Vitamin D is essential for neurological health. It is synthesized in the skin upon sun exposure and supports calcium absorption and bone health. Low vitamin D levels are common and associated with increased risk of multiple sclerosis (MS), where each 10 nmol/L increase in vitamin D is associated with lower odds of MS lesions and relapses. For other conditions like Parkinson's and Alzheimer's, low vitamin D is linked to higher risk, though the mechanisms are still being explored. Screening and supplementation can help maintain sufficient vitamin D levels to support neurological and overall health.