High-dose vitamin D does not slow MS lesion development

Taking a high-dose vitamin D supplement as an add-on to standard treatment for multiple sclerosis (MS) doesn’t slow the development of new lesions, a sign that the brain or spinal cord have been damaged, according to a meta-analysis study.

Vitamin D also had no effect on how fast disability worsened or how often relapses occurred, which is consistent with previous findings that taking a high-dose supplement of vitamin D doesn’t change the course of disease, at least not within up to about two years.

The study, “Vitamin D3 as an add-on treatment for multiple sclerosis: A systematic review and meta-analysis of randomized controlled trials,” was published in Multiple Sclerosis and Related Disorders.

MS occurs when the immune system mistakenly targets the myelin sheath, a protective fatty layer that envelops nerve fibers. This misguided attack leads to observable damage in the form of lesions on magnetic resonance imaging (MRI), giving rise to various symptoms.

There appears to be a link between a low level of vitamin D, which helps in immune responses, and an increased chance of developing MS. However, there’s no clear evidence that taking a vitamin D supplement can prevent or keep MS symptoms from getting worse.

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Studying high-dose vitamin D

To get a better understanding of the effect of high-dose vitamin D (at least 1,000 International Units a day) in people with MS, researchers in Brazil combined data from nine randomized controlled trials until mid-December 2022 that were identified through a literature search.

The trials included 867 patients with a diagnosis of MS. Most had relapsing-remitting MS, where relapses, or periods of new or worsening symptoms, are followed by periods when symptoms ease.

Compared with a placebo or low-dose vitamin D, taking a high-dose vitamin D supplement as an add-on to disease-modifying therapies didn’t result in a significant reduction in Expanded Disability Status Scale (EDSS) scores, where higher scores indicate greater disability, over six months to about two years.

A high dose also had no significant effect on the number of T2 lesions seen on MRI scans. There was a nonsignificant tendency for fewer lesions with high-dose vitamins D. T2 lesions reflect overall lesion load, including both old and active lesions.

A high dose also had no effect on the annualized relapse rate (ARR), a measure of the number of relapses adjusted to a one-year window, indicating “vitamin D3 supplementation has no significant impact on clinical outcomes.”

As an “add-on for the treatment of MS,” the researchers wrote, high-dose vitamin D supplementation “has no significant impact on EDSS, ARR or new T2 lesions in the short and medium term,” but the “nonsignificant reduction of new T2 lesions could precede long-term clinical benefits and should be validated in additional studies.”