Effects of preventive iron supplementation on school-age children cognition and school performance : systematic review and meta-analysis

Abstract

Background: Iron is an essential nutrient for the development and functioning of the brain. The aim of this systematic review and meta-analysis is to review the evidence from published randomized clinical trials to evaluate the effects of preventive iron supplementation on cognitive development and function among school age children. Method: PubMed/MEDLINE, EMBASE, Scopus, Web of Science and Cochrane library were used to search for published articles. Included studies were randomized controlled trials evaluating effect of iron supplementation on cognition in school age children 6 – 12 years of age. Endnote, DistillerSR and Review Manager Software were used to identify duplicates, screening and data extraction, and data analysis. The outcome measurements were based on one of the cognitive domains: intelligence, memory, attention, concentration, or academic achievement. Result: A total of 6,599 records were identified using the five databases. Thirteen articles were included in this systematic review. From eleven studies that were included, five studies showed that iron supplementation increased significantly the intelligence of the children. Additionally, iron supplementation increased significantly the memory, and attention and concentration of children in four out of five studies that evaluated these domains. Iron supplementation significantly improved the school performance of children in only two studies (out of six studies). Overall, iron supplementation had significant effect on intelligence (standardized mean difference (SMD) 0.46, 95% confidence interval (95%CI): 0.19, 0.73), attention and concentration (SMD 0.45, 95%CI: 0.09, 0.80), and memory (SMD 0.45, 95%CI: 0.04, 0.69) of school children. However, iron supplementation did not have a significant effect on school achievement of the children (SMD 0.06, 95%CI: -0.15, 0.26). Conclusion: Iron supplementation improved intelligence, attention and concentration, and memory of school age children but did not affect school achievement. The systematic review and meta-analysis showed overall that iron supplementation remains an effective intervention that can affect the cognition of school-age children. Key words: Cognition, Iron deficiency, Iron supplementation, Randomized controlled trials, School-age children