Vitamin E supplements and prostate cancer risk
Can vitamin E supplements decrease the risk of prostate cancer?
Question from the Field
Can you provide information on vitamin E supplements and prostate cancer risk in men?
Vitamin E supplements
Vitamin E, a fat-soluble vitamin, has eight different forms, the most active (i.e., actively maintained in the human body) being alpha-tocopherol. Its main function is as an antioxidant, which helps to destroy free radicals that damage cells in the body. Scientific studies suggest that taking vitamin E supplements may decrease the risk of prostate cancer in men, but the scientific evidence is mixed: Some studies suggest that high vitamin E intake lowers the risk of prostate cancer, and other studies suggest vitamin E supplements may increase the risk of prostate cancer. Most studies to date have used only alpha-tocopherol rather than a mixture of the eight forms.
Vitamin E is found naturally in foods and is also added to many processed foods: fortified breakfast cereals, fruit juices, margarines and spreads, sports bars, energy drinks, to name a few. Good food sources include nuts, seeds, and vegetable oils as well as eggs, green leafy vegetables, and wheat germ. Vitamin E supplements are available in natural and synthetic forms, with d-alpha-tocopherol being the most common natural form. The synthetic form is dl-alpha-tocopherol.
The Recommended Dietary Allowance (RDA) for vitamin E (d-alpha-tocopherol) is 15 mg (22.4 IU) for both men and women 19 to 50. The tolerable upper limit (UL) for adults is 1000 mg (1500 IU).
Several studies have looked at vitamin E intake and/or supplementation with respect to prostate cancer risk. One of the first was a large randomized controlled study of male smokers that showed those taking vitamin E supplements had a lower incidence of prostate cancer. A meta-analysis (a statistical method that combines findings from independent studies) of randomized controlled trials also showed a reduction in the incidence of prostate cancer. However, a recent, large, randomized, placebo-controlled intervention study called the “Selenium and Vitamin E Cancer Prevention Trial” (SELECT) showed a lack of benefit from vitamin E and selenium supplements, taken either alone or together. In fact, the study concluded that vitamin E supplements could increase prostate cancer risk. Since the data are mixed, more research is needed. Vitamin E requirements can be met by eating a well-balanced diet from a variety of foods; such a diet will also provide the other nutrients needed for overall health.