Benefits of vitamin D for MS ‘inconclusive’
Growing evidence suggests that sufficient levels of vitamin D may protect against multiple sclerosis and supplementation may decrease the severity of symptoms in patients who already have the disease. However, the evidence is not conclusive and further research is warranted to better understand the benefits of vitamin D, according to the Mayo Clinic.
Healio spoke with Kathryn Cauley Fitzgerald, ScD, PhD, assistant professor of neurology at Johns Hopkins University School of Medicine, about the relationship between vitamin D and MS.
What does research suggest about the connection between MS and vitamin D?
Many different studies have demonstrated that risk for MS is higher in people with low vitamin D intake or low levels of 25(OH)D, a blood-based biomarker that is often used to characterize an individual’s vitamin D status. These studies were of various designs and included cell-based and animal studies, large observational studies and genetic epidemiology studies.
The genetic epidemiology studies are particularly interesting as they demonstrate that having a genetically-determined high risk for having low vitamin D levels is also associated with a higher risk for developing MS and implicate a potentially causal role of vitamin D in the development of MS risk in individuals of European descent.
One important note to consider is that many of the existing research studies were conducted in largely populations of European descent. It’s less clear if vitamin D levels contribute to risk in other populations, as there are some studies that suggest a differential association between vitamin D and MS risk in other racial/ethnic groups.
How do vitamin D levels influence MS disease activity?
In addition to MS risk, low vitamin D levels could also contribute to a more severe MS clinical course and higher levels of disease activity, as suggested by results of some observational studies. These studies implicate low levels as potential contributors to lesion development, relapse risk and faster accumulation of clinical disability. However, these studies were largely observational studies. The results of a few randomized clinical trials of more rigorous design evaluating the effects of vitamin D supplementation on MS outcomes are bit less clear.
Should clinicians recommend vitamin D supplementation to reduce MS symptoms?
Several studies have found a beneficial role of vitamin D supplementation, while others have not. Interpretation of these results as a whole is also challenging as each considered slightly different inclusion/exclusion criteria for participants, primary endpoints, and level of vitamin D supplementation. Further, there are several large, ongoing randomized trials of vitamin D supplementation in people with MS that are still ongoing.
From a research perspective, it’s currently too uncertain to provide recommendations for MS patient care based on vitamin D research.
What questions remain unanswered about the link between MS and vitamin D?
Right now, the effect of vitamin D supplementation on MS outcomes is relatively inconclusive. Several studies have demonstrated a positive effect of vitamin D on MS outcomes, but some of the larger randomized studies have failed to meet their primary endpoints. Because some randomized trials evaluating the effects of vitamin D supplementation are still ongoing, it will be important to consider the results of these studies in conjunction with what we know now. The optimal vitamin D levels to be achieved in people with MS is still inconclusive. If vitamin D supplementation is found to be generally beneficial in people with MS, the optimal supplementation dosage will be another existing question.
Reference
- Mayo Clinic. Vitamin D and MS: Is there any connection? Available at: https://www.mayoclinic.org/diseases-conditions/multiple-sclerosis/expert-answers/vitamin-d-and-ms/faq-20058258. Accessed January 31, 2020.