. These compounds are typically contained in one clove of garlic or in 0.5-1.0 g of dried garlic powder.

    For acute respiratory infections and catarrh adults must take between 2-4 g of dried bulb or 2-4 ml of tincture (1:5, 45% ethanol) three times daily or 180 mg garlic powder per day.

  • Plant parts used

    Bulb (cloves)

  • Constituents

    Carefully dried, powdered material contains about 1 per cent of alliin as the main sulphur-containing amino acid. In the presence of the enzyme alliinase, alliin will be converted to allicin (1 mg of alliin is equivalent to 0.45 mg of allicin).

    In turn, allicin is the precursor of various transformation products, including ajoenes, vinyldithiines, oligosulphides and polysulphides. The formation of these metabolites depends on the conditions applied such where medicine is prepared by steam distillation. Extraction in an oily medium contains a number of allicin transformation products.

    Garlic also contains ubiquitous amino acids; steroids; triterpenoid saponins; flavonoids; lectins; adenosine; (+)-S-methyl-L-cysteine sulphoxide; gamma-L-glutamyl peptides and S-allyl-cysteine (1).

garlic illustration
  • Habitat

    Garlic is native to South Asia, Central Asia and northeastern Iran.

  • Sustainability

    According to the IUCN Red List of Threatened Plants Status garlic in the wild has not yet been assessed.

    Habitat loss and over-harvesting from the wild are two of the biggest threats faced by medicinal plant species. There are an increasing number of well-known herbal medicines at risk of extinction. We must therefore ensure that we source our medicines with sustainability in mind.

    The herb supplement industry is growing at a rapid rate and until recent years a vast majority of medicinal plant products?? in global trade was of unknown origin. There are some very real and urgent issues surrounding sustainability in the herb industry. These include environmental factors that affect the medicinal viability of herbs, the safety of the habitats that they are taken from, as well as the welfare of workers in the trade.

    The botanical supply chain efforts for improved visibility (transparency and traceability) into verifiably sustainable production sites around the world is now certificated through the emergence of credible international voluntary sustainability standards (VSS). Read our article on sustainable sourcing of herbs to learn more about what to look for and questions to ask suppliers about sustainability.

  • Quality control

    Garlic is a common food product which can be bought in any grocery store. It is however best to source organic garlic for medicinal purposes. This is due to the fact that a higher content of medicinal compounds is often found in organically grown produce over conventionally farmed.

    Herbal Medicines are often extremely safe to take, however it is important to buy herbal medicines from a reputed supplier. Sometimes herbs bought from unreputable sources are contaminated, adulterated or substituted with incorrect plant matter.

    Some important markers for quality to look for would be to look for certified organic labelling, ensuring that the correct scientific/botanical name is used and that suppliers can provide information about the source of ingredients used in the product.

    A supplier should be able to tell you where the herbs have come from. There is more space for contamination and adulteration when the supply chain is unknown.

  • How to grow

    Garlic is easy to grow and is highly resilient to low temperatures. If garlic is planted at the proper time and depth, it can be grown as far north as Alaska.

    • Choose a warm sunny location with well-drained soil
    • Break apart cloves from the bulb a few days before planting keeping the papery husk on each individual clove intact.
    • Late autumn is an ideal time to plant garlic. Plant cloves 4 to 8 inches apart and around 2 inches deep, in their upright position (with the pointed end facing up and the wider root side facing down). Plant in rows spaced 6 to 12 inches apart.
    • Ongoing care for garlic is simply to keep weeds at bay and water during dry spells. The garlic bulbs will be ready from early summer onwards.
  • References

    1. Allii sativi bulbus Garlic Monographs. (n.d.). Available at: https://escop.com/wp-content/uploads/edd/2019/07/Allium-sativum-ESCOP-2019.pdf.
    2. Bayan, L., Koulivand, P.H. and Gorji, A. (2014). Garlic: a review of potential therapeutic effects. Avicenna journal of phytomedicine, [online] 4(1), pp.1–14. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4103721/.
    3. Silagy CA, Neil HAW. A meta-analysis of the effect of garlic on blood pressure. J Hypertension 1994a;12:463-8. http://dx.doi.org/10.1097/00004872-199404000-00017
    4. Jung, E.M., Jung, F., Mrowietz, C., Kiesewetter, H., Pindur, G. and Wenzel, E. (1991). Influence of garlic powder on cutaneous microcirculation. A randomized placebo-controlled double-blind cross-over study in apparently healthy subjects. Arzneimittel-Forschung, [online] 41(6), pp.626–630. Available at: https://pubmed.ncbi.nlm.nih.gov/1930351/ [Accessed 3 May 2023].
    5. Imaizumi, V.M., Laurindo, L.F., Manzan, B., Guiguer, E.L., Oshiiwa, M., Otoboni, A.M.M.B., Araujo, A.C., Tofano, R.J. and Barbalho, S.M. (2022). Garlic: A systematic review of the effects on cardiovascular diseases. Critical Reviews in Food Science and Nutrition, pp.1–23. doi:https://doi.org/10.1080/10408398.2022.2043821.
    6. Bordia A. Knoblauch und koronare Herzkrankheit. Wirkungen einer dreijährigen Behandlung mit Knoblauchextrakt auf die Reinfarkt- und Mortalitätsrate. Dtsch Apoth Ztg 1989;129(Suppl 15):16-7.
    7. Josling P. Preventing the common cold with a garlic supplement: a double-blind, placebo-controlled survey. Adv Ther 2001;18:189-193. https://doi.org/10.1007/BF02850113.
    8. Xiong, X.J., Wang, P.Q., Li, S.J., Li, X.K., Zhang, Y.Q. and Wang, J. (2015). Garlic for hypertension: A systematic review and meta-analysis of randomized controlled trials. Phytomedicine : international journal of phytotherapy and phytopharmacology, [online] 22(3), pp.352–61. doi:https://doi.org/10.1016/j.phymed.2014.12.013.
    9. De B, Dutta D, Pal S, Gangopadhyay S, Das Baksi S, Pani A. The role of garlic in hepatopulmonary syndrome: a randomized controlled trial. Can J Gastroenterol 2010;24:183-8. https://doi.org/10.1155/2010/349076
    10. Orekhov, A.N. and Grünwald, J. (1997). Effects of garlic on atherosclerosis. Nutrition (Burbank, Los Angeles County, Calif.), [online] 13(7-8), pp.656–663. doi:https://doi.org/10.1016/s0899-9007(97)83010-9.
    11. Pole, S. (2013). Ayurvedic medicine : the principles of traditional practice. London ; Philadelphia: Singing Dragon, Cop.
    12. Allicin as an Adjunct Immunotherapy against Tuberculosis. (2020). Journal of Cellular Immunology, 2(4). doi:https://doi.org/10.33696/immunology.2.039.
    13. Dwivedi, V.P., Bhattacharya, D., Singh, M., Bhaskar, A., Kumar, S., Fatima, S., Sobia, P., Kaer, L.V. and Das, G. (2019). Allicin enhances antimicrobial activity of macrophages during Mycobacterium tuberculosis infection. Journal of Ethnopharmacology, 243, p.111634. doi:https://doi.org/10.1016/j.jep.2018.12.008.
    14. Tudu, C.K., Dutta, T., Ghorai, M., Biswas, P., Samanta, D., Oleksak, P., Jha, N.K., Kumar, M., Radha, null, Proćków, J., Pérez de la Lastra, J.M. and Dey, A. (2022). Traditional uses, phytochemistry, pharmacology and toxicology of garlic (Allium sativum), a storehouse of diverse phytochemicals: A review of research from the last decade focusing on health and nutritional implications. Frontiers in Nutrition, [online] 9, p.949554. doi:https://doi.org/10.3389/fnut.2022.929554.
Aromatic
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 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 (eg 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) they can seal a damaged surface. One group of tannins, the reddish-brown ‘condensed tannins’ are procyanidins, which can reduce inflammation and oxidative damage.
Bitter
Bitters are a very complex group of phytochemicals that 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 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 colouring
Any fruits with a blue-purple colouring contain high levels of the polyphenols known as anthocyanins. 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.
Cooling
Traditional ‘cold’ or cooling’ remedies often contain bitter phytonutrients such a iridoids (gentian), sesiquterpenes (chamomile), anthraquinones (rhubarb root), mucilages (marshmallow), some alkaloids and flavonoids. They tend to influence the digestive system, liver and kidneys. Cooling herbs do just that; they diffuse, drain and clear heat from areas of inflammation, redness and irritation. Sweet, bitter and astringent herbs tend to be cooling.
Hot
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. .
Mucilaginous
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. .
New-mown hay aroma
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 are chemically categorised as benzopyrone lactones and are important phytochemicals, with strong antioxidant activity in the laboratory and likely effects in modulating inflammation. They were most often associated with the calming effect linked to their use in stuffing mattresses and pillows and plants, high In coumarins were commonly used for these properties.
Resinous
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 expensive glassware! For use in the mouth, gums and throat hey 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!
Salty
The salty flavour is immediately distinctive. A grain dropped onto the tongue is instantly moistening and a sprinkle on food enkindles digestion. This easily recognisable flavour has its receptors right at the front of the tongue. The salty flavor creates moisture and heat, a sinking and heavy effect which is very grounding for the nervous system and encourages stability. People who are solid and reliable become known as ‘the salt of the earth'.
Sharpness
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.
Sweet
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.

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