Garlic
Effective against: Stomach, colon and most cancers
Works because: The smelly compounds in garlic are potent anti-cancer agents. All of the onion family, including leeks and shallots, contain these compounds but garlic is the most rich. Trials have shown that chemically induced cancers can be interrupted by the active compounds formed from allicin from garlic. To get the most out of garlic chop the clove and leave it to "mature" in the air for 15 minutes, and then use it in your cooking. Heating prior to this "maturation time" by air neutralizes the important compounds.

Tofu
Effective against: Breast, ovarian and prostate cancers
Works because: The isoflavones the soya bean contains have a gently estrogen-mimicking effect in the human body. This helps to block the effects of more aggressive estrogens, both natural and those from environmental chemicals from sources such as plastics and pesticides. This has the effect of limiting the risk of hormone-linked cancers in both women and men. Tofu may be more effective than other soya products or soya supplements as it has been fermented and some potentially negative compounds have been neutralized. The Japanese and Chinese who eat tofu regularly have low risks of these cancers.

Oily Fish
Effective against: Colon, prostate and breast cancers
Works because: The omega-3 fatty acids have a profound effect on cell metabolism and communication. These fatty acids also act as anti-inflammatory agents, which may be a reason for their influence on colon cancer. When the diet is higher in polyunsaturated fatty acids, such as the omega-3s, it also limits the intake and the effects of saturated fats, which are linked to increased risk of some cancers.