Effects of age of introduction of complementary foods on iron status of breast-fed infants in Honduras

To evaluate the effect of introducing complementary foods before 6 mo of age, we randomly assigned 164 infants who had been exclusively breast-fed for 4 mo to continue being exclusively breast-fed until 6 mo (EBF group) or to receive iron-fortified foods in addition to breast milk from 4 to 6 mo (BF+SF group). At 6 mo, the BF+SF group had higher mean iron intake (4 mg/d compared with 0.2 mg/d in EBF infants) and higher hemoglobin, hematocrit, and ferritin values than the EBF group (P < 0.05). The percentage with low hemoglobin (<103 g/L) did not differ significantly between groups, but fewer infants in the BF+SF group had a low hematocrit (<0.33, 21.4% compared with 32.0%, respectively; P < 0.05). The percentage of infants with ferritin concentrations <12 mu g/L at 6 mo was lower than the percentage with low hemoglobin or hematocrit, raising questions about the validity of the cutoffs at this age. Infants at greatest risk for anemia and low ferritin were those with birth weights <2500 g; no infant with a birth weight >3000 g had a low ferritin value at 6 mo. We conclude that the risk of iron deficiency is low among infants with birth weights >3000 g who are exclusively breast-fed for 6 mo. Iron drops are recommended for low-birth-weight infants; for breast-fed infants with birth weights between 2500 and 3000 g, further research is needed to determine whether iron drops are more effective than complementary foods for preventing iron deficiency before 6 mo.