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Hibiscus is native to West Africa where it is traditionally used to treat high blood pressure

Hibiscus

Hibiscus sabdariffa / Hibiscus rosa-sinensis Malvaceae

Hibiscus is an important medicine for cardiovascular health that has been well researched for its hypotensive effects. Herbalists also use hibiscus to support urinary system, specifically in the treatment of cystitis and recurrent urinary tract infections.

Sustainability Status

Sustainability status

At risk from overharvesting and habitat loss. Read more about our sustainability guide.

Key benefits
  • Cardiovascular diseases
  • High blood pressure
  • Urinary tract inflammation
  • Diabetes
  • Obesity and hyperlipidaemia
  • Antioxidant
  • Coughs
  • How does it feel?

    Hibiscus has a fruity, sweet and sour taste profile. An infusion made from hibiscus flowers is pleasant, refreshing and easy to drink. It also has an astringent quality that can be sensed upon tasting with a distinct puckering or drying action in the mouth.

  • What can I use it for?

    Hibiscus flowering (Hibiscus sabdariffa)
    Hibiscus flowering (Hibiscus sabdariffa)

    Hibiscus is a popular herbal tea that can be taken as a cold or hot infusion. It is rich in many nutrients and bioactive substances that have a wide range of benefits to health. One such group of compounds in hibiscus are anthocyanins. These powerful antioxidant compounds are what give hibiscus its rich red colour (1).

    Hibiscus has many benefits to systemic health through these antioxidant qualities, supporting the cardiovascular system and improving the health of the mucous membranes throughout the body. Hibiscus helps to improve the appearance of the skin, brightening the complexion and promoting hair growth (2).

    It is useful for those who are prone to urinary tract infections (UTIs) as it helps to nourish and repair the inflamed tissues. Hibiscus is an important herb for cystitis and as part of a healing strategy for recurrent UTIs both during and after. It works via an astringent and anti-inflammatory action. Hibiscus also has antimicrobial actives and mild diuretic actions which help to flush out the urinary tract (2,3).

    NOTE: It is, however, important to note that whilst hibiscus may be able to assist in healing of the urinary tract, it cannot be used alone to treat the infection itself (3). One must ensure that UTIs are treated appropriately to tackle the infection, either by consulting a medical herbalist or under treatment of a qualified medical professional. Hibiscus is often used alongside diuretic herbs like corn silk and anti-infectives such as uva-ursi or juniper berry. A herbalist will often advise a course of herbal treatment along with dietary changes and other supplements to create a lasting resolution, as well as to reduce the chances of recurring infections.

    One of hibiscus’s most popular uses is for the treatment of hypertension (high blood pressure). It is best to work alongside a quailed medical herbalist if you have moderate to severe hypertension. However, hibiscus can be used as a home remedy in mild hypertension or prophylactically to help maintain healthy blood pressure. It also offers great benefit to the physiological health of the cardiovascular system (4).

    Hibiscus has a number of benefits to metabolic health, as it has been found to reduce blood lipids and blood sugars as well as to address obesity via a number of effects on body weight. Obesity and high blood pressure along with high levels of fat and sugar in the blood can lead to increased risk of serious cardiovascular disease. Hibiscus may be used to help maintain healthy metabolic function and reduce the risks of cardiovascular disease (5).

    • rosa-sinensis cold infusion is an easy and effective remedy to help bring down a fever. It may also be helpful to reduce virally induced respiratory inflammation that leads to a cough (2).
    • sabdariffa and H. rosa-sinensis are both often referenced for use in treating high blood pressure, although much of the research for this has been focused on H. sabdariffa — the most commonly used species. Both have powerful antioxidant and anti-inflammatory activities, whilst H. rosa-sinensis is referenced more frequently for coughs and bronchitis (6, 7).
  • Into the heart of hibiscus

    Hibiscus flower close up (Hibiscus sabdariffa)
    Hibiscus flower close up (Hibiscus sabdariffa)

    Hibiscus is sweet, cooling and drying in terms of energetic qualities. It has a rejuvenating action on the cardiovascular system which is attributed to its antioxidant and blood purifying qualities. These combined actions reach out to every cell in the body (2). 

    The tissue state that is most indicated for hibiscus is classically one that is inflamed, hot and ‘excited’. This may refer to pathological heat, which may be caused by excess toxins in circulation around the body, viruses and other pathogens, that classically refers to inflammation or excitation (overactivity) in the tissues. The sour, refrigerant energetic quality of hibiscus is classically applied in the treatment of conditions of this nature, to calm and regulate the physiological activities of the mucous membranes (8). 

    In Ayurvedic medicine, H. rosa-sinensis is deemed to have cooling and refrigerant actions. These are applied where there is heat and inflammation or congestion and tension particularly — in the mucous membranes of the urinary and reproductive systems (2).

    In Ayurveda, H. rosa-sinensis is considered a sacred herb that can be used to increase spiritual connectivity in meditation of devotional ceremonies. It is a remedy of the emotional, spiritual and physical heart that combines well with rose flowers (2).

    The constitutional system in Ayurveda refers to the 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 — governs metabolism, digestion and hormones linked to appetite; kapha — is responsible for strength and stability, muscle growth, weight and the immune system.

    Hibiscus is PK- V+, which means that it is indicated where there is excess or imbalance of pitta and kapha in the body. It increases or rejuvenates the qualities of vata (2).

  • Traditional uses

    Hibiscus plants (Hibiscus sabdariffa)
    Hibiscus plants (Hibiscus sabdariffa)

    sabdaffira

    So named ‘karkade’ in Egypt and Sudan, is used for its refrigerant properties to help lower the body temperature. An infusion of hibiscus is referenced for many medicinal uses including to treat cardiovascular and nervous disorders. It is also used to stimulate diuresis. In other parts of North Africa the flowers of hibiscus are used to relieve coughs, sore throats, and genital problems. A poultice of the leaf is used for treating external wounds and abscesses. In Iran, hibiscus tea is a traditional treatment for hypertension (1).

    rosa-sinensis

    The roots, leaves and flowers of H. rosa-sinensis have a long history of traditional use in Indonesia and Malaysia. A decoction of the root was used to relieve the symptoms of venereal disease, fever and sore eyes. It was also believed that roots made from plants with white or red flowers would serve as an antidote to poison. The juice of the white flower was used for mouth ulcers. Flowers were infused in hot water and drunk for their expectorant qualities in the treatment of bronchitis.  The white-coloured flower buds were ingested to treat hypertension, whilst the leaves were used topically as poultices for boils and sores, as well as to relieve headaches and inflammation (6).

  • 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

    Hibiscus (Hibiscus rosa-sinensis)
    Hibiscus (Hibiscus rosa-sinensis)

    Cardiovascular system

    Hibiscus has been studied extensively for its ability to lower blood pressure with positive results in lowering both systolic and diastolic blood pressure (4). Hypertension is one of the most commonly indicated conditions for the use of hibiscus. The mechanism of hibiscus for the treatment of hypertension includes angiotensin-converting enzyme (ACE) inhibition, vasodilation, and diuretic effects (9).

    Reproductive system

    rosa-sinensis may be used as part of a treatment approach to address dysmenorrhea and menoragghia. It has antispasmodic and relaxant actions that may affect the uterine smooth muscle and reduce symptoms in these conditions (2). This application is most referenced in Ayurvedic medicine and less commonly seen in Western or traditional Chinese herbalism (2).

    Urinary system

    Hibiscus is commonly used for cystitis and painful urination. It is both anti-inflammatory and antispasmodic, which may help relieve the pain and discomfort of this condition (2). Hibiscus shows promise as a remedy that improves the health in the mucous membranes within the urinary tract. This is likely due to its rich anthocyanins content. Anthocyanins are antimicrobial and antioxidant compounds. As such, hibiscus may be useful to counteract the recurrence of urinary tract infections (2,3).

    Hibiscus may be paired with propolis in the treatment of urinary tract infections. It may be incorporated into a prophylactic prescription for recurrent urinary tract infections and cystitis. It would be best used in combination with other herbs to address tissue condition, bacterial or inflammatory afflictions.

    Respiratory system

    rosa-sinensis is well documented for its anti-inflammatory properties with a strong history of use in bronchial asthma in India. This may also be partly due to its essential nutrient content, such as calcium, magnesium, zinc, and potassium, which can help in the management of bronchial asthma (7).

  • Research

    closed Hibiscus flowers (Hibiscus sabdariffa)
    closed Hibiscus flowers (Hibiscus sabdariffa)

    There has been a significant amount of research into the use of hibiscus for hypertension including clinical trials. A number of studies and systematic reviews have been included below to surmount the evidence for some of the traditional medicinal actions discussed in this monograph.

    Effect of Hibiscus sabdariffa on arterial hypertension: A systematic review and meta-analysis of randomised controlled trials

    A systematic review and meta-analysis of randomised controlled trials (RCTs) was carried out to assess the potential antihypertensive effects of H. sabdariffa. Five RCTs were included for the meta-analysis to investigate effects of systolic and diastolic blood pressure (SBP and DBP). In total, 390 participants were randomised, 225 of whom received H. sabdariffa supplementation and 165 received placebo. The meta-analysis confirms significant hypotensive effects in the intervention (4).

    A controlled, randomized clinical trial was performed to identify the comparable antihypertensive effectiveness and tolerability of a standardised extract from H. sabdariffa against the pharmaceutical drug captopril. Patients aged 30 to 80 years old with diagnosed hypertension who had been without intervention for one month were recruited. Subjects were randomised to receive either infusion prepared with 10 g H. sabdariffa (standardised with 9.6 mg anthocyanins), daily before breakfast, or captopril 25 mg twice a day. The study period was four weeks. 

    The study demonstrates that H. sabdariffa was able to decrease the systolic and diastolic blood pressure to within normal range. The study concludes that standardised H. sabdariffa extract and captopril were equally as effective in the treatment of mild to moderate hypertension (10).

    A systematic review of studies as evidence for hypoglycaemic and hypocholesterolaemic effects of Hibiscus rosa-sinensis tea

    A systematic review was carried out to evaluate the evidence for the use of H. rosa-sinensis tea in the management of high cholesterol and high blood sugar. The findings revealed that frequent intake of homemade tea of H. rosa-sinensis is adequate to induce anti-hyperglycemic and anti-hyperlipidemic actions, which may contribute to herbal therapeutic approach in controlling diabetes and hypercholesterolemia without causing acute toxicity (11).

    Hibiscus flower plant (Hibiscus sabdariffa)
    Hibiscus flower plant (Hibiscus sabdariffa)

    Study on H. sabdaffira in the treatment of dyslipidemia in adolescents with obesity

    This study carried out on H. sabdaffira investigated the herb’s effects on adolescents with dyslipidemia and obesity. This triple masked, placebo controlled trial enrolled 90 adolescents aged between 12–18 years old who were randomised to receive 6 g of powdered hibiscus or placebo in divided doses for a period of four weeks. The study demonstrated that hibiscus supplementation significantly modulated triglyceride and LDL concentrations in obese adolescents (12). This study is described as a triple-blind, however the paper does not elucidate to this methodology.

    Sabdariffa in the treatment of obesity and fatty liver disease

    Further research has been carried out to explore the effects of H. sabdariffa in obesity. One study showed a decrease in waist circumference, percent body fat, waist-to-hip ratio as well as improved liver steatosis in patients aged 18–65 who had been diagnosed with obesity and fatty liver disease. Hibiscus contains many bioactive compounds that have been shown to affect weight loss and lipid metabolism, including galloyl ester, chlorogenic acid, caffeic acid, quercetin, tiliroside, and anthocyanins (5).

    These works afford us a deeper insight into the medicinal activities of these fascinating plants and show they have significant potential beyond many of their current uses.

  • Did you know?

    In India, hibiscus flowers are sacred to Ganesh — the elephant god who is associated with wisdom (2).

    Chinese hibiscus is the national flower of Malaysia. In the Malay language, the plant is known as bunga raya, which means “great flower” (6).

Additional information

  • Botanical description

    sabdarifffa is an annual, or biennial, upright herb that can grows up to about 1.5 meters high. The long-stalked leaves are various, continuous-margined, toothed, lobed, or three-parted to five-parted, the lobes pointed. The uppermost leaves are usually small and lance-shaped and the lowermost can reach 20 cm in diameter. The flowers are short-stalked in the upper leaf-axils which are lance-shaped and hairy with around 10 bractlets that appear as a whorl of inflorescence. They can develop in size to about 10 to 12 mm long. They have a red calyx which is about 2 cm long when in flower. On fruiting this can grow up to 3 to 3.5 cm long. The lance-shaped lobes are pointed with 4 or 5 cm long petals that are usually yellow or pin-red in colour — commonly with a purple base. The capsule is ovoid, 2 or 2.5 cm long. The seeds are finely hairy (14).

    rosa-sinensis grows as a small evergreen tree or bushy shrub up to 2.5–5 m tall and 1.5–3 m wide. Its leaves are small, ovate, petiolated and usually around 8 to 10.5 cm long. They are spirally arranged around a long stalk.  Its flowers are bisexual, large, stalked and arising singly from the upper leaf axils. They can grow up to 25 cm wide. The five free petals joined at the base may be white, yellow or red colour (6).

  • Common names

    • sabdariffa: roselle; Jamaica sorrel; red sorrel; sorrel; Indian sorrel; Asam susar
    • Rosa- sinensis: dinner plate hibiscus; rose mallow; clown hibiscus; china rose; rose of Sharon.

    Both of these species have some unique medicinal properties with a significant amount of cross over across the herbal literature. This monograph predominantly focuses on H. sabdariffa, which is most widely used in herbal medicine. Throughout this monograph hibiscus is referring to the H. sabdariffa species. H. rosa-sinensis is mentioned throughout and referred to under its scientific name for clarity.

  • Safety

    Use during pregnancy and lactation is not recommended on the basis of lack of data (13).

  • Interactions

    Hibiscus should not be used alongside high blood pressure (antihypertensive drugs) due to its hypotensive effects.

    Hibiscus may reduce the effects of chloroquine (Aralen), simvastatin and diabetic medications (13).

  • Contraindications

    Hibiscus should be avoided by those who have a known hypersensitivity to other plants of the same family (13).

  • Preparation

    Tea (infusion)

  • Dosage

    Infusion

    To make an infusion place 1.25–1.5 g teaspoon of dried material in 240 ml of boiling water, simmer gently for between 5–10 minutes. This should be drunk hot three times a day (13).

  • Plant parts used

    The calyx (the structure around the petals) is the primary plant part used (1). The leaves, seeds, and flowers are also used in local forms of traditional medicine (1).

  • Constituents

    • Organic acids: Citric, hydroxycitric, malic, tartaric and hibiscus (hibiscic) acids
    • Phenolic acids: Protocatechuic, chlorogenic and caffeic acids
    • Anthocyanins: Delphinidin and cyanidin-based anthocyanins, include delphinidin-3- sambubioside (hibiscin), cyanidin-3-sambubioside (gossypicyanin), cyanidin-3,5- diglucoside and delphinidin (anthocyanidin)
    • Flavonoids: Hibiscetin-3-glucoside (hibiscitrin), gossypitrin, gossytrin, sabdaritrin, quercetin (and its glycoside), luteolin (and its glycoside), rutin and kaempferol
    • Mucilage polysaccharides
    • Miscellaneous: Vitamin C, pectin, carbohydrates (arabinose, galactose, glucose, rhamnose) and volatile compounds (fatty acid derivatives and others) (13)
Hibiscus (Hibiscus sabdariffa)
  • Habitat

    The native range of H. sabdaffira is West Africa and Sudan. It grows primarily in the seasonally dry tropical biome (15)

    Hibiscus rosa-sinensis is understood to have been derived through hybridisation of around eight hibiscus species that are native to the West Pacific (16).

  • Sustainability

    The IUCN red list of threatened species does not yet include information on the at risk status of this species.

    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 produce 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 effect 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 Herbal quality & safety: What to know before you buy and Sustainable sourcing of herbs to learn more about what to look for and questions to ask suppliers about sustainability.

  • Quality control

    A study was carried out to identify the best extraction method for hibiscus. The research suggests that water is the best solvent for extracting the four anthocyanins. An extraction time of ten minutes also presented with the highest level of phenolics in comparison to ethyl acetate and hexane extractions (17).

    Herbal medicines are often extremely safe to take, however it is important to buy 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

    Hibiscus is easy to grow either outdoors or indoors. To grow outdoors hibiscus must be positioned in moist but well-draining soil in a warm and sunny location, ideally sheltered from winds. They also do well in pots of loam-based, peat-free compost.

    To grow hibiscus indoors place in a bright position but away from full, direct sunlight. They need a minimum temperature of 7–10°C and a high humidity, so do well in bright, but not sunny, bathrooms.

    Outdoor hibiscus plants may be fed annually in spring, with a slow-release, high potash formula, such as rose food. To suppress weeds and help maintain soil moisture levels mulch in autumn.

    Once the plant reaches 1.5m or taller (it may take three years to reach this size) it will of benefit to prune annually to keep in shape. If left unpruned, the outer branches may become damaged from the weight of the leaves. It is best to prune after flowering, cutting each branch back to a leaf node at a desired height, removing old wood from the centre of the plant (18).

  • Recipe

    Hibiscus tea (Hibiscus sabdariffa)
    Hibiscus tea (Hibiscus sabdariffa)

    Hibiscus cold infusion

    Ingredients

    • 20–30g hibiscus (dried)
    • 1 unwaxed organic lemon (whole)
    • 2 litres of spring water 

    Method

    Simply place the hibiscus flowers into a large jug of spring water. Squeeze the lemon juice and then chop up the lemon rind, adding this into the infusion.

    Infuse in the refrigerator for between 24–48 hours. You can then pour off the beautiful refreshing cold infusion into a glass and drink freely throughout the day for a refreshing cold and cleansing, health-enhancing tipple!

  • References

    1. Engels. G. Herb Profile: Hibiscus. HerbalGram. 2007; 74:1-6 American Botanical Council. Accessed at. https://www.herbalgram.org/resources/herbalgram/issues/74/table-of-contents/article3102/ Accessed May 20, 2024.
    2. Frawley D, Vasant Lad. The Yoga of Herbs: An Ayurvedic Guide to Herbal Medicine. Motilal Banarsidass; 2016.
    3. Flower Power: Hibiscus sabdariffa extract to prevent UTIs and dyslipidemia. NutraIngredients USA. Published February 17, 2020. Accessed April 26, 2024. https://www.nutraingredients-usa.com/News/Promotional-Features/Flower-Power-Hibiscus-sabdariffa-extract-to-prevent-UTIs-and-dyslipidemia
    4. Serban C, Sahebkar A, Ursoniu S, Andrica F, Banach M. Effect of sour tea (Hibiscus sabdariffa L.) on arterial hypertension. J Hypertens. 2015;33(6):1119-1127. doi:10.1097/hjh.0000000000000585
    5. Chang HC, Peng CH, Yeh DM, Kao ES, Wang CJ. Hibiscus sabdariffa extract inhibits obesity and fat accumulation, and improves liver steatosis in humans. Food & Function. 2014;5(4):734. doi:https://doi.org/10.1039/c3fo60495k
    6. Thulaja NR. Hibiscus (Hibiscus rosa-sinensis). National Library Board Singapore. December 2020. Accessed May 22, 2024. https://www.nlb.gov.sg/main/article-detail?cmsuuid=58f5f860-ace3-4819-82c5-be7d2477855f#:~:text=Hibiscus%20leaves%20are%20ovate%2C%20simple
    7. Gulati K, Verma P, Rai N, Ray A. Chapter 7 – Role of nutraceuticals in respiratory and allied diseases. ScienceDirect. Published January 1, 2021. https://www.sciencedirect.com/science/article/abs/pii/B9780128210383000070
    8. Wood M. The Earthwise Herbal: A Complete Guide to Old World Medicinal Plants. North Atlantic Books; 2003.
    9. Salem MA, Ezzat SM, Ahmed KA, Alseekh S, Fernie AR, Essam RM. A Comparative Study of the Antihypertensive and Cardioprotective Potentials of Hot and Cold Aqueous Extracts of Hibiscus sabdariffa L. in Relation to Their Metabolic Profiles. Frontiers in Pharmacology. 2022;13. doi:https://doi.org/10.3389/fphar.2022.840478
    10. Herrera-Arellano A, Flores-Romero S, Chávez-Soto MA, Tortoriello J. Effectiveness and tolerability of a standardized extract from Hibiscus sabdariffa in patients with mild to moderate hypertension: a controlled and randomized clinical trial. Phytomedicine : international journal of phytotherapy and phytopharmacology. 2004;11(5):375-382. doi:https://doi.org/10.1016/j.phymed.2004.04.001
    11. Sanadheera S, Subasinghe D, Solangaarachchi MN, Suraweera M, Suraweera NY, Tharangika N. Hibiscus rosa-sinensis L. (red Hibiscus) Tea, Can It Be Used as A Home-Remedy to Control Diabetes and Hypercholesterolemia? Biology, Medicine, & Natural Product Chemistry. 2021;10(1):59-65. doi:https://doi.org/10.14421/biomedich.2021.101.59-65
    12. Sabzghabaee A, Ataei E, Kelishadi R, et al. Effect of Hibiscus sabdariffa Calices on Dyslipidemia in Obese Adolescents: A Triple-masked Randomized Controlled Trial. Materia Socio Medica. 2013;25(2):76. doi:https://doi.org/10.5455/msm.2013.25.76-79
    13. Egyptian herbal monograph. Hibiscus. Vol: 21. Published 2023. https://www.edaegypt.gov.eg/media/hzynjgnk/hibiscus-sabdariffa-l-كركديه.pdf. Accessed April 24, 2024. 
    14. Hibiscus sabdariffa L. NYBG Steere Herbarium. Accessed April 24, 2024. https://sweetgum.nybg.org/science/world-flora/monographs-details/?irn=21841
    15. Hibiscus sabdariffa L. | Plants of the World Online | Kew Science. Plants of the World Online. https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:326388-2
    16. Hibiscus × rosa-sinensis L. | Plants of the World Online | Kew Science. Plants of the World Online. https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:560756-1#synonyms
    17. HerbClip: Water Extraction Yields the Highest Concentration of Phenolic Compounds from Hibiscus Flowers. cms.herbalgram.org. Accessed April 25, 2024. http://cms.herbalgram.org/herbclip/513/091423-513.html
    18. How to grow hibiscus. BBC Gardeners World Magazine. Published May 18, 2021 https://www.gardenersworld.com/how-to/grow-plants/how-to-grow-hibiscus/ Accessed April 21, 2024
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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