Scientists Report that Selenium Supplements May Increase the Risk of Diabetes

A new report published in the August issue of Annals of Internal Medicine suggests that selenium, once thought to be helpful for type 2 diabetes, may be in fact putting people at risk for developing the disease.

According to the American Diabetes Association (ADA), there are 20.8 million Americans with diabetes, a metabolic disorder that is characterized by having high levels of glucose (sugar) in the blood stream. Diabetes patients tend to be at high risk for heart disease, kidney damage, loss of vision, and loss of sensory perception that can lead to infections and risk of amputations.

Diabetes is the 6^th leading cause of death in the U.S. and is estimated to have caused 224,092 deaths in 2002, according to the ADA. Type 2 diabetes, is the most common form of the disease and accounts for 90 to 95% of all new diagnosed diabetic cases. It usually occurs in adults over 40 that tend to be overweight.

The research was conducted by Saverio Stranges, M.D., Ph.D., affiliate with the Clinical Sciences Research Institute at the Warwick Medical School in the UK and Mary E. Reid, PhD., affiliate of the University of Buffalo.

Selenium is a trace mineral that acts as a cofactor for proteins involved in antioxidant activity. Previous research in lab animals had shown that selenium had the capacity to improve glucose metabolism. This prompted the theory that habitual selenium supplementation could be beneficial in preventing diabetes. To clarify this idea, the research team decided to evaluate the relationship between Type 2 diabetes and long-term selenium supplementation.

The study utilized data from a nutritional prevention melanoma cancer trial that included 1,202 individuals that did not have Type 2 diabetes when they began the study. Subjects were divided into two groups, one consisting of 600 individuals that took selenium supplements (200 micrograms), and another group consisting of 602 participants that took placebo pills. The subjects were followed for an average of 7.7 years.

The research team found that during the course of study, 58 people that were in the selenium supplement group, developed diabetes as compared to 39 individuals that were placebo recipients. This translated into 55% more Type 2 diabetes cases in individuals with habitual selenium supplementation. When the researchers accounted for age, sex, smoking status, and body mass index, the results remained constant.

In the University of Buffalo's press release, Dr. Stranges stated that "At the moment we don't know what mechanism or mechanisms account for this finding, we have very little understanding of the possible biological pathways involved. In addition, our findings need to be replicated in larger clinical trials before conclusive evidence can be drawn on whether high doses of selenium supplements increase the risk of type 2 diabetes, as our study suggests."

Dr. Stranges also added that "With selenium, which is a trace element, it may be the case that a little bit is essential, but more can cause detrimental effects, at least in well-nourished populations such as the U.S. It's possible that taking extra selenium overcomes the natural balance. Perhaps excess selenium has a negative effect on the endocrine system."

Sources:

Annals of Internal Medicine: http://www.annals.org/cgi/content/full/0000605-200708210-00175v1

American Diabetes Association: http://www.diabetes.org/diabetes-statistics.jsp

University of Buffalo News Center: http://www.buffalo.edu/news/8751