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herbal medicine

We share traditional, scientific and practical insights written by experienced herbalists and health experts from the world of herbal medicine and natural health

  • Herb overview

    Safety

    May increase risk of bleeding when used with anticoagulants. Not recommended in high pitta states and those at risk of hypoglycaemia.

    Sustainability

    Status: Lower risk

    Key constituents

    Volatile oils: Eugenol
    Phenolic compounds
    Flavonoids
    Triterpenes

    Quality

    Southeast Asia
    Cultivated
    Adulteration with other Ocimum species common

    Key actions

    Adaptogenic
    Circulatory stimulant
    Antimicrobial
    Expectorant

    Key indications

    Stress
    Respiratory infection
    Allergies
    Cognitive impairment

    Key energetics

    Warm
    Dry
    Relaxing
    Aromatic

    Preperation and dosage

    Leaf
    6–15 g/per day
    Tincture: 1:5: 5–15 ml per day

  • How does it feel?

    As you inhale over a cup of tulsi tea you cannot mistake the clove-like aroma of the eugenol, a key constituent of this aromatic herb. The clove taste comes through on the first sip too with the rest of the flavours lemony, slightly camphorous pungency with a touch of eucalyptol. There are wide ranges of essential oil profiles in different varieties of tulsi, so the exact flavours will vary from different sources but a consistent theme is the pleasant aromatic heady impact. There is also a distinct astringent after-taste with the clove flavour lingering the longest.

    The overall impact is heady and uplifting, wholly aligned with the traditional reputation of this sacred herb.

    Tulsi (Ocimum tenuiflorum)
    Adaptogens
    Tulsi (Ocimum tenuiflorum)

  • Into the heart of tulsi

    Energetically, tulsi is considered a warming, pungent herb and closely associated with spirituality and the sacred in Ayurveda. This is also termed as sattvic — promoting light, love and spiritual clarity (4). In this way, tulsi can be seen to rejuvenate the mind, body and spirit and is known to increase prana and sensory acuity (6). Tulsi is traditionally grown in courtyards where it is believed to purify the surroundings and offer protection (2,4). 

    It can be applied to alleviate stagnation resulting from damp, relieve nervous tension or constriction and prevent exhaustive depletion by restoring tone. This can present as mental fog, low mood, low immunity or fatigue (7). In Ayurveda, tulsi helps to reduce excess kapha and vata and increase pitta, and has an affinity for the respiratory, nervous and circulatory systems (4). In essence, tulsi can be used to support nervous exhaustion, and offer resilience to body and mind. 

  • What practitioners say

    Tulsi (Ocimum tenuiflorum)
    Tulsi (Ocimum tenuiflorum)

    Nervous system

    Tulsi heightens awareness and mental clarity, which can help with feelings of mild depression. It is classed as a thymoleptic and offers support for anxious and depleted states (3). As a spasmolytic, it is traditionally used to alleviate tension headaches from high vata and for congestion headaches from excess kapha. This quality also helps improve the quality of sleep and so tulsi can help with insomnia. Its adaptogenic qualities increase the body’s resistance to physical, emotional and environmental stress (2).

    It offers adrenal support and can help to lower cortisol levels, helping the body’s response to stress. Tulsi can be used to enhance memory, concentration and offers protection from age-related cognitive decline (4). As an anti-inflammatory, tulsi also offers protection against neuroinflammation which, helps prevent the development of degenerative diseases including dementia.

    Immune system

    Tulsi has antimicrobial properties and therefore can be applied to aid recovery from a bacterial, viral or fungal infection (2,8). It can be used as an adjunct to chemotherapy as it helps to protect healthy cells from the toxic effects of chemotherapy and reduce cell damage (9). Tulsi can be applied to downregulate excessive histamine reactions in conditions like asthma, hayfever and allergic rhinitis (10). As an anti-inflammatory, tulsi helps to reduce both acute and chronic inflammation owing to its high level of antioxidants, which offer protection against lipid peroxidisation (8,10). 

    Respiratory system

    When used as a hot tea, tulsi clears kapha and mucus from the lungs and upper respiratory tract. It is of value in respiratory infections and fever where it reduces temperature by encouraging sweating, whilst its penetrating nature clears dampness and toxins (4,6).

    The antimicrobial actions also help to clear infection from the lungs and upper respiratory system. It is of benefit in bronchitis, rhinitis and other respiratory allergies. In traditional medicine, the lungs are seen as the seat of grief and tulsi’s ability to diffuse prana through the lungs helps with feelings of sadness and grief (4).

    Digestive system

    Where there is sluggish and incomplete digestion, tulsi warms and stimulates, moving stagnation. Its aromatic pungency improves appetite and facilitates effective digestion. Digestive complaints exacerbated by stress will benefit from tulsi’s antispasmodic and sedative qualities (2,4).

  • Tulsi research

    Tulsi (Ocimum tenuiflorum)
    Tulsi (Ocimum tenuiflorum)

    Holy basil (Ocimum sanctum Linn.) leaf extract enhances specific cognitive parameters in healthy adult volunteers: A placebo controlled study

    This placebo controlled study evaluated the effect of tulsi on cognitive function in healthy adults. Participants (number and demographic not specified) were administered 300 mg per day of an ethanolic leaf extract or placebo over a course of 30 days.

    The primary outcome measures included cognitive performance assessed via Sternberg and Stroop tests, while secondary outcomes included neurophysiological and stress-related parameters such as P300 latency, salivary cortisol, and State–Trait Anxiety Inventory scores, alongside autonomic measures (heart rate, galvanic skin response).

    Results showed that although both groups improved initially, cognitive improvements in the placebo group plateaued after 15 days, whereas the tulsi group demonstrated significantly greater improvements in reaction time across multiple cognitive tasks. Within the tulsi  group, improvements were also observed in P300 latency, cortisol, and anxiety scores, though only P300 latency reached statistical significance between groups (11).

    A randomised, double-blind, placebo-controlled trial investigating the effects of an Ocimum tenuiflorum (holy basil) extract (HolixerTM) on stress, mood, and sleep in adults experiencing stress

    This randomised, double-blind, placebo-controlled clinical trial examined the effects of a standardised extract of Ocimum tenuiflorum (Holixer™) on stress and sleep quality in adults experiencing stress. A total of 100 participants aged 18–65 years were assigned to receive either 125 mg of the extract twice daily or placebo over eight weeks.

    The primary outcome measure was the Perceived Stress Scale (PSS), with secondary outcomes including mood (Profile of Mood States), sleep quality (Athens Insomnia Scale, Restorative Sleep Questionnaire), overall health (PROMIS-29), objective sleep tracking (Fitbit), and physiological stress markers (hair cortisol, and responses to the Maastricht Acute Stress Test including salivary cortisol, amylase, blood pressure, and subjective stress ratings). Results demonstrated significant improvements in perceived stress (PSS) and insomnia scores (AIS) in the treatment group compared to placebo, alongside reduced cortisol levels.

    Additionally, participants receiving the extract exhibited attenuated stress responses to acute stress exposure, with significantly lower salivary cortisol, salivary amylase, blood pressure, and subjective stress ratings. This suggests that Ocimum tenuiflorum extract may significantly reduce both subjective and objective markers of stress and improve subjective sleep quality (12). 

    Double-blinded randomised controlled trial for immunomodulatory effects of tulsi (Ocimum sanctum Linn.) leaf extract on healthy volunteers

    This double-blind, randomised, placebo-controlled trial evaluated the immunomodulatory effects of an ethanolic leaf extract of Ocimum sanctum (tulsi) in healthy humans. A total of 24 healthy volunteers (22 completing; demographic details not specified) received 300 mg capsules of Tulsi extract or placebo daily on an empty stomach over a four week period. The primary outcome measures were changes in Th1 and Th2 cytokines—interferon-γ (IFN-γ) and interleukin-4 (IL-4)—assessed in stimulated blood cultures, while secondary outcomes included immune cell profiling (T-helper cells, T-cytotoxic cells, B-cells, and natural killer cells) using flow cytometry.

    Results showed a statistically significant increase in IFN-γ and IL-4 levels, alongside increased percentages of T-helper cells and NK cells in the tulsi group compared to placebo. These findings indicate tulsi exhibits a measurable immunomodulatory effect on cellular and humoral immune responses (13). 

    The clinical efficacy and safety of tulsi in humans: A systematic review of the literature

    This systematic review aimed to assess the clinical efficacy and safety of tulsi (Ocimum sanctum/Ocimum tenuiflorum/Ocimum gratissimum) as an internal medicine. A database search was conducted from November 2016 and included 24 human studies involving 1,111 participants aged 10–80 years, including healthy volunteers and people with metabolic syndrome, type 2 diabetes, hypertension, viral infections, asthma, anxiety, stress, and psychosomatic symptoms.

    Interventions varied widely, including tulsi leaf or whole-plant preparations as aqueous or ethanolic extracts, powders, fresh juice, decoctions, tinctures, or fortified bars, at doses ranging from 300 mg to 3 g/day for extracts/powders, 6–14 g/day whole plant preparations, 10 g fresh leaf extract, or 30 ml fresh juice, over 2–13 weeks. Primary and secondary outcomes varied by study but included blood glucose, lipids, blood pressure, immune markers, viral symptoms, cognition, mood, stress, sleep, fatigue, and safety.

    Across the reviewed studies, tulsi was found to have favourable effects on glucose control, lipid profiles, blood pressure, immune parameters, viral infection outcomes, fatigue, cognition, anxiety, and stress, with no significant adverse events reported. This suggests a wide breadth of medicinal applications for tulsi; however, larger more robust studies are called for to further confirm its effect in humans (14). 

  • Historical use of tulsi

    Tulsi is renowned in India for its religious and spiritual connotations (often grown around temples) and is consumed as a food, drink and medicine very widely. The leaves as well as the seeds have important roles in traditional Ayurveda and other health traditions, with the leaves commonly used in fever management, including in children (8). It has traditionally been applied to supportive digestive health, as it is seen to reduce ama and helps to stimulate bloating and sluggish digestion.  Tulsi has been applied to alleviate respiratory infections and support circulation(4,6).

    It has often been consumed in food, either as a garnish or flavouring, or has also traditionally been drunk as a fresh leaf juice (8). A traditional practice is to chew the leaves to promote digestion and treat stomach issues, as well as mixing it into honey for respiratory complaints (2). 

  • Tulsi’s herbal actions

    Herbal actions describe therapeutic changes that occur in the body in response to taking a herb. These actions are used to express how a herb physiologically influences cells, tissues, organs or systems. Clinical observations are traditionally what have defined these actions: an increase in urine output, diuretic; improved wound healing, vulnerary; or a reduction in fever, antipyretic. These descriptors too have become a means to group herbs by their effects on the body — herbs with a nervine action have become the nervines, herbs with a bitter action are the bitters. Recognising herbs as members of these groups provides a preliminary familiarity with their mechanisms from which to then develop an understanding of their affinities and nuance and discern their clinical significance.

    Western actions

    Ayurvedic actions

  • Tulsi’s energetic qualities

    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 can I use tulsi for?

    Tulsi (Ocimum tenuiflorum)
    Tulsi (Ocimum tenuiflorum)

    Tulsi stimulates the cerebral circulation whilst also relaxing the central nervous system. This unique quality brings mental clarity whilst also calming any nervous tension. Tulsi will counteract brain fog and exhaustion, particularly after trauma, depression and anxiety (1,2).

    Tulsi provides adrenal support, helping the body to adapt to acutely stressful situations and reduce cortisol levels (3). Its supportive actions for stress extend to treating symptomatic presentations of stress including high blood pressure and tension headaches (1).

    The pungent and fragrant volatile oils help to relieve congestion throughout the body and particularly within the respiratory system where it is an effective expectorant and has been used to reduce wheezing and tightness in the chest associated with asthma. Coupled with its potent antimicrobial actions, tulsi increases mucosal defences against chronic and repetitive infection in both the respiratory and digestive systems (2,4). It has been used in larger doses as an aid to fever management due to its febrifuge action (4).

    As a refreshing beverage, tulsi tea can be used as an alternative to coffee or tea as it not only acts as a stimulant but also enhances mental clarity by increasing cerebral circulation (5).

  • Did you know?

    Tulsi is sacred to the Hindu god Vishnu, the Lord of Preservation, and is used in morning prayers to ensure good personal health and wellbeing. It is commonly found in Hindu courtyards and near temples. Meditation beads, mala,  are also often made from the wood of the tulsi shrub (6,7).

  • Botanical description

    Tulsi is a prolific shrub that can grow up to 4m in height. It can naturally be found throughout the lowlands of India but also across Sri Lanka, China and Thailand, the Andaman and Nicobar islands, as well as Northern Australia. Its stems are tall and hairy with opposite green or purple toothed leaves which carry a strong scent. Tulsi flowers are purple and elongated, manifesting in close whorls. It is the scented leaves which are medicinally valued in this plant (15).

    There are several forms of tulsi originating from different species. Notable among these are Rama (green) tulsi and Krishna (red) tulsi. These are varieties of Ocimum tenuiflorum (formerly O. sanctum), also known as Holy Basil, each showing distinctive features, including higher levels of anthocyanins in Krishna tulsi. Differences in chemotype appear to be further modulated by environment and cultivation.

    Vana tulsi, however,  has been variously identified in botanical databases as Ocimum americanum and O. gratissimum. Detailed taxonomic and DNA investigation of vana tulsi has confirmed that it is robustly distinct from the two varieties of Ocimum tenuiflorum. Although apparently hybrid of several species, Ocimum americanum is the convenient botanical definition of vana tulsi (16,17).

    In short there are at least two distinct botanical entities, and significant chemotypical complexity.

  • Common names

    • Holy basil
    • Tulsi (Hindi)
    • Tulasī (Sanskrit)
    • Viṣṇu-priyā (Sanskrit)
    • Divyā (Sanskrit)

  • Habitat

    Ocimum tenuiflorum is native to the Indian subcontinent and tropical areas of Asia, and is widespread throughout India and Sri Lanka. It has also been naturalised across China, Southeast Asia and parts of Australia (15,18). Tulsi prefers warm, humid climates and thrives in well drained soils, and although commonly cultivated, will spread to neighbouring habitats.

  • How to grow tulsi

    Tulsi thrives in tropical climates, but can be grown in cooler environments as long as it has full sun exposure and well drained, fertile soils. It can be easily propagated from seed, and stands the best chance of germination if started indoors. Press the seeds lightly into the top layer of nutrient-rich compost and water regularly but be careful not to waterlog the seeds.

    Germination will typically take between 7–14 days at temperatures of 20–25°C. The seedlings can be planted out once they have developed true leaves, and they prefer to be in a sunny sheltered spot. They are not frost hardy, so it’s recommended to plant out once the last risk of frost has passed (19).

  • Herbal preparation of tulsi

    • Tincture 
    • Tea
    • Powder
    • Leaf juice

  • Plant parts used

    Leaf

  • Dosage

    • Tincture (ratio 1:5| 45%): 2–5 ml, two to three times a day (20)
    • Infusion/decoction: 2–5 g per dose up to three times per day (20)
    • The therapeutic dose for tulsi in the Ayurvedic pharmacopoeia of India is 2–3 g of the leaf powder per day (12). Higher doses have been used for fevers and other acute conditions.
    • Fresh juice: 5–10 ml per day, typically given in small volumes due to the potency (6)

  • Constituents

    • Essential oil (up to 2%): Including eugenol (variable though up to 62%), methyleugenol (up to 86%), and α- and β-caryophyllene (up to 42%), estragole,  limonene, linalool, carvacrol and eucalyptol
    • Phenolic compounds: Rosmarinic acid, caffeic acid, chlorogenic acid
    • Flavonoids: Apigenin, luteolin, vicenin, orientin
    • Tannins: Gallic acid and chlorogenic acid (up to 4.6 %)
    • Triterpenes: Ursolic acid, oleanolic acid 
    • Saponins (21)

  • Tulsi recipe

    Incredible immunity tea

    Bacteria and viruses are most active at lower body temperatures, so when the body has a  fever, this is in response to our immune system’s effort to reduce microbial overload. That is where this delicious Incredible Immunity Tea recipe below comes in. It helps the immune system fight the infection.

    Ingredients

    This will serve 2–3 cups of flu-free freedom.

    How to make a tulsi tea

    • Put all of the ingredients in a pot. Add 500 ml (18fl oz) freshly boiled filtered water.
    • Leave to steep for 5–10 minutes, then strain.
    • Drink while it’s piping hot.
Adaptogens: Herbs to manage stress and stressful situations

Adaptogens: Herbs to manage stress and stressful situations

  • Safety

    No significant safety issues have been noted in accounts of the traditional use of tulsi. Tulsi is considered a generally safe herb with low toxicity and is generally well tolerated with minimal adverse effects (20). Tulsi is not recommended during pregnancy and breastfeeding (22). 

    Different species of tulsi are known sources of methyleugenol, in isolation a carcinogen, but also found in plants such as basil itself, as well as nutmeg, pimento, lemongrass, tarragon, star anise and fennel.

    Given that tulsi is a less familiar plant in Western countries, there have been theoretical safety concerns. Closer investigation shows safety prospects comparable to the other plants naturally containing methyleugenol. Human studies indicate that methyleugenol is short-lived in the body, and despite the exposure through the diet and environment, human blood levels are relatively low (23). Humans have a long evolutionary history of exposure to these constituents as foods and possess a competent detoxification pathway for them (24).

    Tulsi may aggravate excess pitta symptoms including heat, irritation, reflux, inflammation and exacerbate dry constitutions like dry skin or dehydration (4). 

  • Interactions

    There is a theoretical concern of tulsi interactions with some medication — including the increased risk of bleeding when taken in conjunction with anticoagulant or antiplatelet medication, and an increased risk of hypoglycaemia when taken alongside antidiabetic medication (25).

  • Contraindications

    Contraindicated in people susceptible to hypoglycaemia and with a need for close blood sugar regulation (20,25).

  • Sustainability status of tulsi

    Ocimum tenuiflorum is not considered to be at threat or at risk of overharvesting. It is not listed on the IUCN redlist, NatureServe or American Botanical council (26,27,28). 

    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

    Tulsi is commonly cultivated in South Asia in smallholdings or home gardens via seed sharing (29). Adulteration with other Ocimum species is common, in particular between the Rama, Krishna and Vana subtypes, which have notable differences in their chemical composition (30). Key marker compounds include the volatile oil eugenol, which is largely responsible for many of tulsi’s therapeutic effects (31).

  • References

    1. Hedley C, Shaw N. Plant Medicine. (Waddell G, ed.). Aeon Books; 2023.
    2. Mcintyre A. Complete Herbal Tutor : The Definitive Guide to the Principles and Practices of Herbal Medicine (Second Edition). Aeon Books Limited; 2019.
    3. Romm AJ. Botanical Medicine for Women’s Health. St. Louis, Missouri Elsevier; 2018.
    4. Frawley D, Lad V. The Yoga of Herbs : An Ayurvedic Guide to Herbal Medicine. Lotus Press; 2008.
    5. Winston D, Maimes S. Adaptogens : Herbs for Strength, Stamina, and Stress Relief. Healing Arts Press; 2007.
    6. Pole S. Ayurvedic Medicine : The Principles of Traditional Practice. Singing Dragon; 2013.
    7. Wood M. The Practice of Traditional Western Herbalism : Basic Doctrine, Energetics, and Classification. North Atlantic Books, Cop; 2004.
    8. Mcintyre A. Herbal Treatment of Children : Western and Ayurvedic Perspectives. Elsevier/Butterworth-Heinemann; 2005.
    9. Cabrera C. Holistic Cancer Care. Storey Publishing, LLC; 2023.
    10. Easley T, Horne SH. The Modern Herbal Dispensatory: A Medicine-Making Guide. North Atlantic Books; 2016.
    11. Sampath S, Mahapatra SC, Padhi MM, Sharma R, Talwar A. Holy basil (Ocimum sanctum Linn.) leaf extract enhances specific cognitive parameters in healthy adult volunteers: A placebo controlled study. Indian Journal of Physiology and Pharmacology. 2015;59(1):69-77. https://pubmed.ncbi.nlm.nih.gov/26571987/ 
    12. Lopresti AL, Smith SJ, Metse AP, Drummond PD. A randomized, double-blind, placebo-controlled trial investigating the effects of an Ocimum tenuiflorum (Holy Basil) extract (HolixerTM) on stress, mood, and sleep in adults experiencing stress. Frontiers in Nutrition. 2022;9. https://doi.org/10.3389/fnut.2022.965130 
    13. Mondal S, Varma S, Bamola VD, et al. Double-blinded randomized controlled trial for immunomodulatory effects of Tulsi (Ocimum sanctum Linn.) leaf extract on healthy volunteers. Journal of Ethnopharmacology. 2011;136(3):452-456. https://doi.org/10.1016/j.jep.2011.05.012 
    14. Jamshidi N, Cohen MM. The Clinical Efficacy and Safety of Tulsi in Humans: A Systematic Review of the Literature. Evidence-based Complementary and Alternative Medicine : eCAM. 2017;2017. https://doi.org/10.1155/2017/9217567 
    15. Royal Botanical Gardens Kew. Ocimum tenuiflorum L. | Plants of the World Online | Kew Science. Plants of the World Online. Published 2016. Accessed April 24, 2026. https://powo.science.kew.org/taxon/urn%3Alsid%3Aipni.org%3Anames%3A453130-1 
    16. Upadhyay AK, Chacko AR, Gandhimathi A, et al. Genome sequencing of herb Tulsi (Ocimum tenuiflorum) unravels key genes behind its strong medicinal properties. BMC Plant Biology. 2015;15(1). https://doi.org/10.1186/s12870-015-0562-x 
    17. Suthar MK, Saran PL. Anthocyanins from Ocimum sanctum L., a promising biomolecule for development of cost-effective and widely applicable pH indicator. 3 Biotech. 2020;10(9). https://doi.org/10.1007/s13205-020-02380-5 
    18. NCBI. Taxonomy Browser (Ocimum tenuiflorum). Nih.gov. Published 2026. Accessed April 24, 2026. https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=204149 
    19. Earthsong seeds. Tulsi Seeds | Certified Organic | UK Grown. Earthsong Seeds. Published January 5, 2026. Accessed April 24, 2026. https://earthsongseeds.co.uk/shop/herbs/tulsi/ 
    20. Bone K, Mills S. Principles and Practice of Phytotherapy: Modern Herbal Medicine. 2nd ed. Edinburgh Churchill Livingstone, Elsevier; 2013.
    21. Pengelly A. The Constituents of Medicinal Plants. Cab International; 2021.
    22. Guyett C. The Herbalist’s Guide to Pregnancy, Childbirth and Beyond. Aeon Books; 2022.
    23. Robison SH, Barr DB. Use of Biomonitoring Data to Evaluate Methyl Eugenol Exposure. Environmental Health Perspectives. 2006;114(11):1797-1801. https://doi.org/10.1289/ehp.9057 
    24. Minet EF, Daniela G, Meredith C, Massey ED. A comparativein vitrokinetic study of [14C]-eugenol and [14C]-methyleugenol activation and detoxification in human, mouse, and rat liver and lung fractions. Xenobiotica. 2011;42(5):429-441. https://doi.org/10.3109/00498254.2011.637582 
    25. TRC Healthcare. NatMed Pro – Holy Basil. Therapeuticresearch.com. Published 2026. Accessed April 24, 2026. https://naturalmedicines.therapeuticresearch.com/Data/ProMonographs/Holy-Basil#drug-interactions 
    26. Botanic R. IUCN Red List of Threatened Species: Ocimum grandiflorum. IUCN Red List of Threatened Species. Published December 28, 2020. https://www.iucnredlist.org/species/192556681/192556688 
    27. NatureServe. NatureServe Explorer 2.0. explorer.natureserve.org. https://explorer.natureserve.org/Search#q 
    28. American Botanical Council. ABC Herbalgram Website. Herbalgram.org. Published 2026. Accessed April 24, 2026. https://www.herbalgram.org/search/?q=Tulsi 
    29. Bhamra SK, Heinrich M, Johnson MRD, Howard C, Slater A. The Cultural and Commercial Value of Tulsi (Ocimum tenuiflorum L.): Multidisciplinary Approaches Focusing on Species Authentication. Plants. 2022;11(22):3160. https://doi.org/10.3390/plants11223160 
    30. 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 
    31. Raina AP, Kumar A, Dutta M. Chemical characterization of aroma compounds in essential oil isolated from “Holy Basil” (Ocimum tenuiflorum L.) grown in India. Genetic Resources and Crop Evolution. 2013;60(5):1727-1735. https://doi.org/10.1007/s10722-013-9981-4 

Meet our herbal experts

Rebecca Collison-Walker
- Herbalist

Dedicated to the path of natural health and healing, Rebecca Collison-Walker has worked in complementary health for over 10 years.

Read Rebecca's articles

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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
The 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) 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.
Bland
Blandness refers to a mild, plain, non-stimulating taste and an energetic action that neither irritates nor strongly activates physiological processes. In traditional Chinese medicine, bland substances gently drain dampness and promote urination, relieving excess fluid whilst also preserving qi and yin. Western traditional medicine similarly associates healing with bland substances that avoid extremes of heat or cold and promote restoration of balance. Blandness signifies regulation by supporting elimination and normal tissue function without forceful stimulation, helping to create a gentle and balanced state of homeostasis.
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, horseradish 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.
Neutral
Neutral herbs are characterised as by balanced temperature and energetics — neither warming nor cooling, nor strongly dispersing nor consolidating, and are, therefore, used across a wide spectrum of constitutional and pathological states. In Chinese medicine, this level, calm quality supports the centre, and gently strengthens digestion, regulates fluids, and resolves damp without provoking too much heat or cold. In Western medicine, neutral herbs are regarded as equal in relation to hot/cold or damp/dry and capable of maintaining a state of equilibrium. Neutral herbs can be seen as moderating reactivity, and supporting homeostasis rather than forcing change.
Pungent
The pungent flavour refers to the powerful taste of hot spices including mustard (Brassica spp.), ginger (Zingiber officinale), horseradish (Amoracia rusticana), chilli (Capsicum spp.), and garlic (Allium sativum). These herbs act to enliven and invigorate the senses, and they often also have heating qualities. Unlike other tastes, the effect is not linked to a specific receptor on the tongue and instead acts through direct irritation of tissues and nerve endings. Energetically, pungent herbs are known to disperse energy (qi) throughout the body. Pharmacologically, pungent herbs dry excess moisture and mucus, as well as stimulate digestion and metabolism.
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'.
Sharp
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.
Sour
The sour taste occurs because of the stimulation of hydrogen ions which trigger the sour taste receptors on the tongue. The more acidic a substance, the more hydrogen ions will be released. The sour taste comes from acidic substances including citrus, fermented foods, tannins, and vinegars. Sour foods and herbs absorb excess moisture, whilst also increasing the production of saliva. Energetically, sour substances tonify the lungs, playing a role in disease prevention. Excessive use, however, can result in malabsorption of nutrients. Examples of sour herbs include, rosehips (Rosa canina), raspberry (Rubus idaeus), rhubarb (Rheum palmatum), schisandra (Schisandra chinensis), hawthorn (Crataegus monogyna) and ginkgo (Ginkgo biloba).
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.
Umami
The umami taste was originally discovered in 1985 in Japan and is directly translated from the Japanese as a ‘pleasant savoury taste’. It is referred to as the ‘fifth taste’ and is a salty, rich, and meaty flavour. The umami flavour is produced by amino acids (glutamic acid and aspartic acid) found in many food and plant sources including tomatoes, mushrooms, seaweeds and soy-based foods. Umami foods can improve nutritional absorption and digestion as there are also umami receptors in the gut as well as the mouth. Examples of umami herbs include green tea (Camellia sinensis), reishi (Ganoderma lucidum), nettle (Urtica dioica), cordyceps (Ophiocordyceps sinensis), shitake (Lentinula edodes) and bladderwrack (Fucus vesiculosus).

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