Is high prevalence of vitamin D deficiency evidence for asthma and allergy risks?

BACKGROUND

Studies suggest a link between vitamin D deficiency and development of asthma and allergic diseases.

AIM

To determine a) the association between vitamin D and asthma among children, b) difference in level of vitamin D in asthmatic children and control, and c) effect of vitamin D on atopy markers.

SETTING

Case-control study done, between October 2009 to July 2010, on asthmatics and controls (< 15 years) at Pediatric Allergy-Immunology Clinics and Primary Health care Clinics (PHC), Qatar. METHODS & SUBJECTS: A total of 483 cases and 483 controls matched by age, gender and ethnicity. Sociodemographic & clinical data was collected through physician diagnosis and questionnaire. Their health status was assessed by past or present clinical manifestations, family history, physical examination, BMI, and serum 25(OH) vitamin D, calcium, and phosphorus.

RESULTS

44.8% of asthmatic and 50.0% of controls were males, and 55.2% of asthmatic and 50% of controls were females. The mean age (+/- SD, in years)for asthmatic versus controls was 7.0 +/- 3.8 vs. 8.4 +/- 3.6. Vitamin D deficiency was more prevalent in asthmatics than controls. The mean value of Vitamin D in asthmatics was much lower than the normal value, and there was a significant difference found in the mean values of vitamin D between asthmatics (17.5 +/- 11.0) and the controls (20.8 +/- 10.0). Furthermore, there were statistically significant differences between asthmatic subjects and controls with respect to serum level of vitamin D (p < 0.001). Lower Vitamin D levels were associated with more allergic disease and elevated serum IgE.

CONCLUSION

Serum vitamin D levels were lower in asthmatic than control. Vitamin D deficiency was higher among children with asthma, allergic rhinitis, atopic dermatitis, acute urticaria, and food allergy. In addition, vitamin D deficiency was associated with IgE atopy markers in asthmatic children more than controls.