Unmasking Allergies and Other Histamine Related Issues

Histamine Related IssuesAuthor: Dr. Bridget
Anyone who knew me before I became a naturopathic doctor would immediately know why I’m passionate about treating allergies and other histamine related issues—I had a serious problem with environmental allergies.  When I was flared, I would sneeze hundreds of times a day, for days on end. Because I refused allergy medications, I lived in a state of chronic inflammation.I came to palpably understand the intense systemic effects of inflammatory molecules like histamine- symptoms like chronic congestion, fatigue, brain fog, irritability, headaches, body pain, sensitive skin, and inflamed gums.   I didn’t realize how all of these things were connected until I started to get to the root of my allergies. I spent years trying to find the right combination of anti-inflammatory herbs and supplements to address allergies, but it never panned out for lasting effects.

While an anti-inflammatories approach can help, most of the time it is not enough and it is more of a Band-aid solution. In order to really treat allergies, the terrain in which allergies develop needs to be addressed. While allergies are considered an issue with the immune system, ones’ propensity for this type of reactivity depends greatly on the health of the digestive system, where 70% of the immune system resides, as well as the health of the liver and the adrenal glands. When these systems are out of balance, histamine can wreak havoc on the body. In my journey with treating allergies, I have found that lowering overall histamine levels (and getting to the root of why they are elevated) has made the biggest difference in reversing allergies.

So let’s talk about histamine…


Histamine is a major player in the allergic response. It is an inflammatory mediator released by mast cells as part of an allergic response.  Beyond the local swelling of eyes, nose, sinuses, and airways, histamine has potent effects on blood vessels, the brain and nervous system, and on the digestive tract. Histamine is an important biological compound, but high histamine levels are overwhelming and can cause a range of problems. In addition to respiratory allergies, histamine overload can be a culprit in headaches, chronic itching, skin flushing, edema, low blood pressure, gastro-esophageal reflux, intestinal cramping, diarrhea, sleep disturbance and mental health issues including irritability, anxiety, and depression.

There a number of reasons that histamine can be out of balance. I like to use the metaphor of a bucket, wherein all of the factors that increase one’s allergic susceptibility go into the bucket—including genetics, childhood environment, our personal microbiome, stress levels, diet, nutrient status, gut and liver health, hormone balance, exposure to chemicals and other environmental insults, and overall immune system wiring. These factors add up until finally the bucket overflows and symptoms manifest. While we can often identify external causes for allergic responses, such as pollens or foods that trigger cells to release histamine, these external factors make up just one portion of the bucket.

My goal is to assess all of the factors in the bucket and target what we can. While there are several possible causes of elevated histamine, some of the first places I look are at diet and gut health.


In addition to the histamine produced by our own bodies, we ingest histamine in many common foods. Dietary histamines are highest in fermented foods like ripened cheeses, aged or smoked meats and fish, and sauerkraut. Histamine is also released by many nuts especially walnuts and pecans, some fruits such as citrus and strawberries, and a few vegetables including eggplant and spinach. There are several other foods and beverages, most notably alcohol, that block histamine breakdown. A diet high in these foods creates a greater histamine burden. While some of these foods can be quite healthy, if histamine is out of balance, they add fuel to the fire. Many find that reducing their intake of these foods, along with other inflammation causing foods, can help them feel better in times of histamine excess. But we still need to look deeper.


Why would histamine containing foods, many of which have been part of our diet for hundreds of years, cause problems? It is likely because our gut health is more out of balance than ever. The ensuing inflammation damages an enzyme in the small intestine, called Diamine Oxidase (DAO), which is responsible for breaking down histamine in the gut.   When the intestinal lining is injured or inflamed, DAO levels decline and naturally occurring histamines in the diet may not be degraded effectively.   Even if our DAO enzyme activity is good, an inflamed gut doesn’t have good barrier function and allows in compounds from the digestive tract before they are fully processed. This phenomenon, called leaky gut, increases the load on the liver, affecting the liver’s ability to degrade histamine as well.

Increasingly common, leaky gut can be the consequence of maldigestion, imbalanced gut flora, such as SIBO (small intestinal bowel overgrowth) or yeast overgrowth, and other inflammatory issues such as celiac disease and inflammatory bowel disease. Stress, environmental toxins, medications, and dietary irritants are also big factors in leaky gut. In order to restore histamine balance, it is essential to treat the underlying causes of gut inflammation and repair the gut lining.

If allergies persist once the gut is in good health, the next places to look at are at detoxification pathways, adrenal health, and hormone balance.


Our bodies naturally produce and degrade signaling molecules like histamine all day long. Histamine is broken down in the liver and in many tissues throughout the body by several key enzymes, including DAO, histamine N-methyltransferase (HNMT), Monoamine oxidase (MAO), aldehyde dehydrogenase and N-acetyl-transferase (NAT). Genetic variations in these enzymes can impact the rate at which histamine is degraded.  Fortunately, supporting these enzymes with their nutrient cofactors enhances their activity, regardless of genetic status.

The histamine degrading enzymes and their cofactors are required for dismantling a myriad of compounds in the body, including neurotransmitters, hormones and various toxicants.  The more these enzymes work to degrade histamines or other substrates, the more nutrients they require.  The liver in particular can face a heavy load because it receives dietary histamines as well as endogenous ones. Removing environmental exposures, repleting nutrient cofactors, and supporting healthy detoxification will all greatly enhance histamine balance.


In addition to gut and liver health, it is essential to address the role of stress in allergic reactions. In my personal journey, as my seasonal allergies had improved, I was able to pinpoint that stressful events were a major trigger. Like clockwork, I would have intense allergies the morning after final exams during medical school, until I identified the pattern.

There are a few mechanisms at play. Cortisol is a hormone produced by the adrenal glands and is responsible for regulating inflammation and stress responses, among other things. Cortisol also inhibits histamine release. If cortisol levels in the body are low, inflammation goes unchecked. However, the hormone that stimulates cortisol’s production, corticotropin releasing factor (CRF), does the opposite- it promotes histamine release from mast cells.   Stress drives CRF release. The upshot is that supporting balanced adrenal gland activity and using stress reduction techniques like diaphragmatic breathing are important tools for quelling allergies.

Another area to consider is sex hormone balance. Estrogen has a potent effect on stimulating mast cells to make histamine and it lowers DAO activity. Histamine can further stimulate estrogen production, and possibly contribute to estrogen dominance.   Estrogen dominance in women is implicated in conditions like PMS, heavy menstrual flow fibrocystic breasts, fibroids, endometriosis, and premenstrual insomnia and anxiety. As chronic histamine overload is improved, some may be able to pinpoint that allergic symptoms tend to flare around ovulation and menses. Fortunately, treating the gut, liver and adrenals will often bring hormones into balance.


As with most health concerns, the key is to look at the big picture and keep asking whether there is a deeper cause. Often by pulling just a few factors out of the bucket, people experience tremendous relief from their allergies. As improvements are gained, triggers become more obvious. It becomes easier to tune into the subtle signals that one’s bucket is filling up and then to take self-care measures to restore balance before the bucket overflows.  The focus can shift from trying to suppress an allergic response, into a practice of deep listening and responsiveness. I find this approach incredibly empowering.   No matter what symptoms you struggle with, that is my wish for you.


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