BALTIMORE - Giving zinc supplements to young children in developing countries reduces pneumonia by 41% and diarrhea by up to 25%, according to recent studies.
Robert E. Black, MD, MPH, and Sunil Sazawal, MBBS, MPH, of the Johns Hopkins School of Public Health, on behalf of the Zinc Investigators' Collaborative Group, analyzed original data from published and unpublished trials. Seven continuous and three short-course studies of zinc supplementation were included in the two sets of pooled analyses. The continuous trials provided 1 to 2 times the recommended daily allowance (RDA) of elemental zinc five to seven times per week throughout the study. Five of the continuous supplementation trials included persistent diarrhea and three included dysentery.
The three short-course trials provided 2 to 4 times the RDA daily for two weeks during an episode of acute or persistent diarrhea. These were followed by two to three months of morbidity surveillance. The trials primarily occurred in apparently healthy children. However, two trials did recruit children who had recently recovered from diarrheal disease and two others looked at children with growth retardation.
The 10 international trials studied more than 900 children younger than 5 years of age and showed a strong link between dietary zinc supplementation and reductions in pneumonia incidence and diarrhea, the researchers said. The analysis was published recently in the Journal of Pediatrics.
No significant variations were seen in the effects of zinc in subgroups of children stratified by age, gender and weight. Likewise, no significant variations were detected between short-course zinc supplementation and continuous, or long-term supplementation.
The effect of zinc supplementation on the prevention of diarrhea compared favorably with other interventions such as clean water and sanitation or breast-feeding, but zinc had a greater preventive effect for pneumonia than any other current intervention. Zinc supplementation can now be incorporated into child health programs to help reduce deaths from these diseases, the researchers said.
Pneumonia and diarrhea claim the lives of millions of children each year, primarily in the developing world. Cells with a rapid rate of turnover, notably those in the immune and gastrointestinal systems, are most vulnerable to the effects of zinc deficiency. This study was funded by USAID's Child Health Research Project.
For more information:
- Bhutta ZA, Black RE, Brown KH, et. al. Prevention of diarrhea and pneumonia by zinc supplementation in children in developing countries: pooled analysis of randomized, controlled trials. J Pediatr.1999;135:689-97.
- Bahl R, Bhandari N. Hambidge KM, et. al. Plasma zinc as a predictor of diarrheal and respiratory morbidity in children in an urban slum setting. Am J Clin Nutr. 1998; 68(suppl):414S-7S.
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