Myasthenia gravis and vitamin D

Last updated Nov. 22, 2024, by Agata Boxe
Fact-checked by Patricia Silva, PhD

Vitamin D supports immunity and muscle health, and it can play a role in the treatment of myasthenia gravis (MG).

MG is a neuromuscular disease. Symptoms often include muscle weakness, fatigue, droopy eyelids, and swallowing issues.

Research suggests people with MG may have lower serum vitamin D levels than those without the disease and that these levels might be linked to symptom severity. Some evidence points to the potential benefits of vitamin D supplementation for MG.

If you have MG, getting enough vitamin D may help you better manage your symptoms, whether through your diet or through prescribed supplements.

Impact of vitamin D on myasthenia gravis

A 2023 review and meta-analysis of data from previous studies involving a total of 450 people, including 219 people with MG, showed vitamin D levels tend to be lower in people with MG compared to people without the disease. Based on these results, researchers suggested the need for routine monitoring of vitamin D levels in a patient with MG and possible supplementation.

A 2021 study including 66 people with MG found those with more severe disease tended to have lower levels of vitamin D than those with less severe symptoms. The finding suggested vitamin D levels could potentially be associated with disease severity, but this result only applied to disease severity measured through the activities of daily living scale, which indicates a person’s functional status. It did not apply to findings through the MG composite (MGC) scale, which is a validated measure of disease symptoms.

Some evidence based on single case reports of patients living with MG suggests vitamin D supplementation at high doses may help alleviate MG symptoms, including swallowing issues and muscle weakness, as well as possibly contribute to disease remission. However, researchers stressed the need for more studies on the effects of vitamin D on MG.

A 2012 pilot study that involved 33 people with MG and 50 healthy controls (people without the disease) suggested that supplementation with vitamin D3 could significantly increase 25(OH)D levels, which is a measure of vitamin D levels in the blood. Moreover, the MGC score assessing fatigue decreased after treatment, suggesting that vitamin D supplementation could reduce fatigue in some people with MG.

Scientists believe the impact of vitamin D on MG symptoms are from its effects on the immune system and on muscle strength.

Role of vitamin D in modulating immune response in MG

Vitamin D may be able to change the way the immune system affects MG symptoms.

MG is often caused by the immune system mistakenly attacking acetylcholine receptors (AChRs), which are found at the neuromuscular junction. This junction is where nerve cells communicate with muscle cells, and plays a role in muscle contraction.

Vitamin D may help to keep the immune system in check. Specifically, it can suppress the immune cells that are involved in the attack while increasing the number of regulatory T-cells, or Tregs, which try to stop the attack.

Vitamin D also plays a role in other autoimmune conditions such as multiple sclerosis and rheumatoid arthritis.

Vitamin D and muscle strength

Vitamin D supports muscle strength and can help manage muscle weakness due to MG in several ways.

First, it helps the body absorb calcium, which is essential for bone health and proper muscle functioning. When your body doesn’t have enough vitamin D, it may not be able to take up calcium, even if you regularly consume calcium-rich foods, such as milk, yogurt, and broccoli.

Second, vitamin D binds to vitamin D receptors in muscle cells, ultimately contributing to muscle contraction, repair, and growth.

Finally, muscle weakness in MG can be the result of inflammation, and vitamin D has been found to potentially reduce muscle damage and inflammation.

Research on vitamin D and muscle strength also supports that the vitamin is involved in overall muscle health.

Sources of vitamin D

Sunlight, specific foods in your diet, and supplements are all sources of vitamin D. However, sun exposure has some risks, and supplements should only be taken with a doctor’s guidance.

Sunlight generates heat, which often worsens MG symptoms, contributing to muscle weakness. Also, because some MG medications, such as certain immunosuppressants, can potentially increase skin cancer risk, you may need to avoid exposure to the sun as much as possible if you are taking them.

Fortunately, you can still get vitamin D from foods and, potentially, supplements. Foods and drinks with higher amounts of vitamin D include:

egg yolks
fatty fish such as salmon, tuna, and sardines
fortified cereal
fortified milk (dairy or plant-based)
fortified orange juice
mushrooms.

Vitamin D deficiency is common in MG, so your doctor may recommend having your blood levels tested. Depending on your results, you may be prescribed supplements. Keep in mind that vitamin D supplementation is not something you should try on your own.

Consuming too much vitamin D, which may happen through supplementation, can be harmful. Potential effects from high doses of vitamin D include nausea, muscle weakness, dehydration, and kidney stones. High dosing can also cause kidney failure and irregular heartbeat. In rare cases, it can be deadly.

Your body limits the amount of vitamin D it produces from sunlight, so you cannot get too much vitamin D through sun exposure.

Incorporating vitamin D into MG treatment plan

Vitamin D might complement existing MG treatments, such as corticosteroids or immunosuppressants, for managing the disease. It may also be part of a plan that includes a safe exercise program and lifestyle adjustments such as regular rest breaks and home adaptations.

However, only your doctor can determine whether vitamin D supplementation should be part of your MG treatment.

You can also follow the Myasthenia Gravis News website for updates on MG and vitamin D, and many other topics.

Myasthenia Gravis News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.