Effects of Zinc Supplementation on the Physical Growth of 2-5 Years Old Children

Physical growth disorder in children, aged under 5-years, is a common health problem in developing countries, including Iran, where national studies have shown that the prevalence of stunted growth disorder is approximately 15 percent. The aim of this study was to determine effects of supplemental zinc on physical growth in children with retarded growth. The study was a 12-month community-based RCT which incorporated 6 months of zinc supplementation to 2-5-year-old children with height-for-age index less than the 25th percentile of NCHS (n=90) children were assigned randomly into either the Zinc Group receiving 5 ml of a solution containing 5 mg of zinc as zinc sulfate (ZG, n=40) or the Placebo Group who received placebo (PG, n=45) daily (7d/wk) for 6 months. The children's weight, height, mid-upper arm, Z-score for height for age, weight for age and weight for height were measured at baseline and monthly for 12 months. Data were analyzed by the SPSS statistical package. Student-t test was used for comparing the means and chi-square and Fisher's exact test were performed to compare categorical variables. Eightly-five children completed (55.3% girls, 44.7% boys) the study supplementation compliance with supplement consumption was 95-100% and the two groups were not significantly different. The means of total weight increments (Kg) among girls in the PG and ZG groups were 2±0.9 and 2.6±1.1 (PV=0.05), respectively and for boys were 2.1±0.8 and 2.7±0.8 (PV=0.04), respectively. The mean of total mid arm circumference increments (Cm) among girls in the PG and ZG groups were 1.23±0.46 and 1.7±0.51 (PV=0.8), respectively these figures for boys were 1.43±0.51 and 1.19±0.39 (PV=0.1), respectively. The means of total height increment (Cm) among girls, in the PG and ZG groups were 8.28±2.23 and 9.64±1.7 (PV=0.02), respectively these figures for boys were 8.34±3.14 and 11.7±1.96 (PV=0.001), respectively. At baseline, stunted rates in the ZG and PG groups were 26.7% and 15% respectively (NS). However, these rates in the 6th month of intervention in ZG and PG were 2.5 and 20%, respectively (PV= 0.01). The results of this study showed that administration of 5 mg zinc daily to young children have significant effects on growth, particularly if the interventions are focused on stunted children.