"Taking Selenium or Vitamin E at the doses that we used in the select trial for an average of five years did not prevent prostate cancer," said Dr. Eric A. Klein of the Cleveland Clinic.
This is just the latest in a string of disappointing news about vitamin pills, a nearly $8 billion industry. Last month, a study showed neither vitamins E nor C prevent heart disease.
CBS News asked the government's top authority on supplements, Paul M. Coates, director of the Office of Dietary Supplements for the National Institutes of Health, for the bottom line on:
And what about taking a daily multivitamin?
"There is a lack of ... solid evidence taking multivitamins regularly have an impact on disease prevention," Coates said.
There are some useful supplements. For example: folic acid during pregnancy, Vitamin B12 for patients who can't absorb it and calcium when dietary sources aren't enough.