*This article explains how mast cell activation syndrome (MCAS), one of the root causes of Long COVID, affects the body and how nutrition can help improve symptoms.*

Updated February 20, 2024

According to the NIH, mast cells are important cells for immune defense against selected pathogens, germs and infections. They are found on mucosal surfaces (mouth, eyes, intestines, bladder, etc.) and have the ability to initiate much of the early immune response, making them an essential part of the immune system. However, the interactions of mast cells with viruses and pathogen products are complex and can have both negative and positive impacts on the body. There is substantial evidence showing mast cell mobilization and activation following viral exposure. Mast cells have been identified as a major contributor to inappropriate inflammatory responses, long term fibrosis, and vascular leakage associated with viral infections.

Selected, critical and early mast cell (MC) responses to viral infections which occur without a requirement for MC degranulation. MCs can be activated directly by active viral infection or by contact with viral particles. They can also be activated by alarmins released as a result of infection of neighboring or epithelial cells. This MC activation leads to the production of multiple mediators including large amounts of type I interferons (IFNs) and type III IFNs by virus infected human cells. While inducing an antiviral state in neighboring cells, such IFN responses also initiate multiple additional responses (blue arrows), the expression of a number of chemokines which together with MC-derived cytokines enhance the local recruitment of effector cells such as NK cells, T cells, and CD56-positive T cells from local blood vessels and promote the activation of NK cells, enhancing their cytotoxic functions. Such IFNs also act in an autocrine fashion to further promote selected mediator production by MCs. MC mediators, in several infections, would also act to enhance lymph node hypertrophy and mobilize local dendritic cell populations promoting the development of a subsequent acquired immune response. Resource: Mast

How MCAS fits into the Long COVID process

How nutrition fits into the MCAS picture

Multiple studies link post viral syndrome symptoms to allergies, histamine release and inflammation to mast cell activation syndrome, a common Long COVID issue. Several symptoms may be minimized with the introduction of a low histamine, low sugar diet. It is important to eat foods that are low in histamine levels that are within your threshold. Note: There is no such thing as an “histamine-free” diet.

Elimination diet take around 4 weeks to show results, and different people will have different triggers. Most of the learning is by trial and error, so listen to your body. You may have a reaction to some foods within minutes of eating or drinking. Other reactions may take a day or so to build up. Use a food journal to track your symptoms.

General guidelines:

Listen to your body and don’t compare your experience to othersEat fresh produce and fresh meats, as opposed to canned foods like tuna, frozen dishes with preservatives, or dried foods like boxed potatoes
Cook fresh foods - Simple meals can be made in one pan in about 10 minutes
Avoid prepared meals with chemical additives or preservatives
Avoid most fermented foods (cheeses, alcohol, products containing yeast, pickled foods)
Avoid over ripe fruits and vegetables and older leftovers
Promptly refrigerate foods and leftovers, especially meat products

Common low histamine foods

Remember some people may not tolerate these foods while than others can:

Fresh meats and chicken (cooled, frozen or fresh)
Fresh/frozen fish packaged within a day or two - avoid fish with a slimy feel to it
Eggs (fresh) - avoid eggs that have been stored for several months
Fresh fruits – with the exception of plantain, banana, and avacado
Fresh vegetables – with the exception of tomato, eggplant, asparagus and spinach
Grains – rice noodles, white bread, rye bread, rice crisp bread, oats, puffed rice crackers, millet flour, pasta - watch for bloating and pain after eating complex grains
Fresh milk and milk products - watch for bloating and pain after eating dairy products
Milk substitutes – goat, sheep, rice, almond, coconut or soy
Cream cheese, mozzarella, butter, (without the histamine generating rancidity)
Most cooking oils
Most leafy herbs
Most fruit juices without citrus fruits
Most herbal teas

Common high histamine foods

Remember some people may tolerate these foods better than others:

Alcohol
Eggplant
Pickled or canned foods – sauerkrauts
Matured cheeses
Smoked meats – salami, ham, sausage, etx.
Shellfish
Beans and pulses – chickpeas, soy flour
Long-stored nuts – e.g peanuts, cashew nuts, almonds, pistachio
Vinegar
Prepared meals, chemically preserved foods, and fast foods
Sweets
Citrus fruits – lemon, lime, oranges
Walnuts, peanuts
Papaya, pineapples, plums, kiwi and bananas
Legumes
Tomatoes
Wheat germ
Vinegars
Chemical additives and dyes
Yogurt – depending on the bacteria culture used to start the fermentation

Caffeinated drinks
Energy drinks

Things you can do to help yourself

Minimizing physical & psychological stressors is essential in recovery from Long COVID.

Nutrition: Try to eat protein and fresh vitamin rich foods daily and avoid chemicals, preservatives, sugars, fast foods, prepared foods and high histamine foods.
Don’t skip meals. Your body needs protein, vitamin C, and vitamin D to heal from any injury or illness. A low histamine or low carbohydrate (sugar) diet is recommended by doctors treating Long COVID (PASC), and many people report a reduction in symptoms within 1-3 days of the diet change, including decreases in sneezing, itching or hives, irritable bowel syndrome, body pain, along with a reduction in swelling and inflammation.
Hydration: A minimum of eight 8 oz glasses of plain water daily is recommended.
Avoid drinks with chemical additives. You can easily make a fresh electrolyte drink yourself by adding a dash of mineral rich Epsom salt and a piece a fruit like a raspberry for flavor instead of spending money on commercial drinks like Gatorade that contain chemicals and sit in plastic bottles for long periods of time. Remember that caffeine and alcohol have dehydrating effects.
Sleep hygiene: Getting 7-9 hours of sleep so your body can repair itself. You need at least 4 hours of uninterrupted sleep to get into the restorative phase of sleep.
Avoid stimulating activities after dinner like thrilling movies or books, arguments, negative news or frustrating stimuli.
If you wake up frequently or with a startle, you may be experiencing drops in your oxygen level, which signal your brain to release adrenaline to force you to take a breath. This could be a temporary inflammation issue or more enduring sleep apnea. Ask your doctor for a sleep study to evaluate your need for a CPAP or BiPAP, a machine that pushes air into your lungs when it senses an apneic episode (periods of not breathing).
Stress management: Stress effects every component of your life.
The only thing you can control about stress is your reaction to it. Try to avoid or minimize your exposure to stressful situations: Turn off the news, make family visits that end unpleasantly short, wait for the morning to have intense discussions, let go of things that annoy you but don’t really matter in the big scheme of things, avoid intense conversations or entertainment in the evening.
Exercise within tolerance: Pace yourself and do not push your body to extremes in any way.
For some this may mean seated breathing exercises, walking to the mailbox. Rest when your body says to slow down. Gradually build on your activity endurance as your body cues you to progress. This can be hard to gauge, because when you feel good you naturally do more, but if you do too much you may experience symptom flare ups 1-3 days later as the post exertion inflammation builds. Some people describe this as post exertional malaise, others experience severe recovery set backs.
Breathwork: You can literally stop the fight or flight reaction by taking slow deep breaths.
Deep slow breathing shuts down the adrenaline flow, slows your heart rate, lowers your blood pressure and decreases stress related histamine release. When you do this, your blood reroutes back to your brain and nervous system to allow you to think clearly. It also allows your body to use its energy and oxygen to heal your inflamed nerves and organs.

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