Vitamin D is a fat-soluble vitamin that plays an important role in regulation of the immune system. However, there is still a lack of consensus on the relationship between vitamin D and allergic rhinitis (AR). In this study, we explored the relationship between 25-hydroxyvitamin D [25(OH)D3] and moderate-to-severe persistent AR.

Thirty-nine adult patients with moderate-to-severe persistent AR and 20 healthy people serving as a control group were recruited at the affiliated Chengdu University Hospital of Traditional Chinese Medicine from June 2018 to January 2019. The subjects were selected at random and participated voluntarily in our research. Vitamin D3 levels were determined in the blood samples of all subjects. Levels of IFN-γ, IL-4, IL-10 and total immunoglobulin E(IgE) were measured in the AR group, and scores on a visual analogue scale (VAS) and on a nasal-ocular- conjunctival quality-of-life questionnaire (Rhinoconjunctivitis Quality of Life Questionnaire, RQLQ) were also recorded for the AR group.

There was a significant difference in 25(OH)D3 levels between the control group and the AR group (P<0.01). In the correlation analysis, a positive correlation was observed between IFN-γ and 25(OH)D3, but a negative correlation was seen between total IgE, IL-4, VAS and RQLQ scores in the AR patient group. However, multiple linear regression analysis revealed no significant correlation between total IgE, IL-4 and 25(OH)D3.

In the correlation analysis, we confirmed that serum 25(OH)D3 displays significant negative correlation with total IgE, IL-4, VAS and RQLQ scores, which indicates that the lower the 25(OH)D3 level, the higher the VAS and RQLQ scores, and thus the more severe the symptoms in AR patients.