A study published this year by the American Neurological Association investigated the relationship between 25(OH)D levels and the development of new brain lesions in patients diagnosed with multiple sclerosis (MS).
MS is an autoimmune disease that causes the body’s immune system to attack its own central nervous system. The majority of MS sufferers experience attacks that alternate with periods of relapse. The damage from these attacks can show up on an MRI as lesions on the brain. An increase in lesions is associated with an increase in disability, as measured by the Expanded Disability Status Scale (EDSS).
Low vitamin D status, along with cigarette smoking and infection by the Epstein-Barr virus, is a known risk factor in the development of MS. Recent research has associated lower vitamin D levels with an increased risk of relapse in patients with MS, but this research has not investigated whether lower vitamin D levels are associated with changes in the brain as measured by MRI. This is likely a more objective method of measuring the progression of the disease, rather than self-assessed health status.
In this study, led by Ellen M. Mowry, MD, 469 white MS patients between the ages of 18 and 70 were included in the five year study. Subjects received a yearly MRI and gave a blood sample to measure 25(OH)D status. The number of new T2 or gadolinium-enhancing lesions, as well as relapses, was recorded along with a measurement of the EDSS score.
Data was adjusted for multiple variables, including HLA-DRBI status (a gene associated with enhanced MS risk). Subjects were also assessed individually to isolate within-person changes in 25(OH)D levels and subsequent disease outcome.
Over the five year period, average 25(OH)D levels rose by 5.3 ng/mL as compared to baseline. This is most likely due to self-reported vitamin D supplement use, as only 9% of subjects were taking vitamin D at baseline compared to 43% at the conclusion of year five.
In univariate models, each 10 ng/mL increase in 25(OH)D levels was associated with a 15% lower risk of developing new T2 lesions. This effect persisted even after adjustment of the data for multiple variables. The effect was also seen for gadolinium-enhancing lesions, such that each 10 ng/mL increase in serum vitamin D levels was associated with a 32% reduction in the risk of developing such lesions.
A potential interaction between 25(OH)D levels and HLA-DRBI status was noted, with subjects testing positive for at least one HLA-DRBI allele receiving less protection from vitamin D than HLA-DRBI negative subjects. Although those subjects in the highest quintile of serum vitamin D levels had the lowest risk of relapse, the results were not statistically significant.
It is noteworthy that the within-person effect of vitamin D on MS progression is even more protective than the effect seen study-wide. This strengthens the association found within the study because within-person effects are less likely to suffer from confounding at the individual level. The prospective nature of the study was also more likely to accurately assess the relationship between serum vitamin D levels and disease outcome. A prior study that found no association between vitamin D status and MS outcome was cross-sectional in design, potentially diminishing its ability to detect an effect between the variables.
Interestingly, the authors conclude that their results do not justify the use of vitamin D supplements in patients with MS and call for randomized controlled trials to determine the actual effects of vitamin D, both positive and negative. This stands in sharp contrast to the results of a recent expert review on the role of vitamin D in the prevention and treatment of MS the Vitamin D Council recently covered:
While the authors of the review concede there is not sufficient evidence to recommend a specific 25(OH)D blood level to patients with MS, they conclude that the majority of the evidence indicates higher vitamin D levels might very well be protective to MS patients and there is no compelling reason to avoid supplementation.
The Vitamin D Council recommends that individuals maintain blood levels of 50 ng/mL, and this may very well prove to be therapeutic for patients suffering from MS, something future research will better discern in years to come.