How does vitamin D work in multiple sclerosis?
A reader recently asked, after noticing a plethora of articles on vitamin D and multiple sclerosis (MS), how does vitamin D actually work in this condition? Yes, we see it’s probably important for MS, but why? How does it work? The Vitamin D Council asked me to write on this topic, which I systematically reviewed just this past March.
To start, I’d like to note that while it appears that vitamin D and sunlight play a strong role in preventing the development of (MS), researchers are still trying to pinpoint exactly how it works. Researchers may discover that vitamin D is essential for preventing MS without fully understanding the mechanisms.
MS is an autoimmune condition where the body’s immune system attacks the nerves in the brain and spinal cord. In 1974, Goldberg was the first to suggest a link between vitamin D and MS. He noted that MS was much more common in areas with less sun and proposed that the resulting low vitamin D levels of people in these areas interfered with their ability to properly form nerve cells.
In 1986, Goldberg performed a very small study in which he supplemented MS patients with 5,000 IU of vitamin D per day by giving them cod liver oil. The patients also received magnesium and calcium. There was no placebo group, but those receiving the vitamins had a significantly lower rate of relapses than before treatment.
Since Goldberg’s work, a large amount of research continues to link low sun exposure and vitamin D levels with MS. Several recent clinical trials have yielded promising results, but they include too few people to make solid conclusions about the role of vitamin D in preventing and treating multiple sclerosis.
But just what are the proposed mechanisms for how vitamin D might treat and prevent MS?
The majority of the research linking vitamin D and MS is actually research studying the link between the amount of sun exposure people get and whether or not they develop MS. Because people that report being in the sun more have less risk of developing MS, and because most people get their vitamin D by exposing their bare skin to sunlight, it is assumed that vitamin D is primarily responsible for this protective effect, though we need more research to say for sure.
As mentioned above, multiple sclerosis is an autoimmune disease where the body’s own immune system attacks insulating sheaths of nerve cells in the brain and spinal cord. The result is the body has a hard time communicating with itself. Vitamin D and sunlight – if effective – probably work by smartening the immune system and decreasing inflammation.
Sunlight contains ultraviolet (UV) A and B radiation. UV radiation affects the immune system, making it less inflammatory and less likely to attack other cells of the body. A handful of animal studies show that UVB radiation alone, without any significant vitamin D production, suppresses the symptoms of MS.
Many cells of the immune system have vitamin D receptors and activate vitamin D for their own use. In laboratory studies, when immune cells are exposed to active vitamin D, they become less inflammatory and decrease the amount of antibodies they produce. These changes might mean that the immune system can function more normally and not attack other areas of the body, like the brain and spinal cord.
Cells throughout the brain and spinal cord also have vitamin D receptors. In studies where very large doses of vitamin D are given, the type of nerve cell break down usually seen in MS patients is significantly reduced. Thus it appears that vitamin D works somehow by promoting normal nerve cell development and protecting the cells from attack by an immune system gone awry.
Lastly, researchers are looking at differences in genes that encode for the enzymes that make and break down vitamin D. This could mean inheriting certain genes increases your risk for developing MS because your ability to make and maintain levels of activated vitamin D is altered. The HLA-DRB1*1501 gene is most strongly associated with multiple sclerosis, and in vitro studies show that vitamin D regulates how it expresses itself.
The link between vitamin D deficiency and MS is one of the most exciting areas in vitamin D research, and researchers are scrambling to learn more about the role vitamin D can play in the prevention and treatment of MS. We should have a better idea of just how it is vitamin D works to prevent MS from developing and a better understanding of how much oral vitamin D people with MS should take to treat their condition in the next 5 years or so.
Sources
Goldberg, P. Multiple sclerosis: vitamin D and calcium as environmental determinants of prevalence (A viewpoint) part 1: sunlight, dietary factors and epidemiology. Intern. J. Environmental Studies. 1974;6(1)19-27.
Goldberg P, Fleming MC, Picard EH. Multiple sclerosis: decreased relapse rate through dietary supplementation with calcium, magnesium and vitamin D. Med Hypotheses. 1986;21(2):193-200.
Holmøy T, Kampman MT, Smolders J. Vitamin D in multiple sclerosis: implications for assessment and treatment. Expert Rev Neurother. 2012;12(9):1101-12.
Faridar A, Eskandari G, Sahraian MA, Minagar A, Azimi A. Vitamin D and multiple sclerosis: a critical review and recommendations on treatment. Acta Neurol Belg. 2012;112(4):327-33.
Ho SL, Alappat L, Awad AB. Vitamin D and multiple sclerosis. Crit Rev Food Sci Nutr. 2012;52(11):980-7.
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