How to Calm Your Mast Cells: MCAS Management Guide

If you’ve never heard of mast cells before, you’re not alone. Yet these immune cells play a huge role in how your body reacts to its environment, and when they become overactive, they can be at the root of many chronic, confusing, and seemingly unrelated symptoms.

This post explores what mast cells are, what happens in Mast Cell Activation Syndrome (MCAS), and the most effective strategies for MCAS management using a functional medicine approach.

What Are Mast Cells?

Mast cells are a type of white blood cell found throughout the body, particularly in tissues that connect the internal environment to the external world, such as the skin, lungs, sinuses, and gut lining. Their primary job is to act as patrollers for the immune system.

When they detect potential threats, they release chemical messengers known as mediators (these include including histamine, tryptase, cytokines, prostaglandins and many more). These substances help create inflammation, fight infection, and recruit other immune cells to the area.

From an evolutionary perspective, mast cells are essential. They respond to physical, emotional, and environmental triggers through a large array of receptors on their cell wall. These receptors allow mast cells to respond to allergens, pathogens, hormones, toxins, stress, and temperature changes within seconds.

They are designed to protect you, but when they become overly sensitive or chronically triggered, they can cause significant disruption.

When Mast Cells Go Rogue: Understanding MCAS

Mast Cell Activation Syndrome (MCAS) occurs when mast cells become dysregulated and start releasing mediators too frequently or inappropriately.

While some individuals with MCAS are extremely reactive to foods, scents, or environmental exposures, the condition actually exists on a spectrum. Many people experience milder, more chronic symptoms, such as fatigue, digestive symptoms, headaches, brain fog, flushing, or anxiety, without realising mast cells are involved.

Research suggests that up to 17% of the population may be affected by MCAS. At The Autoimmune Clinic, more than half of the clients we support show signs of mast cell overactivation, from subtle intolerance to complex multisystem illness.

MCAS Management: Our Functional Medicine Approach

Our approach to MCAS management always focuses on two key goals:

1. Reducing symptoms and calming the immune system in the short term, allowing the individual to feel more stable and less symptomatic.

2. Identifying and addressing the root causes of mast cell activation to for long term management and relief.

Here are the core pillars we consider when helping clients calm and regulate their mast cells.

1. Diet: Reducing the Histamine Load

Diet is often one of the first steps in MCAS management. Many otherwise “healthy” foods, such as fermented foods, spinach, avocado, or apple cider vinegar, are naturally high in histamine, one of the key mediators released by mast cells.

If the body’s “histamine bucket” is already full, consuming more histamine through food can quickly worsen symptoms. A low-histamine diet, trialled for a couple of weeks, can help reduce that load. If improvement is seen, we continue short-term while working on underlying causes before gradually reintroducing foods.

A low-FODMAP diet can also be beneficial for those with bacterial overgrowth or gut inflammation, as this helps restore gut balance and improve DAO enzyme activity, the enzyme responsible for breaking down histamine.

We sometimes remove other inflammatory food proteins temporarily, such as gluten or dairy, to help calm the immune system. A detailed food and symptom diary is invaluable in guiding this process, and identify possible patterns between foods and symptoms.

2. Supplements: Supporting Mast Cell Stability

Targeted supplementation can play a central role in MCAS management.

Example of mast cell stabilisers include:

• Quercetin

• Luteolin

• Perilla extract

• Black cumin seed

• Omega-3 fatty acids

• Vitamin D

These compounds help regulate immune balance and reduce the excessive release of histamine.

We also support the enzymes responsible for histamine breakdown — DAO (gut) and HNMT (body), using cofactors such as vitamin B6, copper, and magnesium.

Binders like zeolite may be used to mop up excess histamine and other inflammatory molecules from the gut, reducing total load and improving tolerance.

Of course, some individuals with MCAS have become overly reactive to almost anything that enters their mouth, whether food or supplements. In these situations, it is important to work with a practitioner who understands MCAS and can guide you through the careful and gradual introduction of some of these beneficial compounds. This ensures that therapeutic interventions are introduced safely and effectively, without worsening symptoms.

3. The Nervous System: Calming Cortisol’s Impact

The nervous system and mast cells are deeply interconnected. Did you know that mast cells have receptors for cortisol, the body’s main stress hormone? When cortisol surges frequently, mast cells can become more reactive, explaining why many people notice their symptoms worsen under stress.

In MCAS management, supporting and regulating the nervous system can be a vital piece of the puzzle. Finding practices that help you feel calm and grounded, such as deep breathing, gentle yoga, nature walks, or mindfulness, can make a signficant difference.

Sometimes, we bring in other modalities to support emotional regulation. Even simply recognising that stress is contributing to symptoms can make a difference. Understanding is key and eliminate the element of anxiety behind the not knowing what causes a flare.

4. The Environment: Hidden Triggers

Environmental factors are often overlooked yet highly relevant to MCAS management. Common triggers include:

• Allergies to dust, pets, mould, or pollens

• Hidden food reactivities

• Hormonal fluctuations (especially oestrogen and progesterone changes during the menstrual cycle)

Tracking symptoms across seasons, locations, meals and activities can reveal important patterns. Keeping a symptom diary helps identify environmental or hormonal correlations over time.

We also assess environmental exposure through the lens of CIRS (Chronic Inflammatory Response Syndrome), a form of immune dysregulation caused by biotoxin exposure from mould, water damage, or chronic infections. CIRS can directly stimulate mast cells and worsen MCAS symptoms.

We always consider CIRS involvement and investigate through environmental screening and functional testing when relevant for the individual.

5. Medications

While lifestyle and nutritional strategies form the foundation of MCAS management, certain cases benefit from medical support.

We collaborate closely with medical prescribers who can prescribe medications such as:

• Mast cell stabilisers (e.g. ketotifen, sodium cromoglycate)

• Low-dose naltrexone (LDN)

These can be particularly helpful for clients who haven’t seen enough improvement with foundational interventions. However, not everyone tolerates or benefits from medication, so decisions are always made on a case-by-case basis.

Getting to the Root Cause of MCAS

The ultimate goal of MCAS management is to uncover and address the root causes driving mast cell dysregulation. Otherwise, individuals can become stuck in long-term symptom management, needing to remain on restrictive diets and heavy supplement protocols which is far from ideal.

In our clinical experience, root causes often include a combination of the following:

• Genetic susceptibility

• Environmental or biotoxin exposure

• Gut imbalances, microbial overgrowth or infections

• Hormonal and adrenal imbalance

• Nutrient insufficiencies/ deficiencies

• Emotional or physical stress

By identifying and resolving these drivers, the immune system can begin to regulate, shifting from reactivity to balance.

The Bottom Line

Mast cells are not inherently harmful, they are your body’s protectors. But when they become overactive, they can create wide-ranging symptoms that are difficult to pinpoint.

Effective MCAS management involves a multi-layered, individualised approach:

• Calming the immune system through diet and supplements (and medications when indicated)

• Regulating stress and cortisol

• Investigating environmental and hormonal triggers

  
  

At The Autoimmune Clinic, we work with many clients across the MCAS spectrum, from mild histamine intolerance to complex, multi-system presentations. Our aim is always the same: to reduce reactivity, restore balance, and help you regain peace in your body once again.

If this post resonates with you, and you’ve perhaps already tried implementing some of these steps without finding the relief you were hoping for, it may be time to dig deeper into your health picture.

Working with practitioners who understand MCAS and its many implications can help you make sense of your unique health web and move beyond surface-level symptom management.

Feel free to get in touch or book a discovery call via our website to chat with one of our practitioners and start your journey with us.