From sunlight to MS fight: impact of vitamin D levels on multiple sclerosis activity

BACKGROUND: Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system with a multifactorial aetiology, including vitamin D levels, that have been linked to disease activity. Given the inconsistent findings on the vitamin D supplementation in MS, we aimed to analyse the connection between 25(OH)D levels and disease activity and to identify an optimal level of 25(OH)D in MS utilizing our real-world database. METHODS: This study utilized a 10-year dataset from the Czech national multiple sclerosis registry (ReMuS), encompassing 1,861 adult MS patients. Patients had a minimum of one year of follow-up, with subgroup analysis for those with at least five years. A mixed-effects model tested the impact of 25(OH)D and cholesterol levels on relapse incidence. Subgroup analysis categorised patients by average 25(OH)D levels and analysed relapse incidence using the Kruskal-Wallis test and Kaplan-Meier survival analysis. RESULTS: Higher serum 25(OH)D levels and age correlated with reduced relapse risk (p < 0.001 for both). Each 10 nmol/L increase in 25(OH)D levels associated with a 6.7% decrease in relapse risk (p < 0.001). Cholesterol levels and sex did not significantly affect relapse rate. Subgroup analysis revealed that patients with 25(OH)D levels above 100 nmol/L had significantly fewer relapses compared to those with levels below 75 nmol/L. CONCLUSION: Our findings suggest that optimising 25(OH)D levels may reduce the risk of relapse in pwMS. Causation cannot be confirmed. Results highlight the importance of personalized vitamin D supplementation strategies and support the potential benefit of maintaining optimal serum 25(OH)D levels in MS management.