Infant iron supplements linked to fewer behavior problems at age three
· Medical Xpressby Johanna Nordström, Umea University
edited by Lisa Lock, reviewed by Robert Egan
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Healthy, breastfed infants who receive iron supplementation show fewer aggressive behaviors at age 3 compared with children who did not receive supplementation, according to new research from Umeå University. However, more research is needed before iron supplementation can be recommended for all infants. The paper is published in Scientific Reports.
"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.
The 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 ages 4 and 9 months, while the other half received a placebo. At age 3, the children were followed up and assessed for aggressive and externalizing behaviors, attention difficulties and withdrawn behavior.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," Chmielewska says.
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," Chmielewska says.
Chmielewska's research group will now conduct a follow-up study of the same children at age 8 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 1 in 5 children younger than 5 has iron deficiency. I hope our findings will contribute to recommendations that help prevent serious behavioral problems in children," Chmielewska says.
Publication details
Ludwig K. Svensson et al, Iron in breastfed infants and behavior at 3 years: a randomized trial, Scientific Reports (2026). DOI: 10.1038/s41598-026-56401-z
Journal information: Scientific Reports
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