Histamine block by Seeking Health is the best diamine oxidase supplement for histamine intolerance as it helps with the degradation of excess histamine in the gut and from high histamine-rich foods or drinks. The release of diamine oxidase in the small intestine immediately starts breaking down histamine so your body doesn’t have to. This is very beneficial for anyone who is intolerant to high histamine foods.
Following a low-histamine diet can help reduce symptoms of histamine intolerance, but at times you may want to enjoy some high histamine foods without having a histamine reaction.
And that’s where a DAO enzyme supplement comes in handy, as you can take it 15 minutes before you consume histamine rich foods or beverages to help with histamine metabolism in the digestive tract. SNP’s in the DAO enzyme or a DAO deficiency due to leaky gut syndrome, dysbiosis, IBS, and small intestinal bacterial overgrowth can all cause someone to be prone to histamine intolerance symptoms.
DAO supplements do not stop the release of histamine, but instead, it works by helping the body to metabolize high-histamine foods. The high levels of histamine in the body cause histamine symptoms such as abdominal pain, a runny nose, itchy skin, and allergy-like symptoms. Decreased DAO activity is associated with high histamine levels and a wide range of symptoms that are not always easy to pinpoint the cause.
My experience with histamine intolerance
That being said, abdominal pain and skin rashes are common symptoms. When I had histamine issues, I noticed itchy skin sometimes within minutes and up to an hour after consuming high histamine foods that are healthy such as sauerkraut and raw chocolate. Since histamine issues such as this after eating high histamine foods were new to me, I wanted to get to the root of the problem.
After taking a high dose of methylated B vitamins, I noticed I would get itchy skin on my fingers. So, I stopped taking a high amount of B vitamins and instead got a multivitamin with a lower dose of the active B vitamins to support methylation with active methylfolate and B12. After switching to a lower dose, I didn’t get itchy skin after taking the multivitamin but became more intolerant to high histamine foods.
Taking active B vitamins was the only change I could think of, so I stopped taking all methylated forms of B vitamins, and my histamine symptoms after eating high histamine foods disappeared. I later learned through Dr. Ben Lynch that people with inflammation could react to the active forms of B vitamins, and in terms of supporting methylation, such as in my scenario, it’s like pushing on the gas and brakes simultaneously, and the entire cycle gets jammed up.
Now why am I telling you this story? In my case, DAO supplementation may have helped, but I didn’t have SNPs in the DAO enzyme, and I believe the root cause of my histamine symptoms was a blocked methylation cycle and, thus, inadequate SAMe production.
This is important to know because the DAO enzyme metabolizes extracellular histamine, especially in the gut and from food, but the HNMT enzyme metabolizes intracellular histamine and requires SAMe as a co-factor. SAMe is found in Histamine Block Plus which also contains diamine oxidase.
You can learn more about methylation and histamine intolerance in this post.
Histamine metabolizing genes
The body has several histamine-metabolizing genes, including:
- ALDH
- MAOA
- MOAB
- HNMT
- DAO
- NAT2
- HRH1
Genetic testing can help you to determine which genetic SNPs you have that predispose you to histamine intolerance due to a decreased ability to break down and eliminate histamine. Doing genetic testing and running your strategene report can be very helpful to pinpoint the genes that may be genetically slow.
Then you can learn how to support a slow gene by taking a supplement or eating foods high in the nutritional co-factors required by those genes. Histamine intolerance is most associated with a reduced ability to break down and eliminate histamine.
How to use a Diamine Oxidase supplement for histamine intolerance
A DAO supplement is beneficial for someone with a diamine oxidase deficiency or genetic mutations in the DAO enzyme who already has too much histamine in the body and thus reacts to high histamine foods. To support optimal DAO levels in the gut and help with histamine degradation from food, take a DAO enzyme supplement such as Histamine Block ten to 15 minutes before eating high histamine foods.
Taking a diamine oxidase supplement will reduce the amount of histamine in the gut and from the food you just ate. The best way to prevent histamine symptoms associated with high histamine foods is to take it before you eat high histamine foods to ensure you have enough DAO to break down the histamine found in the food.
A DAO enzyme supplement does not stop histamine production in the body or block histamine receptors. Instead, DAO is an essential enzyme among many, crucial for the breakdown of histamine in the body. When histamine levels are brought down to optimal levels, you should be able to come off a low histamine diet and nutritional supplements such as a DAO enzyme.
The Dirty Genes Histamine Workbook highlights an important difference between supplements that help reduce histamine levels in the body and how anti-histamines work. Anti-histamines are very effective at quickly getting rid of histamine symptoms and allergic reactions caused by the release of excess histamine, but they do not reduce histamine levels.
Instead, anti-histamines block histamine receptors and thus histamine symptoms as histamine must bind to a receptor to trigger an effect. Anti-histamines do not stop the production, release, or breakdown of histamine. They only reduce symptoms of histamine by blocking the histamine receptor. For this reason, it is very challenging to stop taking anti-histamines as they don’t solve the root cause.
Gut infections trigger the immune system and the release of histamine, which is why optimal gut health is so important. Histamine intolerance often occurs alongside SIBO and IBS due to excess histamine production from the microbiome in the gut and a decrease in the DAO enzyme found in the intestinal lining due to leaky gut and dysbiosis.
While the best DAO enzyme supplement for histamine intolerance will help reduce histamine levels, you may also need to investigate and eliminate gut infections or rebalance the microbiome with probiotics that degrade histamine instead of producing histamine.
Best Diamine Oxidase supplements for histamine intolerance
- Histamine Block by Seeking Health is a popular supplement that contains diamine oxidase to break down histamine and has over 600 positive reviews. This is one of the best diamine oxidase supplements that supports the healthy breakdown of histamine found in food and works primarily in the small intestine and colon. It is an excellent DAO enzyme supplement for anyone with a dirty DAO enzyme or histamine symptoms after eating high histamine foods. Histamine Block contains 4.2 mg and diamine oxidase to help break down histamine and 10 mg and vitamin C, which helps produce DAO in the body.
- Histamine Block Plus by Seeking Health is another top DAO enzyme supplement for histamine intolerance. It contains the enzyme diamine oxidase plus enzyme to break down histamine in the digestive tract and from foods, but it also has additional nutrients to support other histamine-degrading enzymes. This supplement is excellent for people with histamine overload, seasonal allergies, various symptoms of histamine intolerance, and who need help breaking down histamine from foods and the gut. If you have tried a simple DAO enzyme supplement and still have symptoms of histamine intolerance, try Histamine Block Plus. Below is a list of the additional nutrients and their benefits in histamine metabolism.
- DAO2TM (Diamine oxidase): A patented, porcine-derived enzyme responsible for breaking down histamine in the digestive tract.
- Zinc, Vitamins B1 & B3: Nutrient cofactors for aldehyde metabolism and the ALDH enzyme.
- SAMe: A cofactor for the HNMT enzyme that breaks down intracellular histamine throughout the body.
- Alpha Keto-Glutarate: Supports the normal breakdown of ammonia, a toxic byproduct of histamine metabolism.
- PQQ: supports the normal breakdown of hydrogen peroxide and aldehydes.
- Vitamin C: stabilizes mast cells to support healthy histamine release.
- Vitamin B6: a cofactor for the DAO enzyme.
- Vitamin B5 (pantothenic acid): a cofactor for the NAT2 enzyme, which metabolizes histamine to acetyl histamine and eliminates it in the urine.
- Histazyme by Amy Myers is another one of the best DAO supplements for histamine intolerance. It only contains diamine oxidase, which is perfect for those who need help metabolizing histamine in the digestive tract and from high histamine foods and don’t want or need the additional nutrients to support other histamine metabolizing genes.

References:
Diamine oxidase supplementation improves symptoms in patients with histamine intolerance – PMC (nih.gov)
Histamine and histamine intolerance – PubMed (nih.gov)
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