Histamine intolerance is surprisingly common. There are two main levels of intolerance: the first is associated with food and often results in digestive problems. The second is more systemic and can cause a wide range of symptoms, including hives, flushing, low pain tolerance, sweating, excess mucous production and seasonal allergies. It may result cause hyperactivity, compulsiveness and depression.

Histamine intolerance symptoms

Histamine has many roles in the body. An excess of it can manifest in a variety of ways.

Most people know histamine as the thing to counteract when a person has an allergic reaction such as hay fever, etc taking some form of antihistamine. Histamine is released by cells in the body in response to damage or a perceived threat. Once released it causes swelling, redness and heat and acts as a signal for other immune system factors to come to the scene to help. But histamine also has other roles in the body, including regulating stomach acid and stimulating the brain. As well as all this there is an interaction between female hormones and histamine.

Histamine in Food

Almost all food has the potential to contain, or stimulate the release of histamine. Histamine is produced in food as the result of ageing and bacterial degradation. Some food reactions that suggest histamine intolerance include aged cheese, fish or seafood, deli meats, eggs (especially the whites), fermented foods (such as sauerkraut) and avocado. The older the food (or more aged) the higher the potential histamine content. Some food has the potential to aggravate the gut and cause a histamine release. Citrus fruits are commonly implicated in this, as are mineral supplements containing citrates.  For people with histamine intolerance, alcohol commonly aggravates the problems, resulting in facial flushing, a blocked nose and may also cause headaches. So if “wine & cheese” sets you off, this is a good clue to having a histamine intolerance.

What’s Behind Histamine Intolerance?

Contrary to what you might think, the food is not actually the problem. The body has a couple of mechanisms to break down histamine.

The first is produced in the lining of the intestines – an enzyme called diamine oxidase (DAO) that breaks down histamine in our food. If the gut wall is damaged in any way, or if there are certain nutrient deficiencies, this enzyme may not be produced in adequate amounts and the histamine may aggravate the gut, causing symptoms similar to irritable bowel syndrome, and is also absorbed into the blood stream. Once in the blood stream, histamine is normally broken down by another enzymatic process involving N-methyltransferase (HNMT) and eliminated from the body.

Another common factor is under-methylation. Methylation is a complex biochemical reaction that is on-going in the body and involved in the metabolism of vitamins, hormones, neurotransmitters and more. Removing histamine required methyl groups, and when histamine is high, these groups get depleted, which further exacerbates the problem.

Histamine intolerance occurs when there is either too much histamine being ingested or liberated, or not enough being broken down—or both! Any inadequacy in the clearance mechanisms – either in the gut or in the blood stream – can cause the symptoms of histamine intolerance.

How does Histamine Interact with Hormones?

Women may notice that their tolerance (or intolerance) changes throughout their menstrual cycle, or disappear when pregnant. This is because of a number of different hormonal interactions.

  • Progesterone, which is high in the second half of the menstrual cycle and very high during pregnancy), up-regulates DAO. This means more DAO, and more histamine breakdown early in the luteal phase (soon after ovulation) when progesterone is high.
  • Oestrogen down-regulates DAO. So an excess, or relative excess of oestrogen is associated with increased histamine intolerance.
  • Some forms of hormonal birth control (those containing oestrogen) cause an oestrogen excess and progesterone deficiency – one reason some women do better on a progesterone-only contraceptive.

Normally, your body regulates histamine by making it, and then by clearing it. . It’s a fine balance between “histamine in” and “histamine out”.Did you know? Histamine boosts libido, which is why estrogen increases libido and antihistamines decrease it.

During pregnancy, not only is progesterone very high, but the placenta makes large amounts of DAO. Women often report that histamine intolerance, allergies and food sensitivities improve during pregnancy.

Reasons for Poor Histamine Clearance

There are several reasons for a diminished ability to clear histamine.  These include:

  • Genetic variant of the histamine-clearing enzymes HNMT and DAO.
  • Genetic variant of key enzymes involved in methylation, resulting in poor HNMT function.  This can be tested using a fitGenes test.
  • SIBO (small intestinal bacterial overgrowth) because it can damage the lining of the intestine and impair production of diamine oxidase
  • Vitamin B6 deficiency: an essential cofactor for the formation of DAO.
  • Copper deficiency: Copper is an essential co-factor for the formation of DAO
  • An excess of oestrogen, which down-regulates DAO.
  • Progesterone deficiency (progesterone up-regulates DAO).
  • Hormonal birth control (oestrogen excess and progesterone deficiency).

What can be done about Histamine Intolerance?

Firstly, a consultation with a health consultant can help you determine the underlying cause.  While avoiding high histamine foods is a fast way to feel better, it is a very restrictive diet and difficult to maintain in the long term.Long term dietary restrictions are not advised, as this can lead to nutrient deficiencies. By addressing underlying issues, most people find that they are able to consume histamine foods.

Highest histamine foods:Histamine intolerance wine cheese
  • Wine and beer
  • Aged cheeses
  • Cured meat and fish
  • Bone broth and fish stock
  • Vinegar, pickles and fermented foods such as sauerkraut
  • Chocolate

Identify and Treat the Cause or Causes

Depending on the individual cause the treatment strategy can vary. For women with appreciable fluctuations in histamine intolerance associated with the menstrual cycle, an important strategy is to promote the healthy detoxification of oestrogen. Find our if you have genetic variants that mean that oestrogen clearance is compromised (COMT, CYP1A1, CYP1B1).  We recommend natural treatments to support healthy progesterone levels. This can include herbal medicine and vitamin supplementation. We can also use salivary hormone mapping (over the course of the menstrual cycle) to determine the role of the levels of progesterone and oestrogen.

Ensuring adequate intake of vitamin B6 is important because this vitamin supports healthy progesterone metabolism and upregulates DAO. Food sources of vitamin B6 include meat, chicken, and sunflower seeds.Most people will have some kind of gut involvement – so identifying and correcting dysbiosis and/or small intestinal bacterial overgrowth (SIBO) is important. Avoiding food that may aggravate a histamine release such as gluten and A1 casein (dairy) is also helpful to support the healing phase. These common foods trigger histamine release. Most New Zealand milk is A1, but A2 milk is available at some supermarkets.

Make an appointment now to discuss the factors contributing to your histamine intolerance and let food start being your friend again!


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