MCAS

[Daniel]

Hi @jschwartz1

Thank you for sharing your story! I’m glad to hear how much relief you experienced from a low-histamine diet. Your body gave you a strong clue, and you listened. That’s powerful. Let’s unpack your questions one by one!

A) Can I Explore an MCAS Diagnosis Without a Specialist?
Yes, to a degree. However, there is no single test that definitively diagnoses Mast Cell Activation Syndrome(MCAS). Diagnosing MCAS involves a multi-faceted approach, including assessing symptoms, ruling out other conditions, and using specialised tests to identify mast cell activation.

• Track your “histamine bucket”: Every exposure (be it food, stress, toxins, or hormones) adds to the load. Flare-ups often happen when the bucket overflows.

• Identify patterns: A journal that captures food, symptoms, sleep, menstrual cycle, and stress levels can reveal connections.

• Consider key lab tests (if your provider is open to it):

  • Tryptase (ideally during a flare)

  • Plasma Heparin (Heparin is released by mast cells, but not always/ideally during a flare)

  • CGA or Chromogranin A (Not a primary indicator for MCAS, but it has been used. CGA levels can be elevated by MCAS – but they can be elevated by other causes as well)

  • DAO enzyme levels (Not diagnostic, but it is helpful. DAO or diamine oxidase – your histamine-breakdown helper)

  • 24-hour urinary histamine or prostaglandin D2

These labs don’t always “prove” MCAS, but they help guide your next steps.

B) How Do I Prevent Flare-Ups? Is It Only About Diet?
Diet is a big piece, but it’s only one part of a broader picture. Other triggers can activate your mast cells:

The Core Triggers:

1. Gut dysbiosis and permeability

2. Hormonal shifts

3. Environmental toxins (mold, chemicals, fragrances)

4. Chronic infections (EBV, Lyme, candida)

5. Emotional or physiological stress

All of these can increase your sensitivity threshold. Since Mast cells are part of your immune system, they are highly sensitive to these “danger signals.”

What can you do beyond diet:
Mast cells have corticotropin-releasing hormone receptors, which means psychological stress can directly activate them.

• Nervous system regulation is crucial: breathwork, somatic work, EMDR, or meditation can reduce the limbic overactivation that affects mast cells.

• Nutrients that stabilise mast cells:

  • Quercetin (500–1000 mg/day)

  • Vitamin C (buffered or liposomal is gentler)

  • Magnesium glycinate

  • Omega-3 fatty acids

  • DAO enzyme before meals, especially when eating out

• Safe antihistamines: H1 (loratadine) + H2 (famotidine) combos are sometimes helpful short-term, especially during stressful periods or travel

Realistic Food Strategies:

• Focus on a flexible low-histamine approach, not perfection

• Batch prep 3-4 core meals that freeze well (e.g., simple proteins, zucchini, sweet potato, rice)

• Avoid aged foods, leftovers >24h, and slow-cooked meals (these tend to build histamine)

• Choose restaurants with build-your-own bowls or grilled proteins and fresh sides

• Carry “safe snacks” (e.g., rice cakes, apples, collagen bars)

When it comes to food strategies, the goal isn’t restriction: it’s regulation.

C) IVF & Pregnancy considerations in suspected MCAS

You’re 100% right that pregnancy and fertility treatments can shift mast cell behavior. Hormonal fluctuations (especially estrogen surges) can aggravate symptoms.

Some things you can consider:

• IVF meds can be histamine-liberating (e.g., hCG, estrogen and antibiotics like Doxycycline, which are sometimes used)

• Request preservative-free versions of injectables if available

• Ask about pre-medicating with antihistamines or mast cell stabilisers

• Avoid contrast dyes, if possible, and flag your sensitivity to meds

After IVF or during postpartum (where hormones plummet), flare-ups can occur. You can reduce risks if you plan for gut, liver, and nervous system support upfront.

Here are some ideas:

• NAC (N-acetylcysteine): an antioxidant which also supports liver detox

• Milk thistle (silymarin): which is liver-protective.

• Probiotics: but be careful. Some strains can worsen MCAS because these strains produce histamine. Choose strains that reduce histamine, like Bifidobacterium infants. An example of probiotics that could help you is ProBiota HistaminX from the brand Seeking Health.

Your body has already shown you that histamine plays a role. The goal isn’t perfection. It’s resilience: getting your system strong enough to tolerate more foods, stress, and life as you move into this exciting next phase.

I hope this answer was helpful,

Daniel

• This reply was modified 3 weeks, 6 days ago by  Daniel.

[Bernadette_Abraham]

@jschwartz1 I’m so happy to hear that following a low-histamine diet has not only helped reduce, but also eliminate your symptoms. But yes, I agree with you, it’s not sustainable. It is a tool, and also a helpful way to determine if the body is in fact dealing with histamine overload without having to do any expensive tests.

What I’d like to add to Daniel’s already comprehensive reply is the following. Anytime we seek testing, the goal should be to provide a direction. Not to confirm an assumption. So in your case, what would change if you were able to get a MCAS diagnosis? In reality, not much. You would still need to figure out why the mast cells are overreacting. And the key reasons as Daniel shared above as well are:

• Infections (e.g., Lyme, EBV, mold, parasites)

• Toxins (e.g., mold/mycotoxins, heavy metals, pesticides)

• Gut issues (e.g., leaky gut, SIBO, histamine intolerance, dysbiosis)

• Chronic stress & trauma (nervous system dysregulation, trauma history)

• Hormonal imbalances (estrogen dominance, thyroid dysfunction)

• Nutrient deficiencies (zinc, quercetin, B6, DAO enzyme, magnesium)

• Genetics (e.g., MTHFR, HNMT, DAO, MCAS predispositions)

• Environmental exposures (EMFs, VOCs, synthetic fragrances)

So if I was in your shoes, I would actually put my money and effort towards trying to figure out the root cause(s). All of the above can be tested, but that would also be very costly. So to help, I’m going to share a few symptom questionnaires & the test I would prioritize if I was in your shoes, keeping budget in mind:

-Fill out these Mold Symptom questionnaires, and let us know your scores to help determine if mycotoxin testing is warranted.

-Fill out this heavy metal questionnaire, this one (mercury & lead), and this one for environmental exposures. Let us know your scores.

-Take our Gut Health quiz, and let us know your results. Also list your top 3-5 digestive/gut related symptoms you experience (if any) like gas, bloating, constipation, diarrhea, heartburn, acid reflux, indigestion, etc. This will help determine if GI testing like a GI map is warranted.

-Test in blood some vitamins like vitamin B6, RBC B12 and folate/B9. B6 is critical for producing DAO enzyme needed to breakdown histamine. If low, B complex supplementation may be warranted. This could be due to dietary reasons, absorption issues, and/or genetic SNPs that affect methylation and detoxification. Note, B6 an B12 (and other B vitamins) are tested in the Organic Acids test, which I will touch on below.

-Ask your doc to test tick-borne illnesses and viral panels. You’ll need to find a Lyme literate doc for this. Learn more in this protocol where I share some resources. Check if your insurance would cover this instead.

-Since estrogen dominance can contribute to histamine overload, and given your plans to try and conceive, hormone testing might be warranted. Please read this guide on estrogen dominance, to see if the symptoms match your current experience. Let us know if they do so we can guide you further.

-If there is 1 functional test that I would recommend getting that gives you a good overview, it would be the Organic Acids Test (urine). It can tell us if there are any bacterial or fungal overgrowths, as well as give clues about whether or not mold might be at play. It also provides detoxification status and whether the body might be burdened (it won’t tell us which toxin though). And as I mentioned, it also provides some B vitamin status, as well as other markers like neurotransmitters and the energy cycle. But again, if you can start with the questionnaires and listing your other symptoms related to GI and hormones, this would help us help you be a bit more specific with which tests to spend money on.

Hope this helps!