Story at-a-glance
- Multiple sclerosis (MS) is an autoimmune condition attacking myelin in the central nervous system. Symptoms vary based on nerve damage location and often begin as clinically isolated syndrome (CIS)
- Low vitamin D is consistently linked to higher MS risk, with people living closer to the equator having lower MS rates due to greater sun exposure
- A 2025 clinical trial showed that high-dose vitamin D delayed MS progression in CIS patients, doubling time before new disease activity appeared compared to placebo
- Vitamin D stimulates myelin-rebuilding cells, boosts neurotrophins, reprograms microglia from inflammatory to healing states, and protects the blood-brain barrier
- Optimal vitamin D levels (60 to 80 ng/mL) can be maintained through sensible sun exposure or D3 supplementation, with regular testing recommended to adjust intake accordingly
