Have you ever had mysterious headaches or skin rashes? Does your nose suddenly begin to run when you eat avocados or bananas? You may have thought it was an allergy, but you also felt the same when you ate other types of food like cheese. You may have histamine intolerance based on those foods having higher amounts of histamine than you are able to break down. Luckily, there are treatment options for you. Read on to learn if diamine oxidase (DAO) supplements could be helpful for you!

What is DAO?1,2

DAO is an enzyme that is used to help break down your foods that contain histamine. Histamine is a chemical released by your immune cells to promote inflammation and respond to allergens. When your body detects something that it thinks is going to harm you like if you eat peanuts and have a peanut allergy, it begins a protective response by releasing histamine. If you do not have enough DAO or your body makes too much histamine, you may feel sick after eating foods that are high in histamine. This is called histamine intolerance

What is histamine?2,3

Histamine is a neurotransmitter released by your immune cells to communicate to your intestines, brain, heart, skin, and lungs. It is a promoter of an immediate inflammatory reaction. Histamine is released when it is triggered by an allergen like dust, pollen, or something that it thinks will harm your body. Histamine levels increase and bind to their receptors for activity which can lead to symptoms of runny nose, sneezing, and difficulty breathing. You may have heard of antihistamines being used for seasonal allergy symptoms. Their role is to prevent the histamine reaction from occuring, not lowering histamine levels. Histamines are also involved in food allergies which trigger allergic reactions.

What is histamine intolerance?1,4

Histamine intolerance is a condition where you have high levels of histamine in your body. It can be caused by over-making histamine, not making enough DAO, eating too many foods high in histamine, drinking alcohol, medication, and genetic mutations. If you do not have enough DAO, your body is not able to eliminate histamine normally, so histamine builds up in your body and may cause uncomfortable symptoms. A high amount of histamine in your body can cause the following symptoms: migraines, bloating, gas, stomach pain, constipation, diarrhea, vomiting, muscle aches, pain, runny nose, difficulty breathing, hives or skin rash, itchy skin, and dizziness.

What foods are high in histamine?1,2,5

The following foods are high in histamine and may be causing your symptoms: avocados, nuts, mushrooms, eggs, shellfish, soybeans, chocolate, strawberries, pineapple, dairy products, food preservatives, and alcohol like beer and wine. Have you noticed any histamine intolerance symptoms when eating these foods? It is helpful to know your food triggers, so removing these foods for a month before reintroducing them may help determine your triggers. Your symptoms may be caused by eating some of these foods and some symptoms may be more severe than others. 

Is histamine intolerance an allergy?6

No, histamine intolerance is not an allergy because it is not caused by one type of food. Histamine intolerance is caused by foods that are high in histamine, so it can be several foods that irritate you. This also makes it harder to figure out what foods are giving you symptoms since there can be several different types of food from bananas to a glass of wine. Histamine intolerance may only occur in 1% of the population, but there are treatment options for you!

What are the benefits of DAO supplements?2,4

DAO supplements provide your body with DAO, so it can break down histamine in your food and help relieve your symptoms of histamine intolerance. Based on research, DAO supplements best help with the following symptoms and issues:

DAO supplements do not cure histamine intolerance and do not lower the amount of histamine your body makes, they only break down histamine you obtain from your diet. These supplements may not provide the same level of benefits or work the same for everyone. Studies have shown the benefits of DAO supplements, but more research is needed to fully understand their effects and usage.

What are the risks of DAO supplements?4,7

One of the risks with taking DAO supplements is that there is not a formal test to diagnose it. The symptoms of histamine intolerance can overlap with symptoms of other conditions too. If you think you may have histamine intolerance and take DAO supplements, but do not actually have it, this may be harmful. That is why it is important that you talk with your doctor or pharmacist if you are having symptoms from eating foods high with histamine, so they can help you create an appropriate treatment plan.

Another risk is that not all supplements are made with the same safety and efficacy standards since they are not highly regulated by the Food and Drug Administration (FDA) like drugs are. It is best to speak with a pharmacist before you select a supplement. One thing to look for when selecting a supplement is to find one that has United States Pharmacopoeia (USP) approval. USP approval means that the supplement contains all the ingredients on its label; has been tested for purity, stability, and potency; and has been made following Good Manufacturing Practices (GMP). Once you find a supplement, you should stick with that brand because not all DAO supplements have the same ingredients or the same dose. 

Are there alternatives to DAO?2,4,8

Yes! Instead of taking DAO supplements, you could manage your symptoms by increasing the amount of copper, vitamin B6, vitamin B12, vitamin C, phosphorus, zinc, magnesium, and iron in your diet. These vitamins and minerals are involved in breaking down the amount of histamine in your body, so if you increase their levels, your body will better be able to eliminate histamine. If you are having trouble eating foods with these vitamins and minerals, you could consider taking a daily multivitamin. Here are some great food sources:

Another way is by following a low-histamine diet. Foods that are low in histamine include vegetables except spinach and eggplant; fruits except berries, citrus, and tomato; olive oil; and grains like rice and quinoa. By limiting your histamine intake, this could improve your symptoms by as much as a 50% reduction. You could also try to eliminate those foods that cause you the most symptoms. A low-histamine diet may help you figure out which foods cause you the most symptoms.

If you are having symptoms of histamine intolerance and are considering taking supplements, talk to your doctor or pharmacist today.


  1. What to know about diamine oxidase (DAO) for histamine intolerance. WebMD website. https://www.webmd.com/allergies/what-to-know-about-diamine-oxidase-histamine-intolerance. Accessed October 25, 2021.
  2. Histamine intolerance: All you need to know. Amy Myers MD website. https://www.amymyersmd.com/article/histamine-intolerance/. Accessed October 25, 2021.
  3. What are histamines? WebMD website. https://www.webmd.com/allergies/what-are-histamines. Accessed October 25, 2021.
  4. What is DAO? Diamine oxidase supplements explained. Healthline website. https://www.healthline.com/nutrition/dao-supplement. Accessed October 25, 2021.
  5. Chronic allergies or a histamine intolerance? How to tell for sure. The Demspter Clinic website. https://thedempsterclinic.com/allergies-histamine-intolerance/. Accessed October 25, 2021.
  6. Your mystery food sensitivity might actually be a histamine intolerance. ENT and allergy website. https://www.entandallergy.com/blog-posts/details/your-mystery-food-sensitivity-might-actually-be-a-histamine-intolerance. Accessed October 25, 2021.
  7. What you need to know about dietary supplements. FDA website. https://www.fda.gov/food/buy-store-serve-safe-food/what-you-need-know-about-dietary-supplements. Accessed October 25, 2021.
  8. The best foods for vitamins and minerals. Harvard website. https://www.health.harvard.edu/staying-healthy/the-best-foods-for-vitamins-and-minerals. Accessed October 25, 2021.
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