Secondary analysis of an existing study has found that taking selenium supplements does not appear to prevent type 2 diabetes, and may even increase risk for the disease.
There is epidemiological and experimental evidence to suggest that dietary intake of antioxidants, including selenium, may protect against type 2 diabetes, but there have been no long-term randomised controlled trials on this. The authors of this paper used data from an existing long-term controlled trial of selenium supplementation on cancer incidence to investigate whether any effect on diabetes risk could be shown.
They investigated whether such supplements reduced the risk of nonmelanoma skin cancer in people living in areas of the USA with low selenium consumption. Participants were recruited from dermatology clinics between 1983 and 1991, and were randomised to receive identical tablets containing a high-selenium yeast (equivalent to 200mcg daily) or an ordinary yeast control.
For this analysis, the authors assessed incidence of type 2 diabetes throughout the blinded phase of the trial (1983