Researchers have found that high-dose supplementation with both the trace element selenium and vitamin E increase the risk of high-grade prostate cancer.
These findings are based on data from the Selenium and Vitamin E Cancer Prevention Trial, or SELECT, a rigorously executed, randomized and placebo-controlled trial conducted by the SWOG cancer research cooperative group that involved more than 35,000 men.
The study sought to determine whether taking high-dose vitamin E (400 IU/day) and/or selenium (200 mcg/day) supplements could protect men from prostate cancer.
The trial, which began in 2001 and was designed to last 12 years, stopped early, in 2008, because it found no protective effect from selenium and there was a suggestion that vitamin E increased risk.
While use of the study supplements stopped, men were still followed and after an additional two years the men who took itamin E had a statistically significant 17 percent increased risk of prostate cancer.
The study has been published in Journal of the National Cancer Institute.