Histamine Intolerance and Gastroinestinal diseases

Gastroinestinal diseases	Clinical Consideration
Intolerance/Malabsorption issues • Fructose • Sorbitol • Lactose •Non-coeliac gluten sensitivity (NCGS)	• Lower serum DAO levels trigger elevated histamine producing clinical symptoms. Each of these comorbidities can individually or combined co-exist with HIT with a cross over in clinical symptoms commonly observed between HIT and these conditions.
Functional/Structural •Impaired intestinal permeability (increased zonulin)   •Intestinal dysbiosis (elevated histaminogenic bacteria, lower beneficial bacteria)	• Increased intestinal translocation of exogenous histamine. • Increased bacterial synthesis and impaired histamine catabolism. • Mucosal inflammation. • Reduced DAO activity. Can be primary aetiology or secondary exacerbating factor in HIT onset and severity.
Pathologies • Crohn’s disease and ulcerative colitis • Coeliac disease (HIT found in >50% of non-responding patients) • Irritable Bowel Syndrome (IBS) • Food allergies • Gastroenteritis •Small Intestinal Bacterial Overgrowth (SIBO)	• Increased mucosal histamine synthesis and impaired catabolism. • Increased tryptase secretion. • Mucosal inflammation and damage. • Impaired mucosal immunity. • Reduced DAO activity. Cross over in pathophysiology and clinical symptoms commonly observed between HIT and these conditions.