Vitamin D Status, Vitamin D Receptor Polymorphisms, and the Risk of Incident Rosacea: Insights from Mendelian Randomization and Cohort Study in the UK Biobank.

BACKGROUND: Previous cross-sectional studies have failed to definitively establish a causal relationship between serum 25-hydroxyvitamin D (25OHD) concentrations and the onset of rosacea. OBJECTIVE: To investigate the potential association between serum 25OHD levels, vitamin D receptor (VDR) polymorphisms, and the risk of developing incident rosacea. METHODS: This cross-sectional population-based cohort study utilizing 370,209 individuals from the UK Biobank. Cox proportional hazard regression models and two-sample Mendelian randomization (MR) analyses were applied to explore the causative relationship between 25OHD and incident rosacea. RESULTS: Our findings revealed that elevated levels of serum 25OHD were inversely correlated with the risk of incident rosacea. Specifically, compared to participants with 25OHD levels below 25 nmol/L, the multivariate-adjusted HR for incident rosacea was 0.81 (95% CI: 0.70, 0.94) in those with 25OHD levels exceeding 50 nmol/L. Further, in comparison to individuals with serum 25OHD less than 25 nmol/L and the rs731236 (TaqI) AA allele, those with serum 25OHD higher than 75 nmol/L and the TaqI GG allele had a multivariate-adjusted HR of 0.51 (95% CI 0.32 to 0.81) for developing rosacea. Results from the MR study supported a significant association, with each standard deviation increase in serum 25OHD concentrations correlating to a 23% reduced risk of rosacea (HR = 0.77, 95% CI: 0.63, 0.93). CONCLUSIONS: The findings of this cohort study indicate an inverse association between increased concentrations of serum 25OHD and the risk of developing incident rosacea. While our results highlight the potential protective role of vitamin D, the definitive efficacy of vitamin D supplementation as a preventive strategy against rosacea requires further investigation.