The sulfur compound allicin, produced by crushing or chewing fresh garlic or by taking
powdered garlic products with allicin potential, in turn produces other sulfur compounds:
ajoene, allyl sulfides, and vinyldithiins.1 Aged garlic products lack allicin, but
may have activity due to the presence of S-allylcysteine.
Many publications have shown that garlic supports the cardiovascular system. While earlier
trials suggest it may mildly lower cholesterol
and triglyceride levels in the
blood,2 3 4 more recent trials found garlic to have minimal
success in lowering cholesterol and triglycerides.5 6 7
Garlic also inhibits platelet stickiness (aggregation) and increases fibrinolysis,8
which results in a slowing of blood coagulation. It is mildly antihypertensive9 and has antioxidant activity.10
Garlic’s cardiovascular protective effects were illustrated in a four-year clinical
trial on people 50–80 years old with
atherosclerosis.11 It was found that consumption of 900 mg of a standardized
garlic supplement reduced arterial plaque formation by 5–18%. The benefits were most
notable in women.
In test tube studies garlic has been found to have antibacterial, antiviral, and antifungal
activity.12 However, these actions are less clear in humans and do not suggest that
garlic is a substitute for antibiotics or
Human population studies suggest that eating garlic regularly reduces the risk of
esophageal, stomach, and colon
cancer.13 14 This may be partly due to garlic’s ability to
reduce the formation of carcinogenic compounds.
1. Koch HP, Lawson LD (eds). Garlic: The Science and Therapeutic
Application of Allium sativaum L and Related Species, 2d ed. Baltimore: Williams and
Wilkins, 1996, 62–4.
2. Warshafsky S, Kamer R, Sivak S. Effect of garlic on total serum
cholesterol: A meta-analysis. Ann Int Med 1993;119:599–605.
3. Silagy C, Neil A. Garlic as a lipid-lowering agent—a
meta-analysis. J R Coll Phys London 1994;28:39–45.
4. Neil HA, Silagy CA, Lancaster T, et al. Garlic powder in the treatment
of moderate hyperlipidaemia: A controlled trial and a meta-analysis. J R Coll Phys
5. McCrindle BW, Helden E, Conner WT. Garlic extract therapy in children
with hypercholesterolemia. Arch Pediatr Adolesc Med 1998;152:1089–94.
6. Isaacsohn JL, Moser M, Stein EA, et al. Garlic powder and plasma
lipids and lipoproteins. Arch Intern Med 1998;158:1189–94.
7. Berthold HK, Sudhop T, von Bergmann K. Effect of a garlic oil
preparation on serum lipoproteins and cholesterol metabolism. JAMA
8. Legnani C, Frascaro M, Guazzaloca G, et al. Effects of a dried garlic
preparation on fibrinolysis and platelet aggregation in healthy subjects. Arzneim-Forsch
Drug Res 1993;43:119–22.
9. Silagy CA, Neil HA. A meta-analysis of the effect of garlic on blood
pressure. J Hyperten 1994;12:463–8.
10. Kleijnen J, Knipschild P, Ter Riet G. Garlic, onion and
cardiovascular risk factors: A review of the evidence from human experiments with emphasis on
commercially available preparations. Br J Clin Pharmacol 1989;28:535–44.
11. Koscielny J, Klüendorf D, Latza R, et al. The
antiatherosclerotic effect of Allium sativum. Atherosclerosis
12. Hughes BG, Lawson LD. Antimicrobial effects of Allium
sativum L. (garlic), Allium ampeloprasum L. (elephant garlic) and Allium
cepa L. (onion), garlic compounds and commercial garlic supplement products.
Phytother Res 1991;5:154–8.
13. Dorant E, van den Brandt PA, Goldbohm RA, et al. Garlic and its
significance for the prevention of cancer in humans: A critical review. Br J Cancer
14. Fleishauer AT, Poole C, Arab L. Garlic consumption and cancer
prevention: meta-analyses of colorectal and stomach cancers. Am J Clin Nutr
15. Brown DJ. Herbal Prescriptions for Better Health. Rocklin,
CA: Prima Publishing, 1996, 97–109.
16. Blumenthal M, Busse WR, Goldberg A, et al. (eds). The Complete
Commission E Monographs: Therapeutic Guide to Herbal Medicines. Boston, MA: Integrative
Medicine Communications, 1998, 134.
17. Brown DJ. Herbal Prescriptions for Better Health. Rocklin,
CA: Prima Publishing, 1996, 97–109.
18. Mennella JA, Beauchamp GK. Maternal diet alters the sensory qualities
of human milk and the nursling’s behavior. Pediatr 1991;88:737–44.
19. Mennella JA, Beauchamp GK. The effects of repeated exposure to
garlic-flavored milk on the nursling’s behavior. Pediatr Res