Selenium supplementation of children in a selenium-deficient area in China: blood selenium levels and glutathione peroxidase activities.

Keshan disease is a cardiomyopathy restricted to the endemic areas of China and seen in residents having an extremely low selenium (Se) status. Prophylactic administration of sodium selenite has been shown to decrease significantly the incidence of acute and subacute cases. The aim offthe study was to assess the relative bioavailability of selenite versus organic Se-yeast in a Se-deficient area in China with a randomized double-blind double-dummy design. Healthy children (n=30) between 14 and 16 yr of age were randomized into three equal groups receiving either 200 microg/d selenite Se or 200 microg/d Se-yeast or placebo for 12 wk. Blood was drawn at baseline, 4, 8, and 12 wk and 4 wk postsupplementation. The plasma Se concentration (mean +/- SD) was 0.16+/-0.03 micromol/L at baseline. Selenite and Se-yeast supplementation increased plasma Se to plateau values, 1.0+/-0.2 and 1.3+/-0.2 micromol/L, respectively. In red cells, Se-yeast increased the selenium level sixfold and selenite threefold compared to placebo. The relative bioavailability of Se-yeast versus selenite measured as glutathione peroxidase (GSHPx) activity was similar in plasma, red blood cells, and platelets. GSHPx activity reached maximal levels in plasma and platelets of 300% and 200%, respectively, after 8 wk compared to the placebo group, but continued to increase in red cells for 16 wk. Our study showed that although both forms of Se were equally effective in raising GSHPx activity, Se-yeast provided a longer lasting body pool of Se. Se-yeast may be a better alternative to selenite in the prophylaxis of Keshan disease with respect to building up of body stores.