RESUMO
Almost 300 million children under 5 years of age are anemic worldwide. International policymakers recommend universal distribution of iron-based interventions - either iron supplements or iron-containing multiple micronutrient powders - to alleviate the burden of anemia in young children. When considering whether to implement universal iron interventions, it is essential to balance the putative benefits with possible risks. The key rationale for deploying universal iron interventions to reduce anemia in young children is to improve development, growth, and well-being. While plausible, few randomized controlled trials (RCTs) of iron interventions have carefully assessed these outcomes and there is currently inadequate evidence to support the hypothesis that universal iron interventions provide benefits on functional child health outcomes. Conversely, several important RCTs have found that when iron interventions are given to all children in a population, they may increase infection risk. Other possible risks of iron interventions have not yet been extensively described but include a risk of iron overdose and long-term iron loading in high-risk individuals. Identifying whether these interventions provide a net benefit or harm to populations is challenging. Until the quality of evidence for benefits improves, implementation of universal iron interventions in young children should be undertaken with caution.