Selenium is a trace mineral that is essential for good health, and several studies have linked the nutrient to diabetes. However, some studies say selenium supplements increase the risk for hyperglycemia, while some find the mineral protective. New research finds positive results for men with diabetes who have high plasma concentrations of selenium.
Tasnime Akbaraly from the University of Montpellier and a team of researchers followed 1162 healthy French men and women for nine years, monitoring plasma selenium concentrations and measuring blood sugar levels. During the study period, elderly males who had plasma selenium concentrations in the top tertile of the population were significantly associated with a lower risk of developing dysglycemia.
According to Akbaraly, "The reason we observed a protective effect of selenium in men but not in women is not completely clear, but might be attributed to women being healthier at baseline, having better antioxidant status in general and possible differences in how men and women process selenium".
The study conflicts an earlier result by researchers at Johns Hopkins University examined the diabetes rate and selenium levels of over 900 adults and found that those with a diagnosis of type 2 diabetes had higher levels of selenium in their blood.
The recommended dietary intake for selenium, provided in the Dietary Reference Intakes developed by the Institute of Medicine, is that adults over the age of 19 should aim for 55 micrograms per day. The levels are slightly higher in pregnancy and lactation. Selenium is used by the body in selenoproteins which are important antioxidant enzymes that prevent cellular damage from free radicals, regulate thyroid function, and play a role in the immune system.
Plant foods are the major dietary source of selenium, but the amount depends on the selenium content of the soil. Brazil nuts are extremely high in selenium, containing 544 micrograms per serving. Other good sources grains such as wheat and rice, and meats from animals that eat grains. Deficiency in the mineral is rare in the U.S., but can occur in some severe gastrointestinal problems such as Crohn’s disease or in people with a confounding iodine deficiency.
According to the U.S. Food and Drug Administration, selenium supplements are generally unnecessary because “normal consumption of food and water” provides adequate amounts. Because of its antioxidant properties and possible link to reducing the risk for cancer, nearly one-quarter of Americans over the age of 40 take selenium supplements or multivitamins that contain selenium. The tolerable upper limit for selenium is set at 400 micrograms per day, and toxicity is possible with plasma levels greater than 100 micrograms per deciliter.