Effect of zinc supplementation on growth and body composition of Ugandan preschool children: a randomized, controlled, intervention trial

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Abstract
Despite ample food supplies, the incidence of childhood underweight and stunting remains high in Uganda. Many factors contribute to this situation, but the role of low zinc intakes has not been adequately explored. Our objective was to study the effect of zinc supplementation on growth and body composition of preschool children by using the outcome measures of weight, height, and midupper arm circumference (MUAC). The study was randomized, double-blind, placebo-controlled, parallel, and 8 mo long, and incorporated 6 mo of zinc supplementation. Children (n = 153) aged 55.8 +/- 11.2 mo from 3 randomly selected nursery schools of medium, low, and very low socioeconomic status in a suburb of Kampala took part. The intervention comprised 10 mg Zn (as ZnSO4) or placebo daily in freshly prepared fruit juice, Monday to Friday inclusive. Zinc supplementation increased MUAC by the end of the study (P = 0.029) and led to greater weight gain in children from the school of medium socioeconomic status at 3 and 8 mo (P = 0.019 and P = 0.038, respectively). There was no effect on weight gain of the children from the other schools. Zinc supplementation had no influence on height. Infection rates (of which 82% were recorded as malaria) were lower in the zinc-supplemented group than in control subjects (P = 0.063). Zinc supplementation may counter the age-related decrease in MUAC often observed in preschool children in developing countries. The study provides evidence that zinc may not be the most limiting nutrient for weight gain in children of poor nutritional status, but may become so as nutritional status improves.