Analysis of data from the Nutritional Prevention of Cancer Trial (NPC) -a large randomized, multi-center, clinical trial from the eastern United States designed to evaluate whether selenium supplements prevent skin cancer - found that people who took a 200 microgram selenium supplement each day for almost eight years had an increased risk of developing type 2 diabetes versus those who took a placebo.

Selenium is a naturally occurring trace mineral present in soil and foods. The body need selenium in minute amounts to aid in metabolism. Selenium supplements are widely promoted on the Internet for conditions ranging from cold sores and shingles to arthritis and multiple sclerosis. They are sold to prevent aging, enhance fertility, prevent cancer and get rid of toxic minerals such as mercury, lead and cadmium.

Lead author of ths study - Saverio Stranges, MD, PhD - said that the findings from this study suggest that selenium supplements do not prevent diabetes and might actually be harmful:

"At this time, the evidence that people should take selenium supplements is extremely limited. We have observed an increased risk for diabetes over the long term in the group of participants who took selenium supplements."

Findings will appear online in Annals of Internal Medicine today (July 10) and on Aug. 21, 2007 in the print edition of the journal.

Is anybody taking selenium supplements? Eliseo Guallar, MD, DrPH, from Johns Hopkins University Bloomberg School of Public Health said you shouldn't have to:

"What the U.S. public needs to know, is that most people in the United States have adequate selenium in their diet. Moreover, taking selenium supplements on top of an adequate dietary intake may cause diabetes."

Read the full report.

[In Photo: Nature Made Selenium Supplement Tablets, 200 mcg, 100-Count Bottles (Pack of 3) via Amazon]