Zinc supplementation reduces the incidence of persistent diarrhea and dysentery among low socioeconomic children in India.

Persistent diarrhea (PD) and dysentery (DD) account for most diarrhea-associated deaths among children in developing countries. Zinc deficiency can cause stunting and impaired immune function, both of which are risk factors for these diarrheal illnesses. We investigated the effect of zinc supplementation on the incidence of PD and DD in a community-based, double-blind randomized trial in children 6-35 mo of age. Increase over baseline in plasma zinc concentrations in the supplemented group compared with a control group (3.61 vs. 0.009 mumol.L-1), indicated successful supplementation. The overall reductions in the zinc supplemented group of 21% in the incidence of PD (95% CI -6 to 42%) and 14% in the incidence of dysentery (95% CI -15 to 36%) were not significant. There was a significant interaction of treatment effect with baseline plasma zinc concentration and age for PD and with gender for DD. In the zinc-supplemented group compared with the control group, the incidence of PD was reduced by 73% (P < 0.05; 95% CI 34 to 91%) in children with a baseline zinc < 7.65 mumol.L-1 and by 49% (P < 0.05; 95%CI 24 to 66%) in children > 11 mo of age. Zinc supplementation resulted in a 38% (P < 0.05 95%CI 8 to 59%) reduction in the incidence of DD in boys. There was no effect on PD among children 6-11 mo old or on DD in girls. In conclusion, zinc supplementation had a significant impact on the incidence of persistent diarrhea in children > 1 y old and in children with low plasma zinc, as well as on dysentery in boys. These findings may have important implications for reducing diarrhea-related morbidity and mortality.