In a large nationwide study in Finland, researchers found evidence supporting the link between vitamin D deficiency and an increased risk for multiple sclerosis (MS) in women.
The results were given in an oral presentation, “Serum levels of 25-hydroxyvitamin D and risk of multiple sclerosis among women in the Finnish Maternity Cohort,” at the 32nd Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) that concluded in London on Sept. 17.
Researchers investigated whether there was an inverse association between vitamin D levels during pregnancy and a woman’s future MS risk. They measured the levels of 25-hydroxy vitamin D (25[OH]D), the most accurate way to measure how much vitamin D is present in the body.
The team conducted its nationwide study using the Finnish Maternity Cohort (FMC), which began in 1983 and has stored serum samples taken early in pregnancies for routine prenatal screening of over 800,000 women. Among these, researchers identified 1,247 women with MS diagnosed between 1983 and 2009. These women had at least one serum sample in the FMC collected prior to their MS diagnosis (in 47% of cases, the samples were two or more). On average, serum samples were collected 13 years before MS diagnosis.
Comparing to non-MS controls, women who developed MS showed 25(OH)D levels of 29.7 nmol/L (average), while women who served as controls had levels of 31.1 nmol/L. In their analysis, researchers detected a significant association between the two factors, with a 50 nmol/L increase in 25(OH)D associated with a 37% reduced risk of MS.
Specifically, women with 25(OH)D levels less than 30 nmol/L had a 23% increased risk for MS, when compared to women whose levels were between 30 nmol/L and 50 nmol/L. This risk further increased to 48% relative to women with levels greater than 50 nmol/L.
When researchers analyzed exclusively women with two or more samples (519 women with MS and 838 controls), or cases with medical record confirmation of MS (607 women), they observed the same associations.
These results strongly suggest that vitamin D deficiency increases the risk of MS. This is particularly important for the Nordic population, since it shows a high prevalence of vitamin D deficiency given the region’s short summers and long winters. Public health interventions are needed to improve vitamin D levels and reduced the risk for MS in this population.