Investigating the Effects of Zinc Supplementation on Growth-Related Factors in Infants With Failure to Thrive: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Background and Objectives: Failure to thrive (FTT) is a common developmental disorder in infants. Although the improvement effect of zinc supplementation in these patients was reported in some past studies, the results were conflicting. Accordingly, this study investigates the effect of zinc supplementation on factors related to growth in infants with FTT by conducting a meta-analysis. Methods: Medline, Web of Science, and Scopus databases were comprehensively searched to find randomized controlled trials investigating the effect of zinc on growth-related factors in infants with FTT. Eligible studies were extracted after screening their relevant information. The pooled effect size was estimated as a weighted mean difference with a 95% confidence interval (CI) using the random effect model method. Results: Out of 85 reviewed papers, 4 studies were eligible to enter this review. The present meta-analysis revealed that zinc supplementation in infants with FTT led to a significant increase in weight (weighted mean difference (MD)=-0.25 kg; 95% CI, 0.02%-0.49%), weight-for-age Z-score (weighted MD=0.16; 95% CI, 0.03%, 0.28%), and height-for-age Z-score (weighted MD=0.15, 95% CI, 0.001%, 0.30%), compared to control groups. In contrast, zinc supplementation had no significant effect on height and insulin-like growth factor 1 serum level. Conclusions: The findings of the current meta-analysis indicated the effectiveness of zinc supplementation in improving the developmental status of infants with FTT; however, due to the small number of included trials, it was impossible to draw definitive conclusions, and conducting randomized controlled trials with larger sample size and higher sensitivity is needed.