Vitamin D and multiple sclerosis: what’s going on?

Most neurologists know very little general medicine. OK, minor correction- I no longer know very much general medicine and it is arrogant for me to assume that all my colleagues are the same (although I am pretty sure that they are…). Anyway, the one minor detail regarding endocrinology that I had managed to tuck away deep in some unsuspecting neurones of my hippocampus was that vitamin D was good for your bones. I tell most of my elderly patients and the ‘senior’ female members of my family that there is nothing better than drenching yourself in 15 minutes of the Australian sun every day. In my overly simplistic mind, this will mean that you are less likely to break a bone.

When I was at medical school, I did not think that vitamin D would have much to do with Neurology or more specifically with this wonderful material called myelin. Recently however, there has been a plethora of publications from all corners of the world that have explored the interaction between Vitamin D and multiple sclerosis risk. In this issue of JNNP, Lin et al (1) from Tasmania, Australia provide another contribution from their large ongoing study of the role of environmental factors in the development of MS. In short, their study suggests that there are genetic influences which may modify the effects of Vitamin D and its subsequent role in determining clinical activity in MS.

This is a very interesting paper but until randomised evidence is available, the question still remains: what are we to do in recommending vitamin D supplementation? There are so many things to remember when you are counselling MS patients that this is something that may be forgotten. So, exactly how important do you think it is? In most countries in the world, it is near impossible to maintain normal vitamin D levels all year around. Should all MS patients be on replacement? Do we repeat levels periodically and should we boost supplementation further if we are not hitting the high normal range? A patient of mine the other day had a MS relapse after many years of excellent control on disease-modifying drugs. She asked me if we could check her vitamin D level. It was low and she has put the relapse down to this. I told her that there was no evidence for thinking this way. Her response: ” then why on earth did you ask me to take vitamin D supplements”? I think she has a point…

I would love to hear from other neurologists out there. What exactly do you do and more importantly, why are you doing it?

(1)    Lin et al., Novel modulating effects of PKC family genes on the relationship between serum vitamin D and relapse in multiple sclerosis. J Neurol Neurosurg Psychiatry 2014;85:399-404

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