Penny 2004.

Methods	This randomised, double‐blind, placebo‐controlled, community‐based trial was carried out in Canto Grande, a shanty town on the outskirts of Lima, Peru. The study was carried out in two phases. During the first phase researchers evaluated the effect of zinc or multiple micronutrient supplementation on the recovery from persistent diarrhoea. During the second phase researchers assessed the effect of continued supplementation on morbidity from new infections during the following 6 months.
Participants	412 children aged 6 to 36 months with diarrhoea for 14 days were randomly assigned, after being stratified for breastfeeding status, to receive two weeks of daily supplementation with one of three indistinguishable supplements: placebo; 20 mg zinc daily as zinc gluconate (zinc group); or 20 mg zinc daily as zinc gluconate plus a mixture of other micronutrients, i.e. vitamins and minerals (zinc VM group). A subset of children consisting of the first 246 children enrolled who intended to remain in the study area subsequently received the same assigned supplement at one‐half the initial daily dose (10 mg zinc daily) and continued under observation for a total of 6 months.
Interventions	Supplements were supplied as individual doses of a dry micronutrient mixture with added sugar, colouring and flavouring agents, which were dissolved in clean water in participants’ homes and provided as a liquid beverage under the supervision of study personnel on Monday through Friday and by parents or other caregivers during the weekends. There were two intervention arms, zinc plus vitamins and minerals who were given 10 mg of zinc supplementation along with different combinations of mineral and vitamins. Another interventional arm was given zinc 10 mg and the control group was not given any supplementation.
Outcomes	Changes in plasma zinc, haematocrit, haemoglobin, plasma ferritin, pneumonia incidence.
Notes	In this review, groups with zinc and placebo are included for analysis. Examination included assessment of hydration status, measurement of rectal temperature and monitoring of respiratory rate, which was counted for 1 minute and repeated if the rate was greater than age‐specific upper limits (50/minute for children aged 6 to 11 months and 40/minute for children aged 11 months). Children were referred to the study physician for diagnosis and treatment when the fieldworker or caregiver was concerned about the child’s health status or if the child had any one of several predefined signs of illness, including fever, presentation or worsening of cough with elevated respiratory rate (i.e. fieldworker‐defined acute lower respiratory infection), persistent diarrhoea, diarrhoea with signs of dehydration, or vomiting or skin conditions requiring diagnosis. Sources of funding: Supported primarily by the Thrasher Research Fund and the World Health Organization; additional funds were provided by the University of California Pacific Rim Program.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information to permit judgement
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgement
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote: "double‐masked"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "double‐masked"
Incomplete outcome data (attrition bias) All outcomes	High risk	14/81 (17.3%) in zinc and 13/83 (15.7%) placebo groups lost to follow‐up but no reasons were reported
Selective reporting (reporting bias)	Low risk	We could not locate the protocol of this study. We could not find the trial registration number of the study. The outcomes mentioned in the methods were reported in the results
Other bias	Unclear risk	Sources of funding: funding agencies had no role in views and opinions mentioned in the study