Serum Vitamin D Is Inversely Associated with Blood Eosinophil Count Among Adults with Allergic Asthma

To evaluate the role that serum vitamin D concentration plays in the number of eosinophils in peripheral blood in adults with allergic asthma.

A total of 142 patients were categorized based on different cutoff points for eosinophils: ≥200, ≥300, ≥400, and ≥500 cells/mL. The vitamin D concentration was stratified into <20 and ≥20 ng/mL. The association between vitamin D (independent variable) and eosinophils (dependent variable) was explored using multivariate analysis.

The average number of eosinophils in the included patients was 418 cells/mL, and 33.8% of the included patients had vita- min D concentrations ≥20 ng/mL. Asthmatic patients with vitamin D< 20 ng/mL had a higher mean concentration of eosinophils than did asthmatic patients with vitamin D ≥20 ng/mL (464 ± 377.7 eosinophils/mL vs. 327.8 ± 247.2 eosinophils/mL, P = .025). We also observed that vitamin D was inversely correlated with eosinophil count (rho = 0.244, P = .003). In the multivariate analysis, vitamin D <20 ng/mL showed a significant inverse association with each cutoff value for eosinophilia (odds ratio >1).

Vitamin D concentrations <20 ng/mL are associated with a significant increase in the number of eosinophils in blood. Studies that analyze the use of vitamin D supplements as complementary therapy for the treatment of asthma are needed.