Vitamin E may have cardiovascular and brain-boosting benefits, but a new study found that men who took 400 international units of the supplement every day have an increased risk of developing prostate cancer.

“The results show that men who took vitamin E alone are actually at a higher risk of developing prostate cancer by about 17 percent, compared with a placebo,” said Dr. Eric Klein, who treats prostate patients at the Cleveland Clinic and co-chaired the study.

Researchers studied the effects of vitamin E on more than 35,000 men over the course of seven years because they originally thought vitamin E – and selenium – would decrease the risk of developing prostate cancer.

The study’s results were not what the researchers expected.

Researchers said they need to determine exactly why vitamin E can increase the chances of developing prostate cancer.

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    “The increased risk really emerged after men stopped taking the vitamin E,” Klein said. “People think of vitamins as innocuous substances, but in fact, that’s not true. They’re active agents; they’re part of our normal physiology and getting too much of things that are normal for us can sometimes be harmful.”

    Dr. David Samadi, a Fox News Medical A-Team member and chief of robotics and minimally invasive surgery at Mount Sinai School of Medicine in New York City agreed. "We now have a better understanding of the relationship between vitamin E and prostate cancer. Their key finding...is the reason I am so cautious of prescribing alternative medicines.We should base our practice off of evidence-based clinical trials."

    In the U.S., prostate cancer is one of the most common types of cancers in men.

    The study was published in the Journal of the American Medical Association.