Effect of intake of iron-fortified milk on levels of ferritin and hemoglobin in preschoolers: A systematic review and meta-analysis

Background: Food fortification is often the simplest way to increase iron intake on a broad and sustainable basis. It is one of the most cost-effective global development efforts. Objective: To systematize data from randomized and nonrandomized controlled trials investigating the effect of consumption of iron-fortified milk (IFM) on serum iron status in preschoolers. Methods: The trials were systematically searched in five electronic databases that evaluated the effect of iron-fortified milk (IFM) consumption on hemoglobin and ferritin in children aged 1-6 years. The randomized the meta-analysis model was used to calculate total and stratified effects. Results: Seven trials representing 1210 preschoolers showed a significant effect of IFM on hemoglobin [difference in means (MD) 0.33 g/dL (95% CI 0.23, 0.44; I-2 = 3.85%, p (Q statistic) < 0.01)] and ferritin concentrations [effect size (SMD) 0.57 (95% CI 0.19, 0.95; I-2 = 84.63%, p (Q statistic) < 0.01)]. In stratified analyses, hemoglobin showed an increase when subjects received iron with other co-interventions [MD 0.35 g/dL (95% CI 0.22, 0.48; I-2 = 11.01%; p (Q statistic) = 0.36)]; and when the iron dose was above 5 mg/day [MD 0.34 g/dL (95% CI 0.23, 0.45; I-2 = 2.33%; p (Q statistic) = 0.37)] and the intervention time was over 6 months [MD 0.39 g/dL (95% CI 0.18, 0.60; I-2 = 37.90%; p (Q statistic) = 0.20)]. For ferritin, stratified analyses showed a larger effect size when they used dose higher than 5 mg/day [SMD 0.60 (95% CI 0.02, 1.18; I-2 = 91.06, p (Q statistic) < 0.01)] and intervention was conducted longer than 6 months [SMD 0.96 (95% CI - 0.16, 1.76; I-2 = 93.38%, p (Q statistic) < 0.01)]. Conclusions: Our findings indicate that although milk iron fortification modestly increases serum hemoglobin levels or the effect size of serum ferritin of participants, it cannot be considered in the coadjuvant treatment for anemia. (c) 2023 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.