There are a variety of reactions to food that people can experience. These reactions can include allergies, sensitivities, and intolerances.
An intolerance occurs when someone has difficulty digesting a food, often because of an enzyme deficiency. Unlike an allergy or sensitivity, an intolerance does not involve an immune response.
It is helpful to look at lactose intolerance first to better understand the concept of food intolerance.
Lactose intolerance is an example of an enzyme deficiency that many people are familiar with, either because they have this intolerance themselves or know someone who does.
When there is a deficiency in lactase in the GI tract (the enzyme that breaks down lactose in milk and other dairy products), lactose in foods can’t be digested.
Symptoms of lactose intolerance typically include
Histamine intolerance occurs when someone is deficient in the enzyme diamine oxidase (DAO). DAO is the enzyme in the GI tract that breaks down histamine found in a variety of foods including aged or fermented foods. You'll also find histamine in things like pineapple, tomato, spinach, and deli meats. And more!
Histamine Intolerance is sometimes also called DAO deficiency.
Unlike lactose intolerance where symptoms are only in the GI tract, with histamine intolerance, histamine gets into the blood stream and can travel anywhere in the body and impact any tissue -- hence the wide variety of symptoms that can potentially occur throughout in the body.
Symptoms of histamine intolerance or DAO deficiency can be very broad ranging and include:
High or low blood pressure
Nasal congestion or drip
Heartburn of GERD (reflux)
That's quite a list!
How do I know if I have an intolerance?
If you aren’t producing enough DAO, taking a DAO supplement can be helpful. Supplementing with DAO is comparable to someone with lactose intolerance taking lactase when they consume dairy.
Reducing your histamine consumption in foods and taking a DAO enzyme supplement can help to establish a new balance so that you reduce the histamine entering your bloodstream.
If your symptoms go away by doing these two things, you have a histamine intolerance.
Reasons you have a DAO deficiency can include genetic variations on the AOC1 gene, leaky gut, or inflammatory bowel disease (1).
There are also drugs that can interfere with DAO, so talk to your doctor or pharmacist if you are taking any prescriptions or pain medications to figure this piece out for yourself.
You can also talk to your functional or integrative doctor about doing a test that measures DAO, histamine, and zonulin. This test should be done before starting a DAO enzyme and before reducing histamine in your diet.
High Histamine Foods
Histamine content in foods varies considerably depending on storage times, how long it has been aged, and whether or not it has any additives. The following list is therefore a guideline of foods to replace.
Fermented dairy such as yogurt, cheese, and kefir
Fermented or cured meat or fish such as salami, ham, prosciutto, smoked salmon or gravlax
Fermented vegetables such as sauerkraut, kimchi, or other cultured vegetables
Fermented soy such as soy sauce, miso, natto or tempeh
Fermented grains such as sourdough bread
Pickled foods such as dill pickles, vegetables, or fish
Canned fish such as oysters, tuna or sardines
Condiments such as ketchup or mustard
Vegetables such as tomatoes, eggplant, spinach, or avocado
Fruit such as citrus fruit, banana, strawberries, papaya, or any dried fruits
Nuts such as walnuts, cashews, or peanuts
Black and green tea
Low Histamine Foods
To keep histamine content low it is important to purchase food as fresh as possible, and to consume it right away or freeze it. Enjoy the following foods in abundance:
Fresh or frozen meat; beef is aged, so tends to be higher in histamine
Fresh or frozen vegetables (except tomato, eggplant, spinach, and avocado)
Fresh or frozen fruit (except citrus, banana, strawberries, and papaya)
Tubers such as sweet potato, yam, and cassava
Gluten free grains such as rice, millet, buckwheat, oats, corn, and quinoa
Nuts such as almonds, Brazil nuts, hazelnuts, pecans, and pistachios
Cocoa butter, olive oil, avocado oil, coconut oil, ghee and animal fats
Looking for a concise list of low histamine foods? Download our Shopping List, available on our Resources page.
When It’s not an Intolerance
You may have some of the symptoms of histamine intolerance but have normal levels of DAO. Rather than having an enzyme deficiency, there can be other reasons for excess accumulation of histamine and its resulting symptoms.
Histamine metabolism may be altered elsewhere in the body, particularly in the liver.
Immune cells in the body can be releasing stored histamine. Some foods, drugs, and anesthetics can trigger the release of histamine from immune cells.
Do you have a DAO deficiency?
If not, you don’t have histamine intolerance!
In our next blog we’ll be exploring When It’s Not an Intolerance further. We’ll be looking at what else might be going on in your body that is contributing to your histamine mediated symptoms.
Curious to understand this histamine connection a little deeper? We're doing a free class on this very topic later this month. Consider joining us! It will all be online, so you can join us from the most comfy seat in your house. Register here for the September 29th class, happening at 7pm MDT (Alberta / Santa Fe / GMT - 6).