Selenium status of exclusively breast-fed infants as influenced by maternal organic or inorganic selenium supplementation.

A longitudinal dietary Se supplementation study on lactating mothers was performed to determine the possibilities of improving the Se status of exclusively breast-fed infants. A total of 200 mothers randomized into three groups received either no Se supplements, 100 micrograms of selenite, or 100 micrograms of yeast-Se daily. Maternal and infant serum Se concentrations showed a linear correlation during exclusive breast-feeding. Yeast-Se in the dose administered was safe and more effective than selenite in increasing the Se concentrations of maternal serum and milk, and infant serum. The mean estimated daily Se intakes of the infants were 7.7 +/- 2.2, 8.9 +/- 2.2, and 11.5 +/- 4 micrograms, in the control, selenite, and yeast-Se groups respectively. Though the infant Se intakes of the unsupplemented and selenite-supplemented mothers were below the lower limit of the safe and adequate range as set by the US National Research Council, their serum Se concentrations increased steadily over the 6-mo study period. As maternal serum Se also increased by over 50% during the same period the results suggest that a maternal daily intake of 50-75 micrograms is adequate during lactation.