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 ) .
Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis.
CONTEXT Epidemiological and experimental evidence suggests that high levels of vitamin D , a potent immunomodulator , may decrease the risk of  multiple sclerosis .  There are no prospect i ve studies addressing this hypothesis . OBJECTIVE To examine whether levels of 25-hydroxyvitamin D  are associated with risk of multiple sclerosis . DESIGN , SETTING , AND PARTICIPANTS Prospect i ve , nested case-control study among more than 7 million US military personnel who have serum sample s stored in the Department of Defense Serum Repository . Multiple sclerosis cases were identified through Army and Navy physical disability data bases for 1992 through 2004 , and diagnoses were confirmed by medical record review . Each case ( n = 257 ) was matched to 2 controls by age , sex , race/ethnicity , and date s of blood collection . Vitamin D status was estimated by averaging 25-hydroxyvitamin D levels of 2 or more serum sample s collected before the date of initial multiple sclerosis symptoms . MAIN OUTCOME MEASURES Odds ratios of multiple sclerosis associated with continuous or categorical levels ( quantiles or a priori-defined categories ) of serum 25-hydroxyvitamin D within each racial/ethnic group . RESULTS Among whites ( 148 cases , 296 controls ) , the risk of multiple sclerosis significantly decreased with increasing levels of 25-hydroxyvitamin D ( odds ratio [ OR ] for a 50-nmol/L increase in 25-hydroxyvitamin D , 0.59 ; 95 % confidence interval , 0.36 - 0.97 ) . In categorical analyses using the lowest quintile ( < 63.3 nmol/L ) as the reference , the ORs for each subsequent quintile were 0.57 , 0.57 , 0.74 , and 0.38 ( P = .02 for trend across quintiles ) . Only the OR for the highest quintile , corresponding to 25-hydroxyvitamin D levels higher than 99.1 nmol/L , was significantly different from 1.00 ( OR , 0.38 ; 95 % confidence interval , 0.19 - 0.75 ; P = .006 ) . The inverse relation with multiple sclerosis risk was particularly strong for 25-hydroxyvitamin D levels measured before age 20 years . Among blacks and Hispanics ( 109 cases , 218 controls ) , who had lower 25-hydroxyvitamin D levels than whites , no significant associations between vitamin D and multiple sclerosis risk were found . CONCLUSION The results of our study suggest that high circulating levels of vitamin D are associated with a lower risk of multiple sclerosis
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 ) .