Study finds men who take high doses are at risk.
For the past decade or so doctors believed vitamin E might reduce the risk for prostate cancer.
That belief has been challenged by a large study from the Cleveland Clinic's Dr. Eric Klein.
"The finding was a bit of a surprise," said Klein.
Dr. Klein and his colleagues have been following a group of about 35-thousand men for at least 7 years to study potential benefits of supplemental use of vitamin E or Selenium.
Neither pill reduced the risk for prostate cancer -- and the men were advised to stay away from the supplements. But even after they stopped taking them -- researchers found this:
"Men who took vitamin e alone have a 17% higher chance of being diagnosed with prostate cancer," said Klein.
This is the latest in a string of recent studies that have suggested Americans' use of vitamins is leading to overkill, literally.
On Monday, researchers said daily doses of multivitamins and other minerals like iron appear to raise the risk of an early death in older women.
"We saw an increased risk of total mortality," said Jaako Mursu, Ph.D. University of Minnesota.
And a study from the national institutes of health found most people who take dietary supplements don't need them because they tend to eat healthy diets -- full of all the nutrients their bodies need.
The vitamin E supplement in the Cleveland Clinic trial was 400 international units available over the counter.
Most multivitamins, however, contain much less -- which experts say is a much more appropriate dose.