Selenium biomarkers in Chinese subjects supplemented with selenium

Biomarkers for selenium are used to assess its nutritional status and its potential toxicity. We studied selenium biomarkers in selenium‐deficient Chinese subjects who received selenium supplements for 20 weeks and also in subjects living in a high‐selenium area of China (Enshi County). In supplemented subjects, 24‐h urinary selenium excretion increased in a dose‐dependent manner but it increased twice as much in subjects receiving selenomethionine (semet) as in those receiving comparable amounts of selenium as selenite. Hair selenium concentrations mirrored plasma selenoprotein P for both forms of selenium when the amount of selenium ingested was within the nutritional requirement. These results support earlier conclusions that the bioavailability of selenium in human beings is greater as semet than as selenite and confirm that hair selenium is useful as a biomarker of selenium nutritional status. In Enshi County, plasma samples from city dwellers and farmers were studied. Plasma selenoprotein concentrations were not different between them, but selenium concentrations were greater in farmers, 470 ± 170 mcg/L (n=10), than in city dwellers, 100 ± 27 mcg/L (n=10). These results indicate that farmers have a higher selenium intake in the form of semet than city dwellers, probably because the geographical sources of their food are different. Also, they confirm that high selenium intakes do not cause selenoproteins to rise above their optimal levels. Supported by NIH DK58763.