In analyzing data on participants in the Severe Asthma Research Program, researchers discovered that asthma, when developed later in the lives of obese people, may be due to an imbalance in the metabolism of arginine rather than allergy or airway inflammation, according to the results of research led by the University of Pittsburgh School of Medicine.

Researchers collected blood samples from 155 adults, nearly half of whom had severe asthma; half were obese. When compared to early-onset asthma patients, late-onset obese asthma patients had lower plasma levels of the amino acid arginine and higher levels of an arginine metabolite called ADMA, which interferes with NO production.

“In healthy people, a balance is maintained between arginine and ADMA ensuring normal levels of airway NO,” said Fernando Holguin, MD, MPH, associate professor, Division of Pulmonary, Allergy and Critical Care Medicine, Pitt School of Medicine and co-director of the Asthma Institute. “But in obese, adult-onset asthma, the lower arginine and higher ADMA reduces airway NO levels. This finding is promising because it suggests that increasing arginine could restore NO levels and its positive effect on airways.”

Study results prompted the creation of a pilot project at the University of Pittsburgh Asthma Institute at UPMC to see if patients’ symptoms improve if they supplement their diet with the deficient agent.