Understanding Histamine Intolerance: A Comprehensive Guide

What is Histamine Intolerance?

Histamine intolerance (HIT) occurs when your body struggles to break down histamine. Histamine is a natural chemical found in many foods and produced by your body. When histamine builds up, it can lead to various symptoms. In individuals with this condition, the enzyme Diamine Oxidase (DAO) is less active. Sometimes, another enzyme, HNMT, is also involved. This reduced activity means dietary histamine isn't processed effectively (1, 2, 3, 4).

HIT is different from a food allergy, which involves the immune system. Instead, it is a type of non-allergic food reaction or intolerance (5, 6). Testing and confirming HIT can be tricky. As a result, it remains somewhat controversial and often overlaps with other gut or food-sensitivity issues (7, 8, 9).

Symptoms of Histamine Intolerance

Individuals with histamine intolerance often report a variety of symptoms, which can vary widely:

• Headaches or migraines

• Skin flushing, hives, or itchiness

• Nasal congestion or a runny nose

• Irregular heartbeat or palpitations

• Low blood pressure or dizziness

• Digestive issues: bloating, diarrhoea, abdominal pain, nausea

• Fatigue, anxiety, or brain fog

• Menstrual irregularities or PMS-like symptoms for some women

  
  

These symptoms can overlap with many other conditions, such as IBS, allergies, and food intolerances. Therefore, histamine intolerance may be “what it’s really hiding behind” (10, 11, 12, 13, 14, 15).

Testing for Histamine Intolerance

Testing for histamine intolerance can be challenging, as there is no perfect test available. Some options include:

• Measuring DAO enzyme activity or histamine levels in blood or urine. Some studies have looked at DAO deficiencies (16, 17).

• Allergy tests to rule out true food allergies, as HIT symptoms often mimic allergies. Due to the lack of standardised diagnostic criteria, healthcare professionals often use a combination of test results, dietary trials, and clinical history (18).

  
  

Treatment for Histamine Intolerance

Treatment for histamine intolerance focuses on reducing histamine load, boosting histamine breakdown, and supporting gut health. Here are some practical steps:

• Collaborate with a nutritionist or dietitian to evaluate high-histamine foods and create a low-histamine eating plan.

• Use supplements, when appropriate, to aid in histamine breakdown.

• Improve gut health: Some gut issues can reduce DAO production. Supporting gut lining, motility, and microbiome health is essential.

• Avoid known triggers: Certain medications and conditions can increase histamine or impair DAO activity. For example, alcohol, fermented foods (including probiotics), and drugs like antidepressants can exacerbate symptoms. It's crucial to proceed gradually and monitor symptoms, as a restrictive diet or unsupported supplement use can lead to other issues.

  
  

Supplements for Histamine Intolerance

While diet is foundational, supplements may help in specific cases. These include:

• DAO enzyme supplements: These aim to add the enzyme your body lacks, helping break down dietary histamine. Some observational evidence suggests benefits; however, robust randomised trials are still lacking.

• Vitamins and minerals that support DAO or histamine metabolism. For example, vitamin B12, vitamin B6, zinc, copper, and vitamin C. Some sources link low B12 levels to worsened histamine intolerance due to impaired methylation and enzyme support.

• Antihistamine or mast cell stabilising support: In some cases, this provides symptomatic relief rather than addressing the root cause. As research is still emerging, these supplements should be used under guidance and always alongside diet and lifestyle changes.

  
  

Dietary Considerations for Histamine Intolerance

Key Principles

• Eat fresh foods: Ageing, spoilage, and fermentation raise histamine levels in foods. Avoid or limit high-histamine foods (see the next section) and also avoid leftovers that have been stored for too long.

• Focus on simple, minimally processed meals.

• After symptom improvement, gradually reintroduce foods to discover your personal tolerance threshold. Everyone’s different.

• Support gut health with foods that promote integrity, a balanced microbiome, and motility. One study found that dietary treatment reduced certain histamine-secreting gut bacteria in people with HIT (19). Thus, diet is not just about avoiding bad foods but also about building your gut resilience.

  
  

Foods High in Histamine

Foods Typically High in Histamine or That May Trigger Reactions:

• Aged cheeses, cured meats, smoked fish, and fermented foods (such as sauerkraut, kimchi, and kombucha)

• Leftover meat or fish that has been stored too long

• Alcohol, especially wine and beer

• Certain vegetables and fruits, that trigger histamine release, such as tomatoes, spinach, avocado, strawberries, and citrus.

  
  

Foods Considered Lower in Histamine / Safer Options:

• Fresh meat and fish (freshly cooked, not aged or leftover)

• Fresh eggs and non-matured cheeses (e.g., ricotta, fresh mozzarella)

• Fresh vegetables (except known triggers for you)

• Gluten-free or whole grains like rice, millet, and quinoa (depending on your overall gut health)

• Fresh fruits (like pears, apples, and watermelon) are often better tolerated.

• Herbal teas and fresh herbs (again, check your own response). Keep in mind that tolerance varies; what one person tolerates, another may not.

  
  

Understanding the Histamine Bucket Concept

The “histamine bucket” is a simple way to visualise how your body handles histamine. Picture your body as a bucket. Every time you consume high-histamine foods, experience stress, allergies, or gut inflammation, the bucket fills up. When it overflows, you start to experience symptoms like headaches, flushing, hives, or digestive issues.

Your body naturally breaks down histamine through enzymes like DAO and HNMT. However, when these pathways are sluggish due to genetics, gut dysbiosis, or nutrient deficiencies, histamine accumulates faster than it can be cleared.

Balancing your histamine load, supporting gut and liver health, and identifying trigger foods can help “empty the bucket” and reduce symptoms naturally.

The Role of Vitamin B12 in Histamine Intolerance

There is growing interest in the link between vitamin B12 status and histamine intolerance. Here’s a simplified explanation:

• The DAO enzyme, which helps break down histamine, requires proper nutrition and gut lining health to be produced effectively. A deficiency in B12 (or other cofactors like B6, zinc, and copper) may impair these processes.

• Some sources suggest that low B12 levels can worsen histamine clearance. Conversely, adequate B12 may improve DAO activity.

• For someone with histamine intolerance, checking B12 (and other nutrient statuses) can be part of a comprehensive nutrition strategy. It’s not just about avoiding high-histamine foods but also about building your body’s ability to handle histamine.

• However, some claims suggest that excessive B12 (or certain forms) might trigger histamine release in some individuals. Therefore, it requires individualised monitoring. In summary, B12 is not a cure for HIT, but it is a crucial piece of the nutrition puzzle.

  
  

Final Thoughts

Histamine intolerance is a condition worth considering if your symptoms include digestive issues, skin problems, headaches, or palpitations, especially after ruling out classic allergies and other gut diagnoses. As research continues to evolve, diagnosis and management depend significantly on a solid nutrition strategy, personal experimentation, and collaboration with professionals.

From a nutrition perspective, the goal is not only to avoid high-histamine foods but also to build your body’s capacity to manage histamine through proper nutrients (like B12, B6, and zinc) and gut health support.