Recent Study Reports Vitamin E Supplements Increase Prostate Cancer Risk

 A clinical trial testing the effects of vitamin E and selenium supplementation on prostate cancer shows a statistically significant increase in cancer risk with vitamin E supplementation, according to the latest analysis.

The Selenium and Vitamin E Cancer Prevention Trial (SELECT) was started in 2001 with much enthusiasm and was funded by the National Cancer Institute. Two previous cancer trials (for other forms of the disease) had suggested that people who supplemented with vitamin E and selenium had reduced risk of prostate cancer. This was the first trial designed to specifically test the benefits of these nutrients on prostate cancer, either alone or when administered together.
There were four conditions in the trial. In one condition participants were given a pill of 400 IU of vitamin E (oil based capsules) and another pill of 200 mg selenium (pressed tablets) to take daily. In another condition men were given the vitamin E pill and a placebo pill that looked like selenium. In the third condition participants were given the real selenium pill and a placebo that looked like vitamin E. And in the final condition both pills were placebo.
Researchers hoped they could achieve a 25% reduction in prostate cancer risk with vitamin E or selenium, but in 2008 researchers detected slightly more prostate cancer in men who were taking the vitamin E supplement alone. Though at that time the increase was not significant, the Data and Safety Monitoring Committee terminated the trial since it was obvious that the 25% reduction would not be met.
The latest analysis included 18 months of follow-up on those who had participated in the trial. The new data showed that men who were taking the vitamin E supplement had a 17% increase in prostate cancer risk compared to those taking placebo, and the increase has reached statistical significance. Men taking selenium alone or vitamin E and selenium together also had higher incidence of prostate cancer, though the results did not achieve statistical significance and could be due to chance.
Importantly, the vitamin E dosage of the SELECT trial was particularly high at 400 IU. The current US Recommended Daily Allowance (RDA) for vitamin E is only 22.4 IU, and the previous trial that showed a benefit of vitamin E for prostate cancer risk used only 50 IU. A typical multivitamin has closer to 30 IU of vitamin E, though vitamin E only supplements can often contain more than 100 IU.
Based on the current findings, vitamin E only supplements would not be recommended, particularly for men.

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