A new study finds a link between [synthetic] vitamin E—a popular dietary supplement—and an increased risk of prostate cancer.
In 2001, scientists launched the Selenium and Vitamin E Cancer Prevention Trial (SELECT), to test the widely held belief that the two supplements might help or prevent disease. Analysis from studies on skin and lung cancers had suggested that the mineral supplement selenium or vitamin E might reduce the risk of prostate cancer.
The study enrolled 35,000 healthy men, 50 years or older, at 400 sites in the United States, Canada, and Puerto Rico. Eric Klein of the Cleveland Clinic says the $122 million dollar trial ended in 2008 when it became clear that it would not produce the 25 percent cancer reduction it was designed to show.
“We did notice however at the time the original study was closed that men who were taking [synthetic] vitamin E alone were trending toward having a higher risk of prostate cancer.”
Updated findings, reported in the Journal of the American Medical Association, show no benefit for men who took the 400 International units of [synthetic] vitamin E a day and more importantly, a real risk, says co-author and National Cancer Institute prostate cancer expert Howard Parnes. “At this time the data show a 17 percent increase in prostate cancer, which is statistically significant for the [synthetic] vitamin E alone.”Researchers followed post-study participants for 18 months after SELECT was halted. Klein, who also contributed to the article in the Journal of the American Medical Association, says the researchers found [synthetic] vitamin E can have an effect even after the men stopped taking the supplement.
“There just doesn’t seem to be a reason to be taking [synthetic] vitamin E if you are a man over 55 or 60.”
Klein adds that the study underscores the importance of large-scale, population-based, randomized trials to accurately measure the benefit or harm of micronutrients such as diet supplements.
Note: The SELECT trial employed dl-alpha-tocopherol, a synthetic form of vitamin E derived from petroleum. It did not test natural vitamin E, d-alpha-tocopherol.