Beyond Histamine: Your Guide to Food Intolerances with Mast Cell Activation Syndrome

When you have Mast Cell Activation Syndrome (MCAS) food can become confusing.

Maybe you’ve tried a low histamine diet, but you’re still reacting?

Or you try cutting out more and more foods. And you’re still dealing with:

GI issues – bloating, gas, abdominal pain
Headaches
Insomnia
Hives / Urticaria
Anxiety
Fatigue
And more

Sometimes, you may even be able to eat a food and do okay with it. And the very next day you react!

Does any of that sound familiar?

Food intolerances are very common with MCAS. And they can be challenging to sort out and to navigate!

Here’s something that helps a lot of people, though.

Food intolerances can often be improved or reversed entirely!

They are often a symptom of what’s happening in your body. They aren’t the problem itself.

In this post you will learn:

What food intolerances are and how they differ from food allergies
Why histamine is the starting point with MCAS
How to think about food intolerances
When (and when not) to use food sensitivity testing
An overview of the most common food intolerances beyond histamine
Tips on uncovering your food intolerances and healing

It’s important you know that this blog post is for educational and informational purposes. It’s not meant to treat any health condition or to be prescriptive for anyone. If you have any medical condition, it is critical you work under the care and guidance of a licensed medical healthcare provider.

Prefer to watch? We covered this topic in more depth in a live show recently! You can watch the full replays from all our Lives in our Substack Library!

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Kam’s Story

My MCAS came on fast and it was severe. One day I was fine, the next I was not.

I had no idea what was happening…neither did my doctors. I just knew I was very, very sick.

It took a few months of research before I heard about MCAS. And while that helped make sense of what was going on, I found my doctors still didn’t know what to do (or sometimes even believe me).

And I had so many symptoms, I didn’t even know where to start.

I wasn’t thinking about my body as a whole system that interacted with my environment, my nervous system, or the toxic load that had pushed me over the edge yet, either.

I didn’t know that I had also developed the full gamut of food intolerances we’re covering in this article. Every. Single. One.

I was still eating what I had always eaten. All those foods made me feel good before MCAS.

But I felt awful. And I kept getting sicker. And finding answers was not easy.

When I did finally start figuring out food intolerances, FODMAPs were the most obvious. I was bloating so badly I looked 6 months pregnant after just 2 bites of food.

But a low FODMAP diet only helped a little.

And with each layer I peeled back, I thought, “I can’t possibly have MCAS and FODMAP intolerance and Histamine Intolerance.” After all, a low histamine diet didn’t seem to help much either.

What I didn’t understand at the time is there were a LOT of contributors. And I was in such a bad MCAS flare, it was like trying to put out a forest fire with a spray bottle.

When you’re already on fire all the time, throwing a little more fuel in doesn’t make much difference.

But as I started finding good information and putting what I learned into practice, my symptoms calmed down.

And when you calm those fires down? You start seeing things more clearly.

I found I did have Histamine Intolerance after all. And lectins. And oxalates. And salicylates. And issues with sulfur.

With each discovery, I was a little skeptical. How could I have ALL of those intolerances?

But I also felt empowered. Because now that I knew what was happening, it started to make sense. And I could do something about it!

Changes didn’t happen overnight and I’m still on my own healing journey. But I went from being close to needing a feeding tube to eating a wide variety of foods again.

And the basketball belly bloating? Not anymore!

I spent a couple of years chasing answers and ultimately discovered I needed to think differently. I needed to see healing as a whole system. I needed to both layer in supports and take out stressors (like mold toxins). And I needed to find good, accurate information from people who had already been on similar healing journeys.

This is why I’m so passionate about education. When you understand what’s happening, you can participate in your own healing. That’s power.

Let’s dig in!

Food Intolerances vs. Food Allergies: What’s the Difference?

These 2 terms get used interchangeably sometimes.

And they can certainly feel the same!

But there are some differences.

Even though food allergies and food intolerances are slightly different, they both do involve your immune system.

And symptoms can be similar.

Let’s look at how they are different.

Food Allergies

With a food allergy, your body identifies a food as a threat (allergen). And it launches a full immune reaction, often involving specific antibodies (tiny proteins that help your immune system, like IgE).

Peanut or nut allergies are a classic example. These allergic reactions can be immediate and severe. And they generally don’t go away.

This process happens every time you encounter even small amounts of that food.

Immunotherapy can help some people with food allergies.

But it usually requires regular lifelong exposure (maintenance doses) to keep those benefits.

Food Intolerance

A food intolerance is different.

It’s more like your body struggling to process or break down certain types of food or compounds.

For example, with Histamine Intolerance, low levels of the enzyme diamine oxidase (DAO) mean your body can’t properly break down histamine. And too much histamine causes symptoms.

Food intolerances may develop for many reasons:

An overburdened detox system
A dysregulated nervous system
Leaky Gut / gut dysfunction or damage
Mold Toxicity
Low DAO (diamine oxidase) enzyme activity
Nutrient deficiencies
Or other root causes putting too much pressure on your body

That’s actually good news.

Because that means there’s often a path to getting better once the underlying issue is addressed.

Food intolerances are not necessarily a life sentence. They are your body’s way of signaling that something deeper needs attention.

That’s the lens we use at Mast Cell 360.

Let’s take a look at how we approach food intolerances in the clinic next.

A Note on Food Sensitivity Testing

We get this question a lot, so I wanted to touch on it.

Food sensitivity testing might seem like a logical first step. Just test for everything and then avoid what comes back positive.

But food sensitivity testing has real limitations that are important to understand before spending your money or dropping foods from your diet.

One limitation is that with blood tests that measure immunoglobulin responses (like IgE or IgG), if you’re not eating a specific food, that probably won’t show up on the test.

Or if you have Mast Cell Activation Syndrome (MCAS) and your allergist does skin prick testing, you may react to everything…or nothing. This is because your mast cells are dysregulated and your immune system is haywire.

Plus, if you are already down to a few foods you don’t want to eliminate more! You want to stabilize and add more food back first.

Continuing to eliminate foods in an attempt to get rid of symptoms, especially if you are already very limited, is a slippery slope. You need nutrients to heal!

And ignoring the root causes doesn’t solve the problem, it just kind of puts a bandage on it. Supports can be really useful along the way! But you want to find what’s causing the issue in the first place.

These are reasons why we generally don’t run food sensitivity testing early on.

When we do use food sensitivity tests, it is usually after detox or even in Step 4 – Rebuilding. And it is tailored to the case.

The right tool depends on where someone is in their healing journey and what questions you are trying to answer.

The bottom line: testing is a tool, not a starting point. And like everything else with MCAS, timing matters.

But diets that look at foods you are reacting to can make a big difference for getting stability back. And how you feel while you work on addressing those root causes!

Let’s look at using diets as part of your healing process next.

How to Think About Food Intolerances with MCAS

You may have 1 food intolerance (histamine is very common) or you may have a few. Or even all the ones we’re going to cover today, like I did.

But as you read earlier, food intolerances can often be improved or reversed.

This is one of the most hopeful things we share with clients.

So, the goal isn’t to avoid foods forever. It’s to use them in a way that makes sense for your body. While you work to understand what’s driving the intolerance and address that.

A few key points to keep in mind with diets:

It is NOT complete elimination. You can’t avoid all histamine, FODMAPs, oxalates, sulfur, lectins, or salicylates. And you don’t usually need to. Plus, there is a lot you can do to support your body to better tolerate foods in the meantime!
Keep as many foods as you can. The more restrictive your diet, the harder it is to get adequate nutrition and the more stress it puts on your body. Certain foods may need to be limited, but complete elimination is not the goal.
You will add foods back as you heal. Dietary changes are a temporary support.
Swap instead of drop whenever possible. For example:
- If you’re lowering histamines, swap bananas for apples.
- If you’re lowering FODMAPS, swap apples for blueberries.
- If you’re lowering salicylates, swap blueberries for mango.
Work on root causes! This is what reverses food intolerances.

Food intolerance matters with healing because it contributes to inflammation and mast cell degranulation.

Temporarily easing up on foods that are triggering for your body helps you move forward.

But diet is just 1 piece of the puzzle. Healing is a whole system approach that also includes your:

Environment – air, water, EMFs, other toxins
Nervous system – limbic rewiring and vagal toning
Lifestyle – sleep, movement
And other factors

Where to Start: The Low Histamine Diet

With MCAS, we almost always start with histamine.

Here’s why:

Histamine food intolerance is the most common intolerance we see with MCAS
Triggered mast cells release histamine, which then triggers more mast cell degranulation, which releases more histamine. It’s a cycle worth breaking
Lowering histamine levels helps with symptom relief
If there are other food intolerances, addressing histamine helps uncover them

Sorting Out Other Food Intolerances

As you just read, you need to think about healing as a puzzle that involves your whole system. Food is just 1 of those pieces and you want to work on the other pieces, too.

And when a low histamine diet isn’t enough to get significant symptom relief, other triggers are often at play.

You don’t want to ignore your environment or nervous system balancing. But while you are working on that, you can remain curious about other food intolerances, too.

Here are some tips for sorting food intolerances out:

Keep a simple food journal. Just jot down what you eat, especially if it’s new or you eat a lot of it in 1 day. Then add any symptom changes each day to your journal. It can be quick and easy.
- Over time, you can look for patterns.
Lower 1 category at a time. For example, if you suspect salicylates are also a problem for you, eat lower histamine and lower salicylate for a few weeks and see if you feel better.
- Sometimes, people will reintroduce a few foods higher in what they are testing for 2 to 3 days at the end of that trial (if they aren’t sure). Feeling worse with reintroduction let’s you know it’s an issue.
- You can lower or raise amounts fairly easily with histamine, FODMAPS, salicylates, lectins, or sulfur. But you don’t want to go overboard and put yourself into a flare! We encourage you to work with someone knowledgeable.
- DO NOT stop oxalates cold turkey (all at once). Doing that can cause severe oxalate dumping symptoms. So, work with someone knowledgeable and go slow when it comes to oxalates.
It might not be a whole category! You can test single foods you suspect, too, like dairy or gluten (both common issues with MCAS). Just swap it out for an alternative for a few weeks and see if you feel better.

Now that you know that, let’s take a quick look at intolerances we see with Mast Cell Activation Syndrome.

Common Food Intolerances with MCAS

These are not exhaustive lists. They are just introductions to each group of food intolerances in 1 easy place.

Each of the food intolerances below has links to posts with more information and tips for managing them!

Remember, identifying food intolerances is a bridge of support, not an end goal.

And you don’t want to drop a bunch of foods all at once or unnecessarily.

Before you change your diet on your own, please make sure you’re working with a healthcare practitioner who can help you with this. Never limit foods unnecessarily and always have a licensed medical provider who is supervising your case.

General Foods

We often see people struggle with things like:

Dairy
Wheat
Eggs
Corn
Sugar

These are foods even people without MCAS often struggle with. They can be inflammatory for many people.

These are single foods rather than whole groups of foods. And you don’t always need to reduce entire food groups.

Histamines are a group we often see people struggle with, though.

So, let’s start there.

Histamine Intolerance

Histamine is a normal and necessary part of your body.

It only becomes a problem when there’s too much of it or your body can’t break it down properly.

This happens when histamine levels build faster than your body can clear them. Often due to mast cells releasing too much histamine. Or because of low levels of diamine oxidase (DAO), the enzyme responsible for breaking down histamine. Sometimes, it’s both!

Related Post: What is Histamine Intolerance?

High histamine foods include things like:

Aged meats / cured meats
Aged cheeses
Fermented foods like sauerkraut or yogurt
Chocolate
Spinach
Pineapple
Avocado
Strawberries
And more

The amount of histamine can also vary significantly depending on how the food was stored or prepared. Histamine grows on meat very quickly unless it’s frozen!

Symptoms of Histamine Intolerance may include:

Headaches
Congestion / runny nose
Hives / itching (urticaria)
Flushing
Burning skin GI issues
Fatigue
Anxiety
Blood pressure changes
Shortness of breath
And more

Common supports:

Low histamine diet
DAO (diamine oxidase)
Supplements or medications – quercetin, perilla seed extract, antihistamines
Environmental triggers – identification and reduction
Nervous system work

Let’s take a look at another common intolerance we see in the clinic, FODMAPs.

FODMAP Intolerance

FODMAPs are fermentable carbohydrates. They feed gut bacteria (good and bad).

There are different types of FODMAPs. And you may only have issues with 1 or 2 of them.

FODMAP stands for Fermentable

Oligosaccharides
Disaccharides
Monosaccharides
and Polyols

Oxalate Intolerance

Oxalates are plant-derived compounds. They look like tiny razors under a microscope. So, it’s not surprising that they cause inflammation.

In your body they can bind with minerals, clog detox pathways, and contribute to kidney or gallbladder stones, too.

They can also be produced internally. Or by certain molds that colonize the body.

Salicylate Intolerance

Salicylates are also natural plant compounds.

And they are usually anti-inflammatory. But these can become problematic for some people.

It’s a less common intolerance than histamine or oxalates. And we see it in about 20% of our clients.

They can also often be found in many body care products. So, if this is something you struggle with, you’ll want to look at what you use on your skin, hair, and mouth, too.

Related Post: Salicylates and Salicylate Foods

High salicylate foods may include:

Mint
Blueberries
Apples
Most herbs and spices
Most coffee
Coconut
Grapes
Broccoli
And more

Aspirin is very high in salicylates!

Please don’t test whether you have salicylate sensitivities by trying aspirin. This is just to let you know that if you have struggled with aspirin in the past, that’s a good clue.

Symptoms often include:

Ringing ears
Mouth / throat swelling
Insomnia
Headaches
Anxiety
And more

Supports that often help:

Reduce high salicylate foods in your diet
Eliminate it from body care products
Intolerance Complex
SPMs (specialized pro-resolving mediators) or fish oil (if tolerated) – fish oil is higher histamine, so most sensitive people do best with SPMs

We also often see that clients with Salicylate Intolerance also struggle with oxalates. But not necessarily the other way around.

Mold and salicylates are at least partly cleared through the sulfation pathway (liver detox). And mold, histamine, and oxalates can also use a lot of the resources that pathway needs to run smoothly.

People may notice they struggle with sulfur containing foods if sulfation is overloaded, too.

So, let’s look at Sulfur Intolerance next.

Sulfur Intolerance

Sulfur is one of the most abundant minerals in the body. And it’s found in many common foods.

Sulfur is broken down and converted into sulfate. This is a usable form your body relies on for things like detoxification and building connective tissue.

Some people with MCAS can be more sensitive to sulfur‑related compounds. And certain gut bacteria can produce excess hydrogen sulfide (H₂S). Which may make sulfur‑rich foods harder to tolerate.

We don’t have a full post on this subject yet, but we’re always adding new, helpful content! So, stay tuned.

High sulfur foods include things like:

Onions
Garlic
Eggs
Cruciferous vegetables – broccoli, cauliflower, kale, Brussels, cabbage
Animal proteins (although, these are broken down differently by the body)

Frequent symptoms:

Really smelly gas (bad eggs)
Bloating
Loose stools
Brain fog
Sudden fatigue
Post-meal crashes
Racing heart or palpitations
And more

Supports:

Sulfation support – often requires a deeper dive into what’s missing and why. You don’t want to dump a bunch of ‘support’ on a bottlenecked pathway that has no way to clear things! That just causes more issues.
Reducing high sulfur foods as needed

Note: reactions to several sulfur-containing supplements like glutathione, NAC, ALA may also indicate sulfur issues.

And the last intolerance we’ll discuss is often the least immediately problematic, but can still be an issue for some, lectins.

Lectin Intolerance

Lectins are proteins found in legumes, grains, and nightshades. Studies suggest they can trigger immune reactions in some people.

But soaking and cooking foods can help decrease lectins substantially.

And you don’t want to remove all the health benefits that many foods with lectins can provide!

Related Post: Lectin Intolerance and MCAS

High lectin foods:

Beans
Many grains
Quinoa
Nightshades – tomatoes, eggplant, peppers
Squashes – winter and summer squashes (like spaghetti squash or zucchini)

Possible symptoms:

GI issues – gas, bloating,
Fatigue
Skin breakouts
Brain fog
Joint pain
And more

Helpful supports:

Lowering lectins in your diet
Soaking and cooking neutralizes many lectins – pressure cooking is especially effective
Addressing underlying root contributors

Whew! That’s a lot of information.

Remember, not everyone needs to investigate all of these. This is just here as an easy reference for you to come back to if you need it.

And the goal is always to support healing and get foods back.

A Final Word of Hope

If you made it this far and feel overwhelmed, I get it. As someone who has dealt with all these food intolerances, it can be a challenge.

But here’s what I want you to remember—this information is meant to empower you, not scare you.

Yes, Mast Cell Activation Syndrome is complex. Yes, it often comes with food intolerances. And yes, sorting through it all takes time and patience. Sometimes more than feels fair.

But we also see people get better. Every single day. We’ve experienced it ourselves.

It happens. Not overnight, but it happens.

This post is an invitation to be curious about your own body. To look for patterns. To understand what might be driving your symptoms and get to the roots. So you don’t have to manage it forever.

You don’t have to have all the answers right now. And you definitely don’t have to be perfect.

What we hope you take from this is possibility. Information that helps you participate more fully in your own healing. And knowledge that gives you agency in choosing your way forward.

Be gentle with yourself. Be curious. Keep going.

You’re not stuck here.

Written by Kam, Mast Cell 360 Health Coach

Ready for Personalized Support?

If you’re feeling overwhelmed, remember to just look at 1 thing at a time. And maybe start with histamine and nervous system work.

If you want personalized support, or you are not making progress on your own, our team is here to help.

We offer 1:1 support through our clinic:

Foundational – Strategy Sessions: Get your next action steps with one of our Health Coaches
Advanced Care: Comprehensive, ongoing support with our Lead Practitioners and Health Coaches
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Beyond Histamine: Your Guide to Food Intolerances with Mast Cell Activation Syndrome

Kam’s Story

Food Intolerances vs. Food Allergies: What’s the Difference?

Food Allergies

Food Intolerance

A Note on Food Sensitivity Testing

How to Think About Food Intolerances with MCAS

Where to Start: The Low Histamine Diet

Sorting Out Other Food Intolerances

Common Food Intolerances with MCAS

General Foods

Histamine Intolerance

FODMAP Intolerance

Oxalate Intolerance

Salicylate Intolerance

Sulfur Intolerance

Lectin Intolerance

A Final Word of Hope

Ready for Personalized Support?

More Posts on Food Intolerances and MCAS

References

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Is Olive Oil Low Histamine? The Truth About Quality, Freshness, and What You Need to Know with MCAS and Histamine Intolerance

The Mast Cell 360® Method: Healing MCAS in the Right Order for Sensitive Bodies

Customizing Your Flare Plan for Mast Cell Activation Syndrome and Histamine Intolerance

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