In developing countries, diarrhoea causes around two million child deaths annually. Zinc supplementation could help reduce the duration and severity of diarrhoea, and is recommended by the World Health Organization and UNICEF.
To evaluate oral zinc supplementation for treating children with acute or persistent diarrhoea.
In December 2010, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2010, Issue 11), MEDLINE, EMBASE, LILACS, CINAHL, mRCT, and reference lists. We also contacted researchers.
Randomized controlled trials comparing oral zinc supplementation with placebo in children aged one month to five years with acute or persistent diarrhoea, including dysentery.
Data collection and analysis
Both authors assessed trial eligibility and risk of bias, extracted and analysed data, and drafted the review. Diarrhoea duration and severity were the primary outcomes. We summarized dichotomous outcomes using risk ratios (RR) and continuous outcomes using mean differences (MD) with 95% confidence intervals (CI). Where appropriate, we combined data in meta-analyses (using the fixed- or random-effects model) and assessed heterogeneity.
Twenty-two trials, enrolling 8924 children, met our inclusion criteria. In acute diarrhoea, zinc shortened the diarrhoea duration (MD -9.60 h, 95% CI -18.25 to -0.96 h; 4242 children, 13 trials), with fewer children with diarrhoea by day three (RR 0.77, 95% CI 0.67 to 0.89; 1568 children, three trials), day five (RR 0.74, 95% CI 0.55 to 0.99; 1646 children, four trials), and day seven (RR 0.82, 95% CI 0.72 to 0.94; 5528 children, 10 trials). In children under six months, no benefit was demonstrated. The benefit of zinc in children over six months was consistent in subgroup analysis. In persistent diarrhoea, zinc reduced the duration (MD -15.84 h, 95% CI -25.43 to -6.24 h; 529 children, five trials). In all trials, few reported on diarrhoea severity, and results were inconsistent. No trial reported serious adverse events, but vomiting was more common in zinc-treated children with acute diarrhoea (RR 1.59, 95% 1.27 to 1.99; 5189 children, 10 trials).
In areas where diarrhoea is an important cause of child mortality and the risk of zinc deficiency is from moderate to high, zinc clearly benefits children aged six months or more.
Plain language summary
Oral zinc supplementation for treating diarrhoea in children In developing countries, millions of children suffer from severe diarrhoea every year. This is due to infection and malnutrition, and many die from dehydration due to the diarrhoea. Giving fluids by mouth (using an oral rehydration solution) has been shown to save children's lives, but it seems to have no effect on the length of time the children suffer with diarrhoea. Children in developing countries are often zinc deficient. Zinc supplementation is a possible treatment for diarrhoea though it can have adverse effects if given in high doses. The review of trials identified 22 trials involving 8924 children of all ages. Zinc reduced the time that children over the age of six months suffered from symptoms of acute or persistent diarrhoea. However, there were insufficient data to see any impact on the number of children who died. More children vomited when given zinc, but it was considered that the benefits outweighed these adverse effects. Zinc seemed to have no impact on children aged less than six months. In areas where diarrhoea is an important cause of child mortality, research evidence shows zinc is clearly of benefit in children aged six months or more with diarrhoeal diseases.
Lazzerini, M.; Ronfani, L. Oral zinc for treating diarrhoea in children. Cochrane Database of Systematic Reviews (2008) (Issue 3) Art. No.: CD005436. [DOI: 10.1002/14651858.CD005436.pub2]