Utilization of supplemental iron by premature infants fed fortified human milk*

Abstract

We measured red blood cell iron incorporation (RBC‐inc) in 13 human milk‐fed premature infants (birthweight 1037 ± 289 g, gestational age 27 ± 2 wk, weight at start of study 1571 ± 426 g) who were receiving full tube‐feedings of human milk fortified with a commercial human milk fortifier (FortHM). The relative RBC‐inc of supplemental iron (2 mg/kg/d of ferrous sulfate) was assessed using 57Fe sulfate mixed directly into a 24‐h volume of FortHM, and 54Fe sulfate given as a bolus between two FortHM feedings the next day. RBC‐inc was similar between the two methods of supplemental iron administration (4.7 ± 2.5% vs 4.6 ± 1.5%, respectively). Although these values are lower than RBC‐inc expected from iron native to human milk, the relatively large amount of iron in the supplements contributed most of the iron incorporated into RBC by the infants. There was a significant positive correlation between the reticulocyte count and RBC‐inc. As the high nutrient (especially calcium) content of the FortHM did not interfere with iron utilization, adding iron directly to FortHM, or incorporating it into commercial fortifiers, may be a practical method to provide iron to premature infants. □Human milk, iron absorption, premature infants, stable isotopes