An active area of research is the protective role of vitamin D in MS with evidence growing that vitamin D supplements could be part of an effective strategy in the management of MS.
What is Vitamin D and why is it linked to MS?
Vitamin D is needed by the body to aid in the absorption of a range of nutrients but particularly calcium. The majority of vitamin D is generated within the body through exposure to sunlight and as such is often referred to as the sunshine vitamin. It is however also be found to a small extent if foods such as oily fish, eggs, meat, milk and certain fortified foods.
Research has shown that in countries further away from the equator, that are therefore exposed to proportionally less UV light, the instance of MS is more common. Due to the possible influence sunshine has on these populations it has led researchers to delve deeper into a plausible link between vitamin D and MS.
The results of research so far
Pregnancy - some studies have indicated a 'month of birth' effect in that those people born in winter months seem to be at more risk of developer MS in later life in comparison to those born in the summer months. It's an interesting outcome but conflicting studies do exist and therefore more research is needed to ascertain whether vitamin D levels during pregnancy could affect the probability of a child developing MS later on in life.
Childhood - studies have shown a possible link between lack of vitamin D in childhood may increase the risk of developing MS later on. Research has indicated that people who have moved to a country during childhood tend to adopt the risk of the country they move to while those that migrate later in life keep the risk profile of the country of birth / early childhood. A study of note conducted in Switzerland showed that younger-age onset of MS was significantly associated with low exposure to sun in adolescence.
Genes - researchers in Oxford published a study back in 2009 that identified a link between vitamin D and a gene known to be associated with MS. Specifically they identified that when in the presence of vitamin D the gene signal was stronger and when not the signal was weaker. This research has provided the first bit of evidence indicating that an environmental factor may affect gene behaviour. A later study, published in 2015 by researchers in Canada suggested a causal link. From the research it appeared that people who are genetically predisposed to having low vitamin D levels are more likely to develop MS. Specially they identified four genetic variants closely associated with vitamin D levels and showed that people with those variants were a more risk of developing MS.
Myelin repair - 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 myelin making cells called oligodendrocytes increased by 80%. The focus of vitamin D research has been on a deficiency as a risk factor in MS however this work provides significant evidence that vitamin D could also be involved in the regeneration of myelin once the disease has started.
A number of studies have tried to determine if taking vitamin D supplements could be used to treat the symptoms of MS but these studies used different doses and forms of the vitamin so there is still not enough evidence to determine whether vitamin D supplementation is an effective and safe treatment for MS.
Many people with MS do however take vitamin D supplements despite this fact. It's also important to consider the risks associated with having too much vitamin D - a serious side effect is hypercalcemia - the build-up of high levels of calcium in the blood. Complications associated with hypercalcemia include: 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.