Does the fortified milk with high iron dose improve the neurodevelopment of healthy infants? Randomized controlled trial

BACKGROUND: Since iron plays an important role in several physiological processes, its deficiency but also overload may harm the development of children. The aim was to assess the effect of iron–fortified milk on the iron biochemical status and the neurodevelopment of children at 12 months of age. METHODS: Randomized controlled trial conducted in 133 Spanish children, allocated in two groups to receive formula milk fortified with 1.2 or 0.4 mg/100 mL of iron between 6 and 12 months of age. Psychomotor (PDI) and Mental (MDI) Development Index were assessed by the Bayley Scales before and after the intervention. Maternal obstetrical and psychosocial variables were recorded. The biochemical iron status of children was measured and data about breastfeeding, anthropometry and infections during the first year of life were registered. RESULTS: Children fortified with 1.2 mg/100 mL of iron, compared with 0.4 mg/100 mL, showed higher serum ferritin (21.5 vs 19.1 μg/L) and lower percentage of both iron deficiency (1.1 to 5.9% vs 3.8 to 16.7%, respectively, from 6 to 12 months) and iron deficiency anemia (4.3 to 1.1% vs 0 to 4.2%, respectively, from 6 to 12 months) at the end of the intervention. No significant differences were found on neurodevelopment from 6 to 12 months between children who received high dose of Fe compared with those who received low dose. CONCLUSION: Despite differences on the iron status were observed, there were no effects on neurodevelopment of well–nourished children in a developed country after iron supplementation with doses within dietary recommendations. Follow–up studies are needed to test for long–term neurodevelopmental improvement. TRIAL REGISTRATION: Retrospectively registered in ClinicalTrials.gov with the ID: NCT02690675.