Histamine intolerance: Symptoms, diet and dietary management

Dr Linia Patel (PhD, RD) unpicks the controversial topic of histamine intolerance.

Growing up I watched my brother get hospitalised a couple of times as my parents learned of his allergic tendencies. Fast forward 35 or so years and we are much more aware of allergies and intolerances. My five-year-old hyperallergic nephew is already so informed and can figure out what he can or can’t eat in a very impressive way. Coming from a family that is allergy/intolerance prone, I like to keep up to date in this area.

A ‘new’ intolerance on the block that is relatively controversial and currently widely debated in the medical community is histamine intolerance.

What is histamine intolerance?

Histamine intolerance means you have a high level of histamine in your body. This can happen if your body cannot break down histamine. This means it isn’t a sensitivity to histamine but an indication that you have developed too much of it. You naturally produce histamine along with the enzyme diamine oxidase (DAO) that is responsible for breaking down histamine that you take in from foods. If you develop a DAO deficiency and you are unable to break down histamine, you can develop an intolerance. Reasons why you could develop a DAO deficiency include:

• gastrointestinal disorders such as leaky gut syndrome or inflammatory bowel disease
• medications that block DAO functions or prevent production
• a diet high in histamine-rich foods that cause DAO enzymes not to work
• a diet high in foods that block DAO enzymes or trigger histamine release.

Symptoms of histamine intolerance

Histamine is a chemical responsible for a few major functions. It triggers release of stomach acid, which can help digestion; it is also released by the body after injury or allergic reaction as part of your immune response. Histamine also plays an important role in communicating messages to your brain.

When the histamine levels get too high or when you can’t break it down properly, it can affect normal bodily functions. While symptoms vary from person to person, some common reactions include:

• digestive issues: abdominal pain, bloating, irregular bowels, nausea and vomiting
• skin problems: itching, hives or other forms of skin rash
• respiratory symptoms: nasal congestion, coughing, wheezing
• headaches and migraines
• cardiovascular symptoms: low blood pressure, irregular heartbeat
• nervous system symptoms: brain fog, fatigue, poor concentration, anxiety and dizziness.

Diagnosis

Diagnosing a histamine intolerance can be challenging as there is no specific test currently available, which is why there is much medical debate about the condition. Typically, it is diagnosed based on clinical symptoms, elimination of other allergies and your response to an elimination diet (low-histamine diet) for 14-30 days. Blood analysis may also include the measurement of DAO in your blood or levels of histamine in the blood and urine; however, these tests are not standardised or widely available. Much more research is needed to better understand the underlying mechanisms, diagnosis and management.

Controlling histamine levels with diet

The management of a histamine intolerance should include the following:

1. Supporting good gut health. Addressing underlying digestive conditions such a ‘leaky gut’ and small intestinal bacteria overgrowth (SIBO) is important.
2. Following a low-histamine diet. There is no such thing as a histamine-free diet; however, if you have a histamine intolerance, incorporating low-histamine foods in your diet can help reduce your symptoms. The first step is to follow an elimination diet.
3. DAO enzyme supplementation. Although a topic of debate, some individuals may benefit from DAO supplements which are designed to help break down histamine in the gut. It is important to work with a healthcare professional before starting supplementation to determine appropriate dosing.
4. Addressing non-food-related histamine releases. Apart from foods there are other environmental factors (i.e., pollen and dust mites) or certain medications (e.g., NSAIDs or opiates) or food additives (i.e., artificial colours) that may exacerbate symptoms.

It is important you consult a dietitian before you follow a strict elimination diet. Foods to avoid during the elimination period are shown in the table below.

Foods to include:

• Fresh meat, chicken or fish
• Non-citrus fruits
• Eggs
• Gluten-free grains such as quinoa and brown rice
• Dairy milk alternatives such as almond milk
• All fresh vegetables except tomatoes, avocado, spinach and aubergine

Take-home message

The management of histamine intolerance is highly personal and what works for one person may not work for another. Keeping track of symptoms and triggers, working with healthcare professionals specialising in this condition and making lifestyle adjustments are all key to managing the histamine intolerance effectively.

Have you checked out Linia’s best-selling online educations?

• Nutrition for Menopause
• Gut Health – the power of the microbiome
• Low Carb: the evidence & application
• Sports Nutrition Basics
• Plant-Based Eating: The Essentials
• Food as Medicine? Food and inflammation
• Longevity through Nutrition

About the author

Dr Linia Patel has a BSc degree in biochemistry and physiology and has recently achieved a PhD in public health. Linia is a leading dietitian and sports nutritionist. Her passion is translating nutritional science into easy-to-digest and practical advice.

Further reading

1. Perez et al (2021), Low-Histamine Diets: Is the exclusion of foods justified by their histamine content? Nutrients, 13(5): 1,395.
2. Comas-Baste et al (2020), Histamine Intolerance: The current state of the art, Biomolecules, 10(8): 1,181.
3. Martin S et al (2016), Histamine intolerance and dietary management: A complete review, Allergol Immunopathol., 44(5): 475-83.
4. British Dietetic Association. Allergy Specialist Group: Histamine Factsheet.