What is HIT - Beyond the Label?

Histamine Intolerance (HIT) is a gut–immune regulation disorder in which the body struggles to maintain balance between histamine production, release, and breakdown. Histamine itself is vital — it supports digestion, immune defence, and acts as a neurotransmitter — but when this balance is disrupted, histamine can build up and cause widespread symptoms that often resemble allergy, IBS, or anxiety.

The body’s main enzyme for clearing histamine, diamine oxidase (DAO), may be too low, inhibited, or even overproduced but functionally ineffective. This imbalance can result from genetic variations, gut inflammation, microbiome shifts, nutrient deficiencies, or medication effects. In some people, histamine load simply exceeds the body’s capacity to process it, regardless of DAO levels.

Common symptoms include bloating, abdominal pain, diarrhoea or constipation, headaches, flushing, dizziness, fatigue, irregular heartbeat, or sleep disturbance. Because these overlap heavily with IBS, many people are misdiagnosed or experience both conditions together.
Emerging research suggests that histamine sensitivity can drive IBS-like patterns, especially when symptoms worsen after high-histamine or histamine-releasing foods (like wine, fermented foods, or leftovers).

Managing HIT focuses on restoring equilibrium, reducing histamine load, calming the gut, supporting DAO function, and balancing the microbiome. It’s less about strict avoidance and more about understanding your personal threshold and helping your gut regain control.