diamine oxidase DAO histamine intolerance supplements

Diamine Oxidase & Histamine: How to Increase DAO Enzymes Naturally

A diamine oxidase (DAO) deficiency is one of the most common causes of histamine intolerance. The DAO enzyme is responsible for breaking down histamine in your body. When it can’t break everything down, a build up occurs and you experience histamine intolerance symptoms.

Alongside taking a DAO supplement, there are some easy-to-make shifts in your eating habits that promote healthy DAO enzyme levels, too.

Before we get into solutions, let’s take a look at what histamine intolerance is and what role the DAO enzyme plays in affecting histamine levels.

DAO and histamine intolerance

Research shows that at least 1 percent of the world’s population suffers from histamine intolerance and, of those, almost 80% affected are women.

Histamine Intolerance occurs due to the overproduction and accumulation of histamine in the body and the inability to break it down. This may cause a range of chronic symptoms, such as a allergic-like reaction, digestive tract disorders (IBS), congestion, and asthma, among others.

Although it can be diagnosed by consulting a doctor and observing common symptoms of histamine intolerance, going deeper to find the root cause is vital for managing the symptoms. One common cause is a shortage of DAO enzymes.

In fact, studies show that DAO deficiency accounts for over 70% of all histamine intolerance.

So, how do you know if this is a root cause in your histamine intolerance?

Diamine oxidase deficiency: common causes

When your body needs to decrease its histamine levels, it requires two naturally occurring enzymes known as the DAO enzyme and histamine N-methyltransferase (HNMT). If these enzymes aren’t available, or if your body cannot produce enough, it can cause a histamine build-up.

There are several factors that may cause DAO deficiency, including:

  • Genetic inheritance - Individuals may possess a genetic mutation which results in a diamine oxidase enzyme deficiency.
  • Medications – Both prescription and over-the-counter medications may contribute to reduced diamine oxidase enzyme levels. It’s important to talk to your doctor about side effects and read the labels.
  • Hormonal imbalances - Imbalances in oestrogen and progesterone can impact many of your body’s normal functions, including histamine levels.
  • Gastrointestinal disorders - Disorders such as irritable bowel syndrome (IBS), Crohn’s disease, ulcerative colitis, Celiac disease and small intestinal bacterial overgrowth (SIBO) may all contribute to inflammation in your body causing similar symptoms as a histamine intolerance and even impacting your body’s ability to produce proper amounts of the DAO enzyme.
  • Nutrient deficiencies - A B6, vitamin C, zinc or copper deficiency, may put you at risk or contribute to a DAO deficiency.
  • Consuming histamine-rich food - Some foods may inhibit the functioning of the DAO enzyme, or contribute to symptoms by overloading the body with more histamine than your enzymes can break down.
  • Alcohol - Alcohol is a very potent inhibitor of the DAO enzyme, thus contributing to increased histamine symptoms, on top of being high in histamine itself.

A DAO deficiency can also impact multiple organs (lungs, skin, cardiovascular system, brain, digestion, etc.) leading to numerous additional symptoms. Depending on the severity of the deficiency, these symptoms can occur after eating certain foods.

It's also important to note that symptoms don’t always appear immediately, either. It may take all day for your body to accumulate a buildup of histamine. So, the meal you ate in the morning may have caused the drowsiness or skin irritation you are feeling now.

Because it can be difficult to pinpoint the triggers, many people find that an elimination diet full of low histamine foods is helpful for identifying histamine intolerance and understanding which foods to avoid, but we will cover some of those foods below.

8 ways to increase DAO enzymes naturally

To date, there have been many studies on preventing DAO deficiency in the body and researchers have even identified options to potentially prevent and even reverse histamine intolerance.

1. Adopt a low histamine diet

A recent study found that dietary modification is the first step for reducing symptoms associated with histamine intolerance. By eliminating high histamine foods from your diet, you are allowing your body to catch up to and process the amount that is already present. The study also discovered that these dietary modifications positively impacted how DAO enzymes move throughout your body.

If you aren’t sure how the right diet can reduce your histamine levels and support healthy DAO production, click the button below to download my free eBook. It is a master list of 102 high histamine foods to avoid, along with step-by-step guidance for reducing your symptoms and discovering the root cause of your intolerance.

Get the free guide!

2. Balance your fat intake

When it comes to updating your diet, some of the most interesting and relevant results for increasing DAO enzymes have been in relation to fat consumption.

Studies have shown favourable results when patients increased their intake of the Omega-9 fatty acid - monounsaturated fats, a primary source of oleic acid. Olive oil in particular was shown to increase the the release of the DAO enzyme into the bloodstream by up to 500%!

Oleic acid has been shown to have other health benefits, too, such as reduced blood pressure, especially when consumed as part of a Mediterranean-style diet. You can cook with olive oil or include nuts like macadamias in your meal plan to help prevent a DAO deficiency.

Meanwhile, the inflammatory Arachidonic Acid, a polyunsaturated omega-6 fatty acid, found in offal, fatty red meat and dairy (especially hard cheeses and eggs) was found to cause the highest increase in histamine, when compared to other foods.

Reducing the amount of Omega-6 in your diet - the kind found in processed foods and vegetable oils - while increasing the amount of Omega-3 fatty acids (including fatty fish, seafood) you eat has been shown to moderate inflammation and reduce symptoms of histamine intolerance.

Important factors in balancing fats include using heat stable oils, including ghee and pressed coconut oil for baking and cooking at high temperatures. You can regularly use olive oil and macadamia oil for light, low heat cooking.

3. Eat the right proteins

The process of digesting protein is largely responsible for the release of the DAO enzyme in the gut. This helps your body deal with ingested amines and histamines, while preventing a build-up of histamine levels in the body.

Therefore, eating clean, healthy proteins is important. Look for grass-fed, organic protein and fresh seafood to increase DAO activity.

4. Minimize harmful ingredients

A common theme in this list is healthy, whole foods. That’s not an accident! It’s important to understand that avoiding artificial ingredients and pesticides can make a huge impact on your digestion, DAO production and even food allergies.

Eating as naturally as possible is always going to be a positive for your health!

5. Supporting gut health

As mentioned, the majority of DAO histamine is produced in the gut. Therefore, promoting your gut health and supporting your gut bacteria through the use of low histamine probiotics provides an important foundation for reducing histamine symptoms. Probiotics are able to increase DAO just like a supplement, through the method of supporting your digestive tract and keeping gut bacteria at healthy levels.

6. Take vitamin supplements

Deficiencies of zinc, copper, vitamin B6 and vitamin C, have also been associated with inflammation, elevated histamine concentrations and reduced DAO activities. Regular supplementation of these nutrients can increase DAO enzymes and may offer further relief from the symptoms of histamine intolerance.

A helpful way to ensure you're meeting your nutrient needs is to take a low histamine multivitamin with minerals which can prevent or improve existing nutrient deficiencies.

7. Find a DAO supplement

Another simple way to increase your DAO enzyme levels are with a natural DAO supplement. These can be taken as a capsule and may offer an easy way to help reduce symptoms of histamine intolerance.

Supplementing with DAO enzymes directly is one of the fastest and most and powerful ways to increase DAO levels and help break down incoming histamine to reduce symptoms.

8. Reduce histamine release

This is the method I use with many of my clients via supplementation with my Natural Antihistamine. Although reducing histamine release doesn't directly increase the DAO enzyme, it does give your body a break from the inflammation and destruction in order to allow the DAO enzyme to catch up and calm your symptoms.

Additionally, by controlling the body's natural histamine release, my clients typically find they can tolerate much higher levels of dietary histamine before their body becomes overloaded and shows symptoms.

This means less dietary restrictions and fewer symptoms. Yes, you can eat a wide variety of foods and live a normal daily life with histamine intolerance!

Some of my clients have called Anti-Hist their "miracle in a bottle" or their "wonder-drug."

Implementing changes to improve histamine symptoms

Now that you have 8 ways to naturally prevent DAO deficiency, it's time to get started.

The steps above are all simple and can be done in your own home - so, I encourage you to begin implementing them right away. Why wait?

And, if you haven't already read the low histamine diet eBook I've created, click on the button below. It is the most comprehensive high histamine foods list available online, with additional methods for symptom relief and instructions on how to discover the root cause of your intolerance.

Get the free eBook!


FAQ: DAO Enzyme Supplements

Does everyone with histamine intolerance need to supplement DAO enzymes?

No. There is no hard and fast rule that will apply to everyone who has histamine intolerance, and therapies should be individually tailored. As research shows 70% of histamine intolerance stems from some level of a DAO deficiency, these individuals in particular may benefit from supplementing DAO enzymes.

Additionally, those who do not have a DAO enzyme deficiency but are still histamine intolerant may for other reasons choose to supplement with DAO and still experience benefits. In other words, DAO is helpful for most histamine intolerant individuals, but not necessarily all.

Can diet increase DAO enzyme levels as much as DAO supplements?

Although diet can increase levels of DAO enzymes, it will of course not be as potent as supplementing enzymes. However, not all individuals need such a strong dose of DAO as is gotten through supplementation.

If you have very mild histamine symptoms, for example, then using dietary methods of increasing DAO can be sufficient to improve these.

Are DAO enzyme supplements suitable for vegans and vegetarians?

Unfortunately not. DAO enzyme supplements are a porcine kidney extract, meaning they are extracted directly from an animal. For this reason, these supplements are not compatible with vegan and vegetarian diets.

Do diamine oxidase enzyme supplements have to be taken forever?

This comes down to your root cause. For example, if you currently have a nutrient deficiency that is preventing you from producing enough diamine oxidase enzymes naturally, then you can attend to the nutrient deficiency and fix it at the root, which will most likely result in an ability to produce DAO normally.

In this case, DAO supplementation would no longer be necessary and individuals could wean off.

If, however, you have a genetic inability to produce sufficient DAO, this may be unalterable. It would depend on the severity of the issue and if it can be managed using another route - however, cases like these cause individuals to be more likely to continue relying on diamine oxidase supplements.

Can DAO supplements help with other disorders?

There are major crossovers between histamine intolerance and a variety of other disorders such as IBS, SIBO, chronic migraines, mood disorders and even fibromyalgia.

For this reason, DAO enzyme supplements can often improve overlapping symptoms. One study, for example, showed that supplementing with DAO enzymes for 8 weeks improved symptoms of fibromyalgia.


Author Photo

Anita Tee

My name is Anita Tee. I'm a nutritional scientist who specializes in histamine intolerance. I hold a Master of Science in Personalized Nutrition and a Bachelor of Science in Human Biology and Psychology.For the past ten years, I have used my experience in nutritional and medical health sciences to create a scientifically backed, natural approach to healthcare that relies 100% on evidence-based research.As I previously suffered from - and overcame - histamine intolerance, my focus is to increase recognition and expand the available resources and protocols available for resolving this particular disorder. To date, I have helped over 4,000 individuals fully resolve or better manage their histamine intolerance symptoms.

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