Efficacy of zinc supplementation in reducing the incidence and prevalence of acute diarrhea--a community-based, double-blind, controlled trial.

A community-based, double-blind, randomized trial was conducted in a population of low socioeconomic status in urban India to determine whether daily zinc supplementation reduces the incidence and prevalence of acute diarrhea, especially in those with zinc deficiency. Children 6-35 mo of age were randomly assigned to zinc (n = 286) and control (n = 293) groups and received a supplement daily for 6 mo. Zinc gluconate (10 mg elemental Zn) was given, with both zinc and control groups also receiving multivitamins. The primary outcome measures determined by home visits every fifth day and physician examinations were the number of acute diarrheal episodes (incidence) and total diarrheal days (prevalence). Zinc supplementation had no effect in children 6-11 mo old. In children aged > 11 mo there was significantly less diarrhea in the zinc group. In boys > 11 mo old, supplementation resulted in a 26% (95% CI: 13%, 38%) lower diarrheal incidence and a 35% (95% CI: 20%, 50%) lower prevalence. In zinc-supplemented girls > 11 mo of age, the incidence was 17% (95% CI: 2%, 30%) lower and the prevalence was 19% (95% CI: 4%, 47%) lower. Overall, zinc supplementation resulted in a 17% (95% CI: 1%, 30%) lower diarrheal incidence in children with plasma zinc concentrations < 9.18 mumol/L at enrollment and a 33% (95% CI: 6%, 52%) lower incidence in children with concentrations < 50 mumol/L. In conclusion, zinc supplementation had a significant effect on acute diarrheal morbidity in children > 11 mo old and in children with low plasma zinc concentrations.