Indication: Multiple sclerosis
Source: Neurology, Nov. 20, 2012;79:2083
Research: In this nested case-control study, two population-based biobanks with 291,500 blood samples from 164,000 persons collected since 1975 in the northern half of Sweden were used. Researchers identified prospectively collected blood samples from MS cases (n = 192, controls matched 2:1) and gestational samples from pregnant mothers where the offspring had later developed MS (n = 37, control mothers matched 5:1).
Results: Levels of 25-hydroxyvitamin D ≥75 (vs <75) nmol/L in prospectively collected blood samples were associated with a decreased risk of MS (odds ratio [OR] 0.39, 95% confidence interval [CI] 0.16–0.98). No decrease in MS risk was found in the offspring exposed to gestational 25(OH)D levels ≥75 (vs <75) nmol/L (OR 1.8, 95% CI 0.53–5.8). The prevalence of 25(OH)D levels ≥75 nmol/L in female controls decreased gradually during 1976–2005 (p trend = 0.005). Researchers concluded there is an association between high 25(OH)D levels during the years preceding disease onset and a decreased risk of MS. In the very limited material with samples drawn in early pregnancy, where month-of-birth effects were controlled for, researchers found no association between gestational 25(OH)D levels and MS risk in the offspring. Decreasing 25(OH)D levels may explain the increasing MS incidence that is suggested from epidemiologic studies.