April 2025 Issue
Myasthenia Gravis
By Carrie Dennett, MPH, RDN
Today’s Dietitian
Vol. 27 No. 4 P. 24
The Role of Nutrition in This Rare Autoimmune Condition
Despite increased awareness of autoimmune conditions, myasthenia gravis (MG)—a rare, chronic, autoimmune neuromuscular disease affecting the signals between the nerves and the muscles at the neuromuscular junction—is not a condition that’s on many people’s radars. Because it’s relatively uncommon, many dietitians may have never encountered it professionally. But its seriousness warrants broader appreciation, including how nutrition can and can’t help.
MG is characterized by extreme fatigue that’s worsened by exertion and improved by rest, as well as muscle weakness of the skeletal muscles that may fluctuate throughout the day, week by week, or month by month.1 The short explanation for what’s happening is that impulses from the brain travel down nerves as usual, only to be blocked by antibodies before reaching muscle. The body is essentially attacking itself and stopping muscle function.
The longer explanation is that nerve impulse transmission at the neuromuscular junction requires the release of the neurotransmitter acetylcholine and subsequent binding to an acetylcholine receptor (AChR) on the muscle. Most people with MG have autoantibodies against the AChRs. Less commonly identified autoantibodies in MG include those that target muscle-specific kinase (MuSK) or low-density lipoprotein receptor-related protein (Lrp4). MuSK is a protein essential for proper AChR function, and Lrp4 activates MuSK.1 The thymus gland, which helps with the development of T cells, also plays a role in MG. T cells are involved in the production of antibodies, and a dysfunctional thymus can produce abnormal antibodies that cause MG. Many people with MG develop an enlarged thymus (hyperplasia) or a tumor of the thymus gland (thymoma).
MG has two forms: ocular and generalized. Ocular MG affects the muscles that move the eyes and eyelids, causing symptoms such as double vision and/or drooping eyelids. Most people with MG will have these symptoms at some point, and most people with ocular MG progress to generalized MG within two years of onset. Generalized MG may affect the skeletal muscles, impeding mobility and movement, and the muscles that aid in breathing. Also commonly affected are the bulbar muscles in the face and neck, which interfere with speaking, swallowing, chewing, smiling, and holding the jaw in place. If the axial muscles of the head, neck, and back are affected, MG patients may have trouble holding their head up.1
Prevalence, Diagnosis, and Treatment
It’s likely that the development of MG is multifactorial, probably resulting from a complex gene–environment interaction. The estimated prevalence is 150 to 200 cases per million, and has steadily increased in the past 50 years, largely due to improvements in diagnosis and treatment and, therefore, life expectancy. Anyone can be diagnosed with MG, though it’s more common in adults than children, especially in women under 40 and men over 60. It’s also slightly more prevalent in people of African ancestry. While early diagnosis improves treatment prognosis, MG can be difficult to diagnose, and some people go years without a correct diagnosis.1 A neurologist or neuromuscular specialist usually diagnoses MG with a physical and neurological exam, a blood test, and/or an electrical nerve test.2 Sometimes, an imaging scan of the thymus gland is also performed.
Some people can go into remission, but for many people, MG is a chronic illness, and uncontrolled MG can lead to disability and recurrent hospital admissions, with an estimated mortality rate of about 2%.3 There is no cure for MG, in part because every case is unique, although treatment development is advancing. Current treatments focus on improving strength and managing symptoms and may include the following2,4,5:
• anticholinesterase medications such as pyridostigmine (Mestinon) to slow the breakdown of acetylcholine at the neuromuscular junction;
• immunosuppressive drugs such as prednisone, azathioprine, mycophenolate mofetil, and tacrolimus to improve muscle strength by suppressing production of abnormal antibodies;
• complement inhibition with eculizumab, a medication that inhibits key complement proteins that contribute to neuromuscular junction damage in MG. The FDA has approved this drug for treatment in MG patients who test positive for the AchR antibody; and
• thymectomy, or removal of the thymus gland. This has been shown to reduce muscle weakness and the need for immunosuppressive drugs in MG patients regardless of whether they have visible thymoma, and about 50% of individuals who undergo this procedure experience a complete, long-lasting remission.
An estimated 8.5% to 15% of MG patients still experience varying degrees of disability because current treatments don’t adequately control symptoms or they produce unacceptable side effects. Fortunately, research on emerging treatments that target the underlying pathophysiological pathway is ongoing.3
In terms of lifestyle interventions, regular, gentle exercise may be helpful for some people with MG. At this time, nutrition interventions for MG focus on the autoimmune nature of the disease, medication interactions and side effects, as well as helping patients eat enough through safe and accessible food choices when muscle weakness makes it difficult to eat.
Anti-inflammatory Diets
“While no specific dietary pattern has been identified to benefit myasthenia gravis patients, there is hope in the form of an anti-inflammatory diet,” says EA Stewart, MBA, RD, owner of Spicy RD Nutrition in San Diego (www.eastewart.com). “This diet, which I recommend as a good starting point for most of my clients, has the potential to reduce chronic inflammation, a key component of autoimmune disease.”
Stewart points out that there’s no one-size-fits-all “anti-inflammatory diet.” Rather, it’s about incorporating a variety of foods and dietary patterns that can reduce inflammation while minimizing foods that may exacerbate inflammation.
“In general, anti-inflammatory foods to focus on include colorful polyphenol-rich fruits and vegetables, high-fiber foods (beans, legumes, whole grains, nuts, seeds), foods rich in omega-3 fatty acids (eg, salmon, mackerel, sardines), other unsaturated fats (eg, extra virgin olive oil, avocado oil), and antioxidant-rich spices and herbs,” Stewart says. Foods to avoid or minimize include ultraprocessed foods, refined grains, excess sugar and salt, certain food additives, and foods high in saturated or trans fats. “Diets like the Mediterranean, DASH, and MIND diets, which are rich in anti-inflammatory foods, could be beneficial for MG patients.”
She notes that while some autoimmune diseases are linked to a higher risk of celiac disease, there isn’t any research to date indicating that a gluten-free diet is necessary for MG patients.
Eating for Gut Health
Some research suggests that gut dysbiosis may contribute to development and progression of MG, although it’s currently unclear if the dysbiosis has a direct or indirect effect.6 “While research on preventative diets for MG is limited, there is some evidence to support that establishing a healthy gut microbiome can lower the risk of developing autoimmune diseases,” says Ginger Hultin, MS, RDN, CSO, owner of Ginger Hultin Nutrition (gingerhultinnutrition.com) and author of Anti-Inflammatory Diet Meal Prep. “A diet rich in prebiotic, fibrous foods may help to support a healthy gut, especially for people with autoimmune conditions.”7
When compared with age-matched controls, individuals with MG have demonstrated a distinctive composition in both the oral and gut microbiota, including a reduction in species that produce the short-chain fatty acids that have numerous health benefits. There is some evidence in experimental autoimmune MG—when MG is induced in animal models—that probiotic treatment may improve MG symptoms.6
“Due to the evidence-based links between MG and gut dysbiosis, consider a prebiotic-rich, high-fiber diet, possibly paired with a probiotic supplementation,” Hultin says. “There is some evidence to support that a whole food, plant-forward diet, like an anti-inflammatory or Mediterranean diet, could help manage disease symptoms.8
Hultin says gut-focused dietary interventions may be able to reduce some key symptoms of MG, including muscle weakness and fatigue. “Bacteriotherapeutic approaches such as pre- and probiotic supplements have been shown in some studies to slow the disease progression. It may be worth discussing probiotic-rich foods or supplements with patients who have this condition.”
Addressing MG Symptoms
While anyone can develop nutritional deficiencies, achieving nutritional adequacy in people with MG can be challenging because of fatigue and difficulty with chewing and swallowing (dysphagia). The latter can interfere with nutrition by creating safety issues and limiting food options. “If this occurs, soft foods and thickened liquids may be recommended to increase patient tolerance,” Stewart says.
When chewing and swallowing are difficult, body position during mealtimes is also important. Patients should sit upright in a chair and tilt their head forward. Because dysphagia is associated with poor outcomes in MG patients,9 if this is an ongoing problem, evaluation by a speech language pathologist may be helpful.
Dietitians can also help patients conserve energy by planning meals for when their strength is optimal. For example, if fatigue is a problem later in the day, they may want to eat their main meal earlier or eat five or six smaller meals instead of three larger meals. They may also benefit from timing meals around peak medication times, eating about an hour after taking their medication. Eating slowly and resting between bites may also be helpful.
While dietitians are well-equipped to assess malnutrition risk based on dietary intake and patterns of weight loss, a 2022 case-control study also found that MG patients with malnutrition showed decreased salivary alpha-amylase activity when the enzyme was stimulated by citric acid, and there was a strong positive association between alpha-amylase activity and BMI. The authors said alpha-amylase testing may offer a potential screening tool for MG patients with high risk of malnutrition.10
For MG patients with hyperlipidemia, taking a statin medication may be challenging because both MG and statins can cause muscle fatigue. A small prospective, nonplacebo-controlled 2012 study suggested that taking 3 g of supplemental beta-glucans—a natural ingredient in oats—for eight weeks significantly reduces total and LDL-cholesterol.11
Mitigating Medication Side Effects
As with drugs for many health conditions, medications used to lessen MG symptoms may have side effects that warrant nutritional interventions.
“With long-term use of immunosuppressive drugs like prednisone, bone health, including osteoporosis, is a major concern,” Hultin says. “To protect bone health while on these medications, the National Osteoporosis Foundation recommends adults under age 50 consume 1,000 mg of calcium and 400 to 800 IUs of vitamin D daily, while adults over 50 should aim for 1,200 mg of calcium and 800 to 1,000 IUs of vitamin D per day.”
A small 2012 study did find that plasma vitamin D levels were significantly lower in patients with MG without prior vitamin D3 supplementation when compared with healthy controls.12 Hultin says she recommends that many of her clients have their vitamin D levels tested and notes the important role dietitians can play in helping MG patients get adequate daily levels of calcium and vitamin D through diet and supplements. In addition to dairy products and calcium-fortified plant-based milk alternatives, calcium-fortified juices and cereals, cooked dark green leafy vegetables, and canned sardines or salmon (with bones) are rich in calcium.
Hultin points out that prednisone can also cause fluid retention, so managing salt intake is critical, but attention to blood glucose levels may also be important. “Controlling blood sugar can also be an issue for people on these medications since they can cause hyperglycemia and impair insulin regulation,” she says. “Helping MG patients with strategies for maintaining blood sugar balance while on prednisone and similar drugs is another way dietitians can help support this population.”
Stewart notes that in addition to fluid and sodium retention, decreased calcium absorption and elevated blood sugar, prednisone and other corticosteroids may also increase protein breakdown and increase appetite. She says another nutrient of concern may be magnesium for patients taking pryidostigmine (Mestinon) because pyridostigmine helps electrical signals travel between nerves and muscles. For that reason, while these patients don’t need to avoid magnesium-rich foods, they should avoid magnesium supplements because they may make the medication less effective.
For MG patients on anticholinergic medications, one potential side effect is cramping and diarrhea. While patients may want to talk to their doctor about possibly reducing their medication dosage or adding medications to help control the diarrhea, there are also nutritional strategies that may help. Dietitians can counsel patients to avoid foods that may aggravate diarrhea, including foods that are greasy, spicy, or high in fat. They may also want to limit dairy products to those with active cultures, such as yogurt or kefir, which may be beneficial. And although many high-fiber foods provide prebiotic fuel for the gut microbiota, while experiencing diarrhea, patients may feel better avoiding foods with insoluble fiber such as raw vegetables, bran, dried or unpeeled fruit, whole grains, and popcorn. Coffee, teas, and chocolate containing the stimulant caffeine can also increase gastric motility, making diarrhea worse.
Because diarrhea can cause fluid and mineral loss, patients may benefit from choosing mild, easily digestible foods that are rich in sodium—unless they are on a sodium-restricted diet—and potassium. Foods rich in potassium include potatoes, dark leafy greens, winter squash, apricots, and avocados, as well as some protein-rich foods like yogurt and salmon. Eating smaller, more frequent meals may be helpful, as can choosing foods like white rice, applesauce, very ripe bananas, and baked or broiled chicken or fish. Broth-based soups with white rice and mild, well-cooked vegetables can provide nutrition without aggravating a tender gut.
The Bottom Line
Even in the absence of an “MG diet,” there is much dietitians can do to support the health and well-being of patients with this disease.13 “RDs play a critical role on the myasthenia gravis care team,” Hultin says. “The muscle weakness and medications associated with this disease can make it challenging to meet their needs or consume a balanced diet. Dietitians should work with people who have MG to develop tailored dietary interventions that address their specific symptoms and medication side effects.”
Stewart reiterates that while no studies have to date linked any specific diet to improved outcomes with MG, an anti-inflammatory diet has the potential to help lessen symptoms of MG by lowering inflammatory markers and possibly slowing the progression of the disease. “In absence of research, there’s no harm and possibly benefits in trying an anti-inflammatory diet,” she says.
— Carrie Dennett, MPH, RDN, is the nutrition columnist for The Seattle Times, owner of Nutrition By Carrie, and author of Healthy for Your Life: A Non-Diet Approach to Optimal Well-Being.
References
1. Dresser L, Wlodarski R, Rezania K, Soliven B. Myasthenia gravis: epidemiology, pathophysiology and clinical manifestations. J Clin Med. 2021;10(11):2235.
2. Myasthenia gravis. National Institute of Neurological Disorders and Stroke website. https://www.ninds.nih.gov/health-information/disorders/myasthenia-gravis. Updated July 19, 2024.
3. DeHart-McCoyle M, Patel S, Du X. New and emerging treatments for myasthenia gravis. BMJ Med. 2023;2:e000241.
4. Alhaidar MK, Abumurad S, Soliven B, Rezania K. Current treatment of myasthenia gravis. J Clin Med. 2022;11(6):1597.
5. Narayanaswami P, Sanders DB, Wolfe G, et al. International consensus guidance for management of myasthenia gravis: 2020 update. Neurology. 2021;96:114-122.
6. Schirò G, Iacono S, Balistreri CR. The role of human microbiota in myasthenia gravis: a narrative review. Neurol Int. 2023;15(1):392-404.
7. Kapoor B, Gulati M, Gupta R, Singla RK. Microbiota dysbiosis and myasthenia gravis: do all roads lead to Rome? Autoimmun Rev. 2023;22(5):103313.
8. Kim P, Arnold M, Gunti J. Five-month trial of whole-food plant-based diet in a patient with coexisting myasthenia gravis and Lambert-Eaton myasthenic syndrome. Am J Lifestyle Med. 2021;15(3):230-237.
9. Yoshimoto Y, Ishida S, Hosokawa T, Arawaka S. Assessment of clinical factors affecting outcome of myasthenia gravis. Muscle Nerve. 2021;64(1):90-94.
10. Huang Y, Wang WK, Zheng XM, et al. Decreased salivary α-amylase activity responding to citric acid stimulation in myasthenia gravis with malnutrition. PLoS One. 2022;17(6):e0269621.
11. Haggård L, Andersson M, Punga AR. β-glucans reduce LDL cholesterol in patients with myasthenia gravis. Eur J Clin Nutr. 2013;67(2):226-227.
12. Askmark H, Haggård L, Nygren I, Punga AR. Vitamin D deficiency in patients with myasthenia gravis and improvement of fatigue after supplementation of vitamin D3: a pilot study. Eur J Neurol. 2012;19(12):1554-1560.
13. Nutrition. Conquer Myasthenia Gravis website. https://myastheniagravis.org/life-with-mg/nutrition/. Accessed January 9, 2025.