Are children with asthma in South Korea also associated with vitamin D deficiency?

Abstract

Recently, epidemiologic studies have shown that the lack of vitamin D levels may be associated with high asthma prevalence, but its effect is still controversial, depending on season, area, and food consumption. We aimed to examine the association of serum vitamin D levels with the prevalence of pediatric asthma in Korea. A total of 80 children (50 asthmatic children and 30 healthy controls) aged 6-14 years were participated in this study. Serum 25-hydroxy vitamin D (vitamin D) levels were measured and compared between the two groups. Moreover, the relationship of serum vitamin D levels with results of pulmonary function test and environmental factors (lifestyle habits and residential factors) collected by a questionnaire survey were examined in asthmatic patients. Serum vitamin D levels in asthmatic children (16.63 ± 4.20 ng/mL) were significantly lower than that in healthy controls (24.24 ± 6.76 ng/mL) (P<0.05). Also, we found that the prevalence of asthma increase to 0.79-fold (OR, 0.788; 95% C.I., 0.707-0.879; P<0.001) as serum vitamin D level is 1 ng/mL decreases. The increased time spent in outdoor could affect the increases of vitamin D levels significantly. However, no associations of vitamin D level with pulmonary function and residential environmental factors (i.e., housing type, living floor, and indoor activity time) were observed. Our findings suggest that serum vitamin D levels were also associated with pediatric asthma in Korea. Moreover, management of vitamin D level in asthmatic children would be a promising approach for preventing exaggeration of their severity.