NEWS Healthy, breastfed infants who receive iron supplementation show fewer aggressive behaviors at the age of three compared with children who did not receive supplementation. This is shown in new research from Umeå University. However, more research is needed before iron supplementation can potentially be recommended for all infants.
Children who received iron supplementation as infants showed fewer behavioral problems than the placebo group at the age of three.
ImageJohnér Bildbyrå AB, Plattform“Our results are promising, but more well-designed studies are needed to account for factors such as genetic influences and environmental conditions during childhood that may affect children’s behavior,” says Anna Chmielewska, Associate Professor of Pediatrics at the Department of Clinical Sciences, Umeå University.
Anna Chmielewska, Associate Professor of Pediatrics at the Department of Clinical Sciences, Umeå University.
ImageJohanna NordströmThe study included 221 healthy, full-term children in Sweden and Poland. Half of the children were randomly assigned to receive a low daily dose of iron supplementation between the ages of 4 and 9 months, while the other half received a placebo. At the age of three years, the children were followed up and assessed for aggressive and externalizing behaviors, attention difficulties, and withdrawn behavior. The group that received iron supplementation showed fewer behavioral problems than the placebo group.
“It is remarkable that the group receiving iron supplementation did not have a lower risk of iron deficiency, yet they still experienced certain positive effects from the supplementation,” says Anna Chmielewska.
Iron status is usually assessed through a blood test. However, such tests do not reflect iron availability in the brain, where iron deficiency may occur before it becomes detectable in the blood.
“We lack biomarkers that can show how much iron is available in the brain. At the same time, we know that iron is crucial for the development and functioning of brain cells,” says Anna Chmielewska.
Anna Chmielewska’s research group will now conduct a follow-up study of the same children at the age of eight years to determine whether the effects persist. The hypothesis is that improved iron availability in the brain leads to fewer behavioral problems.
“The first three years of life are critical for brain development. We also know that one in five children under the age of five has iron deficiency. I hope our findings will contribute to recommendations that help prevent serious behavioral problems in children,” says Anna Chmielewska.
Svensson, L.K., Chmielewski, G., Domellöf, M., Konarska, Z., Pieścik-Lech, M., Späth, C., Szajewska, H., Chmielewska, A. Iron in breastfed infants and behavior at 3 years: a randomized trial. Scientific Reports 16, 18664 (2026). https://doi.org/10.1038/s41598-026-56401-z
This text was translated from Swedish using Microsoft Copilot. It has been manually reviewed by the author.
