Selenium status in adults and children in Lusaka, Zambia.

Background: Selenium (Se) is a trace element found in many foodstuffs and critical for antioxidant and immune functions. Widespread Se deficiency has been noted in populations of some sub-Saharan African countries including Ethiopia and Malawi. As a first step towards developing a fuller understanding of problems with the availability of Se in the diet in Lusaka province, Zambia, we measured plasma Se in adults and children in this geographic area. Methods: Total plasma Se was measured using inductively coupled plasma optical emission spectrometry (ICP-OES) in several groups of adults recruited to various pre-existing studies, including those of high and low socioeconomic status (SES) and pregnant women, and children with a range of nutritional states (healthy, stunted or wasted). Results: A total of 660 plasma samples from 391 adults and 269 children were included. Adults had a median plasma Se concentration of 0.27 μmol/l (IQR 0.14-0.43). Concentrations consistent with deficiency (<0.63 μmol/l) were found in 83% of adults. Low SES was associated with low plasma Se among adults, [OR 0.1; 95% CI 0.1-0.3, p < 0.0001]. Among the children, 24% had plasma Se less than 0.41 μmol/l. There was a statistically significant positive correlation between plasma Se and age among children, Spearman's rho 0.47, p < 0.0001. Conclusions: These data suggest that Se deficiency is widespread in Lusaka province and could in part be related to socio-economic status. Supplementation or agronomic biofortification may therefore be needed.