35,000 men participating in a national study on vitamin E and selenium's ability to fight prostate cancer are being told to stop taking their supplements.
The $119 million SELECT study will continue but a letter sent to participants says that “the data to date suggest, but do not prove, that vitamin E may slightly increase the chance of getting prostate cancer, and that selenium may increase the chance of getting diabetes mellitus.”
Participants were supposed to continue taking the supplements for seven years. Their health will continue to be tracked for another three years after they stop the supplements.
Doctors emphasize the findings are not proven, but at this time they do not believe that selenium and vitamin E prevent prostate cancer.
Still, Dr. Eric Klein, a co-chairman of the study and a physician at the Cleveland Clinic, tells NPR the news about vitamin E and selenium is "disappointing."
Klein also said he believes it "highly unlikely" that the supplements will ultimately prove to have harmful effects.
Previous studies had indicated that since vitamin E and selenium, both antioxidants, might help control the cell damage caused by free radicals that can lead to cancer.
A published study in the Journal of the American Medical Association (JAMA) in 1996 suggested prostate cancer incidences were reduced by two-thirds in men taking selenium on a daily basis.
Another study on vitamin E found a one-third reduction in prostate cancer incidence.
Selenium is a nutritionally essential element that occurs in the soil and is absorbed by our bodies through plant and animal products. Organ means and brazil nuts are especially high in selenium. The soil of the southeastern U.S. is poor in selenium.
Vitamin E is a fat-soluble vitamin present in foods in small quantities such as vegetable oils, nuts, vegetables, milk fat and egg yolk.
SELECT, which stands for Selenium and Vitamin E Cancer Prevention Trial, is a research study funded by the National Cancer Institute and coordinated by the Southwest Oncology Group. It was the first study to look directly at the effects of the supplements on the risk of prostate cancer.
Participants took 400 IU of vitamin E per day and 200 micrograms of selenium. Others took placebos and all will now be able to find out which they were taking.
Prostate cancer is the most common type of cancer in U.S. males. This year an estimated 186,320 new cases will be identified and more than 28,000 men will die from the disease.
Men at the highest risk are over the age of 55, have a father or brother with prostate cancer and are African-American.
Money from the study came from the National Institute on Aging, the National Eye Institute, and the National Heart, Lung and Blood Institute.
Vitamins may still provide the answer. Some suggested that the ratio of tocopherols in vitamin E need to be balanced. #