Does high soy milk intake reduce prostate cancer incidence? The Adventist Health Study (United States)

Objectives: Recent experimental studies have suggested that isoflavones (su ch as genistein and daidzein) found in some soy products may reduce the ris k of cancer. The purpose of this study was to evaluate the relationship bet ween soy milk, a beverage containing isoflavones, and prostate cancer incid ence. Methods: A prospective study with 225 incident cases of prostate cancer in 12,395 California Seventh-Day Adventist men who in 1976 stated how often th ey drank soy milk. Results: Frequent consumption (more than once a day) of soy milk was associ ated with 70 per cent reduction of the risk of prostate cancer (relative ri sk = 0.3, 95 percent confidence interval 0.1-1.0, p-value for linear trend = 0.03). The association was upheld when extensive adjustments were perform ed. Conclusions: Our study suggests that men with high consumption of soy milk are at reduced risk of prostate cancer. Possible associations between soy b ean products, isoflavones and prostate cancer risk should be further invest igated.