Are Selenium Levels Linked to Diabetes?

Americans with diabetes have high levels of selenium in their bodies, prompting some health experts to suspect that it could contribute to development of the disease. In response to their new findings, a research team has recommended that U.S. residents stop taking supplements that contain selenium.

Most Americans ingest large amounts of the mineral—substantially more than people elsewhere—because soil in much of the country contains high levels that are absorbed by crops. Selenium occurs naturally in soil and leaches onto farm fields from irrigation and streams.

The research team, led by Johns Hopkins University epidemiologists, examined the diabetes rate and selenium levels of 917 people over the age of 40 who participated in a national health study conducted by the U.S. Centers for Disease Control and Prevention in 2003 and 2004. They found that most had a lot of selenium in their blood, but those with diabetes had substantially more.

The benefits and dangers of selenium have been debated in recent years because some studies show it might help protect people from cancer and heart disease. Selenium is an essential element and antioxidant, but medical experts say there is a fine line between the amount that the body needs and the amount that is harmful.

“Given the current diabetes epidemic, the high selenium intake from naturally occurring selenium in U.S. soil and the popularity of multivitamin/mineral supplements containing selenium in the U.S., these findings call for a thorough evaluation of the risk and benefits associated with high selenium status in the U.S.,” the researchers wrote in a study published online in Environmental Health Perspectives on May 15.

“Furthermore,” they wrote, “our findings suggest that selenium supplements should not be used in the U.S. until there is a better understanding of their potential risks and benefits.”

Supplements containing selenium have gained popularity in the United States because of anti-cancer claims, and selenium levels in people have been rising. Nearly one-quarter of Americans over the age of 40 take selenium supplements or multivitamin supplements that include selenium.