Histamine Intolerance: When Your Histamine Bucket gets Overloaded
For many people embarking on health changes, the journey toward health feels like a series of contradictions. You may start eating fermented foods, drinking bone broth, bulking meals with spinach and avocado, yet feel worse and worse. Experiencing random hives, sudden brain fog, racing heart, and increase in insomnia and anxiety or unexplained digestive symptoms all indicate a condition known as Histamine Intolerance.
Histamine intolerance is not really an intolerance or allergy to histamine, but a Histamine Overload where the body’s ability to break down this biogenic amine cannot keep up with its intake and production.
Histamine Overload Symptoms
Histamine receptors are located throughout the entire body (H1 through H4 receptors), therefore symptoms of Histamine overload are notoriously diverse and can be difficult to pinpoint. They can include:
Skin: Hives, flushing, itching, or eczema.
Digestive: Bloating, post-meal diarrhea, or abdominal cramping.
Neurological: Migraines, brain fog, irritability, anxiety & insomnia
Cardiovascular: Racing heart (tachycardia) or sudden drops in blood pressure.
Respiratory: Chronic congestion, sneezing, or asthma-like symptoms.
What Causes Histamine Intolerance
To resolve histamine intolerance we have to look beyond low histamine diets and anti-histamine treatment. The build-up is usually caused by a combination of impaired breakdown enzymes—primarily Diamine Oxidase (DAO) in the gut and Histamine N-methyltransferase (HNMT) in the cells—and excessive internal production.
SIBO and Microbiome Dysbiosis
The gut is the primary site of histamine regulation. When there is an overgrowth of bacteria in the small intestine (SIBO), or a general imbalance in the large intestine, histamine levels can skyrocket. Certain bacterial strains are histamine producers which drive high levels of histamine. If your microbiome is skewed toward these strains, your internal histamine load is constantly high.
Mould and Mycotoxins
Mould exposure is a significant and often overlooked trigger for Mast Cell Activation Syndrome (MCAS) and histamine intolerance. Mycotoxins from water-damaged buildings act as a direct threat signal to mast cells, causing them to degranulate and dump massive amounts of histamine into the system. In these cases, a low-histamine diet often provides only marginal relief until the mould burden is addressed.
The Estrogen Connection (Perimenopause and Menopause)
There is a profound bi-directional relationship between Estrogen and Histamine. Estrogen stimulates mast cells to release more histamine, and histamine, in turn, stimulates the ovaries to produce more estrogen. This vicious cycle is why many women experience a sudden onset of histamine intolerance during perimenopause, as estrogen becomes volatile and dominant relative to progesterone. Once a woman reaches menopause and estrogen levels drop, the symptoms may shift but often persist if the underlying gut or other causes aren't repaired.
Gluten Intolerance and Digestive Insufficiency
Gluten can trigger the release of Zonulin, a protein that increases intestinal permeability (leaky gut). A leaky gut allows undigested food particles and toxins to cross into the bloodstream, triggering mast cells to release histamine. Furthermore, if you have Digestive Enzyme Insufficiency (low stomach acid or low pancreatic enzymes), undigested proteins linger in the gut, where they are fermented by bacteria into more histamine.
Methylation and Mineral Depletion
The breakdown of histamine is a nutrient-dependent process. The HNMT enzyme requires a functional Methylation cycle to work. If you have snags in your methylation (such as the MTHFR gene) or are depleted in nutrients needed for methylation then your body cannot clear histamine from its cells.
Avoid the High-Histamine Offenders:
Fermented Foods: Sauerkraut, kimchi, kombucha, and kefir.
Aged/Cured Meats: Salami, pepperoni, and aged cheeses.
Leftovers: Histamine-producing bacteria grow on cooked protein the longer it sits in the fridge. Always freeze leftovers immediately.
Specific Produce: Spinach, tomatoes, eggplant, and avocados.
Alcohol: Particularly red wine and beer, which are both high in histamine and "blockers" of the DAO enzyme.
Focus on:
Freshly Caught/Frozen Protein: White fish, chicken, or lamb (thawed just before cooking).
Histamine-Lowering Produce: Onions, garlic, and apples (rich in Quercetin, a natural mast cell stabilizer).
Herbal Support: Nettle tea and ginger act as natural antihistamines.
Histamine Intolerance vs. MCAS: What’s the Difference?
It is essential to distinguish between Histamine Intolerance (HIT) and Mast Cell Activation Syndrome (MCAS), as they require different clinical approaches. Histamine Intolerance is primarily a histamine clearance problem; the body either takes in too much histamine or lacks the enzymes (like DAO) to break it down. In MCAS, the mast cells, a type of immune cell, become hyper-reactive and unstable. Instead of just releasing histamine, dysfunctional mast cells can dump over 200 inflammatory mediators (including leukotrienes and prostaglandins) into the body in response to minor triggers like smells, stress, or temperature changes. While a low-histamine diet helps both, HIT can often be resolved by fixing the gut and replenishing minerals, whereas MCAS requires a deeper focus on calming the nervous system and stabilizing the immune system’s threshold for reactivity.
Dietary Recommendations for Histamine Overload
While the goal is to fix the root cause, a temporary low-histamine diet is often necessary to reduce the histamine load and provide symptomatic relief.
Avoid the High-Histamine Offenders:
Fermented Foods: Sauerkraut, kimchi, kombucha, and kefir.
Aged/Cured Meats: Salami, pepperoni, and aged cheeses.
Leftovers: Histamine-producing bacteria grow on cooked protein the longer it sits in the fridge. Always freeze leftovers immediately.
Specific Produce: Spinach, tomatoes, eggplant, and avocados.
Alcohol: Particularly red wine and beer, which are both high in histamine and "blockers" of the DAO enzyme.
Focus on:
Freshly Caught/Frozen Protein: White fish, chicken, or lamb (thawed just before cooking).
Histamine-Lowering Produce: Onions, garlic, and apples (rich in Quercetin, a natural mast cell stabilizer).
Herbal Support: Nettle tea and ginger act as natural antihistamines.
The Path Forward
Histamine intolerance is a loud signal from your body that your foundations—your gut, your hormones, or your environment—are out of balance. By addressing SIBO, supporting methylation, and balancing minerals like copper and magnesium, you can move from a life of restriction back to a place of resilience.
How I Can Help
In my practice, with my Histamine Intolerance clients, we combine short term low histamine diet with nutrient support to promote histamine clearance and functional testing to identify the underlying cause of histamine overload so we can resolve it in the long term. If you think you are experiencing Histamine Overload then book a free discovery call to discuss treatment options.
