Vitamin D and Multiple Sclerosis
Multiple sclerosis (MS) is an autoimmune demyelinating disorder characterized by distinct episodes of neurologic deficits, separated in time, attributable to white matter lesions that are separated in space. It is the most common of the demyelinating disorders, having a prevalence of approximately 1 per 1000 persons in most of the United States and Europe. The disease may become clinically apparent at any age, although onset in childhood or after age 50 years is relatively rare. Women are affected twice as often as are men. In most individuals with MS, the clinical course takes the form of relapsing and remitting episodes of variable duration (weeks to months to years) marked by neurologic defects, followed by gradual, partial recovery of neurologic function. The frequency of relapses tends to decrease during the course of time, but there is a steady neurologic deterioration in most affected individuals.1 The lesions of MS are caused by an immune response that is directed against the components of the myelin sheath. As in other autoimmune disorders, the pathogenesis of this disease involves both genetic and environmental factors. The incidence of MS is 15-fold higher when the disease is present in a first-degree relative and roughly 150-fold higher with an affected monozygotic twin.
The purpose of this report is to provide a brief description of research findings on the role of vitamin D in multiple sclerosis (MS). Observational studies document a positive relationship between vitamin D from the environment (sunlight or diet), circulating vitamin D status, and improved symptoms or prevention of multiple sclerosis (MS), as the geographic incidence of MS indicates an increase in MS with a decrease in sunlight exposure. The effects of vitamin D on the immune system and in the CNS have begun to be described and there is some information on the mechanisms underlying the effects of vitamin D in MS, It plays an important role in T cell homeostasis during the course of multiple sclerosis. While It’s been found that higher serum 25(OH)D levels robustly predicted a lower degree of MS activity, MRI lesion load, brain atrophy, and clinical progression during the 5 years of follow-up. As evidence continues to accumulate supporting a protective role for vitamin D in MS etiology and progression, additional research on the timing and dose-response relationship will be crucial for designing future prevention and treatment trials.