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In general terms, histamine is found in two major types of immune cells in the body, the mast cell and the basophil. Mast cells typically are found in connective tissue and mucosal linings such as the lining of the nose, the mouth and the digestive tract. They are also located in the lungs, the brain and underneath our skin and are usually near nerve endings. Basophils circulate in our vascular system. Both types of cells and the chemicals they release, including histamine serve very important biological functions and are part of our primary defense against invaders.

Histamine release can be triggered by foreign invaders (germs or parasites), allergens, and other chemicals in the body. The trigger cross links IgE and as a result, histamine is released.

People usually think of the classical symptoms of allergies, red eyes, a runny nose, wheezing, coughing and chest congestion, hives and eczema. These are the classic symptoms, but did you know histamine can cause other reactions? There are four types of histamine receptors and they can cause different symptoms depending on many factors such as where the histamine is released, genetic differences, and the triggers or causes of excess histamine.

Excess histamine can cause joint pain, musculoskeletal or connective tissue pain (fibromyalgia), chronic fatigue, bloating, constipation or diarrhea, estrogen dominance and painful menstruation, hypotension, tachycardia or rapid heart rate, dizziness, trouble regulating your body temperature, and trouble sleeping. It has also been linked to child hood ADHD. Adults will commonly complain of brain fog or trouble multitasking.

Is this common? Yes, it is. Typically, we would think that the immune system is in balanced and that is often the case. High stress and high cortisol can make us more prone to have this part of our immune system activate. However, there are also enzymes that break down histamine and they appear to be a major issue in today’s environment. Two major enzymes are Histamine N-Methyltransferase (HNMT) and Diamine Oxidase (DAO). HNMT requires proper methylation to function and DAO also needs several factors to work properly.

Think for a moment about an old, leaky basement. It’s been raining quite a bit recently, and water is starting to flood the basement. The sump pump should kick on to pump the water out, but it isn’t turning on. Why? Maybe the float is stuck and isn’t triggering it to turn on, maybe a fuse has blown, maybe something else. Maybe all of the above! Now the water is becoming a problem.

The histamine reaction is sort of like that basement. The foods you eat and the environment you’re exposed to is the like water that’s starting to flood your basement. The HNMT and DAO enzymes are your sump pumps that just aren’t working, or aren’t working fast enough to deal with the histamine overload.

The DAO enzymes are produced in the lining of the gastrointestinal (G.I.) tract. When the G.I. tract is injured, the DAO enzyme activity is diminished. Additionally there are foods and things we commonly consume that may inhibit the enzyme, release histamine and there are even foods naturally high in histamine.

What are some of the culprits?

Alcohol is a major cause; it will release histamine and block the enzymes that break it down. Champagne is loaded with histamines. Chocolate, egg whites, nuts, certain types of fish, fermented foods in vinegar, processed meats, soured products such as sour cream and milk, spinach, tomatoes, pineapple, bananas, strawberries, papaya, avocados, artificial sweeteners, citrus fruits, broccoli, kale, parsley, sweet potatoes, coffee and teas (black, green, and mate) to name a few.

This is not an allergic reaction or a reaction triggered by a specific allergen; it is a result of the enzymes that break an important chemical down that are not functioning. Unfortunately, once this cycle begins it results in further damage to the G.I. mucosa and can result in a vicious ongoing cycle of histamine release.

There are many steps that can be taken medically to resolve this issue, including temporary avoidance of the triggers and even taking a DAO enzyme with meals which include foods that may trigger a reaction. Healing the G.I. tract is important and addressing methylation is also very important along with balancing the immune system.

Because the symptoms of histamine reactions can vary so widely, it is advisable to obtain genetic testing. A trained physician will be able to utilize the information in a proper genetic test to know how to best treat the patient.

Ralph Waldo, M.D.

Advanced Integrative Physicians

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