Iron supplementation of breastfed infants from an early age

Abstract

Background: In breastfed infants, iron deficiency at <6 mo of life, although uncommon, is observed in industrialized countries. Iron supplementation starting at an early age may prevent iron deficiency.

Objective: The study assessed the effect of early iron supplementation of breastfed infants and tested the hypothesis that iron supplementation enhances iron status. Potential adverse effects (tolerance and growth) were monitored.

Design: The prospective, placebo-controlled study involved exclusively breastfed infants who were randomly assigned at 1 mo of age to iron (n = 37) or placebo (n = 38). Iron (7 mg/d as multivitamin preparation with ferrous sulfate) or placebo (multivitamin preparation without iron) was given from 1 to 5.5 mo of age. Complementary foods were allowed at >4 mo. Infants were followed to 18 mo. Blood concentrations of ferritin, transferrin receptor, hemoglobin, and red cell indexes were determined at bimonthly intervals. Stool consistency and color and feeding behavior were recorded.

Results: Iron supplementation caused modest augmentation of iron status during the intervention at 4 and 5.5 mo but not thereafter. Iron supplements were well tolerated and had no measurable effect on growth. One infant developed iron deficiency anemia by 5.5 mo of age. Plasma ferritin and hemoglobin tracked over time.

Conclusion: Early iron supplementation of breastfed infants is feasible and transiently increases iron status but not hematologic status. Iron is tolerated by most infants. The prevalence of iron deficiency anemia is low (3%) among unsupplemented breastfed infants in the first 6 mo of life.

FIGURE 1

Flow of participants through the trial. Plac, placebo.

FIGURE 2

Adjusted plasma ferritin (PF) concentration (adjusted for current weight and PF at 1 mo) between 1 and 18 mo. Iron supplementation (n = 31) and placebo (n = 32) subjects at 1 through 5.5 mo, with fewer at later ages. The horizontal bar indicates the intervention period. Error bars indicate SE. P values refer to comparisons between iron supplementation and placebo by ANCOVA. The age × treatment interaction was statistically significant at P = 0.001.