To sum up , low vitamin D  levels are associated with an increased risk of MS
To estimate the associations between vitamin D status and multiple sclerosis ( MS ) .
Vitamin D as an early predictor of multiple sclerosis activity and progression.
IMPORTANCE It remains unclear whether vitamin D insufficiency , which is common in individuals with multiple sclerosis ( MS ) , has an adverse effect on MS outcomes . OBJECTIVES To determine whether serum concentrations of 25-hydroxyvitamin D ( 25[OH]D ) , a marker of vitamin D status , predict disease activity and prognosis in patients with a first event suggestive of MS ( clinical ly isolated syndrome ) . DESIGN , SETTING , AND PARTICIPANTS The Betaferon/Betaseron in Newly Emerging multiple sclerosis For Initial Treatment study was a r and omized trial originally design ed to evaluate the impact of early vs delayed interferon beta-1b treatment in patients with clinical ly isolated syndrome .  Serum 25(OH)D concentrations were measured at baseline and 6 , 12 , and 24 months . A total of 465 of the 468 patients r and omized had at least 1 25(OH)D measurement , and 334 patients had them at both the 6- and 12-month ( seasonally asynchronous ) measurements . Patients were followed up for 5 years clinical ly and by magnetic resonance imaging . MAIN OUTCOMES AND MEASURES New active lesions , increased T2 lesion volume , and brain volume on magnetic resonance imaging , as well as MS relapses and disability ( Exp and ed Disability Status Scale score ) . RESULTS Higher 25(OH)D levels predicted reduced MS activity and a slower rate of progression . A 50-nmol/L ( 20-ng/mL ) increment in average serum 25(OH)D levels within the first 12 months predicted a 57 % lower rate of new active lesions ( P < .001 ) , 57 % lower relapse rate ( P = .03 ) , 25 % lower yearly increase in T2 lesion volume ( P < .001 ) , and 0.41 % lower yearly loss in brain volume ( P = .07 ) from months 12 to 60 . Similar associations were found between 25(OH)D measured up to 12 months and MS activity or progression from months 24 to 60 . In analyses using dichotomous 25(OH)D levels , values greater than or equal to 50 nmol/L ( 20 ng/mL ) at up to 12 months predicted lower disability ( Exp and ed Disability Status Scale score , -0.17 ; P = .004 ) during the subsequent 4 years . CONCLUSIONS AND RELEVANCE Among patients with MS mainly treated with interferon beta-1b  , low 25(OH)D levels early in the disease course are a strong risk factor for long-term MS activity and progression
To sum up , low vitamin D  levels are associated with an increased risk of MS
To estimate the associations between vitamin D status and multiple sclerosis ( MS ) .