Vitamin D and Myasthenia Gravis

Myasthenia gravis (MG) is an autoimmune condition. When you have an autoimmune condition, your immune system cannot tell the difference between invaders (like bad bacteria, fungi, or viruses) and healthy cells. The immune system of people with MG specifically attacks the connection between the nervous system and muscles.¹

Vitamin D has a role in the health and repair of nerve-muscle connections. Vitamins are things that our body needs. We get them from food or a multivitamin. Our bodies also produce vitamin D when we go out in the sun.^1,2

Vitamins do not provide energy or build new tissue. Instead, vitamins help the body do different jobs, like building healthy bones and muscles or defending against colds and other illnesses.^1,2

Because vitamin D has a role in the nerve-muscle connections in the body, some people with MG and their doctors are curious to know if vitamin D could play a role in MG symptoms.²

Vitamin D in MG

People with MG seem to have a higher risk of not having enough vitamin D (called a vitamin D "deficiency") compared to people without MG. Several studies across different countries have looked at vitamin D deficiency and how often people get MG. These studies have found that the 2 conditions are significantly linked.¹

Using vitamin D as a treatment for MG symptoms has had mixed results. One study in Sweden found that vitamin D treatment helped reduce muscle tiredness in people with MG. Vitamin D was also helpful for a person with MG recovering from surgery. The vitamin D therapy helped him to be able to swallow and eat after not being able to.^1,3

But larger studies looking into vitamin D as an MG treatment have not found as strong of a connection. Multiple studies found that vitamin D treatment did not help to improve MG symptoms despite an increase in the amount of vitamin D in the participants’ bodies.^4,5

Vitamin D supports immune function, healthy bones and muscles, and metabolism. People with MG seem to have a higher risk of vitamin D deficiency. But seeing your MG symptoms improve after taking vitamin D may be a result of the vitamin’s overall role in your health and not a direct effect on MG.^1-5

Diet for MG

The link between MG and vitamin D may not be clear, but vitamin D is one of the most important parts of bone and immune health. Doctors generally recommend that a person with MG:⁶

• Eat a variety of fruits and vegetables
• Limit fat and cholesterol from foods
• Limit how much sugar and alcohol they consume

MG can also cause more specific health concerns around weight, bone loss, and diarrhea or upset stomach from medicines. Calcium and vitamin D can both help to prevent bone loss. Adults under 50 need 400 to 800 international units (IU) of vitamin D and 1000 milligrams (mg) of calcium daily. Adults 50 and over need 800 to 1000 IU of vitamin D and 1200 mg of calcium daily.⁶

Doctors recommend that people with MG try to maintain a healthy weight by being active in small, doable ways like adding extra weights during everyday activities. Before beginning any treatment for MG, talk to your doctor about any supplements or medicines you may be taking. This includes over-the-counter medicines.⁶