High Dose Vitamin E May Actually Increase Risk Of Prostate Cancer

High dose supplemental vitamin E does not decrease the risk of developing prostate cancer and may in-fact increase risk slightly according to the results of a study published in the October 12 issue of the Journal of the American Medical Association.

Researchers used data from The Selenium and Vitamin E Cancer Prevention Trial to determine whether supplementation of either vitamin E, selenium, or both in combination could reduce the risk of developing prostate cancer. The initial study was motivated by the observation that those who consume high levels of vitamin E and selenium from dietary sources tend to have lower incidences of some forms of cancer. For example, this study found a 22% reduction in the risk of prostate cancer in Italian men with high dietary intakes of vitamin E.

Now however, it appears that while dietary vitamin E may reduce the risk of developing prostate cancer, supplemental vitamin E is ineffective at preventing the disease.

Researchers found a statistically significant 17% increased incidence of prostate cancer in men taking 400 IU per day of tocopheryl acetate (a vitamin E ester) compared to a control group. Selenium supplementation of 200 μg per day increased prostate cancer risk by 9% while selenium and vitamin E in combination increased risk by 5% although neither of these results achieved statistical significance.

Lead author Dr Eric A. Klein of the Glickman Urological and Kidney Institute in Cleveland cautions against vitamin supplementation in those without an apparent deficiency. According to Klein: “If you have normal levels, the vitamin is probably of no benefit, and if you take too much, you can be harmed.”

Interestingly, previous studies have suggested a reduced risk of prostate cancer in smokers, suggesting a potential protective effect of vitamin E on cigarette smoke carcinogens. This study found a 32% reduced risk of prostate cancer in a group of 29,000 smokers receiving 50mg a day of alpha-tocopherol. Other studies of vitamin E supplementation in smokers however have produced mixed results.

The vitamin industry has taken a battering recently. The research above comes just days after a study, published in the Archives of Internal Medicine found that the use of multivitamins in older women increased total mortality by 6%.