Selenium Absorption and Retention by Very-Low-Birth-Weight Infants: Studies with the Extrinsic Stable Isotope Tag 74Se

Measurements of dietary selenium absorption and retention were obtained after administration of a single dose of the extrinsic stable isotope tag Se 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 μg of Se/dl) or a selenium-supplemented version of that formula (2.03 μg of Se/dl). Each study consisted of one feeding that had been extrinsically labeled with Se (1.03 μg/kg) and a timed stool and urine collection. The percent Se 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 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 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 can be used to study selenium nutrition in growing premature infants.