Plasma selenium concentrations in pregnant women in two countries with contrasting soil selenium levels

Selenium has an important role in antioxidant defense and cell mediated immunity. Plasma selenium is a useful biomarker for comparing selenium status across populations, and influenced by selenium levels of soils and plants.

This cross-sectional study compared plasma selenium (by electrothermal atomic absorption spectrophotometry) of women at 24 weeks gestation in Malawi (n=152) and the Philippines (n=301), countries with low and high soil selenium levels, respectively. Data on anthropometry, smoking, intakes of energy, nutrients and food groups (via 24-h recalls), hemoglobin, serum zinc, and C-reactive protein (CRP) were also collected.

Mean (95% CI) plasma selenium was lower for Malawian than Filipino women (0.79, 0.77, 0.82 μmol/L vs. 1.44, 1.41, 1.47 μmol/L; p<0.001); 83% had concentrations below 1.0 μmol/L compared to 3% in the Filipinos. Cereals provided 78% and 67% of the energy in Malawi and the Philippines, respectively compared to 4% and 8.5%, respectively for cellular animal protein. Plasma selenium was correlated modestly with BMI (r=-0.138; p=0.096) and elevated CRP (>5.0 mg/L) (r=-0.143; p=0.084) in Malawi, and significantly with intake of cellular animal protein (g/d) (r=0.23; p=0.020) and serum zinc (r=0.13; p=0.044) in the Philippines. No comparable relationships were observed in either group for smoking, hemoglobin, or cereal intakes.

Differences in plasma selenium paralleled reported trends in selenium concentrations in soils and staple cereals in Malawi and the Philippines. The biological significance of the lower plasma selenium for the Malawian women, and the extent to which they pose a risk for fetal and neonatal development, is uncertain.