Effect of iron supplements on cognitive development in children: an umbrella review

Aim: To synthesize and critically appraise evidence from systematic reviews and meta-analyses on the effect of iron supplementation on children’s cognitive development. Methods: We conducted a comprehensive search in PubMed, Cochrane Library, Scopus, Web of Science, Embase, and gray literature up to August 2025. Eligible studies were systematic reviews, with or without meta-analysis, assessing iron supplementation and cognitive outcomes in children. Methodological quality was appraised using AMSTAR-2, risk of bias with ROBIS, and overlap through the Corrected Covered Area (CCA). Reporting adhered to the PRIOR guidelines for overviews of reviews. Results: Of 2,725 records screened, 17 systematic reviews were included. Three reviews were rated high confidence with low risk of bias. Iron supplementation showed modest benefits in domains such as intelligence, memory, and attention among anemic children, whereas effects in non-deficient populations were negligible or uncertain. No consistent improvements were observed for broader mental development or school achievement. Conclusion: Evidence from high-confidence reviews indicates that iron supplementation confers small but meaningful cognitive benefits in anemic children, while universal supplementation in non-deficient children is not supported. These findings highlight the need for targeted supplementation strategies and more homogeneous trials to clarify long-term cognitive outcomes. Systematic review registration: doi: 10.17605/OSF.IO/5EKHX.