Low vitamin D blood levels are associated with a significantly higher risk of relapse attacks in patients with multiple sclerosis (MS) who develop the disease during childhood, according to a study conducted by researchers from the University of California, San Francisco.
"We have known for some time that vitamin D insufficiency is a risk factor for developing MS, but this is the first study to assess whether vitamin D levels influence the disease course of those who already have MS," said lead author Ellen Mowry, MD, MCR, a clinical instructor of neurology at the UCSF Multiple Sclerosis Center.
The study, which is now published online by the Annals of Neurology and is available at http://www3.interscience.wiley.com/journal/123246501/abstract, demonstrates that an increase in vitamin D levels by 10 nanograms per milliliter of blood (ng/mL) corresponds with a 34 percent decrease in the rate of subsequent relapses.
In other words, raising the vitamin D level of a person with MS by 15 ng/mL, which requires about 2,000 international units of vitamin D supplementation a day, could theoretically cut a patient's relapse rate in half, explained Mowry.
"Although we do not yet know if vitamin D supplementation will be beneficial for MS patients, the fact that there is a clear association between vitamin D levels and relapse rate provides strong rationale for conducting a clinical trial to measure the potential impact of supplementation," she said.
"This is an exciting finding because it indicates that it is very possible for vitamin D supplementation to have a profound impact on the course of this disease," said senior author Emmanuelle Waubant, MD, PhD, an associate professor of neurology at UCSF and director of the Regional Pediatric MS Center at UCSF Children's Hospital. Waubant said she expects similar findings in adult patients with MS.
Multiple sclerosis is a chronic and often disabling disease that affects the central nervous system, which comprises the brain, spinal cord and optic nerves. A type of autoimmune disorder, MS causes the body's own defense system to break down a substance called myelin, which surrounds and protects nerve fibers.
Although MS occurs most commonly in adults, a small proportion of cases are diagnosed in children and adolescents. According to the National MS Society, two to five percent of all people with MS experience their first symptoms before the age of 18.
The researchers measured vitamin D levels through blood samples from 110 patients whose MS symptoms began at age 18 or younger. The patients were seen at either UCSF Children's Hospital or the State University of New York Stony Brook's Regional Pediatric MS Center of Excellence - two of six multidisciplinary referral centers in the United States sponsored by the National MS Society.
After providing the initial blood sample, patients were followed for an average of 1.7 years, during which the researchers recorded the total number of relapses each patient experienced. According to Mowry, a relapse or flare-up of MS causes new neurologic symptoms or the worsening of old ones, such as impaired vision, problems with balance, or numbness. Relapses can be very mild or severe enough to interfere with a person's ability to function.
During the follow-up period, the researchers assessed the patients' relapse rates and vitamin D levels after controlling for such factors as age, gender, race, ethnicity, use of MS treatments and the duration of follow-up care.
"If we are able to confirm that vitamin D supplementation is an effective treatment, my hope is that it will help improve the quality of life for all MS patients," Mowry said.
In addition to a randomized clinical trial of vitamin D supplementation in MS patients, Mowry said further studies are also needed to determine the mechanism by which vitamin D affects inflammatory processes and, in turn, eases symptoms of MS.
Explore further: Human stem cell model reveals molecular cues critical to neurovascular unit formation