Mast cells are an important part of the immune system and play a key role in immediate hypersensitivity and allergic responses. They originate in the bone marrow and mature in connective tissues throughout the body. These cells act as first responders to pathogens, allergens, and injury.
Mast cells contain granules filled with chemical mediators such as histamine, tryptase, prostaglandins, and leukotrienes. When activated, a process known as degranulation, these mediators are released and contribute to inflammation, allergic responses, and tissue repair.
The primary functions of mast cells include:
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Immune defence
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Allergic response
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Wound healing and tissue repair
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Regulation of vascular tone and permeability
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Response to toxins and environmental triggers
Mast cells are widely distributed in the body, particularly in the skin, lungs, gastrointestinal tract, and around blood vessels and nerves.
What Happens in MCAS?
In Mast Cell Activation Syndrome, mast cells release mediators inappropriately or excessively, either spontaneously or in response to triggers. This leads to symptoms that can affect multiple organ systems.
MCAS is generally categorized into:
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Primary (clonal): Associated with genetic mutations, often involving the KIT receptor. This includes conditions such as systemic mastocytosis.
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Secondary: Mast cell activation occurs in response to identifiable triggers such as allergens, infections, or autoimmune processes.
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Idiopathic: No clear underlying cause is identified, but symptoms and mediator release are present.
Symptoms of MCAS
Symptoms can vary widely between individuals and often involve more than one organ system.
Skin
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Flushing
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Hives (urticaria)
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Itching (pruritus)
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Swelling (angioedema)
Neurological
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Brain fog
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Fatigue
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Headaches
Cardiovascular
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Rapid heart rate
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Palpitations
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Dizziness or lightheadedness
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Fainting
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Low blood pressure
Respiratory
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Wheezing
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Coughing
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Throat tightness
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Nasal congestion
Gastrointestinal
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Abdominal pain or cramping
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Diarrhea
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Nausea or vomiting
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Bloating
Musculoskeletal
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Joint pain
In some cases, symptoms may resemble anaphylaxis.
Common Triggers
Triggers vary by individual but may include:
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Physical or emotional stress
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Exercise
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Temperature changes
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Fragrances or chemicals
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Certain foods
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Medications
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Environmental allergens
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Infections
Diagnosis of MCAS
Diagnosis can be complex and requires careful evaluation. Three key criteria are generally used:
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Clinical symptoms involving two or more organ systems
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Objective evidence of mast cell mediator release
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The most validated test is serum tryptase measured during a reaction and compared to baseline
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A significant increase is defined as: baseline tryptase × 1.2 + 2 ng/mL
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Response to treatment that targets mast cell mediators or stabilizes mast cells
Other laboratory markers may include urinary histamine metabolites, prostaglandin D2, or leukotriene E4, although these are less standardized.
It is important to rule out other conditions that may present similarly.
Conditions That May Overlap with MCAS
MCAS can coexist with or resemble other conditions:
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Ehlers Danlos Syndrome (EDS) and Hypermobility Spectrum Disorders (HSD)
May share symptoms such as joint pain, gastrointestinal issues, and dysautonomia -
Postural Orthostatic Tachycardia Syndrome (POTS)
Overlaps with symptoms such as dizziness, tachycardia, and fatigue -
Endometriosis
Mast cells may contribute to inflammation and pain -
Metabolic conditions such as Type 2 Diabetes
Mast cells have been implicated in chronic inflammatory pathways
While associations exist, these relationships are still being studied and are not fully understood.
Natural Treatments
Nutrition and MCAS
There are currently no universal dietary guidelines for MCAS. However, some individuals may benefit from reducing dietary histamine or avoiding known triggers.
Commonly reported food triggers include:
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Dairy
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Wheat and gluten-containing grains
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Food additives such as sulfites, benzoates, and nitrates
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Monosodium glutamate
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Alcohol, particularly wine
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Tomatoes, citrus, and strawberries
Foods higher in histamine may include:
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Aged or cured meats (such as salami and processed meats)
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Fermented foods (such as yogurt, vinegar, and soy sauce)
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Alcohol
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Chocolate
Foods generally lower in histamine may include:
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Fresh meats and fish
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Gluten free grains
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Olive oil
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Seeds such as flax and chia
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Non dairy milk alternatives
Individual tolerance varies, and overly restrictive diets are not recommended without guidance.
Nutraceutical and MCAS
Nutritional supplements may support symptom management, but should be used under the guidance of a qualified healthcare provider.
Probiotics
Certain strains may help modulate inflammation and histamine metabolism, including:
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Bifidobacterium longum
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Lactobacillus rhamnosus
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Lactobacillus plantarum
Some strains may produce histamine and may not be tolerated by all individuals, including:
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Lactobacillus casei
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Lactobacillus bulgaricus
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Streptococcus thermophilus
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Lactobacillus helveticus
Other nutraceuticals
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Quercetin
May help stabilize mast cells and reduce histamine release -
Vitamin C
Supports histamine breakdown and has antioxidant effects -
Curcumin
May help reduce inflammatory signalling -
Diamine oxidase (DAO)
Supports breakdown of dietary histamine -
Omega 3 fatty acids
May support anti inflammatory pathways and gut barrier function
Evidence varies, and responses are individual.
Final Thoughts
Mast Cell Activation Syndrome is a complex condition involving inappropriate activation of mast cells and release of inflammatory mediators. Symptoms can affect multiple systems and vary significantly between individuals.
Early recognition, proper evaluation, and a personalized approach to management can help improve quality of life. If MCAS is suspected, working with a knowledgeable healthcare provider is essential to ensure accurate diagnosis and appropriate treatment.
About the author:
Hi, I’m Abinaa, a fourth-year naturopathic medical student at the Canadian College of Naturopathic Medicine with a deep-rooted passion for natural healing, inspired by my South Asian upbringing. Through this blog, I hope to share my journey, explore topics in holistic health and wellness, and offer simple, thoughtful insights that support a more balanced and mindful way of living.
