A to Z of MS
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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.
Vitamin D (vitamin D3) is created in the skin when exposed to ultraviolet B radiation in sunlight. In the UK, between May and September, about 20 to 30 minutes a day spent outdoors in short sleeves in direct sunshine in the middle of the day will meet vitamin D needs for most fair skinned people. 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.
Levels of vitamin D in the UK are generally low. The Department of Health reports that a quarter of the population have no more than a third of what is considered an adequate level.
For people with MS who have difficulty getting outdoors regularly or who find heat increases fatigue, supplements can also be useful. However, there is much debate as to what is an appropriate dose for people with MS.
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.
A review of blood samples taken from US military personnel showed that those with lower vitamin D levels had a higher risk of subsequently developing MS.
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.
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.
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.
Some small studies have suggested that treatment with vitamin D may reduce the number of relapses experienced and two larger studies, involving about 250 people each, are still ongoing.
Vitamin D dosage
The recommended daily intake in the UK (400IU) is based on reducing the risk of rickets and is widely considered to be too low. In August 2012, the European Food Safety Authority increased the Tolerable Upper Intake Levels (the levels that can be taken daily without causing harm) to 4000IU. Some authors feel this is also too low.
NICE has begun to consider the implementation of existing guidance on vitamin D, a review that will look at its role in general rather than specifically in MS. A consultation on the draft version of this is expected towards the end of 2013.
Davies SC, et al.
Vitamin D - advice on supplements for at risk groups.
London: DH; 2012.
download - (pdf 127kb)
Munger KL, et al.
Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis.
Dobson R, et al.
The month of birth effect in multiple sclerosis: systematic review, meta-analysis and effect of latitude.
Journal of Neurology Neurosurgery & Psychiatry 2012 Nov 14. [Epub ahead of print]
Smolders J, et al.
Association of vitamin D metabolite levels with relapse rate and disability in multiple sclerosis.
Multiple Sclerosis 2008;14:1220-1224.
European Food Safety Authority.
Scientific opinion on the tolerable upper intake level of vitamin D.
EFSA Journal 2012;10(7):2813.
Implementing Vitamin D guidance.
read on the NICE website