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Onions and Garlic for Longevity

Do These Odorous Vegetables Help Prevent Cancer?

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Updated August 30, 2012

Onions and Garlic for Longevity

Can onions and garlic prevent cancer?

Sharon Basaraba

While exotic foods like goji berries and acai might get all the anti-aging accolades, the fact is that many familiar vegetables like garlic and onions offer great nutrition and protection against serious diseases like cancer.

According to cancer researchers from the University of Quebec’s Molecular Medicine Laboratory in Montreal, members of the Allium family –- which includes garlic, onions, leeks, shallots and chives –- have been employed as medicine for thousands of years. The Egyptians believed the plants brought them strength, endurance, and longevity. Today, these foods are emerging as significant weapons in the fight to prevent many cancers, particular those of the digestive system like colon, stomach and esophageal.

In their book Foods That Fight Cancer, biochemist Richard Béliveau and researcher Denis Gingras credit the sulfurous compounds these vegetables contain for their anti-cancer properties. Released or activated only after crushing, mincing or chopping breaks down the plants’ cell walls, these chemicals pack a powerful (if smelly) punch against carcinogenic compounds and the tumors themselves.

While the exact mechanism of action is unclear, compounds in plants from the Allium family appear to inhibit cancer growth in a few ways. First, they may prevent the creation of carcinogenic compounds by interrupting their activation in the body. Garlic, for example, appears to keep nitrites -- a food additive in processed meats like bacon and ham -- from converting into harmful nitrosamines. Garlic and onions may also speed up the elimination of such carcinogens from the body, reducing their exposure time to various bodily systems.

In addition, sulfur-containing compounds in these vegetables may attack and kill tumor cells directly. Research conducted in Beliveau’s lab have shown that when cancer cells (from colon, breast, lung and other cancers) were treated with garlic extracts, the death of those cells was accelerated.

A 2006 review of studies conducted in Italy and Switzerland confirmed that consuming garlic and onions more frequently was linked to a lower incidence of certain cancers like colorectal, esophageal, and breast cancer. The findings, published in the American Journal of Clinical Nutrition, held, despite differences among subjects in lifestyle habits like tobacco use and physical activity. The researchers suggest that additional factors may also contribute to the protective effect of garlic and onions, including the fact these foods are often eaten or cooked with tomatoes and olive oil.

Supplements or food? The US National Institutes of Health, which rate various foods and supplements regarding health claims, states that eating garlic “seems to reduce the risk” of developing colon, rectal and stomach cancers (though it cautions garlic supplements do not appear to have the same effect.) It also states that taking garlic supplements appears not to reduce the risk of breast, or lung cancer.

In their book, Béliveau and Gingras explain why supplements may not be as powerful in the fight against cancer. The primary component of garlic credited with anti-cancer properties is “allicin”, a highly unstable compound that is quickly converted in the body into a variety of other chemicals. Supplements may contain vastly different amounts of the key components of allicin that are activated once inside the body. Béliveau and his team, like many nutritionists, recommend eating garlic as a whole food, rather than distilled into pill form.

Furthermore, as many as twenty or more compounds in garlic have been shown to have anti-cancer properties, and may interact alone or in concert against carcinogens and tumors.

Allium vegetables are a delicious and healthy component of an anti-aging diet, and eating them regularly appears to help you avoid certain cancers, especially those of the digestive system. As always, consult your health-care provider if you have any questions about your health, or diet.

Sources:

Kim JY, Kwon O. Garlic intake and cancer risk: an analysis using the Food and Drug Administration's evidence-based review system for the scientific evaluation of health claims. Am J Clin Nutr. 2009 Jan;89(1):257-64.

Galeone C, Pelucchi C, Levi F, Negri E, Franceschi S, Talamini R, Giacosa A, La Vecchia C. Onion and garlic use and human cancer. Am J Clin Nutr. 2006 Nov;84(5):1027-32.

Garlic. US National Institutes of Health Medline Plus Public Information sheet. Accessed Aug.27, 2012.
http://www.nlm.nih.gov/medlineplus/druginfo/natural/300.html

Richard Béliveau and Denis Gingras. Foods That Fight Cancer: Preventing Cancer Through Diet. McClelland & Stewart; May 23 2006.

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