The first years of life are crucial for brain development, and iron is essential for the brain to develop and function normally.
At the same time, researchers are still unable to measure how much iron is available in the brain itself.
Blood tests only show the body's overall iron levels, Umeå University said in a press release sent to VIA.
The researchers therefore plan to follow up with the same children when they are eight years old to determine whether the findings remain consistent over the longer term.
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Researchers urge caution
The study, published in Scientific Reports, included 221 healthy children from Sweden and Poland.
Half of the children received a small daily iron supplement from the age of four to nine months.
The other half received a placebo, a supplement containing no active ingredients.
The researchers emphasize that the findings are not sufficient to recommend iron supplements for all infants.
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According to Umeå University, further studies are needed, including research that takes factors such as genetics and upbringing into account.
Effects appeared later
When the children reached the age of three, their behavior was assessed.
The results showed that children who had received iron supplements displayed fewer aggressive and externalizing behavioral problems than those in the placebo group.
The researchers also examined difficulties with concentration and withdrawn behavior.
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At the same time, they found that the iron supplements had not reduced the risk of iron deficiency as measured by blood tests.
The findings therefore suggest that iron may influence brain development in ways that cannot be detected through blood tests.
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