Effects of long-term alpha-tocopherol supplementation on serum hormones inolder men

BACKGROUND. alpha -tocopherol supplementation significantly reduced risk of prostate cancer in the Alpha-Tocopherol Beta-Carotene Cancer Prevention (A TBC) Study. Sex hormones are thought to be involved in the etiology of pros tate cancer. We examined whether long-term supplementation with alpha -toco pherol modified serum hormone levels. METHODS. Men who were cancer-free consumed greater than or equal to 90% of the study capsules, and who had both baseline and follow-up blood available , were eligible for the study. One hundred men who received alpha -tocopher ol were matched on age, study center, and length of time between blood draw s to 100 men who received a placebo. Multivariate linear regression models which allowed for a separate intercept for each matched pair were used to e valuate the effect of alpha -tocopherol supplementation on follow-up hormon e concentrations. RESULTS. Compared to men who received a placebo, we found significantly low er serum androstenedione (P = 0.04) and testosterone (P = 0.04) concentrati ons among men who received alpha -tocopherol, after controlling for baselin e hormone level, follow-up serum cholesterol concentration, body mass index , smoking, and fasting time. Geometric mean (95% confidence interval; CI) a ndrostenedione concentration among men who received alpha-tocopherol was 14 5 ng/dl (CI, 137-153) after adjusting for covariates, compared to 158 ng/dl (CI, 148-167) among men who received a placebo. Mean testosterone concentr ations for men who received alpha -tocopherol and placebo were 539 (CI, 517 -562) and 573 (CI, 549-598) ng/dl, respectively CONCLUSIONS. These results suggest that long-term alpha -tocopherol supplem entation decreases serum androgen concentrations, and could have been one o f the factors contributing to the observed reduction in incidence and morta lity of prostate cancer in the alpha -tocopherol treatment group of the ATB C Study. Prostate 46:33-38, 2001. (C) 2001 Wiley-Liss, Inc.