Research Summary: High dose vitamin D supplementation does not affect biochemical bone markers in multiple sclerosis – a randomised controlled trial

There has been a lot of online coverage during the past two weeks of a study reporting that high-dose vitamin D supplementation does not prevent bone loss or improve bone health in people with multiple sclerosis.  Considering this, and knowing that many people with multiple sclerosis do use vitamin D capsules, we thought it important to provide our analysis of the article.

For those interested, the trial in question was published in BMC Neurology, and was conducted by researchers from the University of Oslo, University Hospital of North Norway and the University of Troms⌀.

To determine whether high-dose vitamin D could help improve bone health, 68 people with relapsing-remitting multiple sclerosis (RRMS) were split into two groups – one group received a once-weekly 20,000IU vitamin D3 capsule and the other was given a placebo.  All 68 people in the study also received 500mg of calcium daily.  All participants had blood samples taken at the beginning of the study, as well as at the 48 week and 96 week timepoints.  These samples were checked to see whether there was any difference in the levels of markers in the blood that are associated with bone formation.

At the end of the study, the findings were that vitamin D levels increased in the blood of people taking the supplement, and that vitamin D supplementation did not cause a change in the levels of the bone formation markers measured.

While this would indicate that vitamin D supplementation doesn’t appear to improve bone health in people with RRMS, I think there are a number of questions that need to be addressed before we can make this conclusion:

  1. The researchers commented that a number of people in the control group continued to take personal vitamin D supplements throughout the study.  Even though the levels of vitamin D were measured during the study, this was only at 2 timepoints across almost 2 years.  It is hard to say that this would have had no impact in the comparison of the two groups.
  1. The researchers also mentioned that weekly supplementation may not be the best method and that daily vitamin D capsules may have had a greater effect.
  1. The starting vitamin D levels varied quite a bit in individuals within groups.  With larger group numbers, it would be possible to see whether or not those that had very low levels at the start of the trial received benefits in terms of their bone health from the vitamin D supplementation.
  1. The bone mineral density scans at the beginning of the study showed that the vitamin D group had higher levels than those in the control group.  As many people in the study were in the very early stages of multiple sclerosis, it is possible that bone loss was not a major issue in these people.  In that case, we may not actually expect to see any changes in this group of people with MS.  If the study was to be repeated in people with a more advanced progression of multiple sclerosis, the results may show a bigger difference between the groups.
  1. It is probably important to see what was happening on a more regular basis throughout the study to have a greater idea as to how the levels of vitamin D and the bone formation markers varied.  It is possible that this would have shown more subtle changes, as well as trends that differed between the groups that didn’t show up in the analysis.

With all of this in mind, I don’t think that this trial provides conclusive evidence that vitamin D supplementation doesn’t impact on bone health in people with multiple sclerosis.  There are studies showing that low vitamin D levels may impact on multiple sclerosis progression, so levels should be monitored and a discussion around supplementation could be had with healthcare professionals.  It will be interesting to see a larger study around the impact on bone health that addresses the queries mentioned above.  Studies like these are very important though, as with an increased risk of fall in people with multiple sclerosis, improved bone health can help reduce the risk of fractures.

The abstract for this study can be read in full here.

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