Zinc supplementation for treating diarrhea in children: a systematic review and meta-analysis

To update the available evidence about zinc use for treating diarrhea in children and to assess its effect on the malnourished population, a subgroup that has not been fully explored in previous analyses.

A systematic review was performed of randomized clinical trials that assessed children up to 5 years old with acute diarrhea who received zinc supplementation. Controls received a placebo or oral rehydration therapy. After searching the main databases, without language restrictions, two independent reviewers selected eligible studies, extracted the data, and assessed the risk of bias of included studies. Meta-analyses were calculated using Mantel-Haenszel or inverse variance random effects.

Eighteen of 1 041 studies retrieved were included in the review (n = 7 314 children). Zinc was beneficial for reducing the duration of diarrhea in hours (mean difference [MD] = -20.12, 95% confidence interval [CI] = -29.15 to -11.09, I² = 91%). The effect was greater in malnourished children (MD = -33.17, 95% CI = -33.55 to -27.79, I² = 0%). Diarrhea prevalence on days 3, 5, and 7 was lower in the zinc group. The incidence of vomiting was significantly greater in the group that received zinc than in the control group. Included randomized controlled trials were of low risk of bias in most domains assessed.

Oral zinc supplementation significantly decreases diarrhea duration and has a greater effect on malnourished children. Zinc supplementation seems to be an appropriate public health strategy, mainly in areas of endemic deficiencies.