Vitamin D Facts
Where does vitamin D come from?
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 direct sunshine in the middle of the day will meet vitamin D needs for most fair skinned people1. Factors such as darker skin, the use of sunscreen, levels of pollution and the unpredictability of the British summer can all lower availability and between October and April, the level of ultraviolet is too low for vitamin D to be made.
There are dietary sources of vitamin D3 from fish and dairy products and vitamin D2 from plant sources, but at much lower levels than from sunlight.
As a result, 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.
Does vitamin D affect the risk of getting MS?
A number of studies have demonstrated an association between vitamin D levels and the risk of developing MS.
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. Another study of nurses found those who had later developed MS had lower levels of vitamin D from diet or supplements.
Exposure to vitamin D before birth has also been studied. A review of previous pooled information about the birth month of more than 150,000 people with MS. Instead of an even pattern across the year, they found that November was the higher risk month and April the lower. From this the researchers infer that the mother's exposure to vitamin D from sunlight during pregnancy is a factor on their child's risk of developing MS.
Vitamin D is not the only factor in the jigsaw that goes together to cause someone to develop MS, but it does seem to be one of the pieces.
What is known of vitamin D in people who have MS?
Whilst research has suggested a possible association between vitamin D levels and the risk of developing MS, what of vitamin D in people who already have MS?
A Dutch study of samples from 267 people with MS found that higher levels of vitamin D were associated with a lower relapse rate. People with progressive forms of MS had lower levels than those with relapsing remitting MS.
Although there seems to be an association between more active MS and low vitamin D levels, the nature of this association is difficult to determine. Are vitamin D levels a cause of MS activity or a result of it? Research in other conditions has shown that inflammation significantly reduces levels of vitamin D.
How much should you take?
The recommended daily intake in the UK 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 - for instance, the authors of the birth month data suggest 5000IU per day for adults and 10,000IU for pregnant women.
NICE (National Institute of Clinical Excellence) 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 the year 2013.
Sources of Vitamin D
- Fortified Cereals -
- Cheese -
NOTE: Before you take any form of medication please seek medical advice.
This information was sourced from the MS Trust Website.
For more on Vitamin D please visit the MS TRUST and MS SOCIETY.
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