Effects of zinc supplementation on growth of children under 5 years of age: A meta‐analysis of randomized controlled trials

Background Zinc interventions have received much attention as a cost‐effective and promising strategy to improve child health, but their roles in preventing growth retardation in early childhood remain unclear. Objective Meta‐analyses of randomized controlled trials were conducted to evaluate the effect of zinc interventions on the growth of children < 5 y old. Design Eligible studies were identified by PubMed database search and other methods. Weighted mean effect sizes and 95% CI were calculated for changes in height, weight and weight‐for‐ height Z‐scores (WHZ) using random effect models. Tests for homogeneity and stratified analyses by predefined characteristics were conducted using meta‐regression techniques. Tests for publication bias were done using funnel plots. Results Forty‐three trials (56 datasets) had relevant information. There was no evidence of publication bias. Zinc interventions had a small positive effect on change in WHZ (effect size: 0.06; 95% CI: 0.006, 0.11) but no effect on height or weight gain (effect size: 0.07; 95% CI: ‐0.03, 0.17 and 0.06; 95% CI: ‐0.10, 0.23, respectively). The results were similar across categories of age, duration of intervention, and baseline anthropometric status. Conclusions Contrary to the earlier findings, we failed to detect any benefits of zinc supplementation in improving early childhood growth. Other strategies are needed to prevent stunting.