Zinc deficiency in childhood and pregnancy: evidence for intervention effects and program responses

Zinc is a key micronutrient of particular importance during childhood and pregnancy. Zinc deficiency has been linked to increased infection and stunting among children and is a risk factor for adverse pregnancy outcomes and preterm delivery. Targeted interventions have the potential to alleviate the adverse effects of zinc deficiency via therapeutic and preventive supplementation, fortification and biofortification, but implementation is challenging. A growing number of low- and middle- income countries have introduced national policies for zinc treatment of diarrhea among children under 5 years in response to mounting evidence of reduced episode duration and severity as well as reduced incidence in the ensuing months, but coverage remains low in the absence of effective scale-up efforts. Implementation of preventive zinc supplementation in young children has also been slow, despite evidence linking routine daily supplementation and treatment regimens with reductions in stunting and the incidence of diarrhea and pneumonia. Acceptance of other zinc interventions, including traditional fortification, fortification with micronutrient powders and biofortification, is hindered by unclear evidence on efficacy. Additional research is therefore warranted to ascertain the efficacy of delivering zinc through fortified and biofortified foods and in combination with other micronutrients in supplements or powders. Operations research is also necessary to establish best practices for scale-up of therapeutic zinc supplementation for diarrhea.