Effect of Zinc Added to Multivitamin Supplementation Containing Low-dose Vitamin A on Plasma Retinol Level in Children—A Double-blind Randomized, Controlled Trial

In a community-based double-blind randomized trial in children aged 6–35 months, both intervention and control groups received a multi-vitamin syrup containing vitamin A, while the intervention group had zinc gluconate (equivalent to 10 mg of elemental zinc) additional in the syrup. There was a significant decrease in diarrhoea and pneumonia in the intervention group. This study was undertaken to investigate if addition of zinc to vitamin A had improved plasma retinol levels, which, in turn, was responsible for the effects observed in the intervention group. In a randomly-selected subsample of 200 children—100 each from the intervention and the control group, plasma retinol levels after 120 days of supplementation were measured. There was no difference in the mean plasma retinol levels [the difference in the mean 0.46 μg/dL (95% confidence interval -1.42–2.36)] between the two groups following supplementation. No difference in plasma retinol levels was observed in the subgroups based on baseline nutritional status and plasma zinc levels. Addition of zinc to low-dose vitamin A in this study did not improve the vitamin A status of children and cannot explain morbidity effects of the intervention.