I, Dr, Conor Kerley, recently posted a video about vitamin D and multiple sclerosis on Instagram
Vitamin D is probably one of the most talked about supplements for MS and probably the most commonly used supplement by people with MS
A nice 2025 study called the D-Lay trial from France included:
The patients with MS had less disease activity and better MRI results
Patients with severe vitamin D deficiency benefited the most from vitamin D supplementation.
But, there was no benefit for relapse rate
The researchers concluded that high dose vitamin D every 2 weeks significantly reduced disease activity in CIS and early relapsing-remitting MS'
So is high dose vitamin D3 the key to stopping MS?
Not so fast...
A similar trial comes from expert researchers in Ireland in 2017
This trial gave patients with clinically isolated syndrome 5,000 IU or 10,000 IU vitamin D3 every day for 24 weeks
High dose vitamin D had no benefit for the immune system, MRIs or symptoms!
Yet another similar trial comes from 2024 and was funded by MS Australia
92 adults with CIS or relapsing remitting MS were assigned:
-placebo
-1000IU vitamin D3 per day
-5000IU vitamin D3 per day
-10,000IU vitamin D3 per day
There was no benefit of vitamin D at any dose on MS disease activity after one year
In 2021, An expert commentary from neurology experts in the Netherlands reported:
There is no solid evidence to support the application of vitamin D therapy, based on current available supplementation trials
In 2018, there was a meta-analysis (which combines results of many studies) from Australia reported:
a significant increase in relapse rate, increased disability (EDSS) and increased MRI lesions in people with MS taking high dose vitamin D
The researchers concluded:
'high dose vitamin D potentially being associated with worse outcomes'
Another meta-analysis from China in the same year reported the same thing
Vitamin D had no significant therapeutic effect on MS
The relapse rate was higher in the vitamin D group than in the placebo group
The researchers concluded:
'vitamin D appeared to have no therapeutic effect in the patients with MS.
I'm writing this blog in August 2026 and there are some research review fresh off the press from this month, reporting:
Vitamin D supplementation does not consistently reduce relapse rates in adults with MS
clinical and radiological benefits remain inconsistent
Vitamin D did NOT affect relapse rates or final disability scores
I think we can all agree that these results are disappointing for those of us with MS.
However, some other supplements are safe and have documented benefits in MS, particularly:
Alpha Lipoic Acid
and
Nanocurcumin
Check out our blog:
Best Vitamins and Supplements for Multiple sclerosis: What Does the Science Say for MS?
