The sun sets over a field of snow

What we know about vitamin D and MS

Short winter days and long nights mean most of us are getting precious little sunshine. And this means lower levels of vitamin D.

We know the sunshine vitamin is good for us, but what do we know about its relationship with MS? We spoke with consultant neurologist Dr Ruth Dobson to find out more.

Hi Ruth! So, should people be taking vitamin D supplements?

In short, yes. But there’s no perfect dose for everyone.

The NHS recommended daily intake for all adults and children over the age of one is 400 IU (10 µg). This helps prevent vitamin D deficiency and promote healthy bones.

For people with MS, where vitamin D deficiency is more common, many clinicians recommend that people take a much higher dose of vitamin D, around 4,000–5,000 IU a day. This is particularly recommended for women of childbearing age who are planning a family.

This dose won’t do harm and importantly it may actually do some good in MS or for people who may be at risk of MS, like family members or anyone prone to vitamin D deficiency. But make sure to check with your neurologist or GP before taking this higher dose.

Should we be changing how much vitamin D we take across the seasons?

Vitamin D levels do fluctuate with the seasons. But actually, with modern lifestyles keeping us inside more, it’s probably better to take the supplements all year round. Especially as they do no harm at the recommended doses.

We know there’s a link between vitamin D levels and MS – can vitamin D supplements prevent MS?

We know people with lower levels of vitamin D at birth and throughout childhood have an increased risk of MS. But we don’t yet know if taking vitamin D supplements can have a significant impact on the risk of developing MS.

Finding this out would require following tens of thousands of people (or more) from early childhood through to adulthood over a period of about 30 years. This is something that is very hard to do!

However, researchers in Australia are looking at skin markers to sun exposure and their correlation with MS. There are hints that people who go onto develop MS have less sun exposure in childhood, but unfortunately the findings are far from conclusive.

What about taking vitamin D to slow MS progression?

We don’t know if taking vitamin D supplements will have an effect on MS progression.

Studies in mice have linked vitamin D to the immune system and myelin repair. And excitingly a recent human trial found that high doses of vitamin D reduced the number of some immune cells associated with MS.

So there’s definitely potential that vitamin D can play a role in MS treatment, but we’ve got quite a long way to go.

Can you tell us a bit about your own research?

The ultimate goal for us is to have a study to see if taking vitamin D supplements help people with MS. But before we can do this, we need an accurate picture of vitamin D levels across the MS population in the UK, and the factors that can influence this.

We know in general that people with MS have lower levels of vitamin D than the population as a whole. But as there are so many things that can influence vitamin D levels in the blood, including supplements, levels of sunlight, ethnicity and genetics, we don’t have a true representation of whether people with MS are actually vitamin D deficient.

So we recruited over 1,500 people through the MS Register, who completed a questionnaire about their MS and lifestyle choices that could affect vitamin D levels. The next stage will be to look at blood and saliva samples from these volunteers to measure their vitamin D levels and look at whether certain genes can affect it.

We hope the results of this study will inform any future trial testing whether vitamin D supplements could be an effective treatment for MS.

Read more about Ruth's research into MS and vitamin D

This blog first appeared as an article in Research Matters magazine. To get Research Matters by post please contact supportercare@mssociety.org.uk about subscription. You can also download the full issue for free.

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