WESTPORT, CT (Reuters Health) - Eating a lot of garlic, but not garlic supplements, seems to protect against stomach and colorectal cancer. So report investigators from the University of North Carolina at Chapel Hill, after they conducted meta-analyses of studies reporting a relationship between consumption of garlic and the risk of cancer in humans.

A search of MEDLINE yielded 18 articles estimating relative risk associated with garlic intake, write Dr. Lenore Arab and associates in the October issue of the American Journal of Clinical Nutrition. The mean intake of the highest consumers of raw or cooked garlic was 18.3 g/week--approximately six cloves--with a range extending to >28.8 g/week.

The random-effects relative risk estimate based on six studies "suggests that high consumption of raw or cooked garlic decreases the risk of colorectal cancer from 10% to nearly 50%, with a point estimate of an approximate 30% reduction," the investigators write. Based on four case-control studies, the relative risk of developing stomach cancer was 0.53 for those who consumed the most garlic.

Dr. Arab's group notes that the inverse associations were consistent across studies. However, consumption of garlic supplements was not associated with cancer risk. The researchers caution that the studies are hampered by such problems as heterogeneity of effect estimates, indications of publication bias, and possible confounding by total vegetable consumption.

(From Reuters Health)