Allicin is a sulfur-containing compound formed in garlic when an intact clove of garlic is crushed.

Allicin has been found to reduce inflammation, stimulate phase 2 detoxifying enzymes and act as a natural antibacterial and antifungal agent.

Because allicin is destroyed by heat, it is important to eat raw garlic to get its benefits.

References

Tapiero H, Townsend DM, Tew KD. Organosulfur compounds from alliaceae in the prevention of human pathologies. Biomed Pharmacother. 2004;58(3):183-193. Lawson LD, Wang ZJ. Allicin and allicin-derived garlic compounds increase breath acetone through allyl methyl sulfide: use in measuring allicin bioavailability. J Agric Food Chem. 2005;53(6):1974-1983. Ali M, Thomson M, Afzal M. Garlic and onions: their effect on eicosanoid metabolism and its clinical relevance. Prostaglandins Leukot Essent Fatty Acids. 2000;62(2):55-73. Dirsch VM, Kiemer AK, Wagner H, Vollmar AM. Effect of allicin and ajoene, two compounds of garlic, on inducible nitric oxide synthase. Atherosclerosis. 1998;139(2):333-339. Kim KM, Chun SB, Koo MS, et al. Differential regulation of NO availability from macrophages and endothelial cells by the garlic component S-allyl cysteine. Free Radic Biol Med. 2001;30(7):747-756. Chang HP, Huang SY, Chen YH. Modulation of cytokine secretion by garlic oil derivatives is associated with suppressed nitric oxide production in stimulated macrophages. J Agric Food Chem. 2005;53(7):2530-2534. Keiss HP, Dirsch VM, Hartung T, et al. Garlic (Allium sativum L.) modulates cytokine expression in lipopolysaccharide-activated human blood thereby inhibiting NF-kappaB activity. J Nutr. 2003;133(7):2171-2175. Song K, Milner JA. The influence of heating on the anticancer properties of garlic. J Nutr. 2001;131(3s):1054S-1057S.