Effect of Zinc Supplementation on Growth Outcomes in Children under 5 Years of Age

Abstract

(1) Background: The effects of zinc supplementation on child growth, and prior reviews of these studies, have shown mixed results. We aim to systematically review and meta-analyze randomized controlled trials evaluating effects of preventive zinc supplementation for 3 months or longer during pregnancy or in children up to age 5 years on pregnancy outcomes and child growth; (2) Methods: We searched PubMed, EMBASE, Cochrane Library, Web of Science, and trial registries for eligible trials up to October 10, 2017. Inclusion selection and data extractions were performed independently and in duplicate. Study quality was evaluated by the Cochrane Risk of Bias tool. Findings were pooled using random effects meta-analysis, with heterogeneity assessed by I2 and τ2 statistic, stratified analyses, and meta-regression, and publication bias by Egger’s and Begg’s tests; (3) Results: Seventy-eight trials with 34,352 unique participants were identified, including 24 during pregnancy and 54 in infancy/childhood. Maternal zinc supplementation did not significantly increase birth weight (weighted mean difference (WMD) = 0.08 kg, 95%CI: −0.05, 0.22) or decrease the risk of low birth weight (RR = 0.76, 95%CI: 0.52–1.11). Zinc supplementation after birth increased height (WMD = 0.23 cm, 95%CI: 0.09–0.38), weight (WMD = 0.14 kg, 95%CI: 0.07–0.21), and weight-for-age Z-score (WMD = 0.04, 95%CI: 0.001–0.087), but not height-for-age Z-score (WMD = 0.02, 95%CI: −0.01–0.06) or weight-for-height Z score (WMD = 0.02, 95%CI: −0.03–0.06). Child age at zinc supplementation appeared to modify the effects on height (P-interaction = 0.002) and HAZ (P-interaction = 0.06), with larger effects of supplementation starting at age ≥2 years (WMD for height = 1.37 cm, 95%CI: 0.50–2.25; WMD for HAZ = 0.12, 95%CI: 0.05–0.19). No significant effects of supplementation were found on the risk of stunting, underweight or wasting; (4) Conclusion: Although the possibility of publication bias and small study effect could not be excluded, the current meta-analysis indicates that zinc supplementation in infants and early childhood, but not pregnancy, increases specific growth outcomes, with evidence for a potentially stronger effect after 2 years of age. These findings inform recommendation and policy development for zinc supplementation to improve growth among young children.

Nutritional Gaps and Supplementation in the First 1000 Days

“…There is also evidence that zinc supplementation can reduce the risk of respiratory infection [287,288] and pneumonia [99,288] in the same population. Recent meta-analyses of both observational data and clinical trials have shown that zinc supplementation can increase weight, height, and weight-for-age z-score in term infants [288][289][290], and that supplementation has the largest impact when begun before two years of age [289]. However, the authors conclude that multiple micronutrient supplementation is still superior to zinc supplementation alone in this age group [290].…”

Antimicrobial and micronutrient interventions for the management of infants under 6 months of age identified with severe malnutrition: a literature review

“…Furthermore, three MAs demonstrated a reduction in incidence and duration of all-cause diarrhoea (GRADE –Moderate) ( Lazzerini & Wanzira, 2016 ; Brown et al., 2009 ; Mayo-Wilson et al., 2014 ), and one MA identified a significant reduction in mortality when used as an adjunct to treatment for severe pneumonia ( Wang & Song, 2017 ). A further four MAs noted improved, albeit across different anthropometric indices, with zinc supplementation ( Brown et al., 2009 ; Ramakrishnan, Nguyen & Martorell, 2008 ; Imdad et al., 2011 ; Liu et al., 2018 ), with more marked improvements when supplemented after two years of age ( Liu et al, 2018 ). No impacts on mental or psychomotor development were demonstrated by one MA (GRADE –Moderate) ( Gogia & Sachdev, 2012 ).…”

Zinc status in infants and children with cholestatic liver diseases and its effect on growth

“…It was reported that undernourished children with serum zinc concentrations of < 750 μg/l experienced significant increase in height, weight, weight-for-age, and BMI-for-age Z-scores after 12-and 24-week zinc supplementation when compared with the children with a serum zinc concentration of ≥ 750 μg/l (Chao et al, 2018). Zinc supplementation in infants and early childhood improves specific growth outcomes, with evidence for a potentially stronger effect after 2 years of age (Liu et al, 2018). Moreover, consumption of zinc (50 mg/day for 2 months) improved the secretion of growth hormone in children aged 3.7-16.2 years.…”