Efficacy of antioxidant vitamins and selenium supplement in prostate cancer prevention: a meta-analysis of randomized controlled trials.

Several studies have evaluated the possible association between antioxidants vitamins or selenium supplement and the risk of prostate cancer, but the evidence is still inconsistent. We systematically searched PubMed, EMBASE, the Cochrane Library, Science Citation Index Expanded, Chinese biomedicine literature database, and bibliographies of retrieved articles up to January 2009. We included 9 randomized controlled trials with 165,056 participants; methodological quality of included trials was generally high. Meta-analysis showed that no significant effects of supplementation with beta-carotene (RR 0.97, 95% CI 0.90-1.05) (3 trials), vitamin C (RR 0.98, 95% CI 0.91-1.06) (2 trials), vitamin E (RR 0.96, 95% CI 0.85-1.08) (5 trials), and selenium (RR 0.78, 95% CI 0.41-1.48) (2 trials)versus placebo on prostate cancer incidence. The mortality of prostate cancer did not differ significantly by supplement of beta-carotene (RR 1.19, 95% CI 0.87 -1.65) (1 trial), vitamin C (RR 1.45, 95%CI 0.92-2.29) (1 trial), vitamin E (RR 0.85, 95%CI 0.58-1.24) (2 trials), and selenium (RR 2.98, 95% CI 0.12-73.16) (1 trial). Our findings indicate that antioxidant vitamins and selenium supplement did not reduce the incidence and mortality of prostate cancer, these data provide no support for the use of these supplements for the prevention of prostate cancer.