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Background: Intervention studies with vitamin D in asthma are inconclusive for several reasons, such as inadequate dosing or duration of supplementation or uncontrolled baseline vitamin D status. Our aim was to evaluate the benefit of long term vitamin D add-on in asthmatic patients with actual vitamin D deficiency, that is a serum 25-hydroxy vitamin D (25-OHD ) below 20 ng/mL., Methods: Serum 25-OHD, asthma exacerbations, spirometry and inhaled corticosteroids (CS) dose were evaluated in a cohort of 119 asthmatic patients. Patients with deficiency were evaluated again after one year vitamin supplementation., Results: 25-OHD was low in 111 patients and was negatively related to exacerbations ( p < 0.001), inhaled CS dose ( p = 0.008) and asthma severity ( p = 0.001). Deficiency was found in 90 patients, 55 of whom took the supplement regularly for one year, while 24 discontinued the study and 11 were not adherent. Patients with vitamin D deficiency after 12 months supplementation showed significant decrease of exacerbations (from 2.6 ± 1.2 to 1.6 ± 1.1, p < 0.001), circulating eosinophils (from 395 ± 330 to 272 ± 212 10⁶/L, p < 0.001), and need of oral CS courses (from 35 to 20, p = 0.007) and improvement of airway obstruction., Conclusions: Asthma exacerbations are favored by vitamin D deficiency and decrease after long-term vitamin D replacement. Patients who are vitamin D deficient benefit from vitamin D supplementation., Competing Interests: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.

Vitamin D is a fat-soluble vitamin, which is obtained by conversion of 7-dehydrocholesterol in the skin by UV ray and by diet. Its role on bone mineralization has been known for over two hundred years, while its non-skeletal effects have been acknowledged only in the last few years. The discovery of important vitamin D properties on the innate and adaptive immune system created a lot of interest in a potential role of vitamin D on diseases characterized by heightened inflammation and oxidative response, and impaired antimicrobial response, such as asthma and chronic obstructive pulmonary disease (COPD). Recent studies have demonstrated that vitamin D and its deficiency have a number of biological effects which are potentially important in altering the pathogenesis and severity of both asthma and COPD. Vitamin D may improve lung function and response to steroids therapy, reduce airway remodeling and disease exacerbations. The aim of this study is to review the role of Vitamin D in asthma and COPD.

Background: Acute exacerbations of COPD (AECOPD) are common and strongly influence disease severity and relative healthcare costs. Vitamin D deficiency is frequent among COPD patients and its contributory role in disease exacerbations is widely debated. Our aim was to assess the relationship of serum vitamin D levels with COPD severity and AECOPD. Methods: Serum vitamin D (25-hydroxyvitamin D) levels were measured in 97 COPD patients and related to lung function, comorbidities, FEV1 decline, AECOPD and hospital admission during the previous year. Results: Most patients (96%) had vitamin D deficiency, which was severe in 35 (36%). No significant relationship was found between vitamin D and FEV1 or annual FEV1 decline. No difference between patients with and without severe vitamin D deficiency was found in age, gender, BMI, smoking history, lung function, and comorbidities, apart from osteoporosis (60.9% in severe deficiency vs 22.7%, p = 0.001). In multiple logistic regression models, severe deficiency was independently associated with AECOPD [adjusted odds ratios (aOR) of 30.5 (95% CI 5.55, 168), p < 0.001] and hospitalization [aOR 3.83 (95% CI 1.29, 11.4), p = 0.02]. The odds ratio of being a frequent exacerbator if having severe vitamin D deficiency was 18.1 (95% CI 4.98, 65.8) (p < 0.001), while that of hospitalization was 4.57 (95% CI 1.83, 11.4) (p = 0.001). Conclusions: In COPD patients severe vitamin D deficiency was related to more frequent disease exacerbations and hospitalization during the year previous to the measurement of vitamin D. This association was independent of patients' characteristics and comorbidities. [ABSTRACT FROM AUTHOR]