Editor’s note: This is the first story in a three-part report examining the question “Should vitamin D supplements be recommended for MS patients?”, which was a topic discussed at this year’s Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS). Here, we provide a synopsis of the argument.

***

While a large body of epidemiological data suggest that low vitamin D levels increase the risk of multiple sclerosis (MS) onset, establishing its benefit for a person who already has the disease remains a challenge.

The question prompted a hot topic discussion at this year’s ECTRIMS, held Sept. 11–13 in Stockholm, where a group of clinicians shared their views and discussed the scientific evidence supporting or rebutting the benefits of vitamin D supplements for people with MS.

Normally, most vitamin D production in our body is triggered by sun exposure (UV radiation), but it also can be obtained from food and dietary supplements, either as vitamin D2 or vitamin D3, also known as cholecalciferol. The recommended dietary intake of vitamin D in healthy children and adults up to age 70 is 600 IU (15 micrograms) daily.

To become biologically active, vitamin D is first converted in the liver to 25-hydroxyvitamin D [25(OH)D], also known as calcidiol. This is what is measured in a vitamin D blood test.

According to the National Institutes of Health (NIH), generally a serum concentration of 50 nanomolar per liter (nmol/L) or higher (up to 125 nmol/L) is the reference for adequate levels.

At ECTRIMS, the discussion was led by Alberto Ascherio, MD, researcher and professor at the Harvard T.H. Chan School of Public Health in Boston, who believes MS patients should be advised to take vitamin D. Ellen Mowry, MD, researcher and professor of neurology at Johns Hopkins University in Baltimore, also supports the clinical practice use of vitamin D supplements, in moderate doses, for MS patients. 

The “no” side to supplementation was represented by Joost Smolders, MD, PhD, neurologist at the Dutch Canisius Wilhelmina Hospital and a researcher at the Netherlands Institute for Neuroscience (NIN).

So far, there is little evidence to support the idea that vitamin D supplements reduce flare-ups and disease activity in the brain. All three speakers agreed this needs to be tackled by well-controlled and consistent trials.

According to Ascherio, ongoing trials “are not addressing the key question.” They are limited in time and sample size, include patients with no vitamin D insufficiency, and are testing supplement doses that are too high.

On top of that, vitamin D’s true effects can be hard to analyze, given confounding factors, i.e., patients with MS may go to the beach less often, or otherwise be exposed to less sunlight; or they can change their diet or their treatment.

Nonetheless, Ascherio believes that vitamin D supplements can provide a clinically significant benefit in MS patients with a low 25(OH)D serum level — of 50 nmol/L and below.

He recommends taking 3,000 IU of oral vitamin D3 per day. This amount “it’s completely safe, there is no evidence of significant side effects, and the probability of giving a benefit I would put it at 80% if you don’t know the vitamin D level of your patient, and probably higher if you do,” Ascherio said.

Mowry also advises her patients to take vitamin D supplements, but with just enough to reach a target concentration of vitamin D in the blood.

“Instead of giving a generic advice of a certain dose, I usually treat to a target of vitamin D levels, typically between 40 to 60 ng/mL,” Mowry said. Patients “typically need anywhere between 2,000 IU and 5,000 IU per day,” she said.

The neurologist says she talks “pretty frankly” with her patients about the “holes in the evidence” regarding vitamin D. But overall, she believes MS patients should be recommended a low, adequate daily dose.

She also is alert for an apparent “sweet spot” of vitamin D doses. Very high doses of vitamin D supplements do not seem to bring any added benefit; rather, they are likely toxic and potentially harmful.

On the “no” side of the question, Smolders explained why he thinks vitamin D supplementation should not be a general advice in MS.

According to Smolders, questions that “require clarification” include the fact that low levels of vitamin D do not predict the risk of relapses and MRI (magnetic resonance imaging) lesions in all MS patient groups. Furthermore, he believes there are alternative reasons to explain the link between low vitamin D levels and worse disease activity.

MS-related inflammation by itself, for instance, may lower vitamin D levels, and sunlight exposure seems to play a much more relevant, and independent, role in MS disease course and disability.

“Not vitamin D supplementation but rather UV light exposure could be explored as a therapy for people early in disease” Smolders said.

The data supporting vitamin D’s effect on the disease process are “too premature” and do not give “a quantitive estimate of the effect of vitamin D supplementation. These studies do not tell us how much vitamin D we should supplement, and whether this results in a clinically relevant, meaningful improvement in the lives of people with MS,” he said.

The only situation in which Smolders advocates for vitamin D supplement in MS patients is if  they have low vitamin D levels and he wants “to prevent the loss of bone mineral density.”

For more on this topic, go here to read about arguments in favor of vitamin D supplementation and here to see the arguments against it.