Low levels of vitamin D are linked to lower lung function and greater medication use in children with asthma, according to a study.

Researchers, led by Dr. Daniel Searing at National Jewish Health, also reported that vitamin D enhances the activity of corticosteroids, the most effective controller medication for asthma.

`Asthmatic children in our study who had low levels of vitamin D were more allergic, had poorer lung function and used more medications. 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,` said Searing.

The researchers analysed electronic medical records of 100 pediatric asthma patients referred to National Jewish Health.

Overall, 47 percent of them had vitamin D levels considered insufficient, below 30 nanograms per milliliter of blood (ng/mL).

Seventeen percent of the patients had levels below 20 ng/mL, which is considered deficient.

The levels were similar to vitamin D levels found in the general population.

Patients low in vitamin D generally had higher levels of IgE, a marker of allergy, and responded positively to more allergens in a skin prick test. Allergies to the specific indoor allergens, dog and house dust mite, were higher in patients with low vitamin D levels.

Low vitamin D also correlated with low FEV1, the amount of air a person can exhale in one second, and lower FEV1/FVC, another measure of lung function.

Use of inhaled steroids, oral steroids and long-acting beta agonists were all higher in patients low in vitamin D.

`Our findings suggest two possible explanations. It could be that lower vitamin D levels contribute to increasing asthma severity, which requires more corticosteroid therapy. Or, it may be that vitamin D directly affects steroid activity, and that low levels of vitamin D make the steroids less effective, thus requiring more medication for the same effect,` said senior author Dr. Donald Leung.

The researchers performed a series of laboratory experiments that indicated vitamin D enhances the action of corticosteroids.

`Our work suggests that vitamin D enhances the anti-inflammatory function of corticosteroids. If future studies confirm these findings vitamin D may help asthma patients achieve better control of their respiratory symptoms with less medication,` said Leung.

Text courtesy: ANI