Vitamin D and Asthma
Low vitamin D reduces effectiveness of asthma medications
Researchers at National Jewish Health have found an association between low levels of vitamin D and lower lung function in children with asthma. They also report that vitamin D boosts the ability of corticosteroids to control asthma. These findings were published in the Journal of Allergy & Clinical Immunology.
The study involved 100 pediatric asthma patients, 47 percent of whom had insufficient vitamin D levels (below 30 nanograms per milliliter of blood) and 17 percent of whom were deemed deficient in vitamin D (below 20 ng/mL). These levels are consistent with the general population. Patients with low vitamin D levels were found to have lower lung function, as well as more indicators of allergies, as measured by IgE levels and skin prick tests. Low vitamin D was also found to correlate with higher use of steroid medications.
"Our findings suggest two possible explanations," said Dr. Donald Leung. Low vitamin D levels could lead to more severe asthma symptoms, requiring more corticosteroid therapy. Alternatively, vitamin D could be required for steroid medications to be most effective, and therefore patients with low vitamin D would need more medication for the same effect.
A series of laboratory experiments seem to support the latter hypothesis, suggesting that "vitamin D enhances the anti-inflammatory function of corticosteroids," said Dr. Leung. Further research into this effect could lead to better symptom management with less medication for asthma patients.
A previous study at National Jewish Health found similar correlations between vitamin D levels and both lung function and responsiveness to corticosteroids in asthmatic adults.
April 15, 2010