Vitamin D and MS: Can supplements of the sunshine vitamin reduce relapse risk?

How is vitamin D connected to MS? Can it affect disease activity?

According to a 2022 review published in Frontiers in Neurology, people who live in areas with less sunlight, especially those farther from the equator, are more likely to develop multiple sclerosis (MS). One reason may be lower levels of vitamin D, a nutrient the body produces when exposed to sunlight. This geographic link has led researchers to explore how vitamin D might influence the development and progression of MS.

Vitamin D is well known for supporting bone health, but it also plays an important role in the immune system. It affects immune cells like T cells, which are involved in MS. Research shows that low levels of vitamin D are linked to a higher risk of developing the disease.

For people already diagnosed with MS, vitamin D may help manage the condition. Rising evidence suggests that maintaining healthy vitamin D levels may reduce relapse rates and support nerve repair, potentially resulting in fewer brain lesions seen on MRI and a slower progression of MS.

Biologically, vitamin D helps in several ways. It may lower the activity of harmful T cells that trigger inflammation in MS, while increasing the number of regulatory T cells that calm the immune response. It may also help brain cells called oligodendrocytes repair myelin, the protective coating around nerve fibres that is damaged in MS.

What does the research say about vitamin D supplements for MS prevention and treatment?

A growing body of research links low vitamin D levels to a higher risk of developing MS. A recent meta-analysis found that people with vitamin D deficiency have a 54% higher risk compared to those with healthy levels. This supports earlier observational studies and provides strong evidence of an association.

Genetic studies have added even more weight to this connection. Using a method called Mendelian randomization, researchers have shown that low vitamin D levels may not just be linked to MS, they may directly contribute to its development.

This has raised interest in vitamin D supplementation as a way to prevent MS, especially in people at higher risk, such as those with a family history or children in low-sunlight regions. While the ideal dosage and timing for prevention are still being studied, keeping vitamin D levels in a healthy range is seen as a potentially helpful step.

For people already living with MS, observational studies have linked higher vitamin D levels to fewer relapses, less inflammation on MRI scans, and possibly slower disease progression. These findings support the role of vitamin D in managing disease activity, although it is not a cure or replacement for standard treatments.

How much vitamin D is safe and potentially beneficial for people with MS?

For most adults, the general recommended daily intake of vitamin D is 600 to 800 international units (IU), depending on age. The safe upper limit is considered to be 4,000 IU per day. Staying within this range can help maintain healthy blood levels and avoid side effects.

Some studies in people with MS have explored higher doses, such as 5,000 IU per day or more. These higher doses were often well tolerated, but in some cases led to side effects such as high calcium levels (hypercalcemia) or kidney stones, especially if taken long-term without medical supervision.

Vitamin D needs vary based on age, body weight, skin tone, sun exposure, diet, and overall health. Because of this, it’s important to avoid a one-size-fits-all approach. People with MS should have their vitamin D levels tested regularly with a blood test called 25-hydroxyvitamin D [25(OH)D], which most experts consider healthy when between 30 and 60 ng/mL.

If levels are low, doctors may recommend a short period of high-dose supplementation, followed by a maintenance dose tailored to the person’s needs. Regular monitoring helps ensure safe and effective vitamin D use.

Key takeaways

Vitamin D deficiency is a recognized and modifiable risk factor for multiple sclerosis. Strong evidence from observational and genetic studies shows that low vitamin D levels increase the risk of developing MS. Maintaining adequate levels may offer protective benefits.

For those already diagnosed with MS, vitamin D may support immune system balance and help repair damaged nerves. It appears to regulate harmful immune cells, promote remyelination, and potentially slow disease progression.

However, vitamin D supplementation is not a cure or a standalone treatment. High doses should not be taken without medical guidance, as they may cause serious side effects. Safe and effective use requires proper testing, monitoring, and supervision by a healthcare provider.

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