Onions and garlic are members of the Allium vegetable family. This family includes onions, garlic, leeks, chives, shallots and scallions. These vegetables are rich in organo sulfur compounds, which reduce the risk of oral, esophageal, colorectal, laryngeal, breast, ovarian, and prostate cancers by 50%-80%. One major substance that reduces the risk of cancer is quercetin. Quercetin stops damaged cells from becoming cancer cells and exists mainly in garlic and red and yellow onions. There is not as much quercetin in white onions. Garlic and onion phytochemicals can kill cancer cells and stop cancer cell reproduction. Another substance that helps prevent cancer are anthocyanins. Red onions are rich in anthocyanins, which also exists in many berries. Not only are the Allium vegetables healthy, they are also tasty. You can add onions or garlic to your salad or any vegetable dish you like.

Onions, Garlic, Leek, etc...

The Allium Vegetable Family

As you may know, when an onion is cut, a gas is released from the onion that irritates our eyes. This gas is a sign that the chemicals in the onion are reacting and producing the anti-cancer compounds. To reduce the gas and eye irritation you can put the onion in the freezer for five minutes and then cut it. One thing to keep in mind is that the onion nearest to the roots has the highest concentration of anti-cancer compounds. Try to keep this part. Another way to get the most anti-cancer compounds is to eat it raw and chew it very well. The final piece of advice is to chop the onion very thinly before cooking so that the anti-cancer compounds can form.  Onions and garlic can be added to so many dishes and are a great way to keep our bodies healthy.

AHG

Source:
http://www.drfuhrman.com/library/anti-cancer-foods-onions-garlic.aspx