Is Excess Selenium in Your Dietary Supplements Dangerous?

In an earlier study, selenium supplements raised the risk of aggressive prostate cancer in men who already had high levels of this mineral in their bodies. A new study finds that selenium supplements may also make men who already have prostate cancer more likely to die of the disease.


U.S. scientists followed roughly 4,500 men with non-metastatic prostate cancer for nine years. Those who took supplements with at least 140 micrograms a day of selenium after their diagnosis were 2½ times more likely to die of prostate cancer than those who took no selenium.

What to do: Don’t take more than the RDA (55 mcg) of selenium in your multivitamin or a separate supplement. It’s too early to be certain that selenium promotes prostate cancer, but it doesn’t prevent or slow the disease, so why take a chance?

Source: J. Natl. Cancer Inst. 2015. doi:10.1093/jnci/dju360.

Other relevant links:

• Selenium and prostate cancer. See: Should You Be Worried About High Doses of Vitamin E and Selenium?

• Whole milk and prostate cancer. See: How to Diet: Dairy and Prostate Cancer

• Cruciferous vegetables and prostate cancer. See: What to Eat: Cruciferous Vegetables and Prostate Cancer

2 Replies to “Is Excess Selenium in Your Dietary Supplements Dangerous?”

  1. Several of the ‘best multis’ on this site have over double the selenium recommended here, especially those labeled for men. I switched from a “men’s” vitamin to Equate Complete “Adults” which has just 55 mcg. and as a bonus was half the price per tablet in a twin pack. I hope the “best multis” list will be updated due to the latest findings on selenium.

    1. From Nutrition Action Healthletter: The best multis list included some products with 100 or so micrograms of selenium. This was a compromise so that the list would include a variety of good multis that consumers could easily find in stores. If we restricted the list to only those products with no more than 55 mcg, it would have been a short list. We’ll re-evaluate this the next time we review multivitamins when there may be more brands with just 55 mcg.

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