Multiple sclerosis is a degenerative, neurological disease.
Around 400,000 Americans live with MS, and approximately 10,000 new cases are diagnosed each year.
Dr. Benjamin M. Greenberg, of the University of Texas, explains in a linked editorial that early theories linking MS to vitamin D deficiency noted that the disease is more prevalent in northern latitudes, where low vitamin D levels can result from a relative lack of sunlight.
The fact that northerly regions with lower rates of MS, such as Japan and Alaska, tend to have a national diet rich in sources of vitamin D supported the potential link, and this raised a case for further study.
Scientists have subsequently hypothesized that low vitamin D during critical growth periods could create "weak myelin," making damage more likely for people with MS.
Studies have produced conflicting results. Some have associated high levels of vitamin D with a lower prevalence of MS in adulthood, while others have suggested that vitamin D exposure in utero increases the risk. Two studies have indicated no relationship.
Prevalence 90% higher among those whose mothers lacked vitamin D
Kassandra L. Munger, of the Harvard T.H. Chan School of Public Health in Boston, MA, and coauthors looked at the association between high levels of serum 25-hydroxyvitamin D - 25(OH)D, or vitamin D - in early pregnancy and the incidence of MS in children.
They identified 193 individuals with a diagnosis of MS, of whom 163 were female. The subjects' mothers were enrolled in the Finnish Maternity Cohort (FMC). The researchers compared 176 case patients with 326 control participants.
Maternal blood samples were collected to measure vitamin D levels, 70% of them taken during the first trimester. Average maternal vitamin D levels were in the "insufficient" vitamin D range, or 25(OH)D levels less than 12.02 ng/mL.
Results indicated a 90% higher risk of MS among children whose mothers who were vitamin-D deficient, compared with those whose mothers had adequate vitamin D.
Limitations of the study include the fact that measuring maternal vitamin D levels during pregnancy is not the same as measuring those to which the fetus is exposed.
The authors conclude:
"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 whether there is a dose-response effect with increasing levels of 25(OH)D sufficiency. Similar studies in populations with a wider distribution of 25(OH)D are needed."
Dr. Greenberg comments that while the FMC was not originally intended as a resource for MS research, it provides "a powerful tool for understanding complex biology and disease."
Medical News Today recently reported that coffee may help to reduce the risk of MS.