SIBO and food intolerance
SIBO and food intolerance
Medically reviewed by:
Dr John Freeman
Let’s talk about histamine intolerance
Many people with SIBO experience symptoms that feel like food allergies, even when allergy testing is normal. One of the most common and misunderstood reasons for this is histamine intolerance.
Why “gut superfoods” can worsen symptoms in SIBO
SIBO can significantly increase the risk of histamine intolerance. Histamine is a naturally occurring compound found in many foods commonly promoted as “gut-healing” or “gut superfoods.” These include aged or fermented foods such as:
Bone broth
Sauerkraut and other fermented vegetables
Vinegars
Aged meats and cheeses
While these foods may support a healthy gut in people without SIBO, they can worsen symptoms in those with bacterial overgrowth, leading to increased inflammation and discomfort.[1]
The role of DAO and the intestinal lining
The connection between SIBO and histamine intolerance lies in an enzyme called diamine oxidase (DAO). DAO is produced in the intestinal lining and is responsible for breaking down histamine from food.
In SIBO:
Bacterial overgrowth damages the intestinal lining
DAO enzyme activity is reduced
Histamine is not adequately broken down
As histamine accumulates in the body, it can trigger symptoms that resemble allergic reactions, even though no true allergy is present.[2]
Common symptoms of histamine intolerance
When histamine is not properly metabolised, it may cause symptoms such as:
Facial bloating or swelling
Headaches or migraines
Skin rashes, itching, or hives
Watery or red eyes
Nasal congestion or allergy-like symptoms
Flushing or a feeling of being “inflamed”
This response is often described as a secondary or functional allergic reaction, driven by gut dysfunction rather than immune allergy.
Why histamine intolerance is often missed
Many people with SIBO do not realise they have histamine intolerance. Symptoms can be inconsistent and delayed, making them easy to attribute to stress, hormones, seasonal allergies, or individual food sensitivities.
The link between gut health, DAO activity, and histamine intolerance has only become clearer in recent medical literature, which is why this condition remains under-diagnosed.
Key takeaway
Histamine intolerance in SIBO is not caused by histamine-rich foods alone—it is caused by the gut’s reduced ability to break histamine down. Until bacterial overgrowth and intestinal lining damage are addressed, even foods considered “healthy” may provoke symptoms.
1 Sorathia and Rivas, 2020
2 Comas-Basté et al., 2020
3 Comas-Basté et al., 2020
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