Research appearing in the November, 2006 issue of the American Journal of Clinical Nutrition, shows that eating onions and garlic may help to prevent cancer. Italian researchers examined at data from several studies that looked at the relationship between garlic and onion consumption and the incidence of cancer. They found that the more onions a subject ate, the less likely he or she was to have cancer of the esophagus or larynx. Consumption of garlic was linked to a lower rate of cancers of the kidney and colon. It seems that those who ate the most garlic enjoyed greater amount of protection from cancer.
Earlier research appearing in the October, 2000 issue of the American Journal of Clinical Nutrition, produced similar results. Researchers from the University of North Carolina reviewed 300 research papers from studies around the world. From those 300 papers, they chose 22 studies deemed to be relevant and well-run. The UNC researchers found that those who regularly eat garlic are only about two-thirds as likely to have colon cancer and only half as likely to develop stomach cancer as those who consume no garlic. The findings pertained to fresh garlic (raw or cooked), and not garlic supplements.
Earlier research on animals has shown that a compound in garlic called allium, offers some protection from cancer. Some scientists believe that this may also work in humans. Some scientists believe that garlic may protect against stomach cancer because it is antimicrobial and may protect against Helicobacter pylori. Helicobacter pylori has been linked to ulcers and its presence can increase the risk for stomach cancer.