Vegetable intake, particularly intake of cruciferous vegetables such as cauliflower and broccoli, substantially lowers the risk of prostate cancer in men.Prostate cancer risk was not affected by fruit intake.
The investigators considered total vegetable intake, and they found that men who ate 28 or more servings of vegetables per week had a 35% lower risk of prostate cancer compared with men who ate fewer than 14 servings per week.
In addition, men who ate three or more servings of cruciferous vegetables per week had a 41% decreased risk of prostate cancer compared with men who ate less than one serving per week, even after the researchers accounted for total vegetable intake.
Cruciferous vegetables, in particular, are high in substances called isothiocyanates, which activate enzymes that detoxify carcinogens. Vegetables evolved mechanisms to avoid being eaten, such as cytochemicals that are quite bitter and toxic.
Humans evolved the ability to detoxify these cytochemicals, and the enzyme systems that we use to detoxify cytochemicals are the same enzymes that detoxify naturally occurring carcinogens.
It may be that upregulation of these enzyme systems has a protective effect against cancer.
Journal of the National Cancer Institute January 5, 2000;92:61-68
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