A meta-analysis and trial sequential analysis demonstrated a significant association between allergic rhinitis and reduced vitamin D levels. The vitamin D receptor (VDR) polymorphism does not appear to be linked with a raised susceptibility to suffer from rhinitis. Fei Ju et al. aimed to explore the potential role of levels of vitamin D and VDR (rs2228570) polymorphisms in the predisposition to develop allergic rhinitis.

For relevant literature search, databases such as Science Direct, Google Scholar, and PubMed were explored. Rigorous exclusion and inclusion criteria were applied to identify suitable studies. From the eligible reports, extraction of information on VDR genotype, levels of vitamin D, and allele frequencies was done. Comprehensive meta-analysis software v3.3 was utilized to perform the meta-analysis.

Overall, 14 reports involving 1504 allergic rhinitis subjects and 1435 healthy controls were analyzed. It was found that allergic rhinitis patients had substantially declined vitamin D levels in comparison with the healthy controls (standard difference of means = -1.287). However, the meta-analysis of two separate assessments, including 917 cases and 847 controls, did not indicate  allergic rhinitis predisposition. To further investigate the role of VDR polymorphism in rhinitis, the trial sequential assessment highlighted the requirement for future case-control studies.

In conclusion, allergic rhinitis is associated with lower levels of vitamin D, and there may be potential advantages in incorporating vitamin D supplementation alongside standard treatment. However, the role of VDR polymorphism in this relationship remains inconclusive, necessitating further research to gain a clearer understanding of its involvement.