The relationship between elevated Body Mass Index, exhaled nitric oxide, vitamin D serum concentration, and asthma control: a cross-sectional pilot study

Background. Numerous studies have demonstrated an association between obesity and asthma. The link between vitamin D deficiency and uncontrolled asthma has been shown in several papers. Objectives. The aim of this study was to evaluate the relationship between increased BMI and other indicators (body composition, lipid accumulation product, and Body Adiposity Index), serum level of Vitamin D, and asthma control. Material and methods. The study was conducted on 63 adults with asthma. Atopy was confirmed by skin prick tests. Body composition, BMI, BAI, LAP, forced expiratory volume in one second (FEV1), and fraction of exhaled nitric oxide (FeNO) were measured for the study subjects. All patients completed the Asthma Control Test and International Physical Activity Questionnaire. Results. The groups with BMI <= 25 and BMI > 25 were uniform in age and daily dose of inhaled corticosteroids. In men without atopy, independent of BMI, a negative correlation was found between vitamin D and FeNO. A negative correlation was observed between BAI and FeNO in all women. In the men without atopy, vitamin D levels were significantly lower than in the women without atopy, independent of BMI. The women with atopy and BMI > 25 had a lower mean ACT score than the women with atopy and BMI <= 25. Conclusions. The obesity indicators BAI and LAP better describe the influence of obesity on asthma control in women than BMI. Women with a BMI of > 25 have worse asthma control assessed by ACT score than women with normal BMI. In men without atopy, regardless of BMI, an increase in vitamin D level reduces airway inflammation assessed by FeNO.