Low serum zinc is associated with increased incidence of diarrhea and pneumonia. There is sufficient evidence in under-threes that during acute illness, zinc supplementation (1-2 recommended dietary allowance [RDA]) reduces incidence of all episodes of diarrhea, severe diarrhea and pneumonia. A number of initial published trials also show significant effect of zinc treatment on pneumonia. With the large and consistent effects of zinc supplementation on the incidence and severity of infections, an effect on child mortality is likely.