Supplements Offer No Prostate Cancer Protection

Preliminary findings from one of the largest chemoprevention trials revealed that after being taken for more than five years, selenium and vitamin E, taken alone or in combination, do not prevent prostate cancer in healthy men, according to results published in a January issue of the Journal of the American Medical Association.

“The results showed no benefit to taking either agent for any endpoint—prostate cancer, colon cancer, lung cancer, all cancers, cardiovascular disease, and overall survival. There is no evidence that these agents have any beneficial effect,” says Eric Klein, MD, co-chair for the Selenium and Vitamin E Cancer Prevention Trial, known as SELECT, and a physician at the Cleveland Clinic.

As a result of these findings, SELECT participants were notified last October to discontinue taking the daily supplements. Researchers plan to monitor participants’ health for an additional three years. “We hope to learn if there are any health effects—good or bad—after supplements are stopped,” says Klein.

The trial was stopped early after data showed a slight, although not statistically significant, increased risk of prostate cancer in participants taking 400 IU of vitamin E and an increased risk of diabetes with 200 mcg of selenium.

SELECT was initiated in 2001 by the National Cancer Institute after the results of two earlier trials showed prostate cancer risk reduction in men taking selenium and/or vitamin E.

Klein noted that although the results were not favorable for taking selenium or vitamin E as supplements, there is no reason to avoid consuming them. “Eating a balanced diet is important and probably beneficial for health, even if individual supplements are not,” he says.

Selenium and vitamin E are antioxidants, molecules that may prevent cell damage. Selenium is found naturally in rice and tuna, while vitamin E is found in whole grains and nuts. However, there are many more antioxidants found in the diet as well as those produced by the body, so pinpointing the exact supplements or formula that promotes good health may be elusive.