The association between allergic diseases and vitamin D deficiency is a relatively novel topic that has gained the attention of scientists. In this study, we sought to evaluate the serum levels of vitamin D in patients with allergic rhinitis and compare them with those of healthy volunteers. This case-control study was performed during a one-year period (September 2015 to September 2016) on 100 patients with allergic rhinitis confirmed via the positive skin prick test (patients group) and 100 healthy subjects. The subjects were chosen by using the convenience sampling method, and they were matched with regards to age, gender, and socioeconomic status. The total mean level of vitamin D was 16.17±11.41 nmol/L (n=200), while it was 21.09±13.04 nmol/L in the normal population and 11.25±6.53 nmol/L in the patients with allergic rhinitis. The comparison of vitamin D level between the normal population and patient groups showed a significant difference between them (Z=-5.21, P≤0.0005). The comparison of the presence or absence of polyp in patients with allergic rhinitis showed a significant difference in vitamin D level between the subjects with polyp and those without polyp (t=4.74, P=0.03). The comparison of the subjects with allergic rhinitis showed no significant difference in vitamin D level between the patients with asthma and those without asthma (t=0.23, P=0.62). Based on our study, the level of vitamin D was lower in the patients with allergic rhinitis compared to the normal subjects. The prevalence of vitamin D deficiency was 67% in the allergic rhinitis patients. Our findings could be helpful in the therapeutic management of patients with allergic rhinitis, and in turn, improving their health.
