Indexes of selenium status in human populations

This paper considers the factors that affect the bioavailability of selenium to human populations and describes briefly the consequences of an inadequate dietary intake of selenium in the Peoples' Republic of China and in Zaire. A review of human blood selenium concentrations worldwide reveals very large differences in the apparent dietary status of individuals in different areas. The question is raised as to whether blood selenium measurement is a reliable index of actual selenium status in terms of bioavailability and function of the element. It is concluded that the preferred indexes of human selenium status are blood, or plasma and/or serum, concentrations of the element and the level of activity of the selenium-dependent enzyme glutathione peroxidase in erythrocytes or in plasma. Several important caveats to this conclusion are mentioned and other means of assessing selenium status are also considered.