Selenium Protective Against Dysglycemia in French Men

Megan Brooks

March 26, 2010

March 26, 2010 — In a French prospective observational study, older men with higher plasma selenium levels at baseline are less likely to have impaired fasting glucose levels or type 2 diabetes during the subsequent 9 years. However, no such protective effect of higher baseline selenium levels is seen in older women in the study.

The findings, reported online March 17 in the BioMed Central's open-access journal Nutrition & Metabolism, suggest "a sex-specific protective effect of higher selenium status at baseline on later occurrence of dysglycemia," write first author Tasnime N. Akbaraly, PhD, research fellow from the Hospital La Colombiere and University of Montpellier, in Montpellier, France, and colleagues.

In a telephone interview with Medscape Nutrition, Saverio Stranges, MD, PhD, of the Health Sciences Research Institute, Warwick Medical School, Coventry, United Kingdom, said the findings "showed a borderline significant effect of lower risk of dysglycemia in men with higher levels of selenium. However, this was an observational study and the findings from observational studies are always less convincing, less strong, than randomized clinical trials," he emphasized. Dr. Stranges was not involved in the study.

Research Mixed

Research on selenium as it relates to diabetes has been mixed. A preventive role of selenium on diabetes risk has been reported and ascribed to the "insulin-like" activity of this essential trace element and antioxidant properties of selenoenzymes. However, cross-sectional and clinical trial data have suggested that high selenium status and selenium supplementation may increase the risk for type 2 diabetes.

To investigate further, Dr. Akbaraly and colleagues studied 1162 French men and women enrolled in the Epidemiology of Vascular Ageing (EVA) study, who were between 59 and 71 years old and normoglycemic at baseline (1991-1993). As part of the study, fasting plasma glucose level was measured at baseline and 2, 4, and 9 years later.

Mean baseline plasma selenium levels were 1.08 ± 0.21 µmol/L in men and 1.10 ± 0.20 µmol/L in women. During the 9-year follow-up period, 70 men (15.8%) and 57 women (7.8%) went on to have dysglycemia.

Risk Significantly Lower in Men

In unadjusted Cox models, the risk for dysglycemia was significantly lower in men with plasma selenium levels in the top tertile (T3: 1.19 - 1.97 µmol/L) vs those levels in the lowest tertile (T1: 0.18 - 1.00 µmol/L; hazard ratio [HR], 0.48; 95% confidence interval [CI], 0.25 - 0.92).

In analysis controlling for sociodemographics, lifestyle factors, cardiovascular diseases, body mass index, hypertension, and lipid profile, higher plasma selenium levels remained marginally significantly associated with the occurrence of dysglycemia in men (T3 vs T1: HR, 0.50; 95% CI, 0.24 - 1.04).

In women, no significant relationship between baseline plasma selenium level and the risk for dysglycemia was evident in unadjusted analysis (T3 vs T1: HR, 0.89; 95% CI, 0.46 - 1.72) or adjusted analysis (T3 vs T1: HR, 1.13; 95% CI, 0.55 - 2.32).

"The reason we observed a protective effect of selenium in men but not in women is not completely clear," Dr. Akbaraly noted in a news release, "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 current findings, added to those of others, "clearly underline the need for further studies," Dr. Akbaraly and colleagues conclude.

The findings in this French population, Dr. Stranges emphasized to Medscape Nutrition, should not be generalized to the US population, where selenium levels are much higher. In France and in many other European countries, selenium status is "much lower than in US and considered to be somewhat suboptimal."

The EVA study was carried out under an agreement between INSERM and the Merck, Sharp and Dohme-Chibret Laboratories (West Point, Pennsylvania) and was supported by EISAI Laboratory, France. Dr. Akbaraly was supported by a grant from the French Society of Nutrition. The other study authors and Dr. Stranges have disclosed no relevant financial relationships.

Nutr Metab. Published online March 17, 2010. Abstract

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