8. Soy

The active ingredient in soy is genistein, which is a phytoestrogen that protects against hormone-dependent cancers. It's also a powerful inhibitor of several proteins that are implicated in the uncontrolled growth of cancer cells. To get the anti-cancer benefits of soy, you need to consume about 50 grams per day of the whole food, such as raw fresh soybeans, known as edamame, dry roasted soybeans, or tofu. The research to date shows that supplements containing isoflavones don't work with the same action as soybeans themselves and in fact can be bad for you rather than good.