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March 15, 2007

Zinc Supplementation Found to Reduce Mortality in Older Children

Study Examines Impact of Zinc Supplementation in Region Where Malaria Is Prevalent

A clinical trial conducted by researchers at the Johns Hopkins Bloomberg School of Public concluded that daily zinc supplements reduced the risk of death among children aged 12 to 48 months by 18 percent. However, the researchers did not find any significant reduction in mortality among children 1 to 11 months of age. The study is published in the March 17, 2007, edition of The Lancet.

Zinc is one of the most plentiful trace elements in the body, second only to iron. It mediates many physiological functions and is believed to be essential for maintaining a healthy immune system. The trial examined whether zinc supplementation would benefit children living in areas where malaria is prevalent. Pneumonia, diarrhea and malaria account for 45 percent of the 10 million child deaths worldwide each year. 

“This large trial demonstrates that the benefits of zinc supplementation include mortality reduction in addition to the reduction in cases of pneumonia, diarrhea and malaria that we found in previous trials,” said Robert Black, MD, the study’s senior author and professor and chair of the Bloomberg School’s Department of International Health.

The double-blind trial involved 42,546 children living in Pemba, Zanzibar. Half of the children were randomly selected by household to receive daily zinc supplements, while the other half were given a placebo. Overall, the study found a 7 percent reduction in the risk of mortality with zinc supplementation, which was statistically insignificant, and a statistically significant 18 percent reduction in mortality in children aged 12 to 48 months. According to the Hopkins researchers, the interaction between zinc effects and age is consistent with the results of other studies.

They said it is possible that infants acquire sufficient amounts of zinc in utero and through breast feeding to sustain them during the first year of life. The failure to find an effect in infants could also be a result of the lower doses of zinc given to infants compared to the higher doses given to older children. In the trial, infants given zinc received a 5mg dose while children aged 12 months and older received a 10mg dose.

“While further work is needed to evaluate higher dose effects, recommendations for use of zinc as a preventive strategy needs to consider the collective evidence of the effect on growth, morbidity and mortality, which would suggest benefit in children age 6 months and up,” said the study’s lead author, Sunil Sazawal, PhD, associate professor in the Department of International Health.

Additional authors of the study include Mahdi Ramsan, Hababu M. Chwaya, Arup Dutta, Usha Dhingra, Rebecca J. Stoltzfus, Mashavi K. Othman and Fatma M. Kabole.

The research was supported by grants from the World Health Organization Department of Child and Adolescent Health and Development; the United Nations Foundation; United States Agency for International Development; and the Bill & Melinda Gates Foundation.

Public Affairs media contact for the Johns Hopkins Bloomberg School of Public Health: Tim Parsons at 410-955-6878 or paffairs@jhsph.edu.