DENVER, April 19 (UPI) -- Low levels of vitamin D have been linked to increased asthma symptoms and greater use of medication among children, U.S. researchers say.
Researchers at the National Jewish Medical and Research Center in Denver say 47 percent of their asthma patients have vitamin D levels considered insufficient -- below 30 nanograms per milliliter of blood -- and 17 percent have deficient levels -- below 20 ng/mL. The researchers say their findings are similar to the vitamin D levels found in the general population.
The paper, published online in the Journal of Allergy & Clinical Immunology, finds asthmatic children with low vitamin D levels have higher levels of IgE -- a marker of allergy. These children are responding positively to more allergens in a skin prick test, the researchers say.
"Conversely, our findings suggest that vitamin D supplementation may help reverse steroid resistance in asthmatic children and reduce the effective dose of steroids needed for our patients," study researcher Dr. Daniel Searing says in a statement.
Searing and colleagues examined electronic medical records of 100 pediatric asthma patients referred to National Jewish Health and tested vitamin D and corticosteroids interaction in laboratory experiments.
"Our work suggests that vitamin D enhances the anti-inflammatory function of corticosteroids," senior author Dr. Donald Leung says. "If future studies confirm these findings vitamin D may help asthma patients achieve better control of their respiratory symptoms with less medication."