Multiple sclerosis (MS) patients who took high doses of vitamin D had fewer relapses and lesions, said scientists after their recent study suggested that supplementing it in high doses could help reduce symptoms. Experts have warned, however, that excessive doses of the vitamin can be toxic.
Previous research has shown that vitamin D deficiency can increase the risk of MS, and the scientists believe their findings may reinforce those findings.
The study included 303 adults in France who had experienced clinically isolated syndrome (CIS) – which is a single, initial period of neurological symptoms that could lead to MS – within the last 90 days.
One group of participants took high doses (100 000 IU) of cholecalciferol (vitamin D3) every two weeks for 24 months.
Among that group, 60.3% experienced a relapse of symptoms or new or enlarged lesions in MRI scans.
In comparison, 74.1% of those who took a placebo experienced those same effects, which is a “statistically significant difference”, wrote the researchers, who were from CHU Nîmes, Université Montpellier and multiple sclerosis centres in France.
The findings of the double-blind, randomised study were published in the journal JAMA.
“Oral cholecalciferol 100 000 IU every two weeks significantly reduced disease activity in CIS and early relapsing-remitting MS,” the researchers wrote.
“These results warrant further investigation, including the potential role of pulse high-dose vitamin D as add-on therapy.”
Bruce Bebo, executive vice-president of research at the National MS Society in Oregon, was not involved in the research but told Fox News Digital it was a “well-designed study”.
“It is important to note that the JAMA study used a significantly higher dose (100 000 units per day). While they did not report any adverse events, excessive intake of vitamin D can be toxic,” he cautioned.
“High doses can cause excess calcium in the blood leading to nausea, vomiting, weakness, frequent urination and, in some cases, kidney damage.
“These findings suggest that high-dose vitamin D may be a promising approach for reducing disease activity in the very early stages of MS.”
He added that previously published studies, had failed to link vitamin D supplementation with reduced MS disease activity, although they used lower doses.
“Overall, the evidence suggests that the effects of vitamin D supplementation are likely to be modest, will require high doses, and will be most effective when taken early in the course of disease by people deficient in vitamin D,” he said.
The American Academy of Neurology currently recommends a range of 300 to 4 000 units per day for an adult, with 4 000 units as the highest recommended dose by most health authorities, Bebo noted.
Study details
High-Dose Vitamin D in Clinically Isolated Syndrome Typical of Multiple Sclerosis: The D-Lay MS Randomised Clinical Trial
Eric Thouvenot, David Laplaud, Christine Lebrun-Frenay et al.
Published in JAMA on 19 March 2025
Abstract
Importance
Vitamin D deficiency is a risk factor for multiple sclerosis (MS) and is associated with the risk of disease activity, but data on the benefits of supplementation are conflicting.
Objective
To evaluate the efficacy of high-dose cholecalciferol as monotherapy in reducing disease activity in patients with clinically isolated syndrome (CIS) typical for MS.
Design, Setting, and Participants
The D-Lay MS trial was a parallel, double-blind, randomised placebo-controlled clinical trial in 36 MS centers in France. Patients were enrolled from July 2013 to December 2020 (final follow-up on January 18, 2023). Untreated patients with CIS aged 18 to 55 years with CIS duration less than 90 days, serum vitamin D concentration less than 100 nmol/L, and diagnostic magnetic resonance imaging (MRI) meeting 2010 criteria for dissemination in space or 2 or more lesions and presence of oligoclonal bands were recruited.
Intervention
Patients were randomised 1:1 to receive oral cholecalciferol 100 000 IU (n = 163) or placebo (n = 153) every 2 weeks for 24 months.
Main Outcomes and Measures
The primary outcome measure was disease activity, defined as occurrence of a relapse and/or MRI activity (new and/or contrast-enhancing lesions) over 24 months of follow-up, also analysed as separate secondary outcomes.
Results
Of the 316 participants enrolled and randomised (median [IQR] age, 34 [28-42] years; 70% women), the primary analysis included 303 patients (95.9%) who took at least 1 dose of the study drug and 288 (91.1%) ultimately completed the 24-month trial. Disease activity was observed in 94 patients (60.3%) in the vitamin D group and 109 patients (74.1%) in the placebo group (hazard ratio [HR], 0.66 [95% CI, 0.50-0.87]; P = .004), and median time to disease activity was longer in the vitamin D group (432 vs 224 days; log-rank P = .003). All 3 secondary MRI outcomes reported significant differences favouring the vitamin D group vs the placebo group: MRI activity (89 patients [57.1%] vs 96 patients [65.3%]; HR, 0.71 [95% CI, 0.53-0.95]; P = .02), new lesions (72 patients [46.2%] vs 87 patients [59.2%]; HR, 0.61 [95% CI, 0.44-0.84]; P = .003), and contrast-enhancing lesions (29 patients [18.6%] vs 50 patients [34.0%]; HR, 0.47 [95% CI, 0.30-0.75]; P = .001). All 10 secondary clinical outcomes showed no significant difference, including relapse, which occurred in 28 patients (17.9%) in the vitamin D group vs 32 (21.8%) in the placebo group (HR, 0.69 [95% CI, 0.42-1.16]; P = .16). Results were similar in a subset of 247 patients meeting updated 2017 diagnostic criteria for relapsing-remitting MS at treatment initiation. Severe adverse events occurred in 17 patients in the vitamin D group and 13 in the placebo group, none of which were related to cholecalciferol.
Conclusions and Relevance
Oral cholecalciferol 100 000 IU every 2 weeks significantly reduced disease activity in CIS and early relapsing-remitting MS. These results warrant further investigation, including the potential role of pulse high-dose vitamin D as add-on therapy.
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