The government is stopping part of a major study of whether vitamin E and selenium prevent prostate cancer because the supplements aren't working and there's a hint of risk.
More than 35,000 men age 50 and older have been taking one or both supplements or dummy pills as part of a study called the SELECT trial.
But the National Cancer Institute announced that participants will be told to quit the pills. An early review of the data shows neither supplement, taken alone or together, is preventing prostate cancer.
Of more concern, slightly more users of vitamin E alone were getting prostate cancer, and slightly more selenium-only users were getting diabetes, the NCI said.
That doesn't prove there is a risk from the supplements, the institute stressed: Neither blip was statistically significant, meaning it could be a coincidence.