Long term zinc supplementation in improving growth of adolescents: zinc alone or with iron?

Abstract

Multi-micronutrient supplementation has beneficial effects on the improvement o f nutritional status, work productivity, health and diseases. A long term supplementation is needed to better understand the biological basis for potential interactions observed in functional outcomes such as growth and development. A stratified sample o f adolescent school children (n=82J; M= 327, F= 494) o f 12-18 years o f age were randomized into one o f four groups on a double blind approach at class room level. Children in each group received two capsules daily containing either iron (50 mg/d) or zinc (14 mg/d) or iron and zinc combined or placebo capsule for a period o f 36 weeks. Their anthropometric measurements were made and a medical examination carried out prior to study and after the intervention. Mean change o f weight and height in the placebo group was 0.53 kg and 0.73 cm. Iron alone group had 0.89 kg gain in weight and 1.0 cm in height. Zinc alonegroup had higher gain in weight (2.27 kg) and height (2.37 cm) whereas 1.52 kg and 1.63 cm gains were observed with the combined supplement group. The body mass index (BMI) o f all the supplemented groups significantly increased from their respective baseline status (0.32 in supplemented, 0.04 in placebo; p < 0.001). The increase in z scores in zinc supplemented groups was marginally significant when compared with the placebo group (p < 0.05). After correcting for confounding effects o f age and the respective baseline values o f weight, height and BMI, the zinc alone supplemented group had the best anthropometric improvement. It appears therefore, that long term zinc supplementation had positive impact on the growth o f children.