Selenium status of term infants fed selenium-supplemented formula in a randomized dose-response trial

The optimal form and dose of selenium supplementation required to achieve indicators of selenium status equivalent to those in breastfed infants are unclear.

The objective was to evaluate the effect of fortifying infant formula (6 microg Se/L) with 2 concentrations of selenate (7 and 15 microg/L) on biochemical indicators of selenium status and growth at 16 wk in term infants.

A randomized dose-response trial was conducted in 3 groups of term infants fed formula with different selenium concentrations [6 microg/L, F+0 (control); 13 microg/L, F+7; and 21 microg/L, F+15] and in a parallel breastfed reference group (BF; 11 +/- 2 microg Se/L).

One hundred sixty-one (47% males) infants completed the 16-wk study. Baseline plasma selenium was 0.3 +/- 0.1 micromol/L. At 16 wk, plasma selenium had increased in all groups (P < 0.001) and was greater (P < 0.01) in the F+7 and F+15 groups and lower (P < 0.05) in the F+0 group than in the BF group. Plasma glutathione peroxidase increased in the F+15 group, decreased in the F+0 group, and, at 16 wk, was lower in the F+0 group than in the other groups (all P < 0.05). Erythrocyte selenium and glutathione peroxidase decreased in all groups (P < 0.05), but the magnitude of the change was greater in the F+0 than in the F+15 group (P < 0.05). There was no effect of selenium supplementation on growth.

Selenate fortification of formula resulted in an increase in plasma indicators of selenium status relative to indicators observed in infants fed low-selenium-containing formula. Although the erythrocyte indicators decreased in all groups, the 21-microg/L dose (F+15 group) resulted in a smaller decrease and in higher erythrocyte selenium than did the standard formula. Supplementation of low-selenium formula to provide a net selenium concentration close to that found in the breast milk of US women (18 microg/L) may be justified.