(Bloomberg) — Vitamin supplements taken by millions of people to improve health and prevent disease failed to reduce rates of prostate cancer in a test of more than 35,000 men, adding to recent studies showing the pills don't work.

Vitamins E, an antioxidant that prevents the breakdown of other molecules, and selenium, a mineral that aids in the process, didn't reduce rates of prostate cancer in men who took the pills for an average of eight years, according to a study published today in the Journal of the American Medical Association.

A separate study of more than 14,000 doctors found vitamin C, also an antioxidant, didn't help either.

Vitamin supplements are taken by about half of Americans in an effort to remain healthy, researchers said today. Recent studies show the strategy may not be helping.

Research presented at the American Heart Association meeting in New Orleans last month found that vitamins E and C and folic acid didn't prevent heart attacks, stroke or death in older men.

Other studies showed the pills didn't stave off cancer.

Early antioxidant studies created a false "wave of hope," said Peter Gann, Director of Pathology Research at the University of Illinois at Chicago, in an editorial in the journal.

"Twelve years later comes the disappointing news that two major trials conceived during the wave of hope found that neither selenium nor vitamin E supplementation, alone or in combination, produced any reductions in prostate cancer or cancer of any type."