Writing in the Canadian Medical Association Journal (CMAJ) the research team analysed data from more than 7,000 children taking part in 32 studies to assess the effects of iron supplementation on physical and mental health.
Led by Dr Sant-Rayn Pasricha from the University of Melbourne, Australia, the research team found that anaemic children who received iron supplements had higher cognitive scores than children in the control groups, and also showed 'substantial' improvement in IQ scores and other cognitive tests.
Children who received iron supplements were also slightly taller for their age and had improved weight-for-age compared with children who did not.
"We found evidence of a benefit of iron supplementation on cognitive performance among primary-school–aged children," said Pasricha and his colleagues.
"Cognitive performance is associated with educational achievement, future income and productivity," they added. "Daily iron supplementation could benefit educational attainment and economic potential at the individual level and, in set- tings where anaemia is prevalent, population level."
The team also reported that daily iron supplementation decreased the prevalence of anaemia by around 50% and reduced the prevalence of iron deficiency by 79%.
Iron and anaemia
Iron deficiency, which has been associated with impaired cognitive and physical development, is caused by a lack of dietary iron and, in developing countries, by parasites such as hookworm and schistosomiasis.
Pasricha and his team noted that approximately 25% of school-aged children globally are anaemic - with iron deficiency the cause of about half of all cases.
The team searched electronic databases (including MEDLINE and Embase) and other sources for randomised and quasi-randomised controlled trials involving daily iron supplementation in children aged 5–12 years.
"We combined the data using random effects meta-analysis," explained the researchers.
Iron supplementation was found to improve global cognitive scores, IQ scores and measures of attention and concentration in anaemic children.
"Supplementation also improved age-adjusted height among all children and age-adjusted weight among anaemic children."
The team said that the results also showed there to be no adverse effects, with no differences in the prevalence of malaria or gastrointestinal issues between the groups that received iron and the control groups. In addition, some studies reported fewer respiratory tract infections.
"Routine daily iron supplementation is likely to benefit cognitive performance in primary school children in developing settings where anaemia is prevalent and testing hemoglobin before iron supplementation may not be feasible," the team concluded.