Histamine [2-(4-imidazolyl)-ethylamine] is one of a group of biogenic amines, along with putrescine, cadaverine and tyramine, among others, produced by bacterial fermentation [ 7 ]. Decarboxylation (a process requiring the presence of vitamin B6) of the amino acid histidine yields histamine.
Two main histamine metabolic pathways are known in humans, involving the enzymes diamine oxidase (DAO) and histamine-N-methyltransferase (HNMT). The second pathway involves methylation processes, which may be subject to polymorphisms in at least 30% of the Caucasian population. Vitamins B2, B6, B9, B12, zinc, the amino acid L-methionine/ SAme, betaine and choline are all co-factors involved in methylation processes that could be implicated in the dysregulation of the second histamine metabolic pathway.
Histamine intolerance (HIT) is thought to be due to a deficiency in the gastrointestinal (GI) enzyme diamine oxidase (DAO), with the result that the dietary component histamine is not properly degraded and/or absorbed in the GI tract. The involvement of the gastrointestinal mucosa in various disorders and diseases, many of unknown origin, and the effects of certain drugs appear to reduce GI DAO activity.
HIT causes variable, functional, non-specific, non-allergic digestive and extra-intestinal disorders. Evaluation of HIT is not usually included in differential diagnoses of patients with unexplained functional gastrointestinal disorders, or in psychiatric disorders and diseases.
Chronic, unexplained functional gastrointestinal (GI) symptoms affect over 20% of the population. In histamine intolerance (HIT), impaired gastrointestinal histamine degradation leads to functional, non-specific, non-allergic GI and extra-intestinal disorders [ 1 ]. An imbalanced and elevated amount of histamine in HIT appears to be the main consequence of ingesting histamine-containing foods [ 2 ]. Primarily, in HIT , the intestinal enzyme diamine oxidase (DAO) has a reduced capacity to metabolize and degrade histamine. Scientific evidence and studies in support of this idea are multiplying [ 3]. However, in association with a variety of different disorders and diseases, many with unknown underlying pathophysiological mechanisms, the majority report additional unexplained functional gastrointestinal symptoms.
Nevertheless, reliable standardized assessments and/or laboratory tests for a definitive diagnosis of HIT are still necessary. HIT requires a detailed history and diagnostic examination with available tests [ 4 ]. Given the possible presence of additional gastrointestinal diseases or disorders, evaluation of all etiological and symptomatic factors is essential [ 5]. Subsequently, personalized intestinal cleansing therapy with targeted micronutritional intervention for each HIT patient, using a low-histamine diet [ 6 ] and/or oral DAO supplementation, can help provide permanent relief with regard to putrefactive bacteria management and just temporary relief with regard to other management [ 6 ].
Symptoms in the gastrointestinal sphere and elsewhere are listed below:
- Abdominal pain
- Intestinal colic
- Bloating
- Diarrhea
- Constipation
- Nausea
- Eructation
- Vomiting
- Postprandial fullness
- Pruritus
- Reddened skin
- Eczema
- Swollen and reddened eyelids
- Headaches
- Hypotonia
- Menstrual cramps
- Palpitations
- Collapse
- Rhinorrhea
- Nasal congestion
- Sneezing
- Asthma
- Psycho-neurological diseases: Parkinson's, Alzheimer's, depression, autism
- Tourette's syndrome
- Narcolepsy
- Problems sleeping at night and waking up every day
- eosinophilic gastroenteritis (EGE)
- Mast cell activation syndrome (MAS)
-
Non-celiac gluten sensitivity (NCGS)
- Chronic insomnia
-
Irritable bowel syndrome (IBS)
- Celiac disease
- hypermobility
- Ehlers-Danlos syndrome
- Postural tachycardia syndrome
- ...
We'll look at how to deal with this problem in the second part of this article.
*** To find out more, take a look at my next page with links at the bottom for food lists: https://www.humankindwellbeing.com/intolerance-a-l-histamine ***
