Histamine: Not Just a Reaction

What it does, why your body makes it, and what happens when the dial gets stuck on high.

We usually meet histamine in moments of reaction.

The sneezing, the swelling, the skin flare that seems to come out of nowhere. For most people, that’s where the conversation ends, antihistamines, avoid the triggers, move on.

But histamine is more than that. It’s not just a troublemaker, it’s a communicator. A neurotransmitter. A modulator. A first responder in your immune system’s front line.

It helps your stomach digest, your brain stay alert, your cycle regulate, your body protect itself.

Which is why it’s not just about how much histamine you have, but how well your body processes it. Breaks it down. Clears it out. Returns to baseline.

And when that system gets overwhelmed, whether from genes, gut imbalances, stress, or environment, you feel it. Not just in hives or hayfever, but in sleep, mood, migraines, cycles, and those strange symptoms that don’t quite fit into one box.

This isn’t about demonising histamine. It’s about understanding its role. Its intelligence. And what your body might be trying to tell you through it.

Because symptoms aren’t random. They’re responses. And histamine, for better or worse, is part of that internal conversation.

What Histamine Actually Does

Histamine is a biogenic amine, a small molecule that acts like a neurotransmitter, immune modulator, and gut messenger all in one.

It’s produced by mast cells, basophils, and even certain gut bacteria. And it binds to four types of receptors—H1, H2, H3, and H4—each with their own job:

• H1: blood vessels, brain, and allergy-type responses

• H2: stomach acid and gut regulation

• H3: central nervous system, sleep-wake cycle, neurotransmitters

• H4: immune cell activity, especially in inflammation

In other words: Histamine helps you digest food, regulate your brain, mount immune responses, stay alert, and heal. It’s not trying to ruin your day. It’s trying to keep you alive.

When the System Gets Stuck

Histamine is supposed to spike and clear. That’s the deal .But if you’re producing too much, not breaking it down, or your body’s on high alert for too long, you can end up in what feels like histamine hell:

• Flushing, hives, and itchiness

• Headaches, especially around ovulation or PMS

• Dizziness or heart palpitations after eating

• Nasal congestion or sneezing after wine or chocolate

• Fatigue that hits hard after meals

• Gut symptoms like bloating, reflux, or urgency

• Anxiety or insomnia with no clear reason

It’s not in your head. It’s in your nervous system, your gut, your immune cells, and your enzymes, all trying to regulate something that doesn’t like to be quiet.

Where Food Comes In

Histamine is found in food, but also made in your body. You’re not just reacting to what’s on your plate, you’re reacting to how your body’s processing, storing, and clearing those compounds.

Foods That Can Be Higher in Histamine or Trigger Release:

• Aged or fermented foods (sauerkraut, wine, cheese)

• Vinegar (especially balsamic and aged types)

• Smoked or cured meats

• Shellfish

• Avocados (especially when overripe)

• Spinach, eggplant, tomatoes

• Soy products (fermented or aged)

• Bone broth (especially long-cooked)

• Leftovers stored too long

• Alcohol—especially red wine and champagne

This doesn’t mean you’ll react to all of them. But when your histamine load exceeds your clearance capacity, symptoms show up.

 Key Nutrients That Support Histamine Clearance

Nutrient	Why It Matters	Found In
Vitamin B6	Cofactor for DAO enzyme; supports neurotransmitter balance	Poultry, salmon, sunflower seeds, banana
Vitamin C	Helps degrade histamine and stabilize mast cells	Kakadu plum, capsicum, kiwi, parsley
Copper	Essential cofactor for DAO enzyme function	Sesame seeds, liver, cashews, mushrooms
Magnesium	Modulates mast cell activity; supports nervous system balance	Pumpkin seeds, leafy greens, cacao, almonds
Quercetin	Natural mast cell stabiliser; downregulates histamine release	Onion, capers, apples with skin, dill
SAMe	Cofactor for HNMT enzyme (breaks down histamine in the liver)	Made endogenously with support from B12, folate, methionine
Omega-3s	Anti-inflammatory; stabilizes immune response	Sardines, chia seeds, flaxseed, walnuts

DAO: The Gene That Clears the Static

DAO—diamine oxidase, is the enzyme that breaks down histamine from food before it enters your bloodstream. It’s coded by the AOC1 gene and made mostly in your gut lining.

Think of DAO as your histamine gatekeeper, the one stationed at the intestinal wall, clearing excess before it spills into circulation.

When DAO is working well, things stay quiet. But when it’s low or sluggish, because of genetics, gut inflammation, nutrient deficiency, or medications, histamine builds up, and symptoms start shouting.

What Lowers DAO Capacity:

• AOC1 gene variants (lower baseline activity)

• Gut issues: leaky gut, SIBO, IBS, coeliac

• Alcohol, NSAIDs, antibiotics, hormonal medications

• Low copper, B6, vitamin C

• Hormonal fluctuations (estrogen increases histamine sensitivity)

DAO isn’t about intolerance. It’s about threshold. And the good news? Thresholds can shift.

This Isn’t a Ban List. It’s a Conversation.

Histamine overload is real. But it’s not fixed in place. The goal isn’t to cut everything forever, it’s to lower the load, support the system, and slowly rebuild tolerance.

Because your body isn’t broken. It’s communicating. And histamine is part of that language.

You don’t have to fear food. You just need to learn what it’s saying.

Want to see where the science comes from? For the extra curious, the references are here.