Iron Supplementation of Breastfed Babies

Study Examines Early Iron Supplementation of Breastfed Infants

A study published in the February 2009 edition of the American Journal of Clinical Nutrition found, in a randomized, double-blind placebo-controlled trial, that early iron supplementation of breastfed infants transiently increased iron status during the intervention, but did not increase hematologic status.

The objective of this study was to evaluate the effect of iron supplementation of breast fed infants during the first 6 months of life and to test if iron supplementation enhanced iron status thorough the second year of life. Exclusively breastfed infants at one month of age were randomly assigned to receive either iron (7 mg/day as multivitamin preparation with ferrous sulfate) or placebo (multivitamin without ferrous sulfate) until age 5.5 months of age. Infants were eligible to participate if their mothers intended to breastfed (exclusivity was not required) throughout the study period. Infants were monitored until 18 months of age. Growth, tolerance (4 day records), and supplementary feeding were monitored monthly. Blood was analyzed on a bi-monthly basis for various indices of iron/hematologic status, including plasma ferritin, soluble transferrin receptor, hemoglobin, and red cell indices. Findings included supplementation of breastfed infants with iron caused modest preservation of iron status, but this effect did not last beyond the period of supplementation (5.5 months). Additionally, the authors found that iron supplementation was well tolerated by most infants and that infant growth overall was not significantly different between the groups.

Limitations of this study include a high drop out rate that resulted in fewer infants completing the study at 9 months than required to evaluate the primary endpoint of clinically meaningful differences in plasma ferritin, increasing the possibility of a Type 2 error. Additionally, not all subjects were exclusively breastfed for the full 5.5 months of the study intervention (approximately 10% received formula by 4 months and over 90% receiving other foods at 5.5 months), thereby questioning the applicability of the study findings to the iron status of exclusively breastfed infants. Similarly, neither hematologic nor growth data was analyzed for possible effect of formula or cereal supplementation during the study period. Differences in the amount and timing of introduction of complementary feedings could explain gender differences in weight gain during the study period or mask treatment effects on iron parameters beyond the study period. The authors may have evaluated the interaction between feeding and treatment effect, but this data unfortunately was not presented. Strengths of the study include its double-blind randomized design and the inclusion of many markers of iron status.

Based on their findings and since the prevalence of iron deficiency anemia is low (3%) in this population of predominantly breastfed infants, the authors recommend selective treatment of iron deficiency, rather than universal supplementation, as a suitable approach to combat infant iron deficiency. Further study of the impact of early iron supplementation on exclusive breastfed infants is warranted.

References Cited:

Ziegler EE, Nelson SE, Jeter JM. Iron supplementation of breastfed infants from an early age. Am J Clin Nutr 2009; 89 (2):525-32.