Dietary Beta-Carotene, Vitamin C, and Risk of Prostate Cancer : Results from the Western Electric Study

Dietary factors are likely candidates for important determi- nants of prostatic cancer risk. Among the most investigated nutritional factors have been antioxidants. We evaluated di- etary beta-carotene and vitamin C in relation to subsequent risk of prostate cancer in a prospective study of 1,899 middle- aged men. We combined prostate cancer cases diagnosed in the first 24 years of follow-up with incident cases identified from the Health Care Financing Administration hospitalization and outpatient files during an additional 6-year follow-up period. We obtained death certificates for all decedents. During the 30-year follow-up, prostate cancer developed in 132 men. There was no indication that consumption of beta-carotene or vitamin C was related to increased or decreased risk of prostate cancer. Relative risks for highest vs lowest quartiles of beta- carotene and vitamin C intake were 1.27 [95% confidence interval (CI) = 0.75-2.14] and 1.03 (95% CI = 0.59-1.60), respectively, after adjustment for age, number of cigarettes smoked per day, dietary cholesterol and saturated fat, alcohol consumption, total energy intake, and occupation. Associa- tions between intake of these nutrients and risk of prostate cancer differed depending on whether the cancer was diag- nosed during the first 19 years of follow-up or the next 11 years of follow-up. Overall survival over the 30 years of follow-up was positively associated with intake of beta-carotene and vitamin C.