Neuroprotective role of high dose Vitamin D supplementation in multiple sclerosis: Sub-analysis of the EVIDIMS trial

BACKGROUND: Previous evidence suggests that vitamin D may help with neurodegeneration in multiple sclerosis (MS). Considering this, the study aims to investigate whether higher-dose vitamin D supplementation in individuals with MS can lead to reduced atrophy, as measured by optical coherence tomography (OCT) and MRI structural outcomes. This objective builds upon the established notion of thalamic and brainstem atrophy as reliable markers of disease progression and the potential association between adequate vitamin D levels and improved visual outcomes in MS patients. OBJECTIVE: To assess the impact of vitamin D as a neuroprotective intervention on visual and imaging biomarkers. METHODS: Participants enrolled in the EVIDIMS trial underwent an assessment to investigate the impact of high and low-dose vitamin D supplementation at 12 and 18 months using a nonparametric multiple contrast test procedure (MCTP). The primary outcomes included four MRI-radiological measures: change in the mean upper cervical cord area (MUCCA) and hippocampal, thalamic and brainstem volumes, and the visual system outcomes included assessment of the peripapillary retinal nerve fiber layer (pRNFL) thickness and macular combined ganglion cell and inner plexiform layer (GCIPL), and inner nuclear layer (INL). RESULTS: MCTPs indicated that there were no statistically significant differences in the volumes of the thalamus, hippocampus, and brainstem, as well as in MUCCA, between the low and high-dose supplementation groups. Moreover, MTCPs only revealed a different thinning pattern in the INL at 18 months between the low versus high-dose treatment arm attributable to patients who suffered optic neuritis (NO), with no significant differences in neither pRNFL nor GCIPL. CONCLUSION: Vitamin D supplementation did not affect MS imaging parameters. However, future studies should thoroughly evaluate patient histories of attacks and endogenous vitamin D levels before inclusion in dose-related investigations.