Histamine Intolerance

Histamine intolerance is a prevalent issue for many woman, particularly in midlife, and it can significantly impact daily comfort and well-being. The hormonal shifts, stress levels, and changes in digestive health that often occur during this stage of life can exacerbate histamine intolerance, leading to a range of uncomfortable symptoms. In this article, we will explore the common connections and underlying reasons why histamine intolerance can become more pronounced in midlife.


Histamine is a chemical most known for its connection with allergies. It is a natural product of our immune system, released in response to pathogens, viruses, or allergens. The inflammation caused by histamine alerts the body to the location of the threat so it can start to eliminate it. Persistent symptoms occur when histamine levels build up too high or when the body lacks the enzymes to break it down. Since histamine travels in the blood, it can reach every part of the body, leading to systemic symptoms.

When this occurs, your symptoms can move from being localised to systemic. Localised symptoms include redness, itching, tenderness, swelling, sneezing, runny nose, watery eyes, and digestive upsets. Systemic symptoms can be almost anything, but the most common ones include difficulty regulating body temperature, flushing, headaches, anxiety, dizziness, insomnia, brain fog, fatigue, joint pain, and a racing heartbeat.

Does this sound like a familiar list? It includes many common symptoms of menopause. It’s important to consider whether the underlying cause of your symptoms is linked to histamine, hormones, or both. Histamine and estrogen are closely connected. Estrogen stimulates the release of histamine and down-regulates the production of diamine oxidase (DAO), an enzyme that breaks down histamine. This increases the total amount of histamine and reduces the body’s ability to break it down. Conversely, histamine stimulates the production of estrogen, creating a vicious cycle.


The digestive system also plays a crucial role in histamine regulation. Here are some ways it can contribute to histamine issues:

  • Microbial Imbalance: Certain microbes (like Morganella and Klebsiella) in the digestive system produce histamine, while others (like Lactobacillus rhamnosus and Bifidobacterium longum) support the breakdown of histamine. Dysbiosis, or an imbalanced digestive microbiota, can lead to excess histamine levels.
  • Lipopolysaccharides (LPS): Many histamine-producing microbes also produce LPS, an inflammatory substance that increases inflammation and promotes intestinal permeability, making it easier for histamine to enter the bloodstream.
  • Zonulin: This substance also contributes to intestinal permeability and inflammation. A compromised intestinal lining can lead to more histamine entering the bloodstream, heightening symptoms of histamine intolerance.
  • Digestive Inflammation: Anything that increases digestive inflammation, such as food intolerances or digestive disorders like SIBO or IBS, can contribute to histamine increase.
  • DAO Enzyme Activity: DAO is the main enzyme that breaks down digestive-based histamine. DAO activity can be reduced due to genetic factors, intestinal inflammation, or nutrient deficiencies (e.g., B6 and copper). Without adequate levels of DAO, histamine isn’t broken down, leading to histamine intolerance.


Stress exacerbates histamine intolerance symptoms and impacts the body's ability to manage histamine levels effectively. Here’s how stress influences histamine intolerance:

  • Cortisol Release: Stress triggers the release of cortisol, a stress hormone. Elevated cortisol levels can destabilise mast cells, which store and release histamine, leading to increased histamine release.
  • Enzyme Production: The body relies on enzymes like DAO and HNMT to break down histamine. Chronic stress can negatively affect the production and activity of these enzymes, reducing the body's ability to metabolise histamine efficiently. This can result in higher histamine levels and more pronounced symptoms.
  • Inflammation: Stress contributes to systemic inflammation, which can further exacerbate histamine intolerance. Inflammatory responses can increase histamine release from mast cells, leading to a cycle of inflammation and histamine release that worsens symptoms.
  • Digestive Health: Stress impacts digestive health, which is crucial for histamine metabolism. It can alter the gut microbiota, increase intestinal permeability, and reduce the production of digestive enzymes, including those that break down histamine.
  • Immune System Dysregulation: Chronic stress can dysregulate the immune system, leading to an overactive response that increases histamine production. Stress-induced immune changes can exacerbate allergic reactions and sensitivities, contributing to higher histamine levels in the body.
  • Symptom Amplification: Stress can amplify the perception and severity of symptoms. For instance, stress can increase sensitivity to pain and discomfort, making histamine intolerance symptoms like headaches, digestive issues, and skin reactions feel more intense.

Managing stress through relaxation techniques, exercise, adequate sleep, mindfulness, and other stress-reduction strategies is crucial for individuals with histamine intolerance.


Many symptoms of histamine intolerance (fatigue, headaches, digestive issues, skin problems) overlap with those of thyroid disorders. Women with hypothyroidism can have increased mast cell activity, contributing to higher levels of histamine production. These women also have a slower metabolic rate, reducing the rate at which they break down histamine.

Conversely, women with hyperthyroidism can have an increased number of histamine receptors, promoting an increased response to the presence of histamine.

Elevated histamine levels can promote thyroid dysfunction and contribute to autoimmune thyroid conditions.


What Can Be Done to Improve the Situation?

Consider booking an appointment to work together on this. My usual first step involves testing, including a digestive microbiome test. While waiting for these results, it’s a great time to make dietary changes, add enzyme supplementation, and implement stress management techniques.

Dietary changes include avoiding histamine-containing foods, histamine-releasing foods, and DAO activity-blocking foods.

Histamine-containing foods:
- Fermented foods
- Aged cheeses
- Cured meats and smoked fish
- Dried fruit
- Processed foods
- Soured foods
- Vinegars and pickled vegetables
- Leftover foods

Histamine-releasing foods:
- Alcohol
- Tomatoes
- Bananas, strawberries, papaya, pineapple
- Chocolate
- Cow’s milk products
- Gluten-containing foods
- Shellfish

DAO activity-blocking foods:
- Alcohol
- Caffeine: coffee, black tea, green tea
- Energy drinks


For more FREE information on histamine, consider attending the histamine Summit. For more information click below

Reversing Mast Cell Activation and Histamine Intolerance Summit



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