Association Between Sunlight Exposure and Vitamin D Intake and 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 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.