Effects of vitamin D on skeletal and non-skeletal functions, including immune functions, has developed considerably over the past 3 decades. Higher levels of vitamin D are associated with reduced risk for developing multiple sclerosis (MS), and with reduced clinical activity in established MS, including decreased risk of relapse and reduction in disease activity on brain MRI .Vitamin D supplementation may diminish the risk of MS in the general population, as well as in children of mothers supplemented before and during pregnancy . In the information that follows, we will summarize the available data on vitamin D, with a focus on vitamin D’s effects on the risk of onset of MS and on the disease course of MS.

What is Vitamin D ?

Vitamin D is fat soluble vitamin. It helps regulate calcium metabolism. It is important in promoting absorption of calcium/phosphorus in the gut to support bone integrity. Vitamin D is synthesized by the skin from sunlight. Vitamin D needs to undergo conversion from its inert state by process of hydroxylation initially in the liver. Signs and symptoms of the deficiency

• Fatigue and muscle weakness
• Joint pain
• Infections and illness
• Immune system disorders
• Nervous system malfunctions

The Importance of vitamin D

• helping with the absorption of calcium
• maintaining healthy bones
• regulating genes and cell growth
• preventing rickets and osteoporosis
• modulating the immune system
• lower the chances of MS disorder Roles of Vitamin D in immunity.

Since multiple sclerosis (MS) is considered an autoimmune disease, it is of interest to briefly review the potential effects of vitamin D related to immune function. The active form of vitamin D plays an essential role in lymphocyte activation and proliferation, T-helper cell differentiation, tissue-specific lymphocyte homing, the production of specific antibody isotypes, and regulation of the immune response. Targeted immune cell types include macrophages, dendritic cells, and T and B cells. Mora and colleagues summarized the roles and effects of vitamin D on these immune cell types.

Vitamin D levels and MS susceptibility.

Since vitamin D was proposed as an important factor in MS development in the 1970s, numerous experimental and epidemiologic studies have been conducted to answer key questions such as Does vitamin D prevent MS? How does vitamin D impact MS activity? and Can vitamin D supplementation favorably alter the course of MS? Observational study data does suggest that adequate vitamin D levels may reduce the risk of MS and affect the course of the disease. However, study limitations restrict the extent to which inverse associations can be attributed to vitamin D, and additional studies are needed to further understand the nature of this association

Dietary intake of Vitamin D and MS risk (case study)

colleagues evaluated the association between calculated vitamin D intake from diet or supplements and the risk of developing MS .Women who had a higher intake of dietary vitamin D (approximately 700 IU/day) had a 33% lower incidence of MS compared with those with lower intake. In addition, women who used vitamin D supplements (≥ 400 IU/day) had a 41% reduced risk of developing MS compared to non-users. Having higher levels of 25(OH)D (irrespective of dietary vitamin D intake) also seems to predict a lower risk of MS onset. Using a longitudinal study design, Munger and colleagues evaluated serum vitamin D levels derived from blood samples of seven million US military personnel. Those with 25(OH)D levels greater than 100 nmol/L (40 ng/mL) had a 62% lower chance of subsequently developing MS .

Vitamin D supportive food options

Egg yolk , yogurt , cheese , red meat , liver , oily fish ( tuna and sardines ) and fortified breakfast cereal .

Summary

Evidence available to date suggests that the level of serum vitamin D affects the risk of developing MS and also modifies disease activity in MS patients. Until several years ago, evidence that higher levels of vitamin D are associated with favorable effects on MS risk and a reduction in MS activity was supported largely by observational studies. Limitations of these studies restricted confidence in a specific effect of vitamin D in MS. Newer data with Mendelian randomization analyses suggest there is a causal relationship between low vitamin D level and the risk of MS

References

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