Vitamin E Supplements May Raise Prostate Cancer Risk
A new study, funded by the National Cancer Institute has identified that men who take 400 international units (IU) of vitamin E daily have an increased risk of developing prostrate cancer. This is bad news because for the last decade it has been believed that vitamin E supplements could reduce the risk of prostrate cancer.
This follow up study of 35,000 men, which has been published in the medical paper The Journal of the American Medical Association, shows that taking supplements of the antioxidant vitamin E increases the risk of prostrate cancer. It found that those who took vitamin E daily with a dosage of 400 IU increased the likelihood of developing prostrate cancer by 17% over the seven year follow up phase.
The researchers believe that the risk is real because they explain that 17% is too high a percentage to be caused by chance. It is also stated that taking vitamin E in larger amounts may well be dangerous.
Previous studies have also indicated that some antioxidant vitamin supplements have a negative association to the cancers they were thought to avert. Researchers have previously found that beta carotene supplements led to a higher risk of developing lung cancer. Likewise with selenium, which is a trace mineral, which has been associated with higher risk of non melanoma skin cancer in both sexes.
Researcher Eric A. Klein, MD, of the Cleveland Clinic, one of the researchers says, “In the absence of vitamin deficiency, there are no compelling data to indicate that these dietary supplements are beneficial, and some may be harmful”.
The Role of Vitamin E and the Likelihood of Prostrate Cancer
The Selenium and Vitamin E Cancer Prevention Trial (SELECT) is a trial which began in 2001 with the aim of identifying if taking antioxidant vitamin supplements did reduce the risk of developing prostrate cancer. The trial was in response to the growing number of prostrate cancer cases being seen in the U.S. In the next year 33,000 men are predicted to die because of the cancer, and almost a quarter of a million will receive a prostrate cancer diagnosis.
The study was large scale, with over 35,000 men involved. The men came from Canada, Puerto Rico and the U.S. and were allotted to a specific treatment group. The groups either had 200 micrograms of selenium daily, or 400 IU of vitamin E, or a daily supplementation with both vitamins and the last group had no supplementation (placebo group).
Study co-researcher Laurence H. Baker, DO, of the University of Michigan says, “There has never been a trial of this size and magnitude to examine an intervention to prevent prostate cancer”.
The men taking the vitamin E and selenium stopped taking the supplement in late 2008 after five and a half years because it had become obvious that the aim of reducing prostrate cancers by 25% was not going to be achieved. Even then there was an indication that prostrate cancer risks were being increased by taking vitamin E alone. However when the data was assessed it was found to have failed to reach statistical significance.
In July of this year the researchers re-addressed the situation and found that an extra 521 cases of prostrate cancer had been diagnosed. National Cancer Institute acting director for cancer prevention Lori M. Minasian, MD, says, in response to the outcome, “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”.
She was talking about the fact that 147 prostrate cancers developed in the group taking vitamin E only. Whereas the group that took neither supplement, the placebo group, only had 113 cases of prostrate cancer.
Unnecessary Vitamin Use is Dangerous
The study findings identified that those who took vitamin E supplements for 7 years had given themselves a 17% increased risk of developing prostrate cancer. Those in the placebo group were found to have 65 cases of prostrate cancer per 1,000 men, whereas those in the vitamin E group had 76 cases per 1,000.
Otis W. Brawley, MD, is American Cancer Society Chief Medical Officer and he urges caution because of the SELECT trial. He says, “It is now clear that we need to be very cautious in our advocacy of taking excessive amounts of any vitamin. Taking a multivitamin every day may be OK, but we now know that taking excessive amounts of vitamins can be dangerous.”