I saw this on Yahoo this morning. It made me feel good because we eat a tonne of garlic and onions in our diet. Thought you might find it interesting too:

How Garlic and Onions Promote a Healthy Heart

Way back in the first century A.D., Dioscorides, the Roman who codified Greek herbal medicine, wrote in his Materia Medica that garlic "clears the arteries." And the ancient Indian Ayurvedic text Charaka Samhita holds that garlic "maintains the fluidity of the blood, strengthens the heart and prolongs life."

Modern researchers have confirmed that both raw and cooked garlic and onions contain compounds that inhibit the tendency to form artery-clogging blood clots, thus lowering heart-attack risk. There is evidence that a clove a day may also lower elevated levels of blood cholesterol, as well as high blood pressure, although not all studies confirm these benefits.

Other allium compounds have been shown to inhibit cancer in the test tube and in animals. In population studies, people who eat more alliums have lower rates of stomach and other cancers. Garlic appears to stimulate the body's production of an enzyme called glutathione-S-transferase, which helps detoxify potential carcinogens. In a major five-year study of more than 35,000 women aged 55 to 69 in Iowa, garlic was the single most protective food against colon cancer. The women who ate garlic more than once a week had a 32 percent lower risk of colon cancer than those who ate less than a clove a month.

Garlic's sulfur compounds may offer particular protection against cancers of the breast, esophagus, prostate, skin and stomach.