Mast cell activation syndrome (MCAS) is a condition where mast cells in your body mistakenly release excessive amounts of chemicals. While some of the resulting symptoms can resemble an allergic reaction, triggers for MCAS are typically harder to pin down.

Let’s uncover more about the condition, including what you can do to treat it and reduce your risk of triggering MCAS.

Understanding Mast Cell Activation Syndrome

Mast cells are a type of white blood cell responsible for fighting off infection as part of your immune system response. They also play a role in allergic reactions.

If you encounter an allergen, mast cells release chemicals known as mast cell mediators to protect your body. The release of mediators is a process called degranulation.

In MCAS, these mediators can be released regardless of whether or not an allergen is present. Exercise, stress, certain medications, and your diet can all trigger MCAS, but it can also be a spontaneous event.

This can make it very difficult for people with MCAS to pinpoint the cause of why they feel like they’re in a constant state of allergy season.

There are 3 main types of MCAS: primary, secondary, and idiopathic MCAS. (1) The first two come with identified cell mutations (primary) or specific antibodies from external triggers like bee stings and reptile venoms (secondary). Idiopathic MCAS has no obvious cause.

In many cases, MCAS symptoms resemble an allergic reaction or, in more severe cases, an anaphylactic reaction, but symptoms can vary widely. (2)

MCAS symptoms generally fit into 4 main categories: skin, gastrointestinal, cardiovascular, and respiratory.

• Skin: Rash, itching, chronic hives (urticaria), swelling (angioedema), sweating
• Gastrointestinal: Nausea, vomiting, diarrhea, cramping, abdominal pain
• Cardiovascular: Low blood pressure (hypotension), rapid heart rate (tachycardia), lightheadedness, fainting (syncope), exercise intolerance (3, 4)
• Respiratory: Trouble breathing, runny nose, wheezing

In most people, 2 body systems or organs are affected at the same time. Symptoms can also take on a neurological component. That can look like brain fog, fatigue, headaches, anxiety, and an increased risk of mood disorders. (5)

MCAS + Other Health Conditions

Diagnosing MCAS can be a complex task. Comprehensive blood and urine tests for histamine metabolites, prostaglandin D2, and serum tryptase levels can indicate mast cell dysfunction. The problem is that they’re most helpful during or just after an episode. (6)

Your doctor is more likely to rule out other conditions before giving you a diagnosis of MCAS. In functional medicine, a comprehensive approach to diagnostic criteria is always best. There may be other things going on that are unrelated to MCAS or contributing to your symptoms.

If you’re ready to get to the root of your symptoms, the Autoimmune Health Reset takes a personalized approach to chronic inflammation. Get on the path toward healing.

Histamine Intolerance

Histamine intolerance is a condition where histamine builds up in your body because of dysfunction in enzymes like diamine oxidase (DAO) that break down the chemical. It’s often confused with MCAS because both can lead to high histamine levels. (7)

The difference between a mast cell activation disorder and histamine intolerance is that in MCAS, mast cells release more than just histamine. It is possible to have both, and a histamine intolerance can exacerbate MCAS symptoms.

SIBO + Leaky Gut

Researchers may have found a correlation between leaky gut syndrome, small intestinal bacterial overgrowth (SIBO), and MCAS or histamine intolerance. (8) Studies show that histamine intolerance makes you more likely to have one of these gastrointestinal tract problems.

We need more research to understand why this may be the case, but it could be related to the fact that gut issues can cause more toxins that provoke mast cells and trigger inflammation. Gut health issues can also exacerbate MCAS symptoms that affect those organ systems. (9)

MCAS Versus Mastocytosis

MCAS and mastocytosis are both mast cell disorders. (10) While MCAS involves overactive mast cells, mastocytosis causes too many mast cells to grow. The most common type of mastocytosis is cutaneous mastocytosis, which comes with visible skin changes.

While MCAS can be hard to diagnose, mastocytosis can be diagnosed with a skin biopsy. For less common forms of systemic mastocytosis, a doctor may order a bone marrow biopsy to look for blood markers that would show an excess of mast cells.

Avoiding Triggers + Managing Symptoms

How do you fix mast cell activation syndrome? Causes and triggers determine treatment for MCAS. Your personalized treatment plan will likely involve lifestyle changes to not only treat symptoms but also prevent reactions.

There is no cure for MCAS, but it can be managed with a better understanding of the cause of your symptoms.

What are the common triggers for MCAS flare-ups? Common triggers for MCAS include stress, environmental toxins, certain medications, and certain foods.

Diet Is Key

What foods should you avoid if you have mast cell disease? Since many foods naturally contain histamine or trigger the release of histamines in the body, reducing your intake of high-histamine foods may help alleviate reactions.

High-histamine foods or foods that may trigger the release of histamines include:

• Aged cheeses
• Alcohol
• Avocados
• Bananas
• Canned, smoked, cured, or pickled foods
• Chocolate
• Eggplant
• Fermented foods (sauerkraut, kimchi, and kefir)
• Legumes (soybeans, chickpeas, and peanuts)
• Licorice
• Mushrooms
• Processed food
• Some nuts (almonds and pistachios)
• Some seafood (shellfish, sardines, and tuna)
• Soy products (soy sauce and tofu)
• Spinach
• Strawberries
• Tea
• Tomatoes and tomato-based products
• Tropical or citrus fruits (kiwi, lemon, lime, papayas, and pineapple)
• Vinegar

I know what you’re thinking. Most of these are highly nutritious foods that belong in balanced diets. That’s why it’s important to work with a healthcare provider who can get a baseline of food triggers, potential intolerances, and sensitivities before making changes to your diet for MCAS.

In functional medicine, my goal is to get to the root of my patients’ issues. When it comes to foods, it’s not about getting rid of everything that may be a trigger but identifying foods that are actually causing your symptoms.

LISTEN: Microbiome Masterclass: Healthy Guts, Histamine Intolerance, Candida, SIBO, FODMAPS + Food Sensitivities

Work On Healing Your Gut

Poor gut health disrupts the balance of beneficial bacteria, which can lead to more inflammation and trigger immune responses in conditions like MCAS. Addressing gut health through diet, probiotics, and targeted treatments can help manage MCAS symptoms.

The Probiotic supports balanced gut health with 4 different strains of beneficial bacteria that target a healthier microbiome.

Detox From Toxins

MCAS can be triggered by environmental toxins like mold, chemicals, pesticides, and pollutants. Prolonged exposure can worsen your condition and make you more reactive to low levels of toxins. To reduce your exposure, use air purifiers, avoid harsh chemicals, and eat organically.

You should also support your body’s efforts to detox by keeping hydrated, eating an antioxidant-rich diet, getting plenty of rest, and reducing chronic stress.