Vitamin E Supplements May Raise Prostate Cancer Risk
Study Refutes Earlier Suggestion That Vitamin E Lowered Risk of Prostate Cancer
Impact of Vitamin E continued...
In the fall of 2008, about 5.5 years after beginning the supplements, the men taking vitamin E and selenium were told to stop taking them when it became clear that the goal of a 25% reduction in prostate cancers would not be met.
At the time, there was a suggestion that men who took vitamin E alone actually had an increased prostate cancer risk but the association did not reach statistical significance.
Researchers continued to follow the men until July of this year, during which time 521 additional prostate cancers were diagnosed.
A total of 147 prostate cancers occurred in the vitamin E-only group, while 113 occurred in the men who took neither supplement.
"The expectation was that we would see less difference in prostate cancer rates among the two groups when we followed the men longer. But the opposite proved to be true," National Cancer Institute acting director for cancer prevention Lori M. Minasian, MD, tells WebMD.
Risks of Excessive Vitamin Use
For every 1,000 men who took vitamin E supplements for seven years, there were 76 prostate cancers in the vitamin E group and 65 cancers in the placebo group.
The 11 additional cancers represented a 17% increase in risk.
American Cancer Society Chief Medical Officer Otis W. Brawley, MD, says the surprising findings from the SELECT trial should serve as a cautionary tale.
"It is now clear that we need to be very cautious in our advocacy of taking excessive amounts of any vitamin," he tells WebMD. "Taking a multivitamin every day may be OK, but we now know that taking excessive amounts of vitamins can be dangerous."