Finnish Study Links Low Levels of Vitamin D to Higher Risk of MS in Women

Women with low levels of vitamin D in their blood are more likely to develop multiple sclerosis (MS) later in life, finds a large-scale study on women in Finland.

The study, “25-Hydroxyvitamin D deficiency and risk of MS among women in the Finnish Maternity Cohort,” appeared in the journal Neurology.

Several studies have suggested a link between levels of vitamin D, or 25-hydroxyvitamin D (25[OH]D), and MS later in life. However, most of these studies were conducted in small groups and with limited capacity of analyzing vitamin D’s impact on MS.

Hoping to learn more, researchers at Boston’s Harvard T.H. Chan School of Public Health — working with Finland’s University of Turku — analyzed vitamin D levels in more than 800,000 blood samples from pregnant women, as part of prenatal evaluations, and correlated them with the incidence of MS in this population.

The team identified 1,092 cases of MS diagnosed between 1983 and 2009 in women from whom they had at least one blood sample collected prior to the MS diagnosis. Their vitamin D levels  were compared to 2,123 samples collected from women who did not develop the disease.

For the analysis, the team considered adequate vitamin D levels to be equal or higher than 50 nmol/L, while levels between 30 to 50 nmol/L were considered as insufficient vitamin D, and levels lower than 30 nmol/L indicated vitamin deficiency.

Analysis of all 3,215 records revealed that 58 percent of the women who developed MS had vitamin D deficiency, compared to 52 percent in the control group.

The team found that higher levels of vitamin D (50 nmol/L or higher) reduced the risk of MS in women by 39 percent. In contrast, those who were deficient in vitamin D were 43 percent more likely to get MS.

“There have only been a few small studies suggesting that levels of vitamin D in the blood can predict risk,” Harvard’s Kassandra Munger, lead author of the report, said in a press release. “Our study, involving a large number of women, suggests that correcting vitamin D deficiency in young and middle-age women may reduce their future risk of MS.”

These results may, however, not apply to all populations, since the study group only included women, and primarily of white origin. It urged more studies to evaluate vitamin D association with MS in men and for other racial groups. Also, longer follow-up evaluations could provide additional information on time to disease onset and vitamin D association.

“More research is needed on the optimal dose of vitamin D for reducing risk of MS,” said Munger. “But striving to achieve vitamin D sufficiency over the course of a person’s life will likely have multiple health benefits.”

The study was funded by the National Institute of Neurological Disorders and Stroke. Part of the data now published was presented at last year’s 32nd Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) in 2016.