Vitamin D and allergic rhinitis: A mini-review

Allergic rhinitis (AR) is an increasingly common inflammatory disease mediated by immunoglobulin E in response to environmental allergens, substantially impacting the quality of life and healthcare systems worldwide. Recent research has drawn attention to the role of vitamin D, a corticosteroid hormone with immunomodulatory properties, in influencing the onset and severity of allergic diseases, including AR. Vitamin D exerts regulatory effects and inherent and tailored immunity, including suppressing pro-inflammatory cytokines and enhancing regulatory T cell function. A contrary connection among serum 25-hydroxyvitamin D levels has been suggested in observational studies of AR prevalence, particularly among children and male adults. However, interventional studies/ research into the therapeutic effects of vitamin D supplementation in AR have yielded mixed results, with benefits possibly dependent upon baseline vitamin D levels, gender, age, and concomitant therapies. Although emerging evidence implies a link between vitamin D shortage and augmented threat or severity of AR, definitive statements regarding its therapeutic role have not been made. Further high-quality randomized controlled trials are required to clarify the immunological mechanisms engaged and establish standardized clinical guidelines. This mini-review underscores the potential of vitamin D as an adjunctive approach in AR and highlights the need for individual strategies tailored to each patient's profile. This mini-review aims to synthesize evidence about the bond between vitamin D levels and AR, exploring epidemiological findings and underlying immunological mechanisms.