Low Vitamin D Linked to Multiple Sclerosis Symptoms
But large doses may do more harm than good, researchers say (Oct. 2)
Low blood levels of vitamin D are associated with an increased number of brain lesions and signs of a more active disease state in people with multiple sclerosis (MS), a new study finds, suggesting a potential link between intake of the vitamin and the risk of longer-term disability from the autoimmune disorder. But researchers at the Johns Hopkins University School of Medicine caution that more research is needed to determine whether large doses of vitamin D help without harming MS patients.
The findings were announced by Johns Hopkins on October 2 and were published in the Annals of Neurology.
The study shows a strong correlation between vitamin D levels in the body (measured through blood samples) and the characteristic brain lesions of MS, as measured by magnetic resonance imaging (MRI).
In people with MS, the body's immune system attacks the coating of nerve fibers in the brain and spinal cord. The coating, made of a fatty protein called myelin, insulates the nerves and helps them send electrical signals that control movement, speech, and other functions. When myelin is attacked, inflammation interferes with message transmission, and this activity shows up on MRIs as lesions, which look like white spots.
In relapsing-remitting MS — the most common form of the disease — patients may at times have no symptoms, but at other times they may experience relapses of symptoms such as blurred vision, numbness, and weakness. There is currently no cure for MS, but medications help reduce the number of relapses and help reduce symptoms left over if a person hasn’t fully recovered from a relapse.
The new report used data from a 5-year study of 469 patients with MS. Each year, beginning in 2004, the researchers drew blood from, and performed MRIs on, the brains of study participants, looking for both new lesions and active spots of disease, which “lit up” when a contrast dye was used.
The investigators found that each 10-ng/mL increase in vitamin D levels was associated with a 15% lower risk of new lesions and a 32% lower risk of spots of active disease, which require treatment with medication to reduce the likelihood of permanent nerve damage. Higher vitamin D levels were also associated with lower subsequent disability.
Some MS patients take extra vitamin D because of publicity about earlier studies. However, no research has proved that vitamin D alleviates the symptoms of MS or has identified the best or safest dose. Moreover, nothing is known about whether vitamin D can prevent MS, the researchers say.
For more information, visit the Johns Hopkins Web site.