by Lindsey Tanner – Oct. 12, 2011 12:00 AM
CHICAGO – There is more evidence that taking vitamin E pills is risky. A study that followed up on men who took high doses of the vitamin for five years found they had a slightly increased risk of prostate cancer – even after they quit taking the pills.
Doctors say it’s another sign that people should be careful about vitamins and other supplements.
“People tend to think of vitamins as innocuous substances, almost like chicken soup – take a little and it can’t hurt,” said lead author Dr. Eric Klein of the Cleveland Clinic. The study shows that is not true.
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“If you have normal levels, the vitamin is probably of no benefit, and if you take too much, you can be harmed,” Klein said.
Men randomly assigned to take a 400-unit capsule of vitamin E every day for about five years were 17 percent more likely to get prostate cancer than those given dummy pills. That dose, commonly found in over-the-counter supplements, is almost 20 times higher than the recommended adult amount, which is about 23 units daily.
The results mean for every 1,000 men who took vitamin E, there were 11 additional cases of prostate cancer, compared with men taking dummy pills.
The study was actually launched to try to confirm less rigorous research suggesting vitamin E might protect against prostate cancer. Overall, about 160 of every 1,000 U.S. men will develop prostate cancer in their lifetime.
What should vitamin E users do, given the new study results? About 13 percent of American men take it, according to a supplement trade group.
Dr. Otis Brawley, chief medical officer for the American Cancer Society, says they should stop taking large doses and talk to their doctors about the risks and benefits of prostate-cancer screening. Smaller doses, typically found in multivitamins, are probably fine, said Brawley, who was not involved in the research.
Vitamin E is found in foods such as nuts, seeds and vegetable oils. The nutrient helps nerves, muscles, blood vessels and the immune system function.
The new research appears in today’s Journal of the American Medical Association. The National Cancer Institute and National Center for Complementary and Alternative Medicine paid for the multimillion-dollar study.
The study involved more than 35,000 healthy men aged 50 and older, from the United States, Canada and Puerto Rico. They were randomly assigned to take daily vitamin E or selenium supplements, both pills or dummy pills.