Journal of Allergy & Clinical Immunology: Asthmatic children with vitamin D deficiency have more symptoms and use more corticosteroids, according to an April 12 online report in the Journal of Allergy & Clinical Immunology. The study also suggests that vitamin D supplements “might potentiate the anti-inflammatory function of corticosteroids in asthmatic patients and thereby act as a steroid-sparing agent,” first author Dr. Daniel A. Searing told Reuters Health by email.

Dr. Searing and colleagues from National Jewish Health in Denver and University of Colorado Denver in Aurora analyzed serum levels of 25-hydroxyvitamin D in 100 asthmatic children up to 18 years old. The cohort was 79% white, 9% Native American or Alaska Native (including Hispanic), 6% African American, 3% Asian, and 4% mixed race. Forty-seven percent of the children had insufficient vitamin D levels (< 30 ng/mL), and 17% were in the deficient range (< 20 ng/mL). “This demonstrates that vitamin D insufficiency is common in children with asthma,” Dr. Searing said.

Allergy markers, including immunoglobulin E level (p = 0.01) and positive aeroallergen skin test responses (p = 0.02), were inversely correlated with vitamin D levels. In particular, allergies to dog and house dust mite were higher in patients with low vitamin D. Lower vitamin D levels were also significantly correlated with lower lung function. Use of inhaled and oral corticosteroids and long-acting beta agonists were all higher in patients with low vitamin D levels.

“Our findings suggest two possible explanations,” senior author Dr. Donald Leung noted in a written statement. “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.” What’s needed next is to “investigate if vitamin D supplementation for asthmatic patients will lead to lower medication use and improved symptoms,” Dr. Searing concludes.”The relationship between corticosteroid medication use and lower vitamin D levels, especially also with our laboratory data showing the ability of vitamin D to enhance corticosteroid effects, shows a potential pathway for vitamin D’s role in asthma,” he added.

Drs. Backman, Bloom, and Veksler from Allergy & Asthma Care of Fairfield County wish to remind patients that this data does not prove that taking supplemental vitamin D will improve asthma control. However, many people in the Northeast are likely vitamin D deficient. It is strongly recommended that patients speak with their primary care physicians about their vitamin D status. Ensuring that you have adequate vitamin D levels certainly can’t hurt, and may turn out to help, asthma control.