Sunlight and Vitamin D

Oral Vitamin D supplementation – compiling the evidence

18 October, 2018
  • Low levels of vitamin D are associated with the onset of MS.
  • There have been a number of small clinical trials that used different methods to look at vitamin D in MS.
  • Now two studies have combined the findings of some of the smaller studies to enhance the evidence for vitamin D supplementation in MS.

Just recently two meta-analysis studies were carried out looking at the effects of vitamin D treatment on MS. A meta-analysis is a type of study which combines the findings of many smaller studies into one bigger cohesive study to enhance the evidence for a treatment.

Vitamin D has long been associated with MS, with the majority of the evidence to date being based on a link between low vitamin D and the onset of MS. This has led to the strong belief that vitamin D supplements could possibly help people with MS. One strong piece of evidence that has contributed to this notion is the latitude gradient in MS. This is the observation that in places with less sunlight the incidence of MS is higher, and is thought to be linked to vitamin D as most of our vitamin D is generated when sunlight hits our skin.  This has been backed up by studies which suggest that low levels of vitamin D in the blood are also linked to MS.

Despite this it is still unclear whether vitamin D could be beneficial in people who already have a diagnosis of MS: oral supplementation might not have the same effects as naturally generated vitamin D, sunlight might have other beneficial effects, and lastly vitamin D might play a role in preventing MS but once the disease has developed it might not have an effect. This all leaves the question of whether supplementing with vitamin D can reverse MS or improve disease outcomes.

The first study published as part of the Cochrane Database of Systematic Reviews looked at 12 studies enrolling 933 people with MS. Trials were conducted between 2006 and 2015. The earliest trial was published in 2010, and the most recent in 2016, and it included trials from Iran, Israel, USA, Europe and Australia. The trial size ranged from 23 to 232 participants.

The group found that vitamin D supplements had no clear effect on reducing relapse rates of people with MS who were receiving disease modifying therapies, and there was limited evidence suggesting a benefit of vitamin D on worsening of disability and MRI lesions. The doses of vitamin D used seem to be safe in the 12 studies examined. The scientists did note that there are 7 ongoing studies that might provide further evidence for vitamin D as a treatment.

The second study was carried out by a group of Australian scientists and was recently published in the Journal of Neurology. They also compiled 12 studies, some which overlapped with the previous study, but this study was slightly larger with a total of 950 people with MS.

Out of the studies examined very few serious side effects were reported and most were deemed to be unlikely to be related to vitamin D, or in other words, they deemed the doses of vitamin D that were used to be safe. The studies did show a significant rise in levels of vitamin D in the blood and this was related to how much vitamin D people were taking, in both people who were deficient and those who were not.

However, when it comes to comparing the outcomes, the team concluded that there were no significant beneficial effects of vitamin D on MS. The scientists did note that the results do hint at a potential clinically meaningful treatment effect in favour of vitamin D. There is uncertainty with regard to the most appropriate dose, surprisingly with high doses potentially being associated with worse outcomes.

This highlights the need for further well-designed clinical trials of vitamin D in MS. And this is one of the reasons why MS Research Australia is funding one of the largest clinical trials into vitamin D in MS – PrevANZ. PrevANZ is testing a range of doses of vitamin D and is aiming to recruit 240 people with clinically isolated syndrome, a potential precursor to MS. The trial aims to see which dose, if any can, prevent or delay a diagnosis of definite MS. PrevANZ is one of the largest individual vitamin D clinical trials conducted and bigger than most of the clinical trials included in these meta-analysis studies. It is also the only trial testing a range of doses in people with clinically isolated syndrome to prevent MS. It is hoped that the results of PrevANZ and the findings of the seven ongoing trials into vitamin D in MS will combine to give us a better foundation for advice about taking vitamin D supplements, and the optimal doses, for people with MS.

If you have any concerns about your vitamin D levels it is important to talk to your neurologist or health care professional as everybody’s situation is different.

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