environmental allergens histamine

Linking allergies & histamine

Allergies are considered one of the fastest growing chronic diseases in Australia. More than 20% of the population in industrialised countries suffer from a food intolerance or allergy.
Symptoms of allergic disease can range from allergic rhinitis, hay fever, digestive disorders, eczema and asthma, or life-threatening anaphylaxis.
I am going to run you through what allergies & intolerances are, how to identify and treat them.

Understanding Allergies

Allergies occur when our immune system reacts to proteins in the environment that are harmless for most people, such as house dust mites, pets, pollen, other insects, moulds and foods.
An intolerance is considered a “chemical” reaction to a substance, most often food, and will not show up on a traditional allergy test.
The term sensitivity is less clear, however in complementary medicine it is commonly understood as a delayed and milder reaction.
The possible manifestation of a food reaction is widespread and non-specific. They have been linked to gastrointestinal symptoms, skin conditions, respiratory issues, fatigue, headache, migraine, cognitive deficits, neurodevelopmental disorders, anxiety, depression, joint pain, muscle pain, and endocrine disturbances. Regardless of the cause, be it environmental or food-induced, the impact on an individual’s quality of life can be considerable.

What is Histamine?

Histamine is a chemical compound that is involved in the immune system response. It is often associated with seasonal allergies, food allergies and symptoms such as headaches, nasal congestion, sneezing and difficulties with breathing.
Sometimes you may experience symptoms that aren’t associated with the environment, such as a runny nose, sneezing, and itching after wine or certain foods like bananas, avocados, or tomatoes.

Histamine acts like a bouncer in a club. It helps your body get rid of something that’s bothering you, in this case, an allergy trigger or “allergen”.

Histamine plays an important role in helping the body communicate with the brain, alert the immune system to a potential threat, and launch an inflammation response.

What is Histamine intolerance?

Histamine intolerance occurs when there is a build-up of histamines in the blood stream and the body is no longer able to break it all sufficiently.
Typical symptoms of histamine intolerance include:
o Gastrointestinal upset, including altered bowel function, abdominal pain and nausea

o Headaches, dizziness and migraines

o Joint pain

o Hives and flushing skin rashes

o Tissue swelling

o Brain fog, anxiety and depression

o Congestion, runny nose, sneezing and difficult breathing

o Menstrual changes, fluid retention, PMS with mood changes

What are the causes of histamine intolerance?

There can be many reasons for an increase of histamine. Medications, certain medical conditions, nutritional deficiencies, environmental factors and diet can all be potential factors in the development of histamine intolerance.

However, the three most common causes include genetic abnormalities, bacterial overgrowth and high estrogen levels.


Genetics plays a major role in how well your body breaks down histamine. According to Gene Ontology, proteins and enzymes encoded by more than 200 genes are involved in the histamine pathway. However, the key genes responsible for maintaining the physiological level of histamine are HDC, Aoc1 (DAO) and HNMT.
HDC The histidine decarboxylase enzyme (HDC) is the sole member of the histamine synthesis pathway. Histamine cannot be generated by any other known enzyme.
DAO Diamine oxidase (DO) is one of the major enzymes that breaks down histamine. DAO is mostly found in the gut, though it can also be found in the kidney and connective tissues. Because of its presence in the gut, this enzyme is our primary defense against histamine and histamine-producing bacteria in our food.
HNMT Histamine N- Methyltransferase (HNMT) is an enzyme expressed in the central nervous system that works throughout the body to metabolise the histamine created by your body by deactivating it and breaking it down so it no longer triggers a physiological response.

Bacteria overgrowth

SIBO and dysbiosis, which are both characterized by an overgrowth of bacteria, are often likely to be found at the root of a histamine intolerance. Some bacterial strains are more likely to produce histamine, therefore an overgrowth of these strains can promote more reactivity and histamine intolerance symptoms. If you suspect you have SIBO read up on it here.

Estrogen levels

Most people who develop histamine intolerance are women, as high estrogen levels can drive histamine intolerance. When estrogen levels are high, such as in the lead-up to ovulation, mast cells are stimulated to release more histamine. However, the interaction between estrogen and histamine goes both ways. Histamine exerts an additive effect on estrogen, which can cause estrogen levels to escalate even further. The resulting histamine intolerance can cause headaches, migraines, anxiety, gastrointestinal issues that worsen prior to ovulation and premenstrual period.

Histamine and endometriosis

There is a direct correlation between endometriosis and histamine intolerance. Often with endometriosis, we have estrogen dominance, and this excess estrogen can interfere with the enzyme that breaks down histamine, causing symptoms of allergy to worsen. But on the other end, histamine stimulates your ovaries to make more estrogen, and estrogen then stimulates your mast cells to make more histamine.
What results is a vicious cycle of estrogen –> histamine –> estrogen –>histamine

What can we do about it?

1. Try a low histamine diet

It’s difficult to determine the exact level of histamine in food, as it exists in most foods to some degree. However, a good rule of thumb is that foods that are fermented, aged, or overly processed likely contain more histamine than fresh food.
Histamine tolerance can vary greatly from person to person. Eliminating high-histamine foods from your diet before adding them back one at a time will give you an idea of what food your body can tolerate and which foods trigger symptoms.

2. Start with the gut

As mentioned before, your gut health and gut bacteria play an important role in histamine production. Personalized testing can help to rule out underlying causes of symptoms such as coeliac disease, IBS or IBD and determine if histamine intolerance is responsible. Healing the gut with diet and probiotics for histamine intolerance where indicated can often lead to improvement.

3. Pay attention to your menstrual cycle

Because of the correlation between estrogen levels and histamine levels, tracking your menstrual cycle can be helpful in determining if there is a pattern of symptoms worsening during pre-ovulation and premenstrual.

4. Seeking a naturopathic help

Working with a naturopath will enable you to find out what the root cause of your histamine intolerance is. Your naturopath will be able to design a personalised dietary or supplement protocol to help restore balance to your body and help alleviate your symptoms.
Want extra support through your pregnancy? It’s my focus area and I am currently seeing patients. To book in for a free base chat to see if we are the right fit click here.


Serena Di Modugno, Adv Dip Nat, Adv Dip WHM, Currently studying BHSc Nutritional Medicine

Serena is a qualified naturopath with a focus on MTHFR, allergies, anxiety

Learn more about Serena here

Book a session with Serena here

For speaking enquiries on this topic get in touch at hello@halsahealth.com.au