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).
Basil has been used in
connection with the following conditions (refer to the individual
health concern for complete information):
Reliable
and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies
suggesting a health benefit or minimal health benefit. For an herb, supported by traditional use but minimal
or no scientific evidence. For a supplement, little scientific support and/or minimal health
benefit.
Historical or traditional use (may
or may not be supported by scientific studies)
Basil has been a culinary herb in Europe and Central Asia since before the written
word.1 In India the seeds were used for diarrhea, mucous discharges, constipation, and as a general demulcent (soothes
mucous membranes);2 the leaves were used for indigestion and skin diseases. In traditional Thai
herbalism, the plant is used for coughs, skin
diseases, and intestinal problems. The seed is used as a bulk-forming laxative and
diuretic.3
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.4 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.567 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.8 A similar study showed the seeds useful in elderly
people who experienced constipation after undergoing major surgery.9
The volatile oil of basil has shown antibacterial, antifungal, and antiviral activity in
test tube studies.10 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.11
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.12
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.13 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.14 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.
References (To view, roll mouse over the "References" heading; to hide, click on the heading)
1. Grieve M. A Modern Herbal vol 1. New York: Hafner,
1967:86.
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.
The information presented in Healthnotes is for informational purposes
only. It is based on scientific studies (human, animal, or in vitro), clinical
experience, or traditional usage as cited in each article. The results reported may not
necessarily occur in all individuals. For many of the conditions discussed, treatment with
prescription or over the counter medication is also available. Consult your doctor,
practitioner, and/or pharmacist for any health problem and before using any supplements or
before making any changes in prescribed medications. Information expires June 2009.
Reliable
and relatively consistent scientific data showing a substantial health benefit.