In multiple sclerosis (MS) as a chronic autoimmune neurodegenerative disorder, 8‐week vitamin D3 supplementation was associated with reductions in the neuroinflammatory biomarker Chitinase‐3‐like protein 1 (CHI3L1) and oxidative stress markers, while suggesting enhancement of antioxidant capacity. The gene discussed is CHI3L1; the disease is myeloid sarcoma.