Low Vitamin D levels lead to worse asthma symptoms and higher medication use



Researchers at National Jewish Health examined electronic medical records of 100 pediatric asthma patients referred to the clinic. Overall, 47% had vitamin D levels considered insufficient, below 30 nanograms per milliliter of blood (ng/mL); 17% had levels below 20 ng/mL, which is considered deficient. These levels were similar to vitamin D levels found in the general population.

Patients low in vitamin D generally had higher levels of IgE and responded positively to more allergens, particularly to indoor allergens such as dog and house dust mite, in a skin prick test. 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.

The researchers could not be sure whether lower vitamin D levels contribute to increasing asthma severity, so requiring more corticosteroid therapy or whether the 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. They therefore cultured some immune cells with the corticosteroid dexamethasone alone and others with vitamin D first, then dexamethasone. The vitamin D significantly increased the effectiveness of dexamethasone; in one experiment vitamin D and dexamethasone together proved to be 10 times more effective than the dexamethasone alone.

They also incubated immune-system cells for 72 hours with a staphylococcal toxin to induce corticosteroid resistance. Vitamin D restored the activity of dexamethasone.

This study comes on the heels of another paper by National Jewish Health faculty, which showed that low levels of vitamin D in adult asthma patients are associated with lower lung function and reduced responsiveness to corticosteroids.

Journal of Allergy & Clinical Immunology

Courtesy of Medical News Today


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First Published in April 2010


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