What You Need to Know About Histamine

What is Histamine?

Histamine is a neuro-endocrine system mediator. Also known as a neurotransmitter, it plays several critical roles in the body. It acts as a neurotransmitter in the brain, regulates the secretion of gastric acid, manages inflammation, and controls vasodilation (widening of the blood vessels). In addition, histamine regulates bronchoconstriction (narrowing of the airways in the lungs) and acts as a wake-promoting and REM sleep-suppressing neurotransmitter.

Where in the body is it made?

Histamine is synthesized from L-histidine by L-histidine decarboxylase, which is expressed in various cells in the body such as in gastric mucosa, neurons, mast cells, and basophils. Basophils and mast cells produce and store most of the body’s histamine, making them critical to the body’s histamine levels.

Two main pathways

There are two main pathways that metabolize histamine in the body: the HNMT pathway (histamine-N-methyltransferase) and the DAO (diamine oxidase) pathway. Additionally, there are 4 main receptors of histamine: H1, H2, H3, and H4.

Histamine can contribute to:

Given its wide range of functions, histamine can contribute to several conditions such as:

  • urticaria (a skin condition)
  • allergic rhinitis
  • atopic dermatitis
  • asthma, eczema
  • inflammation
  • CVD and atherosclerosis
  • CNS damage.
  • Surprisingly, histamine also inhibits tumor development
  • regulates the inflammatory picture of asthma caused by microbiota derived histamine
  • and favours wound healing in skin lesions.

What is Histamine intolerance?

Histamine intolerance is a disorder that is associated with an impaired ability to metabolize histamine from dietary sources. Certain individuals have an inability to metabolize histamine in the intestine, resulting in a sensitivity to normal or even low levels of histamine in food. The 2 main enzymes that break down histamine in the body are HNMT and DAO.

How your genes are involved

Certain genetic polymorphisms in the genes that encode these enzymes can lead to a buildup of histamine in the body as the body is not able to break it down significantly. This causes the symptoms of histamine intolerance from eating foods high in histamine or taking certain drugs. The symptoms are varied and can include diarrhea, vomiting, nausea, itchy skin, headaches or migraines, red eyes, swollen eyelids, bloating, nasal congestion, sneezing, tachycardia, eczema, and dizziness.

What can you do?

The new Histamine Panel DNA test looks at certain genes that encode the two main enzymes that break down histamine, namely HMNT and DAO. If any of the variants are detected in you, recommendations are given to avoid certain HNMT inhibiting drugs as well as recommendations for diet and further testing. This test can give you a good starting point whether to pursue a possibility of histamine intolerance.

Contact me via email for more information on testing.


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