High-dose enteral iron improves iron status with no gut microbiome disruption in infants

Supplementation with enteral iron 6 mg/kg/day, compared with the recommended 2-mg/kg/day dose, results in improved iron status and reduced intestinal barrier dysfunction without harming the gut microbiome, according to a study.

“Preterm infants routinely receive enteral iron supplementation to support growth, replace phlebotomy losses, and prevent iron deficiency. However, concerns regarding potential harms, including those on the gut microbiome, have contributed to recommendations for lower dosing,” the investigators said.

In this randomized, double-blind clinical trial, the investigators assigned 151 preterm infants born <1,500 g to receive either the recommended dose (n=77) or a higher dose (n=74) of total enteral iron. They then assessed the iron status, adverse events, and auditory brainstem response latencies at 36-week postmenstrual age among participants.

No significant between-group differences were observed in bacterial diversity, individual taxa, virulence potential, bacterial overgrowth, and iron-related functional genes.

Subgroup analysis of singletons revealed significant differences in temporal shifts in overall bacterial community structure between the low- and high-dose groups. Infants receiving enteral iron 2 mg/kg/day showed higher post-treatment urinary claudin-3 concentrations, suggesting possible differences in intestinal permeability, and a higher prevalence of iron deficiency than those receiving the higher dose.

Other biomarkers, clinical outcomes, adverse events, and auditory latencies were not significantly different between groups.

“These findings do not support concerns regarding gut microbiome disruption as a justification for lower iron dosing in preterm infants,” the investigators said.