Sixteen RCTs (n=15,231) for acute diarrhea and six (n=3,104) for persistent diarrhea were included. Five studies were not double-blinded.
Acute diarrhea trials
Children who received zinc compared with placebo had lower duration of diarrhea (WMD 0.24 days, 95% CI: 0.21, 0.27, p<0.001), but there was significant heterogeneity (I2=84.3%; p<0.001). The proportion of participants (11 trials, n=4,438) who vomited after the initial dose was significantly greater for zinc than placebo (RR 1.55, 95% CI: 1.30, 1.84, p<0.001) and again there was significant heterogeneity (p=0.004). No significant differences were reported for other outcome measures.
Persistent diarrhea trials
Children who received zinc compared with placebo (five trials, n=489) had lower duration of diarrhea (WMD 0.30 days, 95% CI: 0.12, 0.48, p<0.001), without significant heterogeneity. In two trials of persistent diarrhea a significantly lower occurrence of diarrhea was observed at day three for those taking zinc compared with placebo (RR 0.70, 95% CI: 0.51, 0.94, p=0.02). A higher proportion (four trials, n=2,969) vomited on zinc than placebo (RR 3.64, 95% CI: 1.02, 13.02, p=0.047).
Results for other outcomes were reported.