What is MCAS?

This post provides a primer on what is MCAS, or Mast Cell Activation Syndrome.

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The following material does not constitute medical advice. This information is for information purposes only and is not intended to be a substitute for professional medical advice, diagnosis, cure, or treatment. Always seek advice from your medical doctor.

What are mast cells?

Mast cells are part of our bodies that cause immediate allergic reactions, and by releasing parts of their cells called “mediators” they cause allergic symptoms. This process works in concert with antibodies; the triggering is known as “activation.” When too many mediators are released the body begins to act as though it is under significant threat, though what is causing the release may be benign. For many people with Mast Cell Activation Syndrome, or MCAS (pronounced em-cass), normal healthy foods, environmental stimuli like scents, temperature variation, and even stress become triggers. When too many mediators are released allergic symptoms escalate leading to major allergic events and even anaphylaxis.

Diagnosis of MCAS

There are a number of issues that stand in the way of being easily diagnosed and treated for Mast Cell diseases. Part of the problem with having a Mast Cell disease (there are several) is that knowledge about them is not yet widely available. Where I live in Minnesota there are only two or possibly three knowledgeable providers who specialize in MCAS. Many functional providers know about it and can help with diagnosis and treatment. But there needs to be much more research and advocacy so that upcoming medical doctors know about (and don’t dismiss) Mast Cell diseases.

Mast Cell diseases can look like other diseases, and patients are often misdiagnosed for years before they finally figure out what is going on. The diagnostic tests for Mast Cell diseases are extraordinarily finicky, and many people are misdiagnosed due to faulty testing. And many uninformed providers suggest that patients stop taking the drugs controlling their symptoms prior to testing, which can cause catastrophic symptom flares.

The Bucket Theory

The Bucket Theory offers a helpful analogy for understanding symptom reactions with MCAS.

Think of your body as an empty bucket that you want to keep from overflowing. Different foods and activities fill your histamine bucket at different speeds but they combine to form the total level of histamine in your body (how full your bucket is). A fuller bucket means you have more histamine symptoms. When you manage triggers, reduce exposure to known triggers, and take medications and supplements to reduce histamine, you can manage the level of your bucket.

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Resources

I’m not a health professional and I can’t begin to do justice to the intricacies of MCAS and other Mast Cell Diseases, but I have found some very good resources available to dig into it and read more:

• This site gives a great short intro about Mast Cell diseases.
• This video explains Mast Cell diseases in under ten minutes.

• Mast Attack. The author of this informative blog is a graduate-level Biologist, who has a Mast Cell disease. She has written exhaustively on the subject, breaking it all down into layperson language.
• This site provides a summary of the ways Mast Cell diseases can affect each organ system, which can be helpful if you are working backward, from symptoms to a possible diagnosis. 
• This site run by a Mast Cell provider gives a good definition of MCAS.
• This functional medicine provider offers online classes, coaching, and helpful information.
• This provider has a good intro page covering diagnosis and treatment succinctly.
• And there are many Facebook groups devoted to Mast Cell diseases to connect with other patients.

Treatments

The most common drugs that are prescribed for treating MCAS include:

Histamine 1 blockers – Hydroxyzine (Atarax), Doxepin (Silenor), Cyproheptadine (Periactin), Loratadine (Claritin), Fexofenadine (Allegra), Diphenhydramine (Benadryl), Ketotifen (Zaditen) and Cetirizine (Zyrtec, Reactine).

Histamine 2 blockers – Famotidine (Pepcid, Pepcid AC), Cimetidine (Tagamet, Tagamet HB), and Ranitidine (Zantac). Famotidine is chosen most often because it has fewer drug interactions than Tagamet.

Mast Cell Stabilisers – Cromolyn (Cromolyn Sodium, Gastrocom—oral form, Nasalcrom—nasal spray, Opticrom—eye drops, and there is a nebulized form and a cream can be made from a bottle of Nasalcrom and Eucerin or DMSO cream), Ketotifen (both a mast cell stabilizer and an H1 blocker) and Hydroxyurea (Hydrea).

Mast Cell Inhibitors – Montelukast (Singulair), Zafirlukast (Accolate), and Zileuton (Zyflo). Pentosan (Elmiron) is used in the genitourinary tract for perineal pain and interstitial cystitis.

Supplements

And here is a list of common supplements that are helpful in treating MCAS:

• Quercetin  – 2000 mg daily, dose divided
• Green tea (EGCG, L-Theanine) – 2 to 3 cups daily. Supplement with 500 mg (175 mg of ECGC) twice daily
• Curcumin (Meriva is a common brand name) – 1 to 4 g daily, dose divided
• Chamomile tea (Apigenin, luteolin) – 1 to 2 cups before bed
• Resveratrol – 20 mg twice daily
• Diamine oxidase enzymes (DAO) – 2 capsules with each meal
• Vitamin C – may need a non-citrus source such as rose hips – 1 to 3 g daily

Knowing your mast cell triggers

Mast Cell triggers can include:

Environmental triggers

• Animal Dander (cat/dog/rat/bird/horse) & Animal Pelts (wool, skins)
• Mold Spores, Dust, Pollen
• Smoke (Cigarettes, fires, room smudges)
• Air Pollution (eg car fumes, smog)
• Chlorinated tap water/pools/spas/baths
• Strong Odors (over-ripe food, seaweed, sewage, coffee, cinnamon, frying spices)
• Fragrance/Perfume, Air Fresheners, Essential Oils
• New Off-Gassing Products (car, carpets, furniture, clothing, house paint)
• Direct Sunlight (Ultra Violet Radiation)
• Bright, Flashing Lights, Fluorescent Light, Laptop/phone screen light
• Sudden Change in Temperature (eg cold water immersion, saunas)
• Low-Pressure Systems (storms, flights, high altitude)
• Extreme Temperatures
  • Heat (Summer, hot bath/shower, sauna, sun)
  • Cold (winter/ snow/ cold ocean swims)
• Unnatural Fabric (non-cotton/linen clothing, bedding, etc.)
• Non-hypoallergenic Jewelry & Metals/Alloys (especially Nickel)
• Venom / Insect Bites (eg mosquitos, bees, wasps, spiders, ants, jellyfish)
• Mechanical Irritation;
  • Vibration (eg car/motorbike rides & loud music (festivals, concerts)
  • Friction (eg clothing, stroking, massages, sex)
  • Pressure on the body (eg tight clothing)
• WIFI radiation (potential Mast Cell destabilizer)

Chemical triggers

• Laundry Detergent (on clothing/bedding/curtains, etc.)
• House Cleaning Product Chemicals
• Personal Care Product Chemicals (Soaps, Shampoo/Conditioner, Toothpaste, Makeup)
• Pine Wood & Trees (eg Xmas trees) / Trees in the fir family (Redwoods)
• Newspaper Ink, Wrapping Paper
• Rubber and Latex
• Medications (eg Anesthetics, NSAIDs, Opioids, Antibiotics, aspirin, pain killers, iodine, quinine, narcotics (codeine, morphine), pills with dyes, vitamins, laxatives)

Physical triggers

• Exercise (especially dehydrated, fatigued, hungry/low blood sugar)
• Overheating and Sweat
• Dehydration (esp when exercising)
• Hunger
• Over Eating / Large Meals (especially high-fat, protein, or salty food)
• Injury, Impact, Pain, Surgeries, Dentistry
• Estrogen (before & during a menstrual period)
• Strong Emotions (anger, sadness, etc.)
• Orgasms
• Stress (emotional, mental)
• Sleep Disturbances (being waked, insomnia, fatigue)
• Infections (viral, bacterial, or fungal)
• Having a full bladder

Food triggers

• Unfiltered Tap Water (chlorinated, heavy metals)
• Caffeine & Alcohol  (DAO inhibitors)
• Charred/ Burnt Food (esp animal meat/skin)
• Leftovers, Aged, Fermented foods, Pickles & Preserves, Olives
• Vinegar (esp rice vinegar)
• Soy Sauce & Products
• Shellfish (Crabs, Prawns, Shrimp, Lobster, Crayfish, Squid, Calamari, Octopus, Mussels, Clams, Oysters, Scallops)
• Bananas
• Citrus Fruit
• Avocado
• Eggs
• All Legumes
• Spicy Food
• Sugar Substitutes
• Salicylates (stevia etc)
• Oxalates, Salicylates, Lectins
• Additives (colorants, flavors, gums, Sulphites, Preservatives (Sodium Benzoate)
• Glyco-phosphates in non-organic vegetables
• Gluten
• Nightshade Family (Tomato, Eggplant, Potatoes, Goji Berries, Peppers)
• Strawberries, Raspberries, Pineapple, Pears, Kiwi Fruit, Papaya
• Nuts (esp. peanuts, walnuts, cashews)

Complexity

So, you can see that MCAS can be extremely pervasive, affect multiple body systems, and be frustrating to diagnose. It can take exhaustive tracking of diet and possible environmental triggers to figure out what your personal triggers are. What is triggering to one person may not be for someone else. And what triggers a symptom flare today may not trigger one tomorrow in the same person, because variables such as past triggers and level of activation play a role.

Here is an example. On Saturday I was outside for part of the day at my son’s Ultimate Frisbee tournament (pollen, heat, sun, dehydration); I came home and mowed the lawn (fatigue, pollen, sun, heat, dehydration); and then I went out for a special anniversary dinner and splurged on a few foods that I know are ordinarily triggering (crab, spices). I took about five extra doses of my mast cell stabilizers over the evening and one extra Claritin, and I didn’t react.

After all of those triggers the previous day, I went to the second day of my son’s tournament (pollen, heat, sun, dehydration); for dinner, I ate one possibly triggering food and started to experience my symptom progression of facial flushing, allergy symptoms, and sciatica. See my post on knowing your symptom progression.

The bucket theory

The Bucket Theory offers a helpful analogy for why this happens. “You could think of your body as an empty bucket. Different foods and activities fill your histamine bucket at different speeds but combine to form the total level of histamine in your body. If you can keep your bucket at a lower level, you may feel better because a fuller bucket could mean you have more symptoms. Managing triggers, reducing exposure to known triggers, and taking medication could all help to manage the level of your bucket.”

So, likely my bucket was still full from Saturday when I had that one possibly triggering food that overfilled my bucket. The result was a pretty bad reaction.

Mast cell mediators

Yet, histamine is not the only mediator that can affect Mast Cells. Others are:

• Tryptase
• Chymase
• Interleukins
• Prostaglandins
• Cytokines
• Chemokine
• Proteases

My mast cell activation 

As I discuss in my second book, and in episode 47 of the Miracle Voices Podcast, both of my daughters have Mast Cell Activation Syndrome (MCAS), though one of them also has disabilities from a neurological disorder. I was my disabled daughter’s full-time caregiver from 2016-2022. In 2020 I experienced a health crisis and realized that I must also have MCAS. The stress of the pandemic, mold exposure, Lyme Disease, moving houses, and long-term caregiving became triggering events that pushed my body from being able to manage occasional triggers, to entering a period of free fall as symptoms that had somehow been suppressed for years went out of control.

Within three months I had to eliminate 75 percent of the foods in my diet because I suddenly could not tolerate them. I was alarmed to need more and more antihistamines to remain stable, and the things I had taken for granted – my toothpaste, my favorite foods, my essential oils, and dozens of other things – had to be discontinued to arrest the cycle of Mast Cell over-activation.

With the help of my functional medicine provider, my MCAS symptoms have been somewhat under control with a daily intake of an H1 blocker (Claritin), Quercetin (a flavonoid which is a mediator blocker), Vitamin C (an antioxidant), Curcumin (an anti-inflammatory), PEA (an endocannabinoid-like lipid mediator with extensively documented anti-inflammatory, analgesic, antimicrobial, immunomodulatory and neuroprotective effects), D-Hist (a targeted blend of flavonoids, antioxidants, proteolytic enzymes and botanicals to support allergies), Histamin Block (an enzyme formula that replenishes DAO in your gut), and NAC (an antioxidant). But I was still experiencing symptom flares several times a week because my bucket was still too full.

My breakthrough

I experienced a big breakthrough though when I added Luteolin (another flavonoid that is a mediator blocker) daily with each meal. Suddenly I could tolerate many more foods, and my reactions were less severe.

This is a big topic, so I think I will stop here for now! I will post about some of the intricacies of managing MCAS in future posts. So stay tuned!

What do you think of this overview of MCAS?

Do you have MCAS or histamine intolerance? I’d love to know what you think of this post! Please comment below!