Effects of vitamin D levels on asthma control and severity in pre-school children

OBJECTIVE: Prevalence of asthma and vitamin D deficiency has been increasing and leading to significant morbidities. This study aimed to compare the vitamin D levels in the pre-school children with asthma and in healthy controls and to assess the relationship between vitamin D levels and asthma clinical parameters and control. PATIENTS AND METHODS: Vitamin D [25(OH) D 3] levels were measured in 102 preschool children, aged 1-4 years with asthma and 102 healthy controls in winter. The patients with asthma were grouped according to serum vitamin D levels as sufficient, insufficient and deficient. Asthma control was classified according to the Global Initiative for Asthma (GINA) guidelines and the Test for Respiratory and Asthma Control in Kids (TRACK) in 1-4 years-old children. RESULTS: Serum vitamin D levels were 22.64 (9.96) ng/ml in the asthma group and 32.11 (14.74) ng/ml in the control group (p = 0.001). Total number of exacerbations during the previous year were significantly lower in the vitamin D sufficient group, compared to the deficient and insufficient groups (p = 0.03). Frequency of patients with controlled asthma was higher in the sufficient group compared to the deficient and insufficient groups (p = 0.001 and p = 0.001, respectively). There was a positive correlation between serum vitamin D levels and asthma control. CONCLUSIONS: The frequency of vitamin D deficiency and insufficiency was higher in children with asthma, compared to the controls. Therefore, we suggest that lower levels of vitamin D are associated with poor asthma control and increased asthma severity.