Zinc supplementation is an effective and feasible strategy to prevent growth retardation in 6 to 24 month children: A pragmatic double blind, randomized trial

BACKGROUND: Zinc is an essential nutrient that is naturally available in most foods. Deficiency of this micronutrient in particular can cause a number of health complications. Zinc deficiency during infancy is more troublesome as rapid growth and nutrient relied development takes place in this period. Most severe outcomes of zinc deficiency during infancy are considered to be, impaired immunity, growth retardation and impaired neurodevelopment. The aim of this pragmatic study is to determine whether zinc supplementation strategy is feasible and effective for reducing growth retardation at national level. METHODS: A randomized, multicenter, double-blind, parallel group effectiveness trial that evaluated the effect of zinc supplementation in infant development. Children aged 6–24 months were recruited from healthcare centers of Damavand, Pishva and Varamin in the beginning of the study (n = 682). The Subjects were then randomly allocated in two groups of intervention (n = 272), and control (n = 308), where a daily dose of zinc sulfate (5ml) suspension containing 5mg elemental zinc and placebo were administered for the period of 6 month. Investigators, care givers and the parents of the children were blinded to the nature of the intervention. Anthropometric measures were evaluated at the beginning and after the six month intervention period. The primary outcome measured was linear growth and length difference, serum zinc and ferritin concentrations were the secondary outcomes. FINDINGS: Following the intervention, compared with the placebo, zinc supplementation was associated with significant difference in the average length increment (primary outcome) (placebo 5·23 ± 2·19 vs. intervention 5·79 ± 2·18 cm, p = 0·02). No significant difference was observed in concentrations of serum zinc and ferritin. After the intervention the prevalence of zinc deficiency was significantly lower in the intervention group compared to the placebo group. No complications and adverse effects were reported and the compliance was very good (7 children out of 344 didn't comply with the intake of syrup). INTERPRETATION: Zinc supplementation for six month among children (6–24 months) had beneficial outcomes on growth and average length increment, therefore we propose it is a feasible strategy for preventing growth retardation.