A new study suggests that in patients with multiple sclerosis (MS), higher levels of vitamin D are associated with a decreased rate of both disease activity and disease progression. Does this mean that all patients with MS should be encouraged to take vitamin D supplements? Or that if—as some media reports have suggested—all people take vitamin D supplements, they can somehow decrease their risk of MS?
Previous research has indicated a connection between low levels of vitamin D and risk of developing MS or having MS symptoms worsen, but those studies included patients with longstanding MS whose vitamin D levels could partly be a consequence, not a predictor, of disease severity. This new study looked at vitamin D levels among patients at the time of their first symptoms and who were taking interferon.
Researchers examined whether blood concentration of 25-hydroxyvitamin D (25[OH]D), a marker of vitamin D status, was associated with MS disease activity and progression in patients with a first episode suggestive of MS.
Blood 25(OH)D levels were measured as part of a randomized trial originally designed to study patients given interferon beta-1b treatment or placebo. A total of 465 patients (of the 468 enrolled) had at least one 25(OH)D measurement. Patients were followed for up to 5 years with magnetic resonance imaging.
Increases of 50 nanomoles per liter (nmol/L) in average blood 25(OH)D levels within the first 12 months appeared to be associated with a 57% lower risk of new active brain lesions, 57% lower risk of relapse, 25% lower yearly increase in T2 lesion volume, and 0.41% decreased yearly loss in brain volume from months 12 to 60. This last metric is an important predictor of disability. The effect was noted in patients who had received either interferon or placebo, suggesting that the effect is not related to the interferon itself.
THE BOTTOM LINE
The authors stopped short of saying that the vitamin D levels are a cause of MS or that all patients with MS should take vitamin D supplements. However, they do believe that vitamin D is not a consequence of MS, but rather a predictor of the eventual course. In other words, newly diagnosed patients with suspected MS who take interferon and have lower vitamin D levels confirmed by testing might be expected to show more deterioration over time. It may be that this subgroup of patients will benefit from vitamin D supplementation.
However, there are some important limitations to this study.
This study was based on people with documented early MS who were taking interferon. We don't know whether the effects can be generalized to people who are in later stages of their disease or to patients who receive oral medications as a first-line treatment. The population studied was primarily white and European, so it's not clear whether ethnicity (and the availability to obtain vitamin D from sunshine) play a role in these results. The average age of the patients was 30, so it's not clear if these results would be the same in older patients. The study was conducted over 5 years. Given the long-term nature of MS and its volatility in producing relapses and remissions, it's not clear whether these results will be sustainable over more than 5 years. And these data certainly do NOT indicate that vitamin D supplementation will cure MS.
Because low vitamin D levels are common and can be easily and safely increased by oral supplementation, these findings may contribute to better outcomes for many MS patients. But remember, vitamin D can be toxic in very high doses over the long term; no patient should receive high doses of vitamin D supplementation without having a blood test first.