March 5, 2014
High Selenium, Vitamin E Supplementation Raises
Prostate Cancer Risk

Seattle—A new study again calls into question the folk wisdom that vitamin supplements are essentially harmless, and that the body will expel any excess.

Research published in the Journal of the National Cancer Institute suggests that high doses of selenium or vitamin E can increase the risk of prostate cancer.

The increased risk is not insignificant, according to study authors from the Fred Hutchinson Cancer Research Center. The risk of prostate cancer is increased as much as 63% in certain men who supplement with Vitamin E, while selenium can actually double the risk of a high grade cancer in others, the researchers emphasize.

The study started out trying to determine if selenium supplement could actually lower prostate cancer risk in men with low levels of the nutrient, according to lead author Alan Kristal, DrPh. “But we found there’s no benefit for anyone. All we did find was a heightened risk. I’m now willing to go on the record and say that there is no evidence that high doses of supplements of anything are good for you.”

Data for the research was extracted from a larger study that included more than 35,000 men, the Selenium and Vitamin E Cancer Prevention Trial (SELECT). SELECT study subjects were divided into four groups: selenium and vitamin E, selenium alone, vitamin E alone, or placebo.

That trial, which began in 2001 and was originally designed to last 12 years, was ended early when results suggested vitamin E might be increasing instead of decreasing the risk of cancer.

In the new analysis of the SELECT data, researchers focused on the impact of vitamin E and selenium in a subset of the original group, finding that supplementation with vitamin E alone raised the risk of prostate cancer by 63% in men who had low levels of selenium at the beginning of the study. Selenium supplementation, meanwhile, appeared to raise the risk of a high grade cancer by 91%.

Noting that other studies also have found that vitamins originally thought to prevent cancer might actually cause it, Kristal advised against supplementation. He instead urging healthy eating, suggesting, “The micronutrients in food are at a level that you need.”

U.S. Pharmacist Social Connect