Mast Cell Activation Syndrome (MCAS): Root Causes, Symptoms, and Natural Support
Mast cells are powerful immune cells designed to protect us from infection and injury. They act like first responders, releasing chemical messengers such as histamine, prostaglandins, and cytokines. When mast cells work properly, they help us heal. But when they become overreactive, they can release too many mediators at the wrong times — leading to widespread symptoms. This condition is known as Mast Cell Activation Syndrome (MCAS).
What Causes MCAS?
From a functional medicine perspective, MCAS is rarely caused by one single factor. Instead, it reflects immune system dysregulation triggered by underlying stressors. Common root causes include:
Gut dysbiosis & leaky gut → microbial imbalances and intestinal permeability stimulate mast cells.
Chronic infections → Lyme, Epstein–Barr virus, Candida, parasites, or mold exposure keep mast cells on “high alert.”
Environmental toxins → chemicals, fragrances, and mold toxins can trigger overactivation.
Hormonal imbalances → estrogen stimulates mast cell activity, which explains flares around menstrual cycles or perimenopause.
Nutrient deficiencies → low vitamin C, B6, magnesium, or copper reduce the body’s ability to break down histamine.
Stress & HPA axis dysfunction → nervous system dysregulation amplifies mast cell reactivity.
Symptoms of MCAS
Because mast cells are found throughout the body, symptoms can appear in multiple systems. Common patterns include:
Skin: itching, hives, flushing, swelling, dermatographia (skin writing).
Digestive system: bloating, diarrhea, abdominal pain, nausea, “IBS-like” flares.
Nervous system: brain fog, headaches, dizziness, anxiety, mood changes.
Respiratory system: nasal congestion, asthma, throat tightness.
Cardiovascular system: palpitations, low blood pressure, POTS-like symptoms.
Whole-body: fatigue, chemical sensitivities, food intolerances, even anaphylaxis-like episodes without a clear allergen.
These symptoms often appear unpredictable, leaving people feeling like their body is reacting to “everything.”
Functional Medicine Approach to MCAS
The goal isn’t just to suppress mast cells but to calm the immune system, reduce triggers, and restore balance.
1. Identify and Reduce Triggers
Remove mold and chemical exposures.
Follow a low-histamine diet (avoid aged cheeses, fermented foods, alcohol, and leftovers).
Rotate foods to prevent immune hyperreactivity.
2. Support Gut Health
Address gut infections or dysbiosis.
Heal the gut lining with L-glutamine, zinc carnosine, and aloe vera.
Choose histamine-lowering probiotics (such as Lactobacillus rhamnosus GG or Bifidobacterium infantis).
3. Stabilize Mast Cells Naturally
Quercetin & Luteolin: flavonoids that calm mast cell degranulation.
Vitamin C: reduces histamine release and supports DAO enzyme activity.
Nettle, curcumin, and omega-3s: anti-inflammatory support.
DAO enzyme supplementation: taken with meals to break down histamine in food.
4. Support Detoxification
Aid liver pathways with sulforaphane (broccoli sprouts), milk thistle, and NAC.
Use binders like activated charcoal or bentonite clay if mold toxins are a trigger (under practitioner guidance).
5. Regulate the Nervous System
Stress management techniques such as breathwork, meditation, or somatic therapy help reduce sympathetic overdrive.
Address HPA axis dysfunction with restorative sleep, gentle movement, and targeted adaptogens (individualized).
The Bigger Picture
MCAS can feel overwhelming, but it is your body’s way of signaling that it’s under stress. By uncovering root causes and gently calming the immune system, many people experience profound improvements in symptoms. Functional medicine doesn’t just ask, “How do we stop the reaction?” but also, “Why is the reaction happening in the first place?”
If you suspect MCAS may be part of your health challenges, consider working with a practitioner who can help identify your unique triggers, guide you through functional testing, and create a personalized plan for healing.
Disclaimer
This article is for educational purposes only and is not intended to diagnose, treat, or cure disease. Always consult your qualified healthcare provider before making changes to your diet, supplements, or medications.
© Positive Shift Wellness