(NaturalNews – Dr. David Jockers) Histamine is an in important neurotransmitter and immune messenger molecule. It is involved in processes involving hydrochloric acid secretion for digestion, triaging water reserves to key areas of the body and the inflammatory response. (1) Individuals with low diamine oxidase (DAO) enzymes are at risk for elevated histamine and a condition called histamine intolerance.

One of the major effects of histamine is causing the blood vessels to swell and dilate. When the body senses that it is threatened, it will secrete higher amounts of histamine. This allows the white blood cells to quickly move through the bloodstream and find the potential threat or infection. This is an important component of a healthy immune response.

When does histamine become a problem?

Histamine only becomes a problem when we have metabolic disturbances that do not allow us to effectively metabolize histamine properly. When histamine is formed, it is broken down by specific enzymes. In the central nervous system, it is metabolized by histamine N-methyltransferase (HMT), while in the digestive tract it is broken down by DAO.

The experts state that DAO is the major enzyme involved in histamine metabolism. (2) The enzyme converts the histamine into imidazole acetaldehyde which does not trigger any sort of reaction in the body. DAO is responsible for ensuring a steady histamine level required for the balance of numerous chemical reactions taking place in the body.

Some individuals have altered DAO production due to a number of different factors including (3):

Small intestinal bacterial overgrowth (SIBO): Some gut microbes produce high amounts of histamines as a byproduct of their metabolism.

Leaky gut syndrome: Intestinal permeability creates major inflammatory stress in the body which can contribute to poor DAO function.

Genetic polymorphisms in DAO enzyme: this can be seen on the 23andMe SNPs. A homozygous DAO would make someone more susceptible to developing a histamine intolerance.

Use of certain medications:

  • Non-steroidal anti-inflammatory drugs (ibuprofen, aspirin)
  • Antidepressants (Cymbalta, Effexor, Prozac, Zoloft)
  • Immune modulators (Humira, Enbrel, Plaquenil)
  • Antiarrhythmics (propanolol, metaprolol, Cardizem, Norvasc)
  • Antihistamines (Allegra, Zyrtec, Benadryl)
  • Histamine (H2) blockers (Tagamet, Pepcid, Zantac)

Who has histamine intolerance?

According to available research, histamine intolerance manifests in approximately 3% of the population. (4) In up to 20% of these cases, the symptoms occur mostly when histamine-containing foods are used in combination with DAO inhibitors such as alcohol. Approximately 80% of individuals with histamine intolerance are women, and most of them are over 40. (5)

The three biggest factors involved with histamine intolerance include leaky gut syndrome or related disorders such as Crohn’s disease, irritable bowel, celiac, gluten sensitivity, etc. (2) The second factor is a genetic polymorphism with the DAO enzyme. Heavy alcohol and/or medication usage is another strong risk factor.

Common symptoms of histamine intolerance include

  • Headaches/migraines
  • Difficulty falling asleep/easy arousal
  • Hypertension
  • Vertigo or dizziness
  • Arrhythmia
  • Difficulty regulating body temperature
  • Anxiety
  • Abdominal cramps
  • Flushing
  • Nasal congestion
  • Difficulty breathing
  • Abnormal menstrual cycle
  • Hives
  • Fatigue
  • Tissue swelling
  • Inability to be in the sun
  • Frequent sneezing

DAO enzymes

DAO is the major enzyme involved in histamine metabolism. (2) Its responsibility is to convert histamine into imidazole acetaldehyde. This is a safe reaction that does not trigger any irritate or inflame any region of the body.

DAO’s job is to ensure a steady histamine level required for the balance of the numerous chemical reactions that it is needed for without allowing it to accumulate in high amounts. Some individuals have deficiencies in DAO enzymes and therefore suffer with histamine reactions. These individuals should look to supplement with DAO enzymes, follow a low-histamine diet and improve the health of their gut.


1) http://www.britannica.com
2) http://ajcn.nutrition.org
3) http://www.deficitdao.org
4) http://www.ncbi.nlm.nih.gov
5) http://www.histamineintolerance.org.uk

Avatar photo

Natural News

Natural News is a science-based natural health advocacy organization led by activist-turned-scientist Mike Adams, the Health Ranger. The key mission of Natural News is to empower consumers with factual information about the synthetic chemicals, heavy metals, hormone disruptors and other chemicals found in foods, medicines, personal care products, children's toys and other items. Natural News covers holistic health, nutritional therapies, consciousness and spirituality, permaculture , organics, animal rights, environmental health, food and superfoods , and performance nutrition.

More Posts - Website