SELENIUM ABSORPTION AND RETENTION BY VERY-LOW-BIRTH-WEIGHT INFANTS - STUDIES WITH THE EXTRINSIC STABLE ISOTOPE TAG SE-74

Measurements of dietary selenium absorption and retention were obtained after administration of a single dose of the extrinsic stable isotope tag Se-74 in 20 appropriate for gestational age premature infants with birth weights between 720 and 1,630 g and gestational ages between 26 and 33 weeks. Infants were assigned randomly to receive a standard premature formula (1.34-mu-g of Se/dl) or a selenium-supplemented version of that formula (2.03-mu-g of Se/dl). Each study consisted of one feeding that had been extrinsically labeled with Se-74 (103-mu-g/kg) and a timed stool and urine collection. The percent Se-74 absorption was 91.2 +/- 5.4% (mean +/- SD) from the standard formula and 86.2 +/- 3.0% from the selenium-supplemented formula (p < 0.05), but the percent of the absorbed Se-74 retained was not different, i.e., 96.6 +/- 2.1% and 95.0 +/- 2.8%, respectively. The percent net absorption and net retention were also not different between the standard and selenium-supplemented formulas; net absorption was 72.7 +/- 18.1% vs. 67.8 +/- 18.8% and net retention was 57.2 +/- 17.6% vs. 53.3 +/- 20.2%, respectively. The percent Se-74 absorption and true selenium absorption were significantly correlated with the percent net selenium absorption and net selenium absorption, respectively. We conclude that an extrinsically administered dose of Se-74 can be used to study selenium nutrition in growing premature infants.