A clinical trial conducted by researchers at the Johns Hopkins Bloomberg
School of Public Health concluded that daily zinc
supplements reduced the risk of death among children ages
12 months to 48 months by 18 percent. However, the
researchers did not find any significant reduction in
mortality among children 1 month to 11 months. The study is
published in the March 17 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, 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 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, a number that was statistically
insignificant, and a statistically significant 18 percent
reduction in mortality in children ages 12 months to 48
months. According to the Johns 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 12 months and older received a 10mg dose.
Sunil Sazawal, the study's lead author and associate
professor in the Department of International Health, said,
"While further work is needed to evaluate higher dose
effects, recommendations for use of zinc as a preventive
strategy need to consider the collective evidence of the
effect on growth, morbidity and mortality, which would
suggest benefit in children ages 6 months and up."
Additional authors of the study are 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, United Nations Foundation, United
States Agency for International Development and Bill &
Melinda Gates Foundation.