Zinc is an essential micronutrient critical to the maintenance of a healthy immune system. Zinc deficiency is often linked with an increased risk for infectious diseases especially among at-risk populations such as young children and pregnant women. Supplementation with zinc has been shown to prevent and treat diarrhea among children under 5 years of age decreasing both diarrhea morbidity and mortality. Zinc deficiency is also correlated with risk for respiratory infections, but the benefit of supplementation appears to be limited to more severe episodes and populations with high rates of zinc deficiency. While there is evidence suggesting a correlation between zinc deficiency and the prevalence of malaria, measles, HIV, and tuberculosis, few studies have shown a benefit of supplementation for either prevention or treatment of these infections. The World Health Organization currently recommends zinc supplementation for the treatment of diarrhea among children under 5 years of age.