A Selenium Surprise

Selenium is an important component of antioxidant enzymes, so that it can be supposed to have healthful properties. Johns Hopkins researchers, therefore, undertook to investigate the possibility that selenium might prevent the development of diabetes. They have published their findings in the journal Diabetes Care.

Data from the 3^rd National Health and Nutrition Examination Survey were used. Over 8,800 adults were classified as not having, or having diabetes, defined as a fasting glucose level above 125 mg/dL; they all had their serum selenium levels measured. After adjusting for age, sex, race, and weight (actually body mass index or BMI), the average serum selenium levels were 126.8 ng/mL in diabetics and 124.7 ng/mL in non-diabetics. Another analysis showed that the likelihood of having diabetes if one was in the highest fifth of selenium levels was 1.57 times that of people in the lowest fifth (or quintile).

These results were the opposite of those expected. Oxidative stress reduces insulin secretion and increases insulin resistance, and is thus a possible contributory cause of diabetes. So one might expect a strong antioxidant like selenium would have a protective effect.

What are the consequences of this finding? Selenium supplements should not be taken to prevent diabetes, unless there is a clearly demonstrated deficiency. And that is rare in the USA , especially if you eat a well-balanced diet.