The influence of feeding regimens on iron status during infancy

Abstract

Iron status as influenced by feeding regimen of 96 apparently healthy, full-term infants was assessed. Infants consuming human milk as a sole milk source for at least 3 months (group I), an iron-fortified formula (14 mg Fe/qt) for 4 months (group II), an iron-fortified formula for 12 months (group III), and the same formula with 1.4 mg Fe/qt for 4 months were studied during the 1st year of life (group IV). At ages 1, 2, 3, 6, 9, and 12 months, 3-day dietary assessments were performed. Hematological determinations were made on blood samples collected at ages 3, 6, 9, and 12 months. Throughout the study, mean hemoglobin and hematocrit levels did not differ significantly among groups. At 6 months, groups I and III had significantly higher mean serum iron concentrations than group IV and higher mean percentage saturation of transferrin than groups II and IV. These differences in serum iron and transferrin saturation were not apparent at 9 and 12 months. Reported dietary iron intakes did not correlate with hemoglobin, hematocrit, serum iron, and percentage saturation of transferrin measurements at any time interval during the study. These data show that infants receiving an iron-fortified formula (14 mg/qt) for 4 months only (group II) fare no differently in terms of iron status than those receiving the same formula containing 1.4 mg Fe/qt for the same period of time (group IV). These data also show that at 6 months infants still fed an iron-fortified formula (group III) or those fed human milk for at least 3 months (group I) had superior biochemical indicators of iron sufficiency as indicated by elevated serum iron and percentage saturation of transferrin.