Most Americans Don’t Need Extra Selenium
Review Finds Evidence That Selenium Supplements May Increase the Risk of Type 2 Diabetes
WebMD News Archive
Feb. 28, 2012 -- Taking selenium? You may not need to. There’s new evidence to suggest that selenium supplements aren’t necessary for most Americans. They may even cause harm.
And if you pop a daily multivitamin, as more than one-third of Americans do, check the label. Many multivitamin and mineral formulas contain selenium.
“It isn’t always that more is better. More often, ‘more’ isn’t better. Really, in terms of selenium, that was one of the points I wanted to bring out,” says researcher Margaret P. Rayman, DPhil, a biochemist at the University of Surrey in the U.K.
In a research review published in The Lancet, Rayman concludes that most Americans get enough selenium in their diets.
And a few studies included in the review suggest that taking more selenium in supplements may increase the risk for type 2 diabetes, though evidence is conflicting on that point.
Experts who were not involved in the study agree that most Americans shouldn’t be taking extra selenium.
“There is no evidence that selenium supplementation of the U.S. population would be helpful,” says Raymond F. Burk, MD, a professor of medicine at Vanderbilt University in Nashville, Tenn.
“In fact, there have been suggestions from recent work that it might be harmful, although this has not been conclusively proven. Thus, based on present knowledge I would not recommend selenium supplementation,” says Burk, who studies the health effects of selenium.
How Much Selenium Do You Need?
Selenium is a naturally occurring trace mineral that is vital to good health. Low selenium has been linked to an increased risk of death and poor brain and immune function.
The government’s recommended daily allowance for selenium is 55 micrograms for adults aged 19 and over. It is 60 micrograms daily for women who are pregnant and 70 micrograms for women who are breastfeeding.
Those levels aren’t hard to reach. Thanks to selenium-rich soil throughout much of the country, most Americans get plenty of this essential mineral through meats and grains like corn and wheat.
“Your wheat that’s used to make bread has quite a lot more selenium in it than ours would in Europe,” Rayman says.
In fact, studies show the average selenium intake for men in the U.S. is about 134 micrograms per day. And that’s a level that seems to be right on target for good overall health.
The U.S. Institute of Medicine has set a tolerable upper limit for selenium at 400 micrograms a day. Too much selenium can cause a condition called selenosis, which includes symptoms such as gastrointestinal upset, hair loss, white blotchy nails, garlic breath odor, fatigue, irritability, and mild nerve damage.
Selenium Supplements: Too Much of a Good Thing?
Hoping that more selenium might add up to even better health, researchers have tested supplements to see if they might boost immune function, brain health, and fertility, and ward off cancer and heart disease and stroke risk.