Harvard Men's Health Watch

On call: Selenium and diabetes

On call

Selenium and diabetes

Q. I've been taking a selenium pill every day to try to reduce my risk of prostate cancer. But now I've read that selenium can cause diabetes. My blood sugar has always been normal, but I'm concerned. Should I continue taking selenium?

A. Supplements have been taking a big hit lately, and with good reason. As randomized clinical trials have been completed, one supplement after another has been a flop. Vitamins have been the greatest disappointment. First, antioxidant supplements proved worthless (or worse). Next, B vitamins that lower blood homocysteine levels failed to protect the heart. And now, men have reason to rethink that old standby, a daily multivitamin. Selenium is one of the few supplements still in play; the others are vitamin D and fish oil.

Selenium is a mineral, not a vitamin. It's present in soil, but amounts vary from region to region. From soil, it finds its way into plants and then works its way up the food chain. Good sources include whole grains, tomatoes, onions, garlic, seafood, nuts, meat, and poultry. The Recommended Dietary Allowance for men is only 55 micrograms, but many men get less.

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