A study by researchers in Canada has found that people who are genetically susceptible to low vitamin-D levels are at a higher risk of multiple sclerosis (MS).
The findings of the large study, published in PLoS Medicine, support the theory that there is a link between low levels of vitamin D and MS.
In the study, the researchers examined the DNA of nearly 34,000 participants of European descent and identified four SNPs (single nucleotide polymorphisms) linked with significantly lower levels of a vitamin D blood marker.
When comparing people with MS and the healthy controls, the researchers found that those who possessed fewer of these SNPs, and were therefore prone to vitamin D deficiency, were twice as likely to have MS.
Previous observational studies have suggested an association between a lack of vitamin D and MS, but this is the first genetic correlation to be found.
The authors, led by Dr Brent Richards from McGill University, wrote: 'The identification of vitamin D as a causal susceptibility factor for MS may have important public health implications, since vitamin D insufficiency is common, and vitamin D supplementation is both relatively safe and cost-effective.'
MS is an autoimmune disease that damages nerves and spinal cord, causing problems in vision, balance and movement. A link between the disease and vitamin D has been posited for a while, as the incidence has been consistently shown to increase with latitude, and therefore decreasing sun exposure.
Vitamin D can be obtained through exposure to sunlight, as well as through diet in foods like eggs, oily fish or fortified foods such as cereal.
'In many of the other examples tried, the notion that all will be well if we simply give patients a large dose of vitamin D supplements has proved too simple,' commented Professor Danny Altmann from Imperial College London.
'However, vitamin D is relatively cheap, safe and many of us would be all the healthier if we could achieve the serum levels that our ancient ancestors presumably acquired when roaming outdoors in temperate climates, unclothed and eating a diverse diet including oily fish.'
Clinical trials are ongoing to assess vitamin D supplementation as a treatment method or preventative measure for MS.