Insufficient vitamin D may increase risk of multiple sclerosis

Added 01.10.2009

What is multiple sclerosis?

Multiple sclerosis (MS) is an autoimmune disorder involving the central nervous system that affects approximately 100,000 people in the UK. It can develop at any age, but people between the ages of 20 and 40 are most likely to suffer from it. MS is characterised by damage to the myelin sheath - the material that covers nerve fibres and ensures electrical signals or messages from the brain are being relayed quickly to the rest of the body. The myelin becomes damaged because the immune system thinks it is a foreign substance and it attacks it, hence the definition autoimmune disorder. When the myelin sheath becomes damaged, electrical signals are interrupted. This leads to MS symptoms, such as difficulty with movement and balance, pain, and muscle tightness and spasms.

The exact cause of MS in inknown; however, scientists have always suspected a combination of environmental and genetic factors played a role. A new study published this year may have found the key to how these two factors interact in the development of MS.

Vitamin D regulates a gene responsible for MS

Researchers have previously known that DRB1*1502 - a gene variant (an altered/mutated version of a similar gene) - played a role in the development of MS. The gene variant is located on chromosome 6, a region that plays a prominent role in the immune system. Individuals who carry one copy of this gene variant appear to be three times as likely to develop MS and those who carry tow copies are 10 times as likely to develop MS compared to individuals who do not carry any copy. What scientists had yet to discover was what environmental factor(s) regulated the function of DRB1*1502. A study published this year in the journal PLoS Genetics may have found just that.

It was discovered that vitamin D appears to control the function of DRB1*1502. More precisely, low levels of vitamin D in pregnant women could activate the variant gene in her children. This could explain why the incidence of MS is higher in Northern latitute countries, where year-round sunlight exposure is scarce. The mechanism is not fully understood; however, researchers think that in people who carry the gene variant and who also have low levels of vitamin D, a malfunction of the thymus occurs. The thymus, a small organ under the breastbone, is involved in the immune system and helps produce T cells (a type of white blood cell) that protect against infection. When the thymus is impaired, some of the T cells start attacking healthy cells including myelin sheath. Based on these findings, researchers hypothesise that "taking vitamin D supplements during pregnancy and the early years may reduce the risk of a child developing MS in later life."

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Dr. Bo Nielsen's comments:

This study is of extreme importance to people at risk of developing MS. For many years it has been well known that MS becomes more prevalent the further away people live from the equator. Several studies, including a recent Harvard study, now find a relationship that explains that the further north you live, the higher the risk of developing this serious disease. Lack of sunshine/lack of vitamin D seems to be an important contributing factor when combined with hereditary disposition. Exactly how much vitamin D you need is still not known.

Several recent studies describe the importance of having high levels of vitamin D - all year round - to prevent the development of several diseases including heart disease and cancer. This has lead many researchers to recommend taking supplements with dosages ranging between 2,000-5,000 IU daily. You should check your plasma levels of vitamin D regularly. Many researchers consider levels of 40-60 ng/ml (100-150 nMol.l) or even 60-80 ng/ml necessary to stay healthy.