Histamine is a naturally-occurring body chemical involved in immune response and food digestion. It is made in the white bloods cells, which are largely responsible for fighting infection. When histamine is activated, such as in response to a foreign invader, it inflames tissues and allows white blood cells to enter in order to fight off the danger. Histamine is also found in the brain, where it acts as a neurotransmitter (like dopamine), and near the stomach.
Histamine is responsible for a number of important body functions. For example, histamine can regulate sleep, protect against negative drug reactions, stress and convulsions, reverse erectile disfunction and decreased libido and research has shown it may even be implicated in schizophrenia.
Although histamine clearly plays a role in allergic reactions to certain substances, such as pollen, it turns out that some food “allergies” aren’t really allergies at all. In fact, most reactions to food that we consider to be allergic are actually “intolerances” caused by histamine toxicity. The confusion between histamine toxicity and food allergies exists because the symptoms of each can be extremely similar. For example, a peanut allergy may result in nausea/vomiting, diarrhea, stomach pain, hives, swelling, breathing problems and anaphylactic shock. Food intolerance, on the other hand, can cause cardiovascular issues, headache, breathing problems, diarrhea, constipation or flatulence.
Whereas allergic responses involve the body’s release of naturally-produced histamine in an immune-related response to foreign matter, food intolerance occurs as a direct result of too much histamine. This overabundance of histamine is not made by the body, however. We ingest it in the food we eat. Many common foods contain histamine including smoked fish, wine, banana and some cheeses and processed meats. If someone is sensitive to histamine, the levels in these foods will cause a reaction that resembles a food allergy. Research has shown that the digestive enzyme diamine oxidase (DAO) is supposed to reduce the level of histamine in the body and prevent a negative reaction to these histamine-rich foods. When faced with an influx of histamine, people without sufficient DAO will be unable to properly digest the histamine and will experience histamine toxicity.
Like with actual allergic reactions to food, common antihistamines will likely help reduce the severity or length of the symptoms of histamine toxicity.