Iron supplements are frequently prescribed during infancy, however their benefits and risks are not well documented.
In this study, a team of international researchers examined whether iron supplements affect growth or morbidity of breast-fed infants.
The team assigned 101 full-term infants from Sweden and 131 full-term infants from Honduras randomly to 3 groups, at 4 months of age.
The first group received placebo from 4 to 9 months, the second received placebo from 4 to 6 months and iron supplements [1 mg/(kg × day)] from 6 to 9 months, and the third received iron supplements from 4 to 9 months.
All infants were exclusively, or almost exclusively, breast-fed to 6 months. They continued to be breast-fed to at least 9 months.
| Gains in length and head circumference were significantly lower in infants who received iron.|
|Journal of Nutrition|
The researchers measured growth monthly, and collected morbidity data every 2 weeks.
The team found that among the Swedish infants, gains in length and head circumference were significantly lower in those who received iron than in those given placebo from 4 to 9 months.
They also found the same effect in Honduras, but only at 4 to 6 months among those with initial hemoglobin (Hb) 110 g/l.
The researchers identified no significant main effect of iron supplementation on morbidity, nor any significant interaction between iron supplementation and site.
However, for diarrhea (with both sites combined), they determined an interaction between iron supplementation and initial Hb.
Among infants with Hb < 110 g/l at 4 months, diarrhea was less common in those given iron, than in those given placebo from 4 to 9 months
The opposite was found to be true among those with Hb ≥ 110 g/l.
Dr Kathryn Dewey’s team concluded, “Routine iron supplementation of breast-fed infants may benefit those with low Hb but may present risks for those with normal Hb”.