Dietary Changes and Risk of Prostate Cancer
April 1, 1998 2 minutes read
Dietary Changes and Risk of Prostate Cancer
April 1998; Volume 1: 47
Source: Fair WF, Fleshner NE, Heston W. Cancer of the prostate: A nutritional disease? Urology 1997;50:840-848.
The title of this review reflects the increasing evidence that nutrition may play a significant role in the prevention and/or progression of prostate cancer. The authors review currently available clinical data and supplement these data with experimental observations on the effects of dietary manipulation.
To date, there have been a total of 14 well-performed case-control studies involving more than 3000 patients with prostate cancer and more than 4600 control subjects. Eleven of the 14 studies showed a positive association between increased dietary fat intake or specific fatty foods and higher risk of prostate cancer, with some studies showing a greater than threefold increase in cancer incidence. Likewise, there have been five cohort studies involving 98,000 subjects followed for a total of more than 600,000 subject-years. Four of the five studies showed a positive association, with an odds ratio of 1.8-2.4.
COMMENT
Norman Schwartzkopf, Robert Goulet, Bob Dole: Men with prostate cancer. Are high-fat diets and low vitamin intake to blame? These Memorial Sloan-Kettering and Cornell authors remind us that African Americans and men with a family history are at high risk. Almost 25% of men with prostate cancer die of it. But, the death rate from this disease is 16 per 100,000 in the U.S. and only 3.5 in Japan, according to late 1980s data.
Two well-performed studies of Asian men who immigrated to the United States are cited and the rising incidence of prostate cancer tracked, with a switch to the Western diet. The authors report experimental data on the effect of the isoflavones genistein and daidzein on human prostate cancer cell lines. These isoflavones, found in soy protein, reduced prostate specific antigen secretion by some of the prostate cancer cells.
Most epidemiologic studies show that vitamin A does not protect against prostate cancer. Vitamin A is found in animal products; unlike beta-carotene, its precursor, which is found primarily in green, yellow, and orange vegetables.The Finnish beta carotene and vitamin E/lung cancer study of 29,000 smokers unexpectedly showed a reduced incidence-by 34%-of prostate cancer in men receiving vitamin E. There are few data about Vitamins C and D; there is no consistent data on selenium, though one study reports a 63% decrease in prostate cancer incidence in men who took supplements.
Recommendation
Because microfocal prostate cancer exists in at least 30% of men over the age of 50, cutting back or eliminating red meat and dairy products-those containing omega-6 (linolenic) fatty acids-and putting plant foods, especially soy foods, in the middle of the plate, is solid, evidence-based advice for men. Men whose total fat intake is low-below 20%-and whose soy and vitamin E intake is high reduce their risk of prostate cancer. Dietary changes may also reduce tumor progression, and prospective trials are needed to test this hypothesis.
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