Association Between Sunlight Exposure and Vitamin D Intake With Multiple Sclerosis Disability and Progression

Background: Some studies on Multiple Sclerosis (MS) have suggested that adequate vitamin D intake can modulate the course of MS and decreases its incidence. However, there are limited studies with conflicting findings on the relation between MS severity, its course, and vitamin D intake. Objectives: The current study aimed to compare vitamin D intake and sunlight exposure between MS phenotypes and evaluate their association with disability and fatigue in each phenotype. Materials & Methods: A total of 197 patients with MS were recruited from patients referring to MS clinic in Kashani Hospital in Isfahan, Iran. Subjects were assessed for sunlight exposure, vitamin D intake, physical activity, and fatigue. SPSS was used for statistical analysis. P<0.05 were set as significant. Results: According to the obtained results, expanded disability status scale and fatigue scale scores in Primary-Progressive MS (PPMS) and Secondary-Progressive MS (SPMS) groups were higher than Relapsing-Remitting MS (RRMS) group. In addition, patients in RRMS group had higher scores of sun exposure and physical activity, compared to SPMS and PPMS groups. We found a negative correlation between the scores of fatigue scale and sunlight exposure scale in RRMS patients. Conclusion: We found higher sunlight exposure in RRMS group and lower sunlight exposure in the PPMS group, while dietary vitamin D intake was not different between the groups. Further studies with larger sample sizes and stronger methodologies are required to evaluate our findings.