Harvard Health Letter

What's up…and what's not

What's up... and what's not

Selenium for prostate cancer prevention

Selenium, a mineral with antioxidant properties, became a cancer prevention candidate in the mid-1990s after a secondary analysis of results from a skin cancer prevention study found that the men assigned to take selenium pills had 63% fewer cases of prostate cancer than men in the placebo group.

Optimism about antioxidants was running high. Other studies also indicated that the mineral might protect the prostate. And at a cost of about a nickel a day, or less than $20 a year, selenium would be an incredible bargain even if the risk reduction was modest. There had also been some results suggesting that vitamin E might protect against prostate cancer. So in 2001, the National Cancer Institute (NCI) launched the Selenium and Vitamin E Cancer Prevention Trial, or SELECT. A total of 35,000 men were enrolled and randomly assigned to take selenium (200 micrograms daily), vitamin E (400 international units), both, or placebo pills. We'd have to wait awhile — final results weren't expected till 2013 — but SELECT was supposed to be the last word on selenium.

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