Serum selenium levels, the selenoprotein glutathione peroxidase and vascular protection: The SABPA study.

Selenium is an important co-factor for the optimal functioning of the antioxidant enzyme, glutathione peroxidase (GPx). Studies investigating the associations of selenium with blood pressure (BP) and hemodynamic measures are sparse. This study investigated whether 24h blood pressure, vascular resistance, arterial compliance and arterial stiffness relate to both serum selenium and GPx activity. In this cross-sectional study selenium levels, GPx activity, ambulatory blood pressure and arterial stiffness of 200 black and 209 white school teachers from South Africa were measured. Serum selenium levels were significantly lower in black compared to white teachers (p<0.001), independent of sex. One in 10 black men and one in five black women were selenium deficient (<8μg/100ml). Only in white men inverse independent associations of 24h systolic BP (β=-0.19; p=0.039) and 24h diastolic BP (β=-0.21; p=0.029) with selenium were found. In the same group, an inverse association between carotid-dorsalis pedis pulse wave velocity (cd-PWV) and GPx activity (β=-0.23; p=0.017) were also found. To conclude, lower serum selenium levels in black populations from the same geographical region as their white counterparts may impact on the loss of the vasculoprotective effects of selenium and selenoproteins such as GPx.