The human body is complex, and different people can have vastly different reactions to different substances that enter the body through the foods we eat. And sometimes a substance that the body needs can become too plentiful and begin to cause problems. Such is the case with histamine intolerance, a relatively rare condition that is estimated to affect about 1-3% of the world population. While histamine plays a pivotal role in immune response and regulation, some individuals develop various symptoms when too much accumulates in the body.

What Are Histamines and How Do They Work?

Histamines are a type of organic compound involved in various physiological processes in the human body. Primarily, though, they function as neurotransmitters related to the immune system and are involved in the body’s standard immune responses to potential allergens and pathogens. Even if they don’t know the name, most people are probably familiar with histamines simply because they are the cause of many of the allergic reactions and related symptoms like sneezing, hives, or having a runny nose.

Histamines can be found all over the body, and they are especially concentrated in blood vessels, internal body surfaces, and other places in the body that are potential points of injury or sites more likely to be entry points for pathogens and allergens. Histamines are produced by mast cells and white blood cells known as basophils, and they are stored there until released in response to an antibody called immunoglobulin E (IgE). The release of histamines can also be triggered as a result of a toxin-related injury.

Histamines are able to trigger a wide range of physiological responses by binding to specific histamine receptors in cells all over the body. The effect of histamine is then directly related to the type of receptor it has been bound to; binding to H1 receptors, for example, can trigger immune responses in the respiratory system and lead to symptoms like itching and sneezing. While annoying to humans, these responses are the immune system’s main way of expelling allergens and pathogens from the body.

What Is Histamine Intolerance?

Histamine intolerance refers to the inability to break down histamine and the resulting excess amount of histamine accumulating in the body. Such excess levels of histamine can trigger a wide range of symptoms that often mimic other conditions, which can make it an overall difficult problem to diagnose. Though there are a variety of contributing factors, the basic mechanism of histamine intolerance is a deficiency of two important enzymes involved in its metabolism: diamine oxidase (DAO) and histamine N-methyltransferase (HNMT).

Of these two enzymes, the one most likely to lead to histamine intolerance is diamine oxidase (formerly known as histaminase). In addition to the triggering of inflammation and other immune system responses, the DAO enzyme is also related to the processes behind wound healing and digestion. Normal DAO levels keep histamines in check, but a deficiency allows histamine to build up. Below are some of the factors thought to contribute to a DAO deficiency:

Symptoms of Histamine Intolerance

While some histamine can be synthesized by the body, much of it comes from bacteria or fermentation processes in the foods we eat. When DAO or HNMT levels are low, the body isn’t able to break down a sufficient amount of histamine in the intestines, and this is how the levels can become too high. And when histamine levels are high because it can’t be broken down, there are a number of common symptoms that can arise:

  • Gastrointestinal: It is not uncommon for histamine intolerance to be mistaken for a gastrointestinal disorder given how many symptoms may present. In addition to abdominal pain or cramping, it is possible to experience diarrhea, bloating, nausea or vomiting, and excessive gas.
  • Skin: Because of the association with the well-known class of drugs called antihistamines, symptoms related to the skin are perhaps most commonly connected to the condition. It is normal to develop hives (urticaria), eczema, itchy skin, inflammation, or raised red welts.
  • Respiratory: Mild respiratory symptoms like congestion or frequent sneezing are also common. It is also possible to develop asthma-like symptoms such as wheezing, shortness of breath, or bronchoconstriction (narrowing of breathing passages).
  • Cardiovascular: In some cases histamine intolerance can cause low blood pressure that can in turn dizziness or fatigue. Heart palpitations or an irregular heartbeat have also been reported.
  • Menstrual: For women, an accumulation of histamine can lead to changes in the menstrual cycle and heavier or more painful periods.
  • General: Histamine intolerance can also cause a variety of general symptoms like an overall feeling of malaise or migraine headaches. Some people also experience feelings of anxiety or nervousness.

Tips for Controlling Histamine Intolerance

Many of the underlying causes of histamine intolerance must be addressed first in order to return the body to normal histamine levels. Apart from that, most people can manage the condition by reducing histamine intake, supporting histamine metabolism, or addressing specific triggers that may exacerbate symptoms. Here are several strategies for treating or controlling histamine intolerance:

  • Low-histamine diet: The first step is to reduce or eliminate foods with high histamine content like aged cheeses, citrus fruits, papaya, legumes, salami and other processed meats, fermented foods (sauerkraut, yogurt), certain fish (tuna, mackerel), and alcohol. Instead of high-histamine foods, focus on unprocessed or minimally processed fresh fruit, fresh vegetables, fresh meat, gluten-free grains, and eggs.
  • Supplements: Further research is needed, but there is some evidence that DAO supplements can be taken orally to help break down histamine in the digestive tract.
  • Medication: Either over-the-counter or prescription antihistamines can be used to help relieve the allergy-like symptoms associated with histamine intolerance.
  • Lifestyle: Both alcohol and smoking can exacerbate histamine intolerance and should be eliminated or avoided. It can also help to generally develop a pattern of eating regular, well-balanced meals.

    Contact Cary Gastro

    Histamine intolerance is the kind of condition that has a wide range of symptoms that can easily be mistaken for something else. If you’ve been experiencing any of these symptoms noted above and aren’t sure of the cause, it might be time to contact a gastroenterologist. At Cary Gastro, our highly qualified team is proud to be a trusted healthcare provider you can rely on. Gastrointestinal symptoms can sometimes threaten to detract from your quality of life, but we are passionate about giving you the best care and putting your mind at ease. Please contact us to request an appointment.