The association between 25 hydroxyvitamin d and airway obstruction in Asthma

Since Vitamin D has anti-inflammatory effects we wondered whether the association between low serum 25OHD and airway obstruction in moderate persistent asthma might be explained by inflammatory pathways that worsen asthma. All subjects examined were Irish Caucasians with moderate persistent asthma and none took systemic steroid therapy. In addition to computerized spirometry, we measured BMI, serum 25-hydroxyvitamin D (25OHD), total IgE, Eosinophil Cationic Protein (ECP), and high sensitive C- reactive protein (hs-CRP). One hundred (47 male) subjects completed the testing. Within single level of asthma severity, 25OHD levels were related to post-bronchodilator FEV1/FVC (r = 0.26, p < 0.01), but multiple linear regression analysis demonstrated that the association was not explained by obesity or inflammatory markers. We find a relationship exists between airway obstruction and 25OHD levels in asthmatic adults, and the effect is not explained by the presence of potential confounders such as obesity, allergy and systemic inflammation.