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Histamine is a miserable substance. This amino acid is naturally released by the immune system when the body is exposed to an allergen, but it is also found in foods and some drinks. While histamine is natural, it can make you feel downright awful without the right checks and balances.
People usually have their own built-in way of getting rid of histamine. The enzyme called DAO (diamine oxidase) is the enzyme that breaks down histamine. But there are many factors that prevent this enzyme from doing its job-preventing excess histamine. Due to certain genes, gut imbalances, nutritional, genetics, and hormonal factors, the body may not make enough DAO to break down the histamine in your system. This can leave anyone feeling off.
The release of histamine by immune cells called mast cells is why you feel miserable while having an allergy reaction. Some people also react to histamine in foods. You should also know that histamine is a brain neurotransmitter, but too much histamine can cause symptoms of histamine intolerance.
Part of the reason that some people have histamine intolerance is that they don’t make enough of an enzyme that breaks down histamine. This enzyme is called diamine oxidase (DAO).
Table of Contents
What is Histamine?
Histamine is not only a neurotransmitter, it is also known as a biogenic amine. Biogenic amines are natural and found in our bodies, as described above, but are also found in foods. Other biogenic amines found in foods like tyramine, putrescine, cadaverine, and spermidine are all related to histamine.
All of these are found in fermented and aged foods, and the older the food gets, the more of these biogenic amines are present. The presence of all of these biogenic amines make it difficult for the body to break down histamine.
What is DAO?
Diamine oxidase (DAO) is also known as histaminase, which is a natural enzyme made in the gut and in the kidney. Its role is to “digest” histamine so that your body doesn’t have excess histamine levels in your body.
An interesting fact about the enzyme DAO is that levels rise over 100-fold during pregnancy compared to other times in life. No one really knows why but a large amount of it is released by the placenta. It is part of the reason that pregnant women sometimes enjoy less allergy symptoms than when they aren’t pregnant. Low levels of DAO during pregnancy may indicate a high risk pregnancy as well.
If you don’t break down histamine properly in your gut, your body can feel miserable. Histamine overload, related to low DAO levels, is inflammatory and can cause many symptoms including headaches, redness and hives, dizziness, fatigue, pain, and low blood pressure symptoms.
While histamine intolerance, allergies, and mast cell activation symptoms (MCAS) have similar symptoms, MCAS is considered more severe because the immune response involves a stronger response in the body. Histamine intolerance usually is accompanied by low DAO levels, while MCAS and DAO levels are not well understood.
Symptoms of Histamine Intolerance
Histamine intolerance can cause any of the following symptoms:
- Flushing or redness of the face, neck, and chest
- Hives (urticaria)
- Eczema
- Swelling of the lips, tongue, or throat
- Itching without any apparent cause
- Rashes
- Psoriasis
- Nausea
- Vomiting
- Indigestion
- Palpitations
- Sneezing
- Low DAO levels
Histamine Intolerance vs Allergies
Histamine intolerance and allergies are related but are distinct as well. Both issues have histamine overload, but the underlying causes are different. Histamine intolerance happens when the body can’t break down histamine adequately, often due to low DAO production, leading to an accumulation of this chemical.
Symptoms of histamine intolerance and allergies can be very similar. Allergies are caused by an immune system response to allergens such as pollen, dust, or animal dander. These allergens cause the immune system to release histamine.
Some foods may support optimal histamine metabolism in both cases or have natural antihistamine properties. These include fresh fruits and vegetables, fish (such as salmon and tuna), beef, organ meats, chicken, turkey, and herbal teas. This is especially true of eating kidney organ meat because it contains natural DAO enzymes. Incorporating these foods into your diet may help balance histamine levels.
What Causes Low DAO Levels?
People can have low DAO levels due to multiple reasons, including medications, digestive issues, genetics, and more. Let’s take a closer look at the reasons you may have a DAO deficiency.
- Gut imbalances: some research suggests that gut damage and inflammation reduce the body’s ability to make DAO. DAO activity may one day serve as a marker for disease assessment in inflammatory bowel disease like Crohn’s disease.
- Enzyme Diamine oxidase deficiency (DAO): related to genetics, medications, and inflammation
- Medications that block the DAO functions or prevent production (see next paragraph)
- Histamine-N-methyltransferase (HNMT) deficiency: is an enzyme that breaks down histamine after DAO by adding a methyl group in the brain.
- Intestinal injury: is related to low DAO levels
- Histamine intolerance: is related to low DAO blood values
- Hormonal changes: women in the luteal phase of their menstrual cycle have higher levels of DAO than when they are in their follicular phase.
Many kinds of medications and substances can cause DAO levels to be reduced or increased as well. These medications include:
- Antibiotics
- Antihistamines
- Antidepressant medications
- Pain medications, both prescription and over-the-counter
- Blood pressure medications
- Alcohol
- Stomach acid medications
Low DAO levels can also be caused by intestinal disorders and genetic variants. If you lack DAO enzymes or have insufficient levels, you may experience histamine symptoms.
What to Do if You Have Low DAO Levels
There are many ways you can increase DAO enzymes in the body to reduce symptoms of histamine overload. One of the cornerstone ways of managing histamine intolerance is to limit histamine-containing or histamine-releasing foods. You can also supplement DAO enzymes as we will discuss soon. Nutritional and supplement strategies can also help you reduce histamine levels.
Avoid High Histamine Foods
Many foods contain the amino acid histidine that are turned into histamine.
Histamine foods include:
- Yogurt
- Milk
- Tomatoes
- Tempeh
- Miso
- Cured meats
- Chocolate
- Cheese
- Red wine
- Other alcohol
Limit Histamine Releasers
Some foods don’t actually contain histamine but can cause the body to release histamine. These foods are:
- Legumes
- Nuts
- Citrus fruits
- Strawberries
- pineapple
- Bananas
- Seafood
- Spices
- curry powder, paprika, black pepper, nutmeg, and cinnamon
Benefits of DAO Supplements
DAO is an enzyme naturally formed in the body and its sole purpose is to reduce histamine. Therefore, another strategy to use if you have histamine intolerance is to take DAO supplements. DAO supplements are particularly helpful if you are eating high histamine foods. They also may be helpful for people who don’t make adequate amounts of DAO enzyme due to medications, gut disorders, or genetics.
Using DAO supplements has several research-backed benefits. Cardiovascular symptoms, including headache, vertigo, palpitations and collapse, significantly improve with DAO enzyme ingestion. Interestingly, low levels of DAO may even predict pregnancy complications such as preeclampsia. Let’s explore the research about how DAO enzymes may help improve many aspects of health for people with histamine intolerance.
DAO Helps Reduce Histamine Intolerance
Dao supplements reduce histamine intolerance symptoms overall according to a study of 28 patients with known histamine intolerance. The study groups received either 0.3 mg DAO or placebo. The participants receiving DAO supplements had reduction in overall histamine symptoms, , including abdominal pain, intestinal colic, bloating, diarrhea, constipation, nausea, belching, vomiting, vertigo, palpitations, headache, itching, rashes, swollen, reddened eyelids, post-meal fullness and painful menstruation—all of these significantly improved with DAO supplementation.
DAO Supplements Reduce Migraines
Impressively, DAO supplements also reduce migraine symptoms and headache symptoms. DAO reduces migraine duration by 90 minutes in one clinical study of 100 participants. Using DAO supplements also reduces the requirement for pharmaceutical treatment of migraines.
DAO Supplements Reduce Fibromyalgia Symptoms
Research shows that genetic DAO deficiency is present in 75% of Spanish women with fibromyalgia symptoms. One very interesting benefit of DAO supplements is that they ease fIbromyalgia symptoms according to one study of 100 people, specifically, less fatigue, anxiety, depression, and burning. They also had less negative thoughts and feelings of helplessness.
DAO Supplements Help Digestive Function
People with histamine intolerance usually have digestive issues and 2 studies demonstrate that DAO supplements can help reduce these digestive symptoms. People with histamine intolerance had less bloating, diarrhea, abdominal pain, belching and fullness when taking DAO supplement with meals. Using DAO supplementation in people with histamine intolerance also helps people with gut symptoms. People with chronic hives may also find benefit from taking DAO supplements according to one research study.
My DAO Supplement Review
Histamine has always plagued me, so trying DAO supplements made a lot of sense. This is because my histamine symptoms resolved when I was pregnant, making a DAO enzyme deficiency during other parts of my life a process of exclusion. I also suffer from motion sickness and have chronic symptoms of histamine overload.
DAO supplements work right away, so it’s pretty easy to tell if they will work or not. In my case, I noticed right away that my ear congestion and sinus passages feel more clear. I also have less itching. The only downside is remembering to take DAO supplements with meals. Regardless of timing, though, I did notice I felt better despite forgetting to take it consistently with meals.
Bear in mind that I also have a baseline intake of lots of natural antihistamine compounds like vitamin C, quercetin, nettles, and probiotics. So the fact that DAO enzyme supplements had an additive benefit is pretty powerful. By the way, the DAO supplement I’m using is called Histagest-DAO that I buy on Fullscript.
Other Natural Histamine Reducers
While DAO supplements can help reduce symptoms of histamine intolerance by breaking it down, other natural compounds may also reduce the symptoms of histamine issues.
These include natural antihistamines like:
- CBD (cannabidiol)
- Ginkgo biloba
- Quercetin
- Feverfew
- Butterbur
- Vitamin C
Considerations For Taking DAO Supplements
Using DAO supplements are generally recognized as safe and may help you if you have many kinds of gut issues, genetic variants, or have symptoms of histamine overload.
DAO supplements may help you if you have any of the following:
- Altered gut microbiome
- Leaky gut
- SIBO
- While breastfeeding you notice your baby has colic when you eat high histamine foods
- Pregnancy
- Motion sickness
- Histamine issues
- Symptoms got better during pregnancy
- ADHD (attention deficit hyperactivity disorder)
- DAO gene variants
- After consuming high-histamine foods or drinks, symptoms like headaches, skin issues, tiredness, sleep problems, indigestion, bloating, bladder issues, heart palpitations, and sneezing occur.
How to Take DAO Supplements
To help reduce histamine intolerance, take DAO supplements right before or during your mealtime. You can also take DAO supplements between meals to reduce the histamine made by your gut microbiome. You can take DAO supplements as needed, in other words.
DAO supplements may support healthy levels of histamine within the small intestine, colon, kidneys, uterus, appendix, placenta, prostate, and testicles.
Children 4 years of age and older may use DAO supplements. Breastfeeding women may use Pregnant women and breastfeeding women may use DAO supplements if approved by their healthcare professional.
Probiotics Can Also Increase DAO Levels
Unfortunately, some probiotic foods can increase histamine levels, such as yogurt. Luckily, some probiotics and probiotic supplements can help the body make DAO no matter what the cause is for low DAO enzymes. In other words, some kinds of probiotics are great for histamine intolerance and I wrote extensively about them in my blog here called The Best Probiotics for SIBO and Histamine Intolerance.
Niacin for Histamine Intolerance
Normalizing histamine levels depends on nutrients, including niacin (vitamin B3). Use of niacin supplements in the form of niacinamide or nicotinamide reduce symptoms of histamine overload. This makes sense because niacin decreases inflammation and supports normal metabolism of histamine. While not all research is consistent in this area, some people with histamine intolerance swear by the beneficial effects of niacinamide in alleviating their symptoms. Be aware that niacin supplements can cause symptoms of temporary flushing.
Precautions
As always, you should discuss any supplement you take with your healthcare provider before starting any new supplement. DAO supplements do not work for food allergies, such as peanuts, shellfish, etc., or for gluten intolerance due to sensitivity or celiac disease.
