Prostate cancer developed more often in men who took 400 international units (IU) of vitamin E daily compared to men who took a placebo, according to an updated review of data from the Selenium and Vitamin E Cancer Prevention Trial (SELECT). Updated results appeared October 12, 2011, in the Journal of the American Medical Association.
The SELECT study began in 2001 and included over 35,000 men from more than 400 clinical sites in the United States, Puerto Rico, and Canada. Participants were randomly assigned to 1 of 4 arms, with more than 8000 men in each arm:
- One arm took both selenium and vitamin E
- Another arm took selenium and a placebo that looked similar to vitamin E
- The third arm took vitamin E and a placebo that looked similar to selenium
- The final arm received placebos of both supplements
The updated review of study findings showed that, over a 7-year period, there were 76 prostate cancers per 1000 men who took only vitamin E supplements, compared to 65 in men on placebo. This represents a 17% increase in prostate cancers relative to those who took a placebo. Now, due to this latest finding, researchers are encouraging all participants to participate in long-term study follow-up so investigators can continue to track outcomes.
“SELECT has definitively shown a lack of benefit from vitamin E and selenium supplements in the prevention of prostate cancer and has shown there is the potential for harm,” said Lori Minasian, MD, study coauthor and acting director of NCI’s Division of Cancer Prevention. “Nevertheless, this type of research has been critically important to understanding the potential benefits and risks from supplements.”
Source: NIH.