July 6, 2010

SPH researchers discover additional benefit of vitamin A

Vitamin A is critical to maternal health and child survival, yet in most developing countries vitamin A deficiency is a leading cause of blindness and increased child mortality. The Johns Hopkins Bloomberg School of Public Health has long been a leader in vitamin A research, and scientists at the school recently discovered a link between offspring lung function and maternal vitamin A supplementation. The results are published in the May 13 issue of the New England Journal of Medicine.

“Children of mothers who received vitamin A supplementation before, during and after pregnancy had significantly improved lung function when compared to those whose mothers received beta-carotene supplementation or placebo,” said the lead author of the study, William Checkley, an assistant professor in the Division of Pulmonary and Critical Care in the Johns Hopkins School of Medicine with a joint appointment in the Bloomberg School’s Department of International Health. “Lung function of offspring in mothers who received maternal vitamin A supplementation improved by about 40 milliliters versus those whose mothers received a placebo. This represents an approximately 3 percent increase in lung function. Furthermore, the magnitude of effect observed in this study is slightly greater than that associated with preventing exposure to parental smoking in school-age children.”

Vitamin A deficiency affects nearly 190 million preschool-age children worldwide and is the underlying cause of 650,000 early childhood deaths annually. To examine the effect of antenatal vitamin A supplementation on lung function, researchers revisited a cohort of children ages 9 to 13 in rural Nepal whose mothers were randomized to receive vitamin A, beta-carotene or a placebo. A portable pneumatochometer was used to measure offspring lung function. The researchers found that children whose mothers received vitamin A instead of a placebo had a significantly greater forced expiratory volume at one second, or FEV1, and a greater forced vital capacity, or FVC, while children whose mothers received beta-carotene instead of a placebo had similar FEV and FVC.

“Improved lung function was likely specific to supplementation received in utero because this population of children was subsequently exposed beyond 6 months of age to semiannual vitamin A supplementation with high coverage as part of a national program during their preschool years,” said Keith West, the George G. Graham Professor in Infant and Child Nutrition in the Bloomberg School’s Department of International Health. “This benefit was limited to children whose mothers received vitamin A and not to those whose mothers received beta-carotene. Early interventions with vitamin A in communities where undernutrition is highly prevalent may have long-lasting consequences in lung health.”

Vitamin A was first discovered in 1913 by E.V. McCollum, the founding chair of the school’s Department of Chemical Hygiene, now Biochemistry and Molecular Biology. It was one of the first essential micronutrients to be identified. In the 1970s, Alfred Sommer, now dean emeritus at the school, and colleagues discovered the link between vitamin A deficiency and night blindness among children in rural Indonesia and found that vitamin A given twice yearly reduced childhood mortality by a third. The World Bank declared vitamin A supplementation as one of the most cost-effective medical interventions of all time.

The current study was written by Checkley, West, Robert A. Wise, Matthew R Baldwin, Steven C. LeClerq, Parul Christian, Joanne Katz, James Tielsch, Subarna Kharty and Sommer, and was supported by the Bill & Melinda Gates Foundation and the Sight and Life Research Institute. The original maternal supplementation trial was supported by the U.S. Agency for International Development. Checkley was further supported by a Clinician Scientist Award from Johns Hopkins and a K99/R00 Pathway to Independence Award from the National Institutes of Health.