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Insufficient vitamin D associated with increased risk for MS

Women who do not consume enough vitamin D during pregnancy may be increasing their child’s risk for multiple sclerosis, according to data published in JAMA Neurology.

“Inadequate vitamin D nutrition has been identified as a risk factor for developing multiple sclerosis (MS), a progressive, neurodegenerative disease of the central nervous system,” Kassandra L. Munger, ScD, of the department of nutrition at the Harvard T.H. Chan School of Public Health, in Boston, and colleagues wrote. “… Whether this inverse association extends to vitamin D exposure in early life is not clear. … Thus, whether adequate maternal vitamin D levels during pregnancy are associated with risk of MS in offspring remains unclear.”

To determine whether serum 25-hydroxyvitamin D, or 25(OH)D, levels in early pregnancy are linked with the risk for MS in offspring, the researchers conducted a prospective, nested case-controlled study, using the Finnish Maternity Cohort, which has collected more than 1.5 million serum samples from 800,000 pregnant women between 10 and 14 weeks of gestation since 1983. In May 2011, they identified 193 expecting mothers who had been diagnosed with MS before Dec. 31, 2009, and whose mothers were included in the Finnish Maternity Cohort and had an available serum sample from the corresponding pregnancy.

The researchers matched 176 cases with 326 individuals who made up the control group, based on region of birth, date of serum sample collection, date of mother’s birth and date of child’s birth. Maternal serum 25(OH)D levels were measured using a chemiluminescence assay.

According to the researchers, the mean vitamin D levels among the pregnant women were in the “insufficient” range, although they were higher in the control group, with a mean of 15.02 [6.41] ng/mL, than among the case samples, which had a mean of 13.86 [5.49] ng/mL. Vitamin D deficiency, defined as 25(OH)D levels of less than 12.02 ng/ML, during pregnancy was linked with a nearly 2-fold increase in the risk for the child developing MS (RR 1.9; 95% CI, 1.2-3.01; P = .006), compared with women who were not vitamin D deficient. There was no statistically significant link between the risk for MS and increasing 25(OH)D levels (P=.12)

“While the range of maternal 25(OH)D spanned levels of deficient to sufficiency, most women in our study had deficient or insufficient levels (< 20.03 ng/mL), and only 10 mothers had levels above 30.05 ng/mL, one of whom had 25(OH)D levels above 40.06 ng/mL,” Munger and colleagues wrote. “Thus, while our results suggest that vitamin D deficiency during pregnancy increases MS risk in the offspring, our study does not provide any information as to where there is a dose-response effect with increasing levels of 25(OH)D sufficiency.” – by Jason Laday

Disclosure: Researcher Merja Soilu-Hännien reports obtaining research grants from Bayer and Biogen Idec Finland, lecture fees and travel reimbursements from Bayer, Biogen Indec Finland, Genzyme, Merck, Novartis, Sanofi, Orion and Teva. See the full article for additional financial disclosures.