RT Journal Article SR Electronic T1 Effects of daily iron supplementation in primary-school–aged children: systematic review and meta-analysis of randomized controlled trials JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP E791 OP E802 DO 10.1503/cmaj.130628 VO 185 IS 17 A1 Michael Low A1 Ann Farrell A1 Beverley-Ann Biggs A1 Sant-Rayn Pasricha YR 2013 UL http://www.cmaj.ca/content/185/17/E791.abstract AB Background: Anemia is an important public health and clinical problem. Observational studies have linked iron deficiency and anemia in children with many poor outcomes, including impaired cognitive development; however, iron supplementation, a widely used preventive and therapeutic strategy, is associated with adverse effects. Primary-school–aged children are at a critical stage in intellectual development, and optimization of their cognitive performance could have long-lasting individual and population benefits. In this study, we summarize the evidence for the benefits and safety of daily iron supplementation in primary-school–aged children.Methods: We searched electronic databases (including MEDLINE and Embase) and other sources (July 2013) for randomized and quasi-randomized controlled trials involving daily iron supplementation in children aged 5–12 years. We combined the data using random effects meta-analysis.Results: We identified 16 501 studies; of these, we evaluated 76 full-text papers and included 32 studies including 7089 children. Of the included studies, 31 were conducted in low- or middle-income settings. Iron supplementation improved global cognitive scores (standardized mean difference 0.50, 95% confidence interval [CI] 0.11 to 0.90, p = 0.01), intelligence quotient among anemic children (mean difference 4.55, 95% CI 0.16 to 8.94, p = 0.04) and measures of attention and concentration. Iron supplementation also improved age-adjusted height among all children and age-adjusted weight among anemic children. Iron supplementation reduced the risk of anemia by 50% and the risk of iron deficiency by 79%. Adherence in the trial settings was generally high. Safety data were limited.Interpretation: Our analysis suggests that iron supplementation safely improves hematologic and nonhematologic outcomes among primary-school–aged children in low- or middle-income settings and is well-tolerated.See related commentary by Gray-Donald at www.cmaj.ca/lookup/doi/10.1503/cmaj.131249