Zinc: the preventive and curative supplement for child health and development

Photo: WFP.

Zinc is an essential nutrient for our immune system, both for keeping infections out and for fighting infections once they invade.  At least 17% of the world’s population is at risk of inadequate zinc intake, making zinc deficiency one of the most prevalent micronutrient deficiencies worldwide. Infants and young children are at particular risk of zinc deficiency given their elevated requirements for this essential nutrient. They are also at greatest risk of diarrheal disease, which depletes the body of zinc.

The use of zinc for treatment of all childhood diarrhea has been recommended by WHO and UNICEF since 2004. Alongside oral rehydration solution, therapeutic zinc supplementation during and 10–14 days following diarrhea decreases diarrhea mortality by an estimated 23% and the duration of illness by 25%, and it can protect against future diarrhea episodes for two to three months.

Therapeutic zinc works in many different ways. It restores the integrity of the gut barrier and the activity of enzymes there; promotes the production of antibodies and immune cells against the diarrhea pathogen, and helps correct the imbalance of fluid movement across the gut, which occurs in diarrhea.

Though zinc is a powerful diarrhea treatment, the majority of IZiNCG’s work is focused on preventing zinc deficiency and its consequences. With good zinc status, a child is less likely to become sick with diarrhea in the first place or have a bout of diarrhea become severe. Indeed, preventive zinc supplementation can reduce the incidence of childhood diarrhea by 13% and reduce deaths in children older than 12 months of age by 18%.

For preventive zinc supplementation, there is a host of research questions related to the optimal physical form, dose, and frequency of supplementation. One question links the therapeutic and preventive uses of zinc. As mentioned above, therapeutic zinc supplementation for diarrhea has been associated with a reduced incidence of diarrhea in the 2-3 months following treatment. But we need more evidence on the longer-term health benefit of therapeutic zinc supplementation to compare the relative benefits of preventive vs therapeutic use of zinc. A recent study in Laos found that zinc for the treatment of diarrhea over a period of 9 months was not enough to see an increase in blood zinc levels or physical growth of these children. IZiNCG is currently also addressing a similar research question in a trial underway in Bangladesh.

Another big question relates to supplement form. Zinc is a component of multiple micronutrient powders (MNPs) – tiny 1g sachets of several vitamins and minerals – that are added to young children’s food to close key nutrient gaps in their diets. MNPs are being scaled up globally as a successful strategy for reducing iron deficiency and present a golden opportunity for delivering preventive zinc supplementation without requiring the initiation of a separate, stand-alone preventive zinc tablet program.

However, there are some outstanding questions related to potential interactions between iron and zinc in MNPs, which could affect changes in the amount of zinc in our blood and may be associated with some negative health effects. IZiNCG is conducting a trial in Bangladesh to determine the best way to co-administer zinc with iron.

That was a small snapshot of some of the work on the preventive side of the equation to defeat diarrheal disease. But let’s finish with treatment. IZiNCG supports global initiatives to improve coverage of zinc as an adjunct treatment for diarrhea, for which coverage has been disappointingly low. For zinc, co-packaging of zinc and ORS would be a quick win, potentially increasing its use to 30% of diarrhea episodes, meaning more lives saved. On the same note, the majority of the half million childhood diarrhea deaths each year could be averted with universal coverage of ORS and zinc. As an international community, we know what it takes to eliminate preventable diarrhea deaths. “The question is no longer what needs to be done to increase the quality of childhood diarrhea treatment – it is when we will collectively as a global community take action on this evidence.”

 
IZiNCG is the International Zinc Nutrition Consultative Group whose primary objectives are to promote and assist efforts to reduce zinc deficiency globally through interpretation of nutrition science, dissemination of information, and provision of technical assistance to national governments and international agencies. Learn more on www.izincg.org.