OverviewParts used and where grown
The leaves of basil and its many close relatives are used as medicine. The seeds are also used medicinally in India and Southeast Asia. Though it originates on the shores of the Mediterranean Sea and the Middle East, common basil now grows in gardens all over the world. Three important relatives with similar properties are Ocimum canum (hairy basil), O. gratissimum (basil), and O. sanctum (holy basil).
Active constituents
Basil contains a strong-scented volatile oil composed primarily of terpenoids, particularly eugenol, thymol, and estragole. Basil also has what are known as chemotypes, minor variations among plants that contain significantly different mixes of constituents. The exact components of basil oil vary widely, being affected not only by these chemotypes but also by factors such as the time of day of harvest. This may account for some of the variability in scientific research and reports of medicinal efficacy of basil from culture to culture.
Preliminary studies on holy basil and hairy basil have shown that the leaf and seed may help people with type 2 diabetes control their blood sugar levels. While the action-mechanism of the leaf is not understood, the seed may work by providing dietary fiber, which helps prevent rapid blood sugar elevations after meals. In addition, the seed has been found to relieve constipation by acting as a bulk-forming laxative in one uncontrolled human study. A similar study showed the seeds useful in elderly people who experienced constipation after undergoing major surgery.
The volatile oil of basil has shown antibacterial, antifungal, and antiviral activity in test tube studies. It is also believed to act as a carminative, relieving intestinal gas, and as a mild diuretic, though these actions have yet to be definitively proven.
Dosage
How much is usually taken?
A tea can be made by steeping 1 teaspoon of basil leaves in one cup of water for ten minutes. Three cups of this tea can be drunk per day. Capsules of basil can be taken in the amount of 2.5 grams per day. The volatile oil can be taken internally in the amount of 2 to 5 drops three times per day.
Side Effects
Are there any side effects or interactions?
Although concerns have been raised about the possible cancer-causing effects of estragole, a component found in variable amounts in basil volatile oil, small amounts of basil would not seem to pose a significant threat. However, because some herbal books suggest that estragole may be potentially carcinogenic and has been thought to stimulate uterine contractions, some herbal experts feel it may be best for pregnant or breast-feeding women to avoid use of the herb, especially the volatile oil. People with serious kidney or liver damage should not use basil volatile oil internally, as they could theoretically have trouble eliminating it from their bodies. However, use of basil as a seasoning in food is unlikely to be of concern.
At the time of writing, there were no well-known drug interactions with basil.
Drug Interactions
At the time of writing, there were no well-known drug interactions with basil.
References
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2. Nadkarni AK, Nadkarni KM. Indian Materia Medica vol 1. Bombay: Popular Prakashan, 1976:861–7.
3. Farnsworth NR, Bunyapraphatsara N (eds). Thai Medicinal Plants. Bangkok: Medicinal Plant Information Center, 1992:180–2.
4. de Vasconcelos Silva MG, Craveiro AA, Abreu Matos FJ, et al. Chemical variation during daytime of constituents of the essential oil of Ocimum gratissimum leaves. Fitoterapia 1999;70:32–4.
5. Viseshakul D, Premvatana P, Chularojmontri V, et al. Improved glucose tolerance induced by long term dietary supplementation with hairy basal seeds (Ocimum canum Sim) in diabetics. J Med Assoc Thai 1985;68:408–11.
6. Agrawal P, Rai V, Singh RB. Randomized placebo-controlled, single blind trial of holy basil leaves in patients with noninsulin-dependent diabetes mellitus. Int J Clin Pharmacol Ther 1996;34:406–9.
7. Rai V, Mani UV, Iyer UM. Effect of Ocimum sanctum leaf powder on blood lipoproteins, glycated protein and total amino acids in patients with non-insulin-dependent diabetes mellitus. J Nutr Environ Med 1997;7:113–8.
8. Kocharatana P, et al. Clinical trial of maeng-lak seeds used as a bulk laxative. Maharaj Nakornratchasima Hosp Med Bull 1985;9:120–36.
9. Muangman V, Siripraiwan S, Ratanaolarn K, et al. A clinical trial of Ocimum canum Sims seeds as a bulk laxative in elderly post-operative patients. Ramathibodi Med J 1985;8:154–8.
10. Farnsworth NR, Bunyapraphatsara N (eds). Thai Medicinal Plants. Bangkok: Medicinal Plant Information Center, 1992:180–2.
11. Farnsworth NR, Bunyapraphatsara N (eds). Thai Medicinal Plants. Bangkok: Medicinal Plant Information Center, 1992:180–2.
12. Valnet J. The Practice of Aromatherapy. New York: Destiny Books, trans. Campbell R, Houston L, 1982:97–8.
13. McGuffin M, Hobbs C, Upton R, Goldberg A (eds). American Herbal Products Association’s Botanical Safety Handbook. Boca Raton, FL: CRC Press, 1997:143–5.
14. Brinker F. Herb Contraindications and Drug Interactions. Sandy, OR: Eclectic Medical Publications, 1998, 33–4.
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