The worldwide prevalence and incidence of multiple sclerosis (MS) are on the increase. The need for strategies to prevent this devastating disease is therefore greater than ever.
As highlighted in a Review in this issue of The Lancet Neurology, vitamin D deficiency might be an important modifiable risk factor for MS. This raises the question of whether population-wide supplementation programmes might be a reasonable prevention strategy.
Vitamin D deficiency is especially common in high latitude regions, such as northern USA, Canada, northern Europe, and New Zealand, where weaker ultraviolet B rays during winter months are insufficient for people to produce enough vitamin D. Vitamin D deficiency has traditionally been linked to bone diseases such as rickets; in addition to MS, links with other diseases such as type 1 diabetes, heart disease, infectious diseases, and some types of cancer are now emerging. Pregnant women, young children, and the elderly are at the greatest risk. Vitamin D deficiency might also adversely affect disease course in many disorders, including MS, although evidence for this is less robust.
The main sources of vitamin D are sunlight and diet, but many people do not get sufficient amounts, so dietary supplements are required. The current recommended daily intake of vitamin D is typically 200—400 IU/day in Europe, and in the USA and Canada, where some foods are fortified with vitamin D, the recommendation is for 200—600 IU/day. The US National Academy of Sciences' Institute of Medicine is currently reviewing the dietary reference intakes for vitamin D and calcium and is due to report its recommendations at the end of summer 2010.
Expert recommendations for optimum serum vitamin D concentrations range from 50 nmol/L to 100 nmol/L; the total daily need for vitamin D, from sunshine, diet, and supplementation, to achieve this concentration is thought to be 1000—4000 IU/day, depending on factors such as age, geographical region, and health status. The risks of taking high doses of vitamin D are thought to be low, and the main concern of overdose is hypercalcaemia. However, given that an adult who spends 20 min in summer sunshine can produce an oral intake equivalent of about 10 000 IU/day, the suggested dose of 1000—4000 IU/day is unlikely to be toxic. Recent evidence suggests that prolonged intake of 10 000 IU/day (and even up to 40 000 IU/day) poses no risk for adults.
So far, the evidence for a protective effect of vitamin D on MS largely comes from ecological and observational studies, although evidence is accumulating on possible mechanisms linking vitamin D deficiency and autoimmunity. Large-scale, long-term randomised controlled trials on high-dose vitamin D supplementation would be needed to definitively establish a protective effect and to identify any unexpected long-term complications. But it could take decades before data on MS prevention become available.
In the meantime, because the risks seem to be low, is there already a case for widespread vitamin D supplementation?
Scotland is one such region where the prevalence and incidence of MS, and other diseases related to vitamin D deficiency, are already so high that the benefits of supplementation are likely to outweigh any potential side-effects. During an upcoming summit in Scotland, hosted by MS Society Scotland and resulting from the Shine on Scotland campaign, researchers will present the case to Scottish government officials for vitamin D supplements to be made freely available for all young children and pregnant women.
As vitamin D is an inexpensive supplement, the potential cost savings of such a programme are enormous, and in addition to MS, might have implications for numerous diseases linked to vitamin D deficiency. In Europe, if the predicted effects of raising serum vitamin D concentrations to 100 nmol/L are realised, the potential savings have been estimated to be €187 billion per year from the direct and indirect burden of disease, set against an expenditure of €10 billion on testing and public education. As well as the possible health benefits, such a supplementation programme might provide important research opportunities to understand the long-term effects of vitamin D.
Trials are needed to address the numerous questions that remain to be answered about dosing levels, potential long-term complications, and causal mechanisms, among others. In the meantime, given the low costs, low toxicity, and possible beneficial effects of supplementation programmes, steps to tackle vitamin D deficiency in high-risk populations seem warranted. Because any benefits for MS in particular will take decades to emerge, a long-term outlook is needed from policy makers, but future health and financial benefits have the potential to make this investment highly rewarding.
Source: The Lancet Neurology Copyright © 2010 Elsevier Limited. (25/05/10)
MS Society Scotland :
Vitamin D – Renewed Hope for MS Prevention
25.05.10The current issue of The Lancet Neurology contains a review of evidence on vitamin D deficiency as a possible risk factor for MS, raising the question of whether supplementation programmes could be a reasonable prevention strategy. The review concludes that “given the low costs, low toxicity, and possible beneficial effects of supplementation programmes, steps to tackle vitamin D deficiency in high-risk populations seem warranted”. Scotland is specifically identified as a country where the large numbers of people living with MS, and other conditions related to vitamin D deficiency, make it likely that the benefits of supplementation would outweigh any potential side-effects.
The Lancet article mentions the Shine on Scotland campaign and the international summit on vitamin D and MS which the MS Society Scotland will be hosting in September. Leading researchers from around the word will be coming to Scotland for the summit and presenting the latest research to build the case for taking action on vitamin D as a public health issue.
Over the longer term, as the article makes clear, trials are needed to address questions about dosage levels, long-term implications and causal mechanisms but this is not viewed as an impediment to beginning a supplementation programme now or in the very near future. The potential savings are simply huge – estimates suggest that €187 billion per year could be saved across Europe by tackling vitamin D deficiency.
Commenting on the article, David McNiven, Director of MS Society Scotland, said:
“The Lancet article is very encouraging because it endorses the arguments that we have been making: that vitamin D supplementation represents a low-cost, low-risk public health intervention with potentially massive benefits. I very much look forward to welcoming internationally renowned scientists to Scotland later this year to explore the issue further. The Shine on Scotland campaign has made incredible progress in just over a year and the MS Society Scotland will continue to work with the Scottish Government and others on this important matter of public health”.
The full Lancet article can be accessed at www.thelancet.com
There is also a review article which discusses some of the areas where research is needed, for example the influence of vitamin D in MS progression. Vitamin D review article
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