Histamine is a natural chemical produced by the body. Your body generally releases histamine when you are stressed or experiencing an allergic reaction. Histamine is also involved in the regulation of stomach acid, permeability of blood vessels, muscle contraction, and brain function.
Histamine Intolerance: What Is Histamine?
In humans, the highest concentration of histamine is found in the skin, lungs, and stomach, with smaller amounts found in the brain and heart.
Histamine is created and stored within the white blood cells, such as mast cells in tissues and basophils, which circulate the blood. When the immune system activates a response that there is a foreign material trying to enter the body, histamine is the first defense chemical released into the inflammation. Inflammation is evidence that the immune system is responding to the threat that has entered the body. When inflammation occurs, histamine is always present—excess histamine could result in symptoms that resemble inflammation.
In addition to controlling vital body processes and defending against threatening foreign materials, histamine is a key mediator in allergic reaction symptoms. Because allergies are an inflammatory reaction, histamine is released in response to the allergen. Allergens are components of living cells that are harmless, such as plant pollen, animal dander, dust particles, dust mites, and foods. An allergic reaction to these components occurs when the immune system mistakenly sees these components as a threat.
Histamine levels of 0.3 to 1.0 nanograms per milliliter (ng/ml) are considered to be normal. Everyone has different levels that their bodies can tolerate without symptoms. Exceeding the recommended level (a person’s tolerance) can result in severe symptoms, including headaches or flushing as a result of consuming large amounts of histamine in a meal. If ingested in lower concentrations, only sensitive individuals will experience an adverse reaction. The difference in levels of histamine that people tolerate could be caused by genetics.
Various abnormal physiological conditions, hormonal changes, and medications can reduce the tolerance-threshold of many individuals. Those who have a low tolerance threshold are considered to be histamine-intolerant.
Histamine Intolerance Symptoms
It doesn’t matter what the source of histamine is, when the total body level exceeds the enzymes’ capacity to break it down, symptoms of histamine excess will occur. Histamine intolerance shows itself in a variety of ways, including:
- Prutitus, which is severe itching of the skin, eyes, ears, and nose
- Panic attacks
- Urticaria (also called hives)
- Swelling of the facial and oral tissues
- Hypotension (drop in blood pressure)
- Tachycardia (when you feel your heart racing)
- Chest pains
- Nasal congestion or a runny nose
- Unexpected fatigue, confusion, and irritation
- Loss of consciousness (typically lasts for one or two seconds)
- Upset digestive tract, including heartburn, indigestion, and acid reflux
- In addition to the symptoms listed above, excess histamine can cause existing conditions to become worse. Eczema, otherwise known as atopic dermatitis, is a perfect example. Eczema is an inflammatory condition in the skin. When foods with high levels of histamine are consumed, people that have less than efficient histamine tolerance could experience an increase in the severity of their eczema.
- Research suggests that people who are already prone to recurrent allergic reactions could add histamine intolerance to their allergies list. In these situations, histamine is released and the allergic response quickly rises to a dangerous level.
- Histamine levels fluctuate with the level of hormones (i.e. during menstruation). Many women with allergies and histamine intolerance find relief of their symptoms during pregnancy. This is because the placenta makes a great deal of DAO— the enzyme that breaks down histamine. The level of histamine will no longer exceed the woman’s tolerance and she remains free from her symptoms throughout the pregnancy.
- Some medications can release histamine; others can reduce the effectiveness of the enzyme that breaks down histamine. When this occurs, the level of histamine will rise and result in adverse effects.
Causes of High Histamine Levels
1. Allergies: When your body experiences an allergic reaction, an allergen stimulates the release of antibodies and attaches to mast cells. Histamine is released from the mast cells and causes the reaction, such as itchy eyes, wheezing, or sneezing.
2. Bacterial overgrowth: People who exceed histamine tolerance may experience bacterial overgrowth in their gut. It’s another sign of intestinal inflammation—if you are experiencing gas or bloating, it is usually the cause of food insensitivity or a gut infection, which can occur from excessive amounts of histamine.
3. Leaky gut: High histamine levels can cause a leaky gut. This occurs when gluten causes the gut to release zonulin, a protein that can break apart tight junctions in the intestinal lining. When these junctions break apart, you have a leaky gut.
4.Diamine oxidase: DAO deficiency is the alteration in the metabolism caused by histamine—it occurs when the diamine oxidase enzyme activity becomes low.
Histamine Intolerance Test
Testing for histamine levels and DAO levels is a good way to help clarify whether you have histamine intolerance. A high ratio of histamine/DAO will signify that you are ingesting excess levels of histamine and that you do not have enough DAO to break it down.
If there is no testing available, you can try avoiding foods rich in histamine and adding DAO supplementation to each meal. If your symptoms are resolved, then you may have low DAO.
Histamine Intolerance Diet
There are a variety of foods that naturally contain histamine, cause the release of histamine, or even block the enzymes that break down histamine.
The following foods are rich in histamine; if you are histamine-intolerant, you may want to either avoid these foods or reduce the amount you consume:
- Soured foods (e.g. buttermilk)
- Beer, wine, and champagne
- Kefir, kombucha, and other fermented foods
- Cured meats
- Dried fruits (e.g. apricots, prunes, dates, figs, and raisins)
- Aged cheese (e.g. goat cheese)
- Nuts (e.g. walnuts, cashews, and peanuts)
- Vegetables (e.g. avocados, eggplant, spinach. and tomatoes)
Foods that release histamine include:
- Wheat germ
Foods that block DOA include:
- Energy drink
- Black tea
- Mate tea
- Green tea
Based on the list provided, you may be wondering what you can eat if you’re histamine intolerant. Here is a list of low-histamine foods that you should be able to consume without experiencing any problems:
- Dairy substitutes (e.g. rice milk, almond milk)
- Freshly-cooked meat, such as poultry
- Gluten-free grains, such as rice and quinoa
- Pure peanut butter
- Fresh fruit
- Leafy herbs
- Herbal teas
Once histamine is formed, it is either stored or broken down by an enzyme. The DOA is the main enzyme that is responsible for breaking down and ingested histamine. So if you are DOA deficient, symptoms of histamine intolerance will follow and you should refer back to the low-histamine food list.
Myers, A., “Everything You Need To Know About Histamine Intolerance,” MindBodyGreen web site, October 3, 2013; http://www.mindbodygreen.com/0-11175/everything-you-need-to-know-about-histamine-intolerance.html.
“Histamine intolerance,” Foods Matter web site; http://www.foodsmatter.com/allergy_intolerance/histamine/articles/histamine_joneja.html, last accessed August 7, 2015.
“All about histamines,” Paleo Leap web site; http://paleoleap.com/histamines/, last accessed August 7, 2015.