DAO (Diamine Oxidase) supplements are being used increasingly often by people afflicted with chronically high histamine levels. It’s become one of the most popular histamine intolerance supplements, in part because it’s now being used as a sort of home test for histamine intolerance— if it lessens your symptoms, you’re on the right track. The idea is that if it manages to decrease or totally rid you of your histamine sensitivity, that indicates that histamine is at least part of your issue.
Symptoms of histamine intolerance (chronically high histamine levels) include migraine headaches, recurrent headaches, nasal congestion, gastrointestinal problems, sneezing, shortness of breath, cardiac arrhythmias (heart rhythm abnormalities), hypotension (low blood pressure), anxiety, and flushing and itching of the skin. The rest of this article is focused upon what DAO is, how to increase DAO naturally, and how to find the best DAO supplement or DAO-boosting activities for your needs.
Medical Disclaimer: as with everything on this site, this article is provided for information only. I strongly urge you to speak with your doctor or a licensed medical professional in order to assess whether or not you should incorporate a DAO enzyme supplement into your regimen.
What is the DAO Enzyme?
DAO is an enzyme essential for histamine degradation; it’s normally produced in the kidneys, the lining of the intestines, and the thymus. Enzymes are a type of protein molecule which catalyze or accelerate the speed of chemical reactions in the body, while chemicals known as co-factors assist these enzymes in the execution of such reactions. The co-factors vitamin B6, vitamin C, and copper are essential for the production and proper functioning of DAO.
The enzyme’s main function is to metabolize (digest) and cause the breakdown of excess amounts of histamine in the body, whether ingested or produced internally. This breakdown results in a vast reduction of histamine intolerance symptoms, and generally within a half hour. It also works in conjunction with another enzyme known as histamine methyl transferase (HNMT) to reduce the levels of two toxic byproducts of histamine breakdown called N-methyl histamine and imidazole acetaldehyde.
DAO supplements have quickly become one of the most commonly-used supplements to treat a histamine reaction, especially when caused by dietary histamine.
DAO & Histamine Intolerance
As you’ll quickly learn, “intolerance” isn’t the most accurate description of what’s going on inside the body of someone with histamine intolerance. The better term would be “histamine overload” or “histamine toxicity,” as the symptoms of the illness are due to the overabundance of histamine in the body. But to backtrack a bit, why does this overabundance of histamine cause symptoms which mimic a food allergy or food intolerance?
The connection lies in the immune system.
Histamine is a nitrogen-containing biogenic amine found in most tissues of the body. This means that it’s not only very important to the functioning of most bodily systems, but it can also have a huge effect on them. Molecules of histamine are produced and stored in histamine-containing granules that are found in mast cells as well as in a type of blood cell called basophils, both of which are integral parts of the immune system.
Histamine release is stimulated as an important part of the body’s inflammatory response to allergens, such as certain foods, pollen, insect bites, various drugs, and dust. The effect of histamine release is incredibly similar to the symptoms typical of an allergic response, in addition to anxiety, dysautonomia, and even mood swings. Reactions can occur in response to endogenous histamine (produced) or to exogenous histamine (consumed), but high histamine food is the number one reported trigger.
Being able to clear histamine from the digestive tract is a major tool in your arsenal, and that’s where DAO comes in.
What is DAO Deficiency?
DAO deficiency occurs when the body’s levels of diamine oxidase have dropped low enough that your body is unable to eliminate unnecessary histamine, resulting in buildup. Once DAO deficiency occurs, your body’s histamine level will naturally continue to rise, leading to all the physical symptoms of excess histamine referenced above. Causes of DAO deficiency include:
- Excess alcohol consumption
- Overgrowth of the bacteria normally found in the intestines (SIBO) or Leaky Gut Syndrome
- Consuming large amounts of high histamine foods
- Genetic mutations which impair your body’s ability to make DAO or make use of its cofactors
- Hormonal imbalances
- Certain types of medications which function as DAO blockers (including drugs such as chloroquine, isoniazid, and verapamil)
- Chronic gastrointestinal disorders such as Irritable Bowel Syndrome (IBS), Crohn’s disease, or Ulcerative Colitis
- Heavy metal poisoning (such as copper toxicity or lead poisoning)
Some of these causes of low DAO can take decades to build up and express themselves. For example, DAO deficiency can be due to genetic polymorphisms that reduce the normal activity of DAO, or even by a reduction in the available amounts of the cofactors needed for DAO production. As you get older, DAO production decreases, so any minor genetic mutations may increase in effect as you age.
DAO deficiency is usually treated with DAO supplements, but it’s also important to make sure you consume a balanced diet, so that you’re healthy enough to produce enough DAO on your own.
Major side effects of DAO supplements are rare, but they have occurred, mainly in people with autoimmune and inflammatory diseases. So always talk to your doctor before starting a new regimen or changing your existing one. Possible side effects of DAO consist of nausea, headache, lethargy, hives, and symptoms similar to those of the flu— so basically the same as those of histamine intolerance.
Best DAO Supplements
DAO supplements are more widely available than ever, but they should not be your first defense against histamine. Their purpose is just to temporarily enhance the level of DAO enzyme in the body, in order to better metabolize high histamine foods and reduce the symptoms of histamine intolerance. If taking a “magic pill” were all that’s needed to clear everyone’s histamine symptoms, we wouldn’t even be here.
So before diving into DAO supplementation, I want to once again state that I am not a medical professional and that you should always speak with your doctor before trying something like DAO. That said, once you’ve done an elimination diet and ruled out other possibilities, like gluten intolerance or an allergic reaction, then you should consider DAO supplements. Every brand will contain varying concentrations, but they’re widely available over-the-counter and even high doses don’t require a prescription.
One study has indicated that a helpful dose of supplementary DAO is roughly 4.2 mg, taken ideally right before meals. One more popular histamine intolerance supplement with this amount of DAO is Seeking Health Histamine Block, which I’ve never used, but is apparently very effective. I personally prefer to consume whole foods when possible, even in supplements, which is why I started with and continue to use Ancestral Supplements’ Bovine Kidney.
The DAO content in whole kidney will vary a bit by brand, but I’ve found it to be the best DAO supplement for histamine intolerance, helping ease my reactions even more than stinging nettle or quercetin have. This may be because all the best DAO supplements contain some amount of kidney, usually derived from grass-fed cattle that have been allowed to graze freely. Pea sprouts are another great source of DAO, but they must be consumed fresh for the DAO to be used by the body.
I’ve learned from experience that taking your source of DAO approximately fifteen minutes before consuming a high histamine meal can help metabolize histamine from any food or drink source, though this only helps if DAO deficiency is to blame for your histamine sensitivity. For those who have a type of mastocytosis or a mast cell activation disorder (MCAD), additional DAO may not help unless you figure out your non-food triggers, as well.
The best DAO supplements for histamine intolerance will have been thoroughly tested for heavy metals and potential contaminants, with all levels well within the range safe for human consumption. They should also be fully tested by a third party laboratory, with results posted on their website, and should not contain any unnecessary fillers. A high quality diamine oxidase supplement will also be free of any GMOs, and formulated based on the latest scientific research.
Histamine blocking supplements often contain vitamin C, which helps to normalize the level of DAO long-term, and aids in the normal breakdown of histamine. In addition, since histamine intolerance is often due to problems with the normal bacterial flora of the gut, many top DAO supplements also contain probiotics, which help to restore intestinal balance. Regardless, studies have found that DAO supplementation by itself does help in the improvement of symptoms of patients who have histamine intolerance, so find what works for you.
How to Increase DAO Enzymes (Naturally)
Now that we’ve looked at supplements, let’s look at how to boost DAO levels without adding more pills to your day. There are a number of different ways to increase DAO enzymes naturally, which you can do in place of or in addition to DAO supplements. You should begin by starting a low histamine diet. To start eating low histamine, first you must eliminate foods that are known to be high in histamine, such as fermented foods and drinks.
You can also increase your DAO enzymes naturally by carefully balancing your low histamine diet— ask your doctor to run a blood test to check your levels of copper, iron, vitamins B6 & B12, and vitamin c (ascorbic acid). All of these are necessary for the proper breakdown of histamine by DAO, so make sure they’re present in your regular diet and that if you have a deficiency, it gets addressed. It’s also important to balance the different types of protein and fat you’re intaking.
This means decreasing your intake of Omega-6 fatty acids, such as those contained in highly processed foods, and increasing your intake of healthier fats, like Omega-3 and Omega-9 fatty acids. An often-cited study into rats found that oleic acid in particular— an Omega-9 fatty acid found in olive oil— increases the amount of DAO secreted into the blood stream. Changing the types of protein you’re eating can also naturally increase the amount of DAO released by the gut.
Particularly eating organic plant proteins and grass-fed meats can help to naturally increase DAO levels in the body. Avoiding additives, artificial preservatives, and pesticide-laden foods has also been found to increase DAO, though it’s more likely that those substances themselves are DAO blockers, artificially inflating histamine levels. Finally, lowering your overall stress has been found to naturally increase DAO, most likely by reducing systemic inflammation and decreasing demand for DAO.