Multimicronutrient interventions but not vitamin a or iron interventions alone improve child growth: results of 3 meta-analyses.

Meta-analyses of randomized controlled intervention trials were conducted to assess the effects of vitamin A, iron, and multimicronutrient interventions on the growth of children < 18 y old. A PubMed database search and other methods identified 14 vitamin A, 21 iron, and 5 multimicronutrient intervention studies that met the design criteria. Weighted mean effect sizes and CI were calculated using a random effects model for changes in height and weight. Tests for homogeneity and stratified analyses by predefined characteristics were conducted. Vitamin A interventions had no significant effect on growth; effect sizes were 0.08 (95% CI: -0.20, 0.36) for height and -0.01 (95% CI: -0.24, 0.22) for weight. Iron interventions also had no significant effect on child growth. Overall effect sizes were 0.09 (95% CI: -0.07, 0.24) for height and 0.13 (95% CI: -0.05, 0.30) for weight. The results were similar across categories of age, duration of intervention, mode and dosage of intervention, and baseline anthropometric status. Iron interventions did result in a significant increase in hemoglobin (Hb) concentrations with an effect size of 1.49 (95% CI: 0.46, 2.51). Multimicronutrient interventions had a positive effect on child growth; the effect sizes were 0.28 (95% CI: 0.16, 0.41) for height and 0.28 (95% CI: -0.07, 0.63) for weight. Interventions limited to only vitamin A or iron did not improve child growth. Multimicronutrient interventions, on the other hand, improved linear and possibly ponderal growth in children.