Vitamin D

Evidence is growing for a protective role of vitamin D in MS, and it remains an active area of research with a number of unanswered questions. Without these answers, we don’t know whether taking vitamin D supplements could be a safe and effective strategy in the management of MS.

What is Vitamin D?

Vitamin D is required by the body to help absorb different nutrients, in particular calcium. It can be made by the skin in response to UVB radiation from sunlight so is sometimes referred to as the ‘sunshine vitamin’. Whilst the majority is generated through sun exposure, vitamin D is also found in small amounts in oily fish, eggs, meat, milk, margarine and some cereals and yoghurts are ‘fortified’ with vitamin D. A lack of vitamin D during childhood can cause rickets, and in adulthood can cause bone weakness.

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What is the link to MS?

Research has shown MS is more common in countries further away from the equator. As these countries also have less sunshine, this may influence the levels of vitamin D in these populations. This has led researchers to investigate a possible link between levels of vitamin D and MS.

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The research story so far

Understanding the link between vitamin D and MS is the subject of many researchers work and whilst there are still a lot of unanswered questions, we are learning more and more about the interaction.

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Some research has suggested a surprising ‘month of birth’ effect, where people born following the winter months appear to have an increased risk of developing MS later in life, compared with people born following the summer months. This could be due to mothers being exposed to lower levels of sunlight in winter than in summer.

Conflicting studies do not show a link and suggest this ‘month of birth’ result is only seen because other factors have not been correctly taken into account, like variations in the birth rate of the general population.

The evidence isn’t conclusive and more research needs to be carried out to determine whether vitamin D levels during pregnancy could influence the risk of the child developing MS later in life.

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Research shows a lack of vitamin D in early childhood or before birth might increase the risk of developing MS later in life. Studies show people who have migrated during childhood adopt the risk of the country they move to. But if people migrate later in life (in their twenties or later), they keep the risk profile of their country of birth. A study from Sweden in 2015 showed younger-age onset of MS was significantly associated with low exposure to summer sun in adolescence.

These studies indicate there may be an important role for vitamin D and other environmental factors in MS during childhood and early development.

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In 2009, researchers in Oxford published some ground breaking research identifying a link between vitamin D and a gene known to be associated with MS. They showed that when vitamin D was present the signal from the gene was stronger, and when absent, the signal was weaker.

This was the first piece of research in MS to show an environmental factor may change the way a gene behaves. It could help us understand more about the interaction between vitamin D and somebody’s risk of MS.

A 2015 study led by researchers at McGill University, Canada, implied a causal link. It suggests people who are genetically predisposed to having low vitamin D levels are more likely to develop MS. They found four genetic variants closely associated with vitamin D levels and showed people with these variants were at a higher risk of developing MS.

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As a treatment

There have been a number of studies which have tried to determine if taking vitamin D supplements could be used to treat the symptoms of MS. However, these studies use different doses and forms of the vitamin, and are often not carried out to a reliable standard, so there is still not enough evidence to tell us whether vitamin D supplementation is an effective and also safe treatment for MS.

A Finnish study from 2012 looked at 100 people with relapsing remitting MS, 66 of whom were given vitamin D supplements in addition to their usual treatment with interferon beta. They found those who received vitamin D had fewer lesions after 12 months, however there was no difference in levels of disability or the number of relapses that people experienced.

Another 2012 study involved 69 people with MS from Norway, and compared the effect of vitamin D3 versus a placebo on relapse rates and disability levels. Although levels of vitamin D were found to be twice as high in the treatment group compared to those taking the placebo at the end of this two-year study, there was no difference between the groups in either the number of relapses or levels of disability.

In a phase 2 clinical trial in Iran, 25 people with relapsing remitting MS received a different form of vitamin D supplement or a placebo. An Australian study in 2011 also used another form of vitamin D, vitamin D2, which is not as well understood as vitamin D3, in 23 people with relapsing remitting MS. Neither of these studies found these alternative forms of vitamin D improved the symptoms of MS.

A small US study in 2015 involving 40 people with relapsing remitting MS uncovered a role for high dose vitamin D in MS. Participants in the study were given either 10,400 international units (IU) or 800 IU of vitamin D3 supplements daily for 6 months. Both of these doses were higher than the 600 IU vitamin D daily recommendation. 

The optimal level of vitamin D in the blood for people with MS has still to be determined, but the study showed a decrease in some of the specific immune system cells associated with MS in people taking the higher dose (10,400 IU). The same was not seen in people taking the lower dose (800 IU) during the study.

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Myelin repair

A piece of research from the Cambridge Centre for Myelin Repair in 2015 has shown vitamin D may have a role to play in myelin repair. Researchers identified the vitamin D receptor protein pairs with an existing protein already known to be involved in myelin repair, called the RXR gamma receptor. By adding vitamin D to brain cells where the proteins were present, they found the production rate of oligodendrocytes (myelin making cells) increased by 80%.

The focus of vitamin D research has been on a deficiency as a risk factor in MS. This work provides significant evidence that vitamin D could also be involved in the regeneration of myelin once the disease has started.

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A research priority

We’d now like to see more studies to understand whether taking vitamin D supplements could, in time, be an effective and safe treatment for people with MS. Investigating vitamin D supplementation as a disease modifying treatment is one of our top 10 research priorities.

Our Clinical Trials Network (CTN) has set up a working group which aims to address this issue for people with MS. The CTN is a diverse group of research experts, clinical trial methodologists and people with MS with individual expertise in different areas. They will work together to commission new research and will work towards developing a clinical trial investigating vitamin D supplements and MS.

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Should I be taking vitamin D supplements?

If you are worried about your vitamin D levels and think you might be deficient, you should discuss this with your health care professional.

In July 2016 the Government's Scientific Advisory Committee on Nutrition recommended that everyone in the UK take supplements to ensure they receive sufficient Vitamin D (10μg/400IU per day for those aged one years and above,  8.5-10μg/400IU per day for those under one). This includes pregnant and breastfeeding women and those at risk of vitamin D deficiency.

These recommendations are to ensure good musculoskeletal health and are not related to MS or other autoimmune diseases. They follow studies suggesting that most people in the UK are not getting sufficient vitamin D from diet and sunshine alone.

Many people with MS take vitamin D supplements, and whilst research so far points towards a role for vitamin D in MS, we don’t know if this translates effectively to someone taking a supplement. We don’t have concrete evidence to show taking supplements will reduce someone’s risk of developing MS or reduces symptoms or slows disease progression. Interestingly, a recent review of vitamin D supplementation research published in the Lancet found supplementation brings no significant health benefits for healthy people.

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As we see more research looking into the role of vitamin D in MS, it is easy to see why vitamin D supplements are attractive. There are risks associated with having too much vitamin D which should be taken into consideration.

One of the more serious side effects of taking too much vitamin D is hypercalcemia - the build-up of high levels of calcium in the blood. Complications associated with hypercalcemia include (but are not limited to): kidney and bile stones, bone pain, nausea, vomiting, psychological effects and abnormal heart rhythms.

The NHS recommends people taking vitamin D supplements not to exceed 1000IU (25 micrograms) per day. The European Food Safety Authority have published new guidance on the upper tolerable levels for vitamin D, which suggest that adults should not exceed 4000 IU (100 micrograms) per day as there no evidence for safety above this level.

If you are concerned about supplements, you should speak to your healthcare professional.

They will be able to test your levels of vitamin D to see if you are deficient and provide guidance.

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Page last updated: 22 Jul 2016

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