Several evidence that supports the effect of therapeutic zinc supplementation on the duration and severity of diarrhoea in children under the age of five years is mostly derived from studies which are conducted in South Asia. China has also experienced a considerable portion of the global burden from diarrhoea, however the effect of zinc treatment in children under five years is not well documented by earlier published systematic reviews.

A systematic literature review with an exhaustive search of the Chinese literature with previously published estimates of the impact of therapeutic zinc was conducted. The systematic search was conducted in various databases that included the China National Knowledge Infrastructure (CNKI), and abstracted appropriate data from studies meeting the inclusion and exclusion criteria. 89 Chinese and 15 non-Chinese studies were identified for the review. It also included studies from 10 countries from WHO geographic regions and analysed a total of 18,822 diarrhoea cases i.e. 9469 zinc group and 9353 control. The Chinese studies were not previously included in published pooled effect estimates. Chinese and non-Chinese studies had reported that the effect of therapeutic zinc supplementation on reduced duration of episode, stool output and frequency, duration of hospitalization and proportion of episodes that lasted beyond three and seven days.

With accumulating Chinese and non-Chinese studies, it produced an overall 26% reduction in the assessed relative risk of diarrhoea that lasted beyond three days among zinc-treated children. Also, studies conducted in and outside China had reported decrease in morbidity due to oral therapeutic zinc supplementation for acute diarrhoea among children under the age of five years. Thus, the WHO has recommended zinc treatment for episodes of diarrhoea in all low- and middle-income countries.

Source: Lamberti LM, Walker CL, Chan KY, Jian WY, Black RE. Oral zinc supplementation for the treatment of acute diarrhea in children: a systematic review and meta-analysis. Nutrients. 2013 Nov 21;5(11):4715-40. doi: 10.3390/nu5114715. PMID: 24284615; PMCID: PMC3847757.