A to Z of MS Vitamin D

The role of vitamin D in multiple sclerosis has been the focus of ongoing research.

Vitamin D is manufactured by the skin when it is exposed to sunlight. In theory then, the less sun exposure, the less vitamin D produced by the body. Studies of the geographical distribution of MS support the link between lack of sunlight exposure, consequent lack of vitamin D production, and the development of MS.

The majority of studies have focused on the role of vitamin D as a protective agent against the development of MS.

A review of blood samples taken from US military personnel found that levels of vitamin D in people who subsequently developed MS were lower than levels in people without the condition. This effect only seemed to occur in samples from white people, and was not demonstrated in the smaller set of samples from black of Hispanic people.

Another study found that amongst sets of identical twins, where only one of the twins had MS, the twin who had engaged in less outdoor activity as a child had encountered less sunlight exposure and was the twin more likely to have developed MS.

In laboratory experiments, researchers showed that a lack of vitamin D alters the DRB1 gene, a gene that has a direct role in the functioning of a healthy immune system. From this it is suggested that a lack of vitamin D during pregnancy and in the early years of life could increase the risk of developing the condition later in life.

Researchers have also observed that a higher proportion of people diagnosed in the spring. The mothers of these people would have been in the later stages of pregnancy during the darker months of the winter.

More recently, studies have focused on the potential immunomodulatory effects of vitamin D in multiple sclerosis. In one study, 132 Hispanic people with MS were studied. The study found that levels of vitamin D were significantly lower in people experiencing relapse than people who were in remission. Further studies are needed to confirm these findings and clarify the potential therapeutic role of vitamin D supplementation throughout the course of MS.

References

Munger KL, et al.
Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis.
Journal of the American Medical Association 2006;296(23):2832-2838.
abstract

Islam T, et al.
Childhood sun exposure influences risk of multiple sclerosis in monozygotic twins.
Neurology 2007;69:381-388.
abstract

Ramagopalan SV, et al.
Expression of the multiple sclerosis-associated MHC class II Allele HLA-DRB1*1501 is regulated by vitamin D.
PLoS Genetics 2009;5(2):e1000369.
abstract

Bayes HK, et al.
Timing of birth and risk of multiple sclerosis in the Scottish population.
European Neurology 2009;63(1):36-40.
abstract

Correale J, et al.
Immunomodulatory effects of vitamin D in multiple sclerosis.
Brain 2009;132(5):1146-1160.
abstract

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