HealthDay News — High vitamin D levels in the years preceding MS onset is associated with a decreased risk for the disease, study results published in Neurology suggest.
Jonatan Salzer, MD, from Umeå University in Sweden, and colleagues, observed an inverse association between levels of 25-hydroxyvitamin D and the risk of multiple sclerosis (MS), in a nested case-control study involving 291,500 samples from two population-based biobanks.
The samples were collected from 164,000 people in the northern half of Sweden since 1975. Blood samples were identified from 192 MS cases (controls matched in a 2:1 ratio), and gestational samples were collected from 37 pregnant women whose offspring later developed MS (control mothers matched in a 5:1 ratio).
Levels of 25-hydroxyvitamin D ≥75 nmol/L correlated with a significantly decreased risk of MS compared with levels <75 nmol/L (odds ratio=0.39; 95% CI: 0.16–0.98), the researchers found.
However, offspring exposed to gestational 25-hydroxyvitamin D levels of ≥75 nmol/L vs. <75 nmol/L had no significantly decreased risk of MS (OR=1.8; 95% CI: 0.53-5.8).
“This study gives further support for the association between vitamin D status and MS,” the researchers wrote. “Our data suggest that vitamin D may act as a protective factor for MS somewhere between late pregnancy and young adulthood.”
During 1976 to 2005, the prevalence of 25-hydroxyvitamin D ≥75 nmol/L gradually decreased in controls, the researchers pointed out, adding decreasing vitamin D levels at the population level may “explain the increasing MS incidence that is suggested from epidemiologic studies.”