Histamine is an inflammatory mediator produced by mast cells throughout the body.
DAO and HNMT are important enzymes that break down histamine and terminate the inflammatory response.
Histamine intolerance can occur when DAO or HNMT function is impaired, when histamine is overproduced, or when foods high in histamine are eaten.
Histamine intolerance is generally managed by following a low-histamine diet, and occasionally with enzyme supplements.
Histamine is produced by animals and by plants, and is present in many foods. Excess histamine — whether produced within the body or consumed in histamine-containing foods — is usually cleared away by enzymatic action. When this fails, or when the body is flooded by more histamine than can be easily cleared, symptoms of histamine intolerance may result. In this article we’ll get into the details of what histamine is, causes and symptoms of histamine intolerance, and how histamine intolerance is treated.
Histamine is a nitrogen-based biological compound that plays a number of roles in the body, from stimulating gastric juices for digestion to carrying signals between neurons in the brain. Histamine is best-known, though, for the role it plays in inflammation and allergic reactions. (Source)
Released by specialized immune cells called mast cells, histamine is an inflammatory mediator that binds with receptors found throughout the body. One of the many effects histamine has on tissues is vasodilation, or relaxation of blood vessels. Histamine also increases vascular permeability, or the ability of molecules and immune cells to move in and out of blood vessels. These effects make it possible for white blood cells and other components of the immune system to reach areas that are injured or under attack by foreign antigens.
The proinflammatory nature of histamine becomes a problem when it causes an overly robust response to a harmless antigen — such as pollen or peanuts. However, histamine is not just at play when you are experiencing an allergic reaction. Histamine is also implicated in many inflammatory conditions such as asthma, autoimmune diseases, and inflammatory skin diseases.
How does your body get rid of histamine when there is too much? There are two enzymes, called diamine oxidase (DAO) and histamine N-Methyltransferase (HNMT), that can break down histamine in your body.
DAO and HNMT are also located in different regions of your body. HNMT is responsible for breaking down histamine inside your cells, whereas DAO is responsible for breaking down histamine in the area surrounding your cells. Both of these enzymes are important for regulating the histamine level in your body. (Source)
When DAO or HNMT are not functioning properly, you can develop histamine intolerance. Histamine intolerance is a disorder in which your body has impaired ability to break down histamine.
Histamine intolerance makes you hypersensitive to dietary histamine. However, it is important to note that histamine intolerance, like any intolerance to specific foods, is different from an allergy.
Histamine intolerance has two main causes:
There are also certain medications that are thought to either prevent DAO from breaking down histamine or cause histamine intolerance directly as a drug side effect. Some of these include:
Symptoms of histamine intolerance usually occur when you consume foods that are rich in histamine, such as wine or aged cheese. These symptoms are usually gastrointestinal symptoms such as:
You may also experience:
About 1% of the population has histamine intolerance, making it an uncommon condition. Histamine intolerance is more common in middle-aged people and, in the case of histamine intolerance caused by impaired histamine degradation, is often genetic. For example, if one of your parents has histamine intolerance caused by faulty DAO or HNMT, you could be at higher risk of having this same type of histamine intolerance.
Histamine intolerance is also associated with inflammatory and gastrointestinal diseases such as Crohn’s disease, food allergies, and ulcerative colitis. If you have one of these conditions, you may be at higher risk for histamine intolerance. (Source)
Although it is not clear whether histamine intolerance can be cured, there are ways to improve symptoms. The most common treatment involves following a low-histamine diet. If you are deficient in intestinal DAO, a health care professional may prescribe you DAO supplements in addition to recommending a low-histamine diet. Antihistamines may play a limited role in treating histamine intolerance. (Source, Source, Source)
Small studies of supplementation with DAO of both animal and plant origin have had some promising results. Research continues into the best sources of the enzyme, optimal dosing, and how to protect it from being broken down in the intestines before it can work. (Source)
Antihistamines work by blocking histamine receptors found on cells throughout the body. They might provide some temporary relief from symptoms of histamine intolerance but haven’t been well-studied for this purpose. Because histamine also performs important beneficial functions in the body, blocking it with antihistamines can cause unwanted side effects. Currently antihistamines don’t provide a long-term solution for histamine intolerance. (Source)
A low-histamine diet is similar to an elimination diet. You eliminate foods that are high in histamine or that trigger symptoms of histamine intolerance. Although there are many recommended foods to avoid, there is no single, correct low-histamine diet plan.
Many studies show positive results and improved symptoms in individuals who follow a low-histamine diet for about 3 to 4 weeks. (Source)
If you have histamine intolerance, it can help to avoid or limit consumption of foods that are high in histamine. Some of these histamine-rich foods include:
There are also groups of foods referred to as histamine liberators. Histamine liberators do not contain high levels of histamine, but there is evidence they may cause mast cells to release their histamine.
It is a good idea to limit your consumption of histamine liberators if you have histamine intolerance. Some of these histamine liberators include:
Source: Mast Cell 360
These blueberry muffins are free of high-histamine foods and are easy to whip up for breakfast. This recipe calls for a special type of flour called cassava flour, which is made from the root of the cassava plant. Cassava flour is nut-free, grain-free, gluten-free, not fermented and is a great flour substitute if you are allergic to nuts or sensitive to gluten. This recipe also uses anti-inflammatory foods such as coconut milk and coconut oil, which could help alleviate symptoms of histamine intolerance. (Source)
Source: Mast Cell 360
Although many diets can feel restrictive, the low-histamine diet has a plethora of recipes to provide for your guilty pleasures. This low-histamine pizza recipe is versatile and suggests swaps you can make for each ingredient. This recipe also uses cassava flour and doesn’t include tomatoes or pepperoni, which are both high-histamine foods. The low-histamine pesto is a great substitution for tomato sauce because pesto contains basil, which has anti-inflammatory effects. (Source)
Source: Randa Nutrition
This turmeric chicken stir fry dish provides a great anti-inflammatory boost. This recipe is gluten- and dairy-free and contains turmeric, which is an anti-inflammatory spice. Anti-inflammatory foods are a great way to counter the effects of histamine in your body. (Source)
There’s no one size that fits all. Like many diets, the low-histamine diet needs to be personalized to you. If you have histamine intolerance it’s important to learn what foods are high in histamine and try to limit your exposure to them, replacing them with low-histamine alternatives.
If you have histamine intolerance due to impaired DAO function, it’s possible taking enzyme supplements in addition to following a low-histamine diet will help your body break down histamine after an inflammatory reaction. In some cases, antihistamines may provide temporary relief from symptoms of histamine intolerance.