Evaluation of vitamin D levels in allergic and non-allergic asthma

Abstract

Background and objective: Some researches show that low vitamin D may play a role in asthma pathogenesis. The aim of this study was to evaluate the serum vitamin D level in asthmatics with different phenotypes and to determine its associations with lung function, IgE, eosinophil count and body mass index (BMI).

Materials and methods: The study population comprised 85 patients with asthma and 73 healthy persons. Patients with asthma were divided into groups according to phenotypes. Allergy was assessed using a skin prick test and measuring eosinophil count in peripheral blood and total IgE in serum. Lung function was evaluated by spirometry. Concentration of vitamin D (25(OH)D3) was measured using a commercial ELISA kit. Smoking history was assessed and BMI was calculated for all individuals.

Results: The vitamin D level was lower in asthmatics than in the control group (14.36±0.57 vs. 22.13±0.84 ng/mL, P<0.01). There were no significant differences in the vitamin D level between the groups with allergic and non-allergic asthma (14.36±0.77 vs. 14.35±0.74 ng/mL). The low vitamin D level increased the risk of asthma 1.2 times (OR, 1.194; 95% CI, 1.109-1.286, P<0.01). The vitamin D level did not correlate with lung function and markers of allergy in asthmatic patients. The vitamin D level correlated with FEV1/FVC (rs=0.72, P<0.05) in smoking patients with asthma. Correlation between the vitamin D level and BMI was found in all studied subjects (rs=-0.18, P<0.05).

Conclusions: The vitamin D level was lower in asthmatic patients than in healthy individuals despite their hypersensitivity and increase risk of asthma. There was no relation between the vitamin D level and lung function, eosinophil count and total IgE level, whereas the lower vitamin D level was associated with higher BMI.

Keywords: Allergy; Asthma; Body mass index; Lung function; Vitamin D.