Lack of vitamin D may be a direct cause of multiple sclerosis (MS), a study has found. MS occurs when the immune system attacks the protective myelin sheath that surrounds nerve fibres and acts as an insulator. Nerve signals are disrupted, leading to symptoms that can range from mild tingling sensations to full-blown paralysis. In rare cases that progress rapidly, the disease can be fatal. Dr Benjamin Jacobs, from the Royal National Orthopaedic hospital in London, said: “This study reveals important new evidence of a link between vitamin D deficiency and multiple sclerosis. The results show that if a baby is born with genes associated with vitamin D deficiency they are twice as likely as other babies to develop MS as an adult. This could be because vitamin D deficiency causes MS, or possibly because there are other complex genetic interactions.”
Scientists who scoured the DNA of 33,996 participants identified four single-letter variants in the genetic code that were closely associated with a vitamin D blood marker.
Vitamin D generated by sunlight is converted in the body into the blood marker 25-hydroxyvitamin D (25OHD). This is then further converted into the active form of the vitamin, calcitriol, which acts as a powerful hormone. 25OHD levels in the blood. Previous studies have suggested an association between lower vitamin D levels and a higher risk of MS. But now scientists have demonstrated a genetic correlation that points strongly to a causal link. The finding provided “strong evidence in support of a causal role of vitamin D in MS susceptibility”, said the scientists. They added: “Whether vitamin D sufficiency can delay or prevent multiple sclerosis onset merits further investigation in long-term randomised controlled trials.”
Prof Danny Altmann, an immunologist from Imperial College London, said: “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.