A study led by Professor Éric Thouvenot on the use of vitamin D in the treatment of multiple sclerosis
The results of the D-Lay MS project, led by Professor Éric Thouvenot, Head of the Neurology Department at Nîmes University Hospital and funded by the National Hospital Clinical Research Programme (PHRC), show that taking high doses of vitamin D significantly reduces the activity of multiple sclerosis (MS).
Multiple sclerosis (MS) and vitamin D. MS is an autoimmune disease caused by an attack by the immune system on the myelin sheath, a protective coating around nerve cells. Although the exact causes of MS are not fully understood, vitamin D deficiency may increase the risk of developing the disease and lead to more severe disability. To date, no studies have shown a therapeutic effect of vitamin D after the disease has been diagnosed.
D-Lay MS trial: significant results. Taken at high doses (2 vials of 100,000 IU per month), vitamin D could almost double the time before the disease shows new signs of activity in people who have had a first attack of MS, the clinically isolated syndrome (CIS). This is according to phase 3 trial data presented by Professor Éric Thouvenot at the annual meeting of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) in Copenhagen in September.
“The participants, recruited from 36 centres in France, were randomly assigned to take either a high-dose vitamin D ampoule or a placebo every two weeks for two years”, explains Prof Thouvenot.
At the end of regular clinical and MRI follow-up, 60.3% of patients taking vitamin D had no new clinical or radiological disease activity, compared with 74.1% in the placebo group, representing a 34% reduction in the risk of disease activity (Figure). In addition, the median time to onset of disease activity was almost twice as long in patients taking vitamin D (432 days versus 224 days). No serious adverse events related to vitamin D were observed in the trial.
“In conclusion, high-dose vitamin D supplementation is safe, well tolerated and effective in reducing early disease activity. These promising results make vitamin D a potential candidate for adjunctive therapy in the MS treatment strategy”, concludes Prof Thouvenot.
The results of this therapeutic trial were published on 10 March 2025, in The Journal of the American Medical Association (JAMA), one of the most prestigious medical journals.
Professor Éric Thouvenot is a member of the “Neuroproteomics and signalling of brain disorders” team headed by Philippe Marin at the IGF.
