Vitamin D and MS
It may not be a miracle cure, but here's why the sunshine vitamin is essential self-care anyway
Original published 24 June 2025 on Best Life with MS
To be honest, I made it too much of a big deal. Winter Equinox, kids! The shortest day of the year.
They thought it would be exciting, like a mysterious "Good morning, it's night-time" sort of day. Sorry kids, not quite Twilight Zone.
We live in the cool climate highlands. Winter is beautiful.
The frost sparkles like the village has been dusted with sugar and we’re inside a snow dome.
The clouds reach street level. Sherbert colours of autumn fall from the trees. Exercise becomes wood chopping and there's a fire burning most nights of the week.
But winter's also a hard slog.
I get chill blains on my fingers. The sun feels weak and there are fewer sunlight hours.
One thing that can really suffer is vitamin D.
When you have multiple sclerosis, keeping strong levels of Vitamin D is especially important.
What is Vitamin D?
Vitamin D is a fat-soluble vitamin that we need for our immune system, bones, and muscles.
There are two types. D2 (ergocalciferol) and D3 (cholecalciferol).
While D2 we get from plants.
It's the D3 I need. It's available from animal sources (which, as a vegetarian, largely counts me out), sunshine, and supplements.
The D-Lay Study Finds the Gold
Early this year, a French study of 303 people rocked the MS world. The D-Lay study looked at a group with CIS (clinically isolated syndrome). That means they'd had one demyelinating event, such as optic neuritis, but were not diagnosed with MS (yet).
Half were put into a placebo group. Half were delivered high doses of vitamin D (100,000 International Units) every two weeks for 24 months.
The average levels of vitamin D3 of participants was 45 nmol/L, which is considered a satisfactory amount for health.
No patients were taking any disease-modifying therapies.
The results? The Vitamin D3 groups delayed the onset of new MS activity by about 7 months. The MRI results also favoured the vitamin D3 group. They had fewer new lesions and lower disease activity.
The study was published in JAMA on March 10.
The lead author of the study, told MedPage Today that the results were "comparable to those of some available drugs, with excellent safety. This constitutes real proof of efficacy in MS."
An earlier study in 2012 in Neurology found that people with MS who had higher serum vitamin D levels had:
Reduced new lesion formation on MRI
Fewer relapses
Slower disease progression
That study showed that a very small increase of 10 nanograms (a nanogram is a billionth of a gram) per millilitre was associated with a 15 percent reduction in relapse rate.
So what’s the problem?
The problem is many of the studies on vitamin D for MS have had mixed results.
The D-Lay result may have been what researchers from an earlier study wanted to find, but didn't. Conducted in Australia and New Zealand, PrevANZ had also looked at potential MS prevention using vitamin D3.
Participants were given doses of either 1000, 5000 or 10000 IU. There was a placebo group (no vitamin D) and no participants were taking an MS drug. The study continued for 48 weeks.
Similarly, the PrevANZ study also found that vitamin D did not prevent the participants from developing MS. Interestingly, it didn't find any particular benefit to MS.
What I think
I can't explain why both PrevANZ and D-Lay didn't find the same results, but the evidence for vitamin D3 is clear.
Personally, I think trying to stop MS with a vitamin may have been an overambitous goal.
However, I'm encouraged by the high-dose D-Lay results. These were done over two years. I also understand that, sure, it's possible to have too much vitamin D3, but it is extremely rare and very safe.
Like everyone else with MS, we can ultimately use our own bodies as the petri dish. I certainly feel much better when I supplement with D3. My physical health and mental health are better.
That's why I included sunshine pills as one of the top 12 Food Medicines for MS.
Other strong evidence
The bulk of evidence leans toward taking vitamin D3 if you have MS.
Neuroprotective effects
Many studies show vitamin D plays an anti-inflammatory and anti-oxidative role. It may reduce inflammation, which is a key driver of nerve damage, and vitamin D can provide protective effects, which may slow disease progression or reduce the severity of symptoms.
Vitamin D for Mental Health
Another effect is on mood. People with depression and anxiety have been shown to have low levels of vitamin D. We need vitamin D for our mental health
OvercomingMS recently adjusted its protocols and recommends people with MS take between 4,000 and 10,000 IU of Vitamin D3 per day.
May Help Repair Myelin
Studies have shown vitamin D3 can help remyelination. This is the holy grail.
My Advice
Get tested! Get your Vitamin D levels checked or get a do-it-yourself-kit. You can get a finger prick test kit from a chemist, or your doctor can do a blood test.
Get sunshine every day you can. Vitamin D forms in the skin when it's exposed to sunlight, according to the Cancer Council. You'll need less in summer, but take several minutes a day in autumn and winter.
Take a D3 supplement. If your test reveals you're low, speak to your doctor about taking a supplement.
If you're low in vitamin D, a doctor will usually recommend you take a supplement that is 1000 IU.
From my experience, that's nowhere near enough.
I take a supplement that 7000 IU marketed as once a week, but I take it every day, or whenever I remember, which is usually two or three times a week. And I only take it in winter and late autumn when I can't get enough sunlight.
When to take it
Vitamin D3 is fat-soluble so it's best to take it with a meal that contains a fat, such as olive oil, nuts, avocado, or similar. I take mine in the morning at breakfast.
Avoid taking it on an empty stomach or you'll be unable to absorb the D3.
Wrapping up
There's no evidence that vitamin D3 supplements will stop your MS or replace drug therapies. But there is overwhelming evidence that plenty of vitamin D will help.
We need vitamin D3 for our immune system, the many anti-inflammatory, and neuroprotective effects, and for our bone mineral density. It may even help repair our damaged myelin. That's all compelling evidence enough for me!
Okay, the kids were underwhelmed by the equinox. Sorry guys.
But I wasn’t.
I'm always excited to hit the halfway point in the ultramarathon that is the Highlands winter.
It means every day will start getting fractionally longer.
Longer days will mean more golden sunshine and plenty of vitamin D from the rays. That's worth a bonfire to celebrate.
Be well XO