This research shows that Selenium supplementation did not benefit men with low selenium status but increased the risk of high-grade prostate cancer among men with high selenium status.
Baseline Selenium Status and Effects of Selenium and Vitamin E Supplementation on Prostate Cancer Risk
Alan R. Kristal, Amy K. Darke, J. Steven Morris, Catherine M. Tangen, Phyllis J. Goodman, Ian M. Thompson, Frank L. Meyskens, Jr, Gary E. Goodman, Lori M. Minasian, Howard L. Parnes, Scott M. Lippman, and Eric A. Klein
2014
Abstract
Background
The Selenium and Vitamin E Cancer Prevention Trial found no effect of selenium supplementation on prostate cancer (PCa) risk but a 17% increased risk from vitamin E supplementation. This case–cohort study investigates effects of selenium and vitamin E supplementation conditional upon baseline selenium status.
Methods
There were 1739 total and 489 high-grade (Gleason 7–10) PCa cases and 3117 men in the randomly selected cohort. Proportional hazards models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for effects of supplementation within quintiles of baseline toenail selenium. Cox proportional hazards models were used to estimate hazard ratios, and all statistical tests are two-sided.
Results
Toenail selenium, in the absence of supplementation, was not associated with PCa risk. Selenium supplementation (combined selenium only and selenium + vitamin E arms) had no effect among men with low selenium status (<60th percentile of toenail selenium) but increased the risk of high-grade PCa among men with higher selenium status by 91% (P = .007). Vitamin E supplementation (alone) had no effect among men with high selenium status (≥40th percentile of toenail selenium) but increased the risks of total, low-grade, and high-grade PCa among men with lower selenium status (63%, P = .02; 46%, P = .09; 111%, P = .008, respectively).
Conclusions
Selenium supplementation did not benefit men with low selenium status but increased the risk of high-grade PCa among men with high selenium status. Vitamin E increased the risk of PCa among men with low selenium status. Men should avoid selenium or vitamin E supplementation at doses that exceed recommended dietary intakes.
