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Garlic May Help Protect from Colon Cancer

According to a large meta-analysis of epidemiological research on the association between garlic consumption and the risk of various types of cancer, the strongest evidence for anti-cancer effects of raw garlic pertains to stomach and colorectal cancers. This extensive meta-analysis took into account epidemiological studies published between 1966 and 1999, and included studies on stomach, colon, head and neck, lung, breast and prostate cancers. The findings of the analysis were published in the American Journal of Clinical Nutrition in 2000.

In 2004, a double-blind study reported that patients with colorectal cancer that were given a high daily dose of aged garlic extract (AGE) had a 29% reduction in the risk of developing at least one new adenoma, compared with cancer patients who received a low dose of AGE during the 12-month trial period. Adenomas, or adenomatous polyps, are cancerous colon polyps. They account for about 75% of all colon polyps.

Eating garlic
Numerous studies suggest that garlic may help prevent and fight colon cancer.

Colon Cancer Fighting Mechanisms

But how does garlic help prevent colorectal cancer? Garlic appears to fight cancer, including rectal and colon cancer, through multiple mechanisms. It has been shown to inhibit the production of free radicals, activate enzymes that detoxify carcinogens (cancer-causing substances that enter the body), and to regulate cell-cycle arrest. Furthermore, garlic has been shown to be capable of inducing apoptosis, or programmed cell death. Apoptosis is the body's normal way of getting rid of unneeded or abnormal cells, but cancer cells develop mechanisms to evade apoptosis.

Cancer Fighting Nutrients in Raw Garlic

Many of the colorectal cancer fighting properties of garlic are thought to be linked to organosulphur compounds which are produced during decomposition of allicin. Allicin, in turn, is formed when raw garlic is crushed or chopped. To maximize the allicin-content of your garlic dishes, let the chopped or crushed garlic sit for 10 to 15 minutes before using it. Research shows that raw garlic that has been allowed to sit for several minutes contains more allicin than garlic that is used immediately after chopping or crushing.

In addition to allicin, raw garlic is loaded with vitamin C, vitamin B6 and calcium, all of which have been identified as important colon cancer fighting nutrients. Furthermore, garlic is a fairly good source of potentially cancer fighting riboflavin and zinc.


1. Fleischauer Aaron, Poole Charles, and Arab Lenore (2000). Garlic consumption and cancer prevention: meta-analyses of colorectal and stomach cancers. American Journal of Clinical Nutrition, 72(4), 1047-1052.
2. Tanaka S, Haruma K, Kunihiro M, Nagata S, Kitadai Y, Manabe N, Sumii M, Yoshihara M, Kajiyama G, Chayama K. (2004). Effects of aged garlic extract (AGE) on colorectal adenomas: a double-blinded study. Hiroshima Journal of Medical Sciences, 53(3-4), 39-45.

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