Mast Cells, Histamine, and Healing from Within
Balancing the Body’s Immune Systems Overreaction through Natural Approaches to MCAS and Histamine Intolerance.
What happens when the Immune System Won’t Calm Down?
Have you ever experienced mysterious reactions such as flushing, headaches, rashes, fatigue, anxiety, or digestive upset hat seem to come and go without warning? You’re not alone. For many people, these unexplained symptoms trace back to a lesser-known cause: histamine overload and mast cell activation. Histamine is a natural chemical messenger that helps regulate digestion, immune response, and even mood but when your body produces too much or can’t break it down efficiently, it can lead to a cascade of chronic inflammation and hypersensitivity. Understanding the difference between Histamine Intolerance and Mast Cell Activation Syndrome (MCAS) can help uncover why your body might be in overreaction mode and what you can do to calm it down naturally.
Mast Cell Activation Syndrome (MCAS) and Histamine Intolerance (HIT)
These two conditions can appear with similar symptoms, but what happens in the body is quite different.
Mast Cell Activation Syndrome (MCAS) occurs when mast cells are overreactive and release excessive inflammatory mediators such as histamine, prostaglandins, and leukotrienes.
Histamine Intolerance (HIT), on the other hand, results from the body’s inability to properly break down histamine, leading to a buildup.
Understanding Mast Cell Activation Syndrome (MCAS)
MCAS is a condition in which the body’s mast cells release too many inflammatory chemicals. It is an endogenous disorder, meaning that the body’s own immune system becomes dysregulated. Mast cells become unstable, overactive, or increase in number, releasing histamine, tryptase, prostaglandins, and cytokines.
It’s like popping a balloon full of confetti—histamine is just one of many chemicals that scatter throughout the body.
Despite the challenges, mast cells play an essential role in immune defense, tissue repair, and communication between immune cells. They are found in the skin, sinuses, lungs, gut, and around blood vessels and nerves, where they help protect the body when functioning properly.
Common MCAS Symptoms
- Flushing, itching, hives, or swelling
- Nasal congestion, runny nose, itchy eyes
- Cough or wheezing
- Rapid heart rate
- Abdominal pain, nausea, or diarrhea
- Brain fog, anxiety, fatigue, memory challenges
- Sensitivity to heat, foods, or fragrances
- Lightheadedness or low blood pressure
Types of Mast Cell Disorders
Mast Cell Activation Syndrome (MCAS) – The most common type. Mast cells release too many inflammatory mediators even though their numbers are normal. Triggers can include allergies, infections, toxins, or stress. Treatment focuses on calming and stabilizing mast cells.
Systemic Mastocytosis – A rare disorder in which the body produces too many mast cells, usually due to a genetic mutation (KIT). It can cause chronic allergic-type symptoms and affect the bone marrow, skin, liver, or spleen.
Cutaneous Mastocytosis – Involves extra mast cells in the skin, leading to brownish or itchy spots or welts (can be seen in children).
Hereditary Alpha Tryptasemia (HαT) – A genetic condition with mildly elevated mast cell activity and tryptase levels that often overlaps with MCAS, allergies, and dysautonomia.
Overlaps and Triggers
MCAS frequently overlaps with POTS (postural orthostatic tachycardia syndrome), Ehlers-Danlos syndrome, chronic infections, and long COVID. Triggers include chronic stress, infections, toxins, and hormonal changes. There may also be hereditary factors.
I came to understand this condition personally after a COVID infection triggered significant MCAS symptoms and POTS. Even as a naturopathic doctor and acupuncturist, it took time, testing, and persistence to reach an accurate diagnosis and find effective treatment.
Conventional Treatments
There is no single medication for MCAS. Treatment focuses on stabilizing mast cells and blocking the mediators they release. H1/H2 antihistamines, cromolyn, and ketotifen are commonly used. Most patients do best with a combination approach introduced slowly and carefully. The goal is to reduce mast cell degranulation and calm inflammation.
Natural and Integrative Support
While medication helps control symptoms, natural therapies address the underlying inflammation, gut imbalance, and nervous system sensitivity that perpetuate mast cell overactivity. Treatment often includes:
- A tailored diet
- Targeted nutrients, herbs, and enzymes
- Specialized probiotics
- Identification and treatment of gut infections
- Microbiome and nervous system regulation
This is truly a multi-system approach.
The Integrative Perspective
Managing MCAS is about restoring balance between body and mind.
- Mast cells are part of the body’s alarm system. MCAS means that alarm is going off too often.
- Relief comes from reducing total inflammatory load through a combination of medication, supplements, nutrition, and stress regulation.
- With individualized care, many patients regain stability and vitality.
At Vitality Integrative Care, we help patients uncover triggers, regulate the immune system, and rebuild resilience through naturopathic and functional medicine.
Histamine Intolerance (HIT)
Histamine Intolerance occurs when the body cannot adequately break down histamine, leading to accumulation. It is primarily an exogenous problem meaning it arises from foods, gut microbes, or impaired breakdown pathways.
Key enzymes involved include DAO (in the gut) and HNMT (in tissues). When these are deficient or inhibited, histamine builds up. Triggers can include high-histamine foods, DAO-blocking medications, dysbiosis, alcohol, and gut inflammation.
How MCAS and HIT Overlap
Both conditions can cause symptoms triggered by even small amounts of food.
Many individuals have both, as gut inflammation reduces DAO activity, leading to histamine buildup. Chronic histamine exposure further activates mast cells, creating a vicious cycle. For this reason, MCAS patients often develop secondary histamine intolerance.
Common HIT symptoms:
- Bloating
- Hives after certain foods
- Nasal congestion
- Headache
- Mild flushing
Testing and treatment may involve measuring DAO enzyme activity or plasma histamine, and following an elimination and challenge diet. Support may include DAO supplementation, a low-histamine diet, and nutrients that enhance histamine metabolism.
The Low-Histamine Diet
A low-histamine diet helps lower the body’s overall histamine load while healing the gut, stabilizing mast cells, and restoring enzyme balance.
Guidelines:
- Eat fresh foods—histamine levels rise as foods age or ferment.
- Avoid fermented, cured, or aged products.
- Freeze leftovers immediately if keeping them for later.
- Choose simple, whole foods and rotate ingredients to prevent new sensitivities.
- Stay hydrated and support digestion with gentle herbal teas such as chamomile, ginger, or marshmallow root.
Generally well-tolerated foods:
- Proteins: Fresh chicken, turkey, lamb, beef, white fish, eggs (if tolerated)
- Vegetables: Zucchini, carrots, broccoli, cauliflower, cucumber, kale, lettuce, sweet potato
- Fruits: Apples, pears, blueberries, mango, watermelon, grapes
- Grains: Rice, quinoa, oats, millet, gluten-free breads
- Fats: Olive oil, coconut oil, ghee, flax or chia seeds (fresh)
- Herbs: Basil, parsley, thyme, rosemary, turmeric, ginger
- Drinks: Filtered water, herbal teas, coconut water
Higher-histamine or histamine-releasing foods:
- Fermented foods (sauerkraut, kimchi, vinegar, soy sauce, miso, kombucha, wine, beer, yogurt, kefir)
- Aged foods (cheeses, cured meats, smoked fish)
- Leftovers stored over 24 hours
- Certain fruits (strawberries, citrus, tomatoes, avocado, banana, pineapple, dried fruit)
- Certain vegetables (eggplant, large amounts of spinach, tomatoes)
- Beverages such as alcohol, black or green tea, energy drinks
- Chocolate, nuts (especially walnuts, cashews, peanuts), shellfish
It’s important to remember that not all foods affect everyone the same way. Overly restrictive diets can become harmful over time. Start slowly, reduce histamine load thoughtfully, and ensure nutritional adequacy.
Although MCAS and HIT share overlapping symptoms, they are distinct in origin. MCAS reflects a systemic immune dysregulation, while HIT is primarily a metabolic or gut-based issue.
If you suspect MCAS, HIT, or both, schedule a comprehensive consultation to explore testing, nutrition, and individualized treatment options.