Vitamin D supplementation shows mixed effects in new MS meta-analysis
Low to moderate doses linked to fewer relapses, but disability unchanged
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Low to moderate vitamin D doses were linked to fewer MS relapses. (Photo from iStock)
- Low to moderate vitamin D doses may reduce relapse rates in people with multiple sclerosis.
- Higher vitamin D doses showed no benefit, and disability scores remained unchanged.
- Vitamin D supplements may serve as an adjunct strategy to help prevent MS relapses.
Low to moderate doses of vitamin D supplements may be linked to lower relapse rates in people with multiple sclerosis (MS), according to a new meta-analysis of clinical trials.
Higher doses did not show the same benefit, and vitamin D supplementation overall did not significantly change disability scores.
“Based on these findings, vitamin D supplementation (preferably low/medium dose) may be recommended as an important adjunct strategy for preventing MS relapses,” the researchers wrote.
The study, “Vitamin D deficiency and multiple sclerosis relapse: a meta-analysis,” was published in Frontiers in Neurology.
How vitamin D may influence MS relapse risk
In MS, the immune system mistakenly attacks healthy tissue in the brain and spinal cord, causing inflammation that damages nerve cells. Many people experience flare-ups, known as relapses, when symptoms suddenly worsen or new symptoms appear.
Symptoms often improve after a relapse, but some people do not fully recover. Over time, repeated damage to nerve cells can contribute to worsening disability.
“Consequently, identifying key factors influencing MS relapse and potential interventions remains a major focus in neurology research,” the researchers wrote.
Vitamin D, best known for helping maintain healthy bones, can also affect the activity of immune cells and may influence MS disease activity. Low vitamin D blood levels have consistently been linked to a higher risk of developing MS, and some studies suggest that lower levels may be associated with more severe disability.
“However, clinical studies examining the relationship between vitamin D and MS relapse rate have yielded inconsistent results,” the team wrote.
To address this gap, researchers in China analyzed previously published clinical trials examining how vitamin D supplements affect people with MS.
Meta-analysis examines vitamin D supplementation in MS
The main goal was to determine whether vitamin D affects MS relapse rates. Disability scores, measured using the Expanded Disability Status Scale (EDSS), and blood levels of vitamin D were also examined as secondary outcomes.
A total of nine studies, published between 2010 and 2020 and involving 1,078 people with MS, were included in the analysis. Across these studies, researchers compared people who received varying doses of vitamin D supplements or had higher vitamin D levels in the blood with those who did not take supplements or had lower vitamin D levels. Follow-up periods lasted at least six months.
When results from six studies were combined, vitamin D supplementation did not significantly reduce relapse rates compared with control groups. However, when researchers examined the data by vitamin D dose, a different pattern emerged.
Data from three studies evaluating high-dose vitamin D supplementation showed no effect on relapse rates. However, pooled results from three studies in which participants received low to moderate doses of vitamin D showed a statistically significant reduction in relapse rates compared with control groups.
The researchers suggested this dose-dependent effect may be due “to the saturation of vitamin D’s biological effects.” In other words, moderate doses may be enough to influence inflammatory processes linked to relapses, while higher doses may not provide additional benefit and could potentially offset the protective effects.
Vitamin D supplementation did not change disability scores
Despite its effect on relapses, vitamin D supplementation did not significantly change disability scores measured using the EDSS. The researchers noted that EDSS mainly reflects long-term nerve damage, which may not be directly affected by vitamin D. They also noted that many of the studies had relatively short follow-up periods, which may not have been long enough to detect meaningful changes in disability.
When blood levels of vitamin D were examined, supplementation significantly increased vitamin D levels compared with control groups, regardless of dose.
“These findings provide important evidence for understanding the role of vitamin D in MS management and highlight the importance of dosage optimization,” the researchers concluded.
