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Study finds maternal diet may predict RSV severity

Mar. 4, 2013, 11:55 AM

A high carbohydrate diet during pregnancy may increase the severity of RSV in infants. (photo by Joe Howell)

An important predictor of the severity of respiratory syncytial virus (RSV) in infants may be what their mothers ate during pregnancy.

Fernando Polack, M.D., Cesar Milstein Professor of Pediatrics, is lead author of an article in the American Journal of Respiratory and Critical Care Medicine that finds the most serious cases of RSV correlate with mothers who ate a diet high in carbohydrates during pregnancy.

“These cases were not just severe, but the sickest of sick.  What we found was the impact of a carbohydrate rich diet was clearly dose dependent,” Polack said.

More than 1,200 infants younger than 2 years old were hospitalized in 12 institutions in Buenos Aires, Argentina, during the 2011 RSV season.

A study by Fernando Polack, M.D., and colleagues found that the most serious cases of RSV in infants correlate with mothers who ate a high-carbohydrate diet during pregnancy. (photo by Joe Howell)

Of those, nearly 800 were found to have RSV infection, and 106 of those babies had oxygen saturation rates below 87 percent: considered life-threatening disease.  Twenty-two infants died in the hospital, and an additional 26 infants died at home with evidence suggesting they died from RSV.

The babies’ mothers filled out a nutrition survey for the final trimester of pregnancy. Polack and his collaborators examined the impact of maternal diets heavy in fruits and vegetables versus protein, fats or carbohydrate-rich diets, on the severity of a baby’s RSV infection.

Overall, the risk of life-threatening or fatal RSV in infants was about 12.7 percent among participants, while the rates were highest — about 55.6 percent — among babies whose mothers ate greatest proportion of carbohydrates.

“Our study suggests where RSV is concerned, the more sugars a mother eats the worse the situation may get for the baby in the first part of life,” Polack said.

Polack’s work is part of one of the largest studies ever done on RSV in developing countries, funded by the Bill and Melinda Gates Foundation.

The researchers say current evidence shows rates of severe RSV have not been positively impacted over the last few decades by any one factor, with the notable exception of breast-feeding. He and his team, both at the INFANT Foundation in Buenos Aires, and here at Vanderbilt, continue to search for modifiable risk factors.

“We decided to look at the maternal diet, because some smaller studies suggested this might be important. This makes evolutionary sense because one would expect human beings that grew up through 99 percent of their existence with a certain diet, might require it for optimal development.

“Our diet today is clearly different from the roots, seeds, vegetables and meat we ate for so long. It is possible we may not be equipped as well to use sugars for certain things,” Polack said.

The authors say more research is needed to confirm the role of maternal diet on the severity of the RSV infection in infants.

Other co-authors from Vanderbilt include Carlos Grijalva, M.D., Ph.D., assistant professor of Medicine, Romina Libster, M.D., adjunct assistant professor of Pediatric Infectious Diseases, and John Williams, M.D., associate professor of Pediatric Infectious Diseases.

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