Men receiving vitamin E supplements in a large randomized trial showed a slight but statistically significant increase in prostate cancer diagnoses, researchers said.
After being followed for up to 10 years after randomization, the hazard ratio for prostate cancer in SELECT trial participants assigned to vitamin E supplements was 1.17 (95% CI 1.004 to 1.36) relative to the study’s placebo group, reported Eric A. Klein, MD, of the Cleveland Clinic, and colleagues.
The four-arm trial also included selenium supplements, given alone or in combination with vitamin E. Participants in those groups showed a smaller increase in prostate cancer risk that failed to reach statistical significance, Klein and colleagues indicated in the Oct. 12 issue of the Journal of the American Medical Association.
SELECT is an acronym for the Selenium and Vitamin E Cancer Prevention Trial, which randomized 35,553 men 50 and older to the four study arms from 2001 to 2004. Klein and colleagues noted that, whatever else may be gleaned from the results, the study demonstrated that these supplements do not prevent cancer.
The findings, they wrote, “underscore the need for consumers to be skeptical of health claims for unregulated over-the-counter products in the absence of strong evidence of benefit demonstrated in clinical trials.”
Physicians contacted by MedPage Today and ABC News suggested that the evidence of harm for vitamin E was relatively weak, but they agreed that, on the basis of this and other studies, that neither the vitamin nor selenium holds any benefit for patients.
Jack Cusick, PhD, of Queen Mary University in London, told MedPage Today and ABC News that the study had a very strong if limited interpretation.
“The evidence is very clear that vitamin E will not protect against prostate cancer and should not be taken for that purpose. Whether it constitutes an important risk when used for another purpose is unclear,” he said in an email.
Tim Byers, MD, MPH, a cancer prevention specialist at the University of Colorado, was even less convinced there was proof of increased risk with the vitamin.
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