In a large prospective study of 332 children presenting to Canadian healthcare facilities with an episode of demyelination, researchers at the Toronto Hospital for Sick Children confirmed the strong associations of MS with genetic predisposition and low vitamin D status.53 They showed that, as well as a little over double the risk of developing MS for children with the particular genetic make-up of having one or more HLA-DRB1*15 alleles (a genetic marker for increased MS risk), for every 10 nmol/L lower the vitamin D level was, there was an 11 per cent increase in risk of going on to develop MS.