In 1997 the International Agency for Research on Cancer reviewed a wide range of epidemiological studies and concluded that there is convincing evidence that a diet high in fruits and vegetables reduces cancer risk.
Specifically the group stated that eating lots of fruits and vegetables reduced risk of cancers of the mouth and pharynx, esophagus, lung, stomach, colon, and rectum. That it probably decreases the risk of cancers of the larynx, pancreas, breast, and bladder; and that it possibly decreases the risk of cancers of the liver, ovary, endometrium, cervix, prostate, thyroid, and kidney.
The exact mechanism for how fruits and vegetables reduce cancer risk remains unknown. It is possible that people who eat fruits and vegetables simply lead healthier lives. It is also possible that both fruits and vegetables are low calorie foods, and this quality alone is what causes them to protect against cancer.
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