A to Z of MS Vitamin D

Vitamin D has several important roles in the body including regulating immune responses. Its possible role in multiple sclerosis is the focus of much debate and research.

Sources of vitamin D

Vitamin D can be obtained in several ways. It is manufactured by the skin when it is exposed to sunlight, can be obtained in the diet or as supplements.

The best way to get vitamin D is summer sunlight. Although it is hard to generalise across the UK, sitting outside for 20 to 30 minutes without sunscreen in short sleeves at midday between May and September should be enough for fair skinned people. However, it is important not to get red or burnt as this raises the risk of skin cancer. Between October and April, the sunlight in the UK usually has too low a level of ultraviolet B (UVB) for vitamin D to be made.

Vitamin D is found in some foods including oily fish, such as salmon and sardines, and cod liver oil. Lower amounts are found in eggs, fortified fat spreads and breakfast cereals and in powdered milk. Vitamin D is not needed in the diet every day. This is because the body stores any vitamin D that is not needed immediately for future use.

Many people can get all the vitamin D they need by eating a healthy balanced diet and by getting some sun. When sunlight levels are low, such as in the winter or in more northerly areas, obtaining vitamin D from the diet or as supplements becomes more important. This applies particularly to people with darker skin, pregnant women, children and older people.

For people with MS who have difficulty getting outdoors regularly or who suffer from heat-induced fatigue, supplements can also be useful. However, there is much debate as to what is an appropriate dose for people with MS.

More information is available in our Vitamin D factsheet.

Vitamin D and MS

Research into the possible role of vitamin D has focused on two areas:

• Whether lack of vitamin D contributes to the risk of developing MS
• Whether low levels of vitamin D affect the number of relapses and the disease course.

Causes of MS

It appears that many factors influence whether someone gets MS including lack of sunlight and vitamin D.

Studies of the distribution of MS around the world show that it is generally more common the further you are from the equator. This suggests a link between lack of exposure to sunlight, consequent lack of vitamin D production and the development of MS.

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

Vitamin D may also play a role before birth as more people with MS are born in May than in November. The mothers of these people would have been in the later stages of pregnancy during the darker months of the winter.

More information is available in our Vitamin D factsheet.

Vitamin D levels in people with MS

There is some evidence that lower levels of vitamin D are associated with higher relapse rates and greater disability. Also, one study found that people with progressive forms of MS had lower levels than those with relapsing remitting MS.

There have only been limited studies on treatment with vitamin D in MS but a significant reduction in relapses was seen. More information on these studies is available in our Vitamin D factsheet.

Studies are underway to look more closely at vitamin D deficiency in people with MS and to investigate what might be a safe and therapeutic dose.

Vitamin D: new guidance
MS Trust news item - 22 December 2010
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