From The January 2001 Issue of Nutrition Science News

Garlic May Protect Against Stomach and Colorectal Cancer

Garlic may protect against colorectal and stomach cancer, according to a meta-analysis of qualifying epidemiologic studies. Aaron Fleischauer, Ph.D., and colleagues at the University of North Carolina, Chapel Hill, reviewed 18 studies on garlic intake and cancer risk. The team used a complex statistical method called the funnel plot analysis to account for large studies being more apt to yield true conclusions than small studies and for the bias resulting from journal editors' preference for publishing studies showing a positive effect, called publication bias.

In the studies selected, garlic consumption was as high as 10 cloves a week. The results of these studies were quite consistent. High consumption of raw or cooked garlic decreases the chances of colorectal cancer by an average of 30 percent and stomach cancer risk by an average of 50 percent.

One possible confounding factor in some studies was inadequate control of total vegetable consumption. It is possible that vegetable lovers use garlic for seasoning, so higher vegetable consumption might actually be the factor responsible for cancer prevention. The researchers believe additional trials are required to form a definitive conclusion. Only a relatively few studies have looked at garlic supplementation.

— American Journal of Clinical Nutrition, 2000 Oct.; 72(4);1047-52.