High histamine: what it does and why it’s so complicated
The word ‘histamine’ often makes us think of hayfever, itchy welts, and sneezing. But there’s a lot more to histamine than allergies.
Histamine is an amine; a biologically active molecule based on the structure of ammonia (NH3). It’s formed by the decarboxylation (the removal of a carboxyl group) of the amino acid histidine.
The highest concentrations of histamine are found in the intestinal mucosa, skin, and bronchial tissues. Basophils and mast cells secrete histamine as part of a local immune response when your body detects a foreign invader. These cells reside in connective tissue and act as potent effector cells of the innate immune system.
Mast cells are the major producer of histamine and express many receptors on their surface. These receptors are activated through stimulants such as allergens, complement peptides, and neuropeptides, which cause the mast cells to release various inflammatory mediators including histamine .
Why do we need histamine?
Histamines play a crucial role in protecting your body from potentially harmful invaders. They act like armed guards, sounding the alarm to let your body know that something foreign has entered and that it needs to be attacked. This causes your immune system to respond with inflammatory chemicals that help get rid of the invader - known as an allergen - that’s bothering you.
When produced during a local immune response, histamine’s main role is to cause inflammation. Its release causes your capillaries to become more permeable to white blood cells and other proteins, which allows the white blood cells to target and attack foreign bodies in the affected tissue.
This inflammatory response is designed to help protect the body against pathogens. Your immune system sees these things as a threat and responds. If it has encountered a particular substance before, it immediately recognizes it as a trigger and launches a chain reaction to defend you.
Histamine also has a few other important functions in the bowel and is also known to act as a neurotransmitter (chemical messenger). It’s also involved in the secretion of gastric acid, inflammation, and the regulation of vasodilation and bronchoconstriction.
While your body’s objective is to keep you safe from what it believes could be harmful, these allergic reactions can be quite difficult to bear.
The process in which your body releases histamine:
- You encounter the trigger (pollen, dust, food, chemical, etc.).
- Your immune system recognizes the ‘invader’ and sends a chemical signal to your mast cells in your skin, lungs, nose, mouth, gut, and blood. The message is: “Send out histamines!”
- The histamines leave the mast cells and increase the flow of blood to the affected area of your body.
- The increased blood flow causes inflammation, alerting even more chemicals in your immune system to head to the site and start repairing any damage.
- Histamines then dock themselves at their respective histamine receptors.
If you’ve breathed in the allergen, histamines will lodge themselves in your nose, causing the membranes lining your nostrils to make more mucus. This leads to a runny or stuffy nose, along with sneezing. The inflammation will also irritate your throat and chest, causing you to cough or make breathing more difficult. Histamines can also make your eyes watery and itchy.
When can histamine be a problem?
When histamine is present in your bloodstream, it can affect your gut, lungs, skin, brain, and entire cardiovascular system. This results in a variety of unpleasant symptoms. It can also make it difficult to pinpoint histamine as a cause of the symptoms, which complicates the diagnosis.
In most cases, histamine is broken down by enzymes in your body, which prevents it from building up. But if these enzymes aren’t working properly histamine quickly accumulates. This can lead to histamine intolerance.
Because histamine plays so many different parts in how your body functions, symptoms of an intolerance are broad and can easily be confused for other things, such as food allergies.
Some of the most common symptoms of histamine intolerance to be aware of include:
- Digestive issues
Abdominal cramping, bloating, diarrhea, and other gastrointestinal discomforts. Histamine plays a part in breaking down food. If your body isn’t able to do this properly, you’ll end up with symptoms like gas, bloating, diarrhea, and stomach pain.
- Headaches and dizziness
Histamine can cause the blood vessels in your brain to dilate, which can lead to headaches and lightheadedness.
- Respiratory issues
Nasal congestion, sneezing, and other respiratory problems. Again, dilated blood vessels in the nasal passageways tend to cause sneezing and congestion. Histamine can also affect other parts of your respiratory system beyond your nose, including your airways. In extreme cases of histamine intolerance, you may have trouble breathing.
- Dermatological problems
Rashes, eczema, and itchy skin are also a result of inflammatory reactions in the skin.
- Cardiovascular reactions
A racing heart or palpitations is caused by histamine acting directly on cells in your heart.
Other symptoms of histamine intolerance include:
- Abdominal cramps
- Abnormal menstrual cycle
- Arrhythmia, or accelerated heart rate
- Difficulty falling asleep
- Difficulty regulating body temperature
- Nasal congestion, sneezing, difficulty breathing
- Nausea, vomiting
- Tissue swelling
- Vertigo or dizziness
What causes high histamine levels?
According to Dr. Ben Lynch, there are numerous causes for histamine intolerance, including:
- Genetic susceptibility (MTHFR, DAO, MAO, HNMT, PEMT)
- Pathogens (a number of which produce histamine or block methylation)
- Nutrient deficiencies (B12, folate, B6, B2, B1, Zn, Cu, C, methionine)
- Nutrient excesses (histidine, excess of protein in the diet)
- Nutrient demands (stress, anxiety, lack of sleep)
- Hormonal insufficiency (adrenal fatigue)
- Hormonal excess (estrogen)
- Lifestyle (excessive exercise, alcohol)
- Diet (fermented foods, aged foods, citrus, fish)
- Environment (pollen, mold, mildew, dust mites)
- Gastrointestinal conditions (leaky gut syndrome, IBD, IBS)
High histamine foods
Pickled or canned foods, including sauerkraut
Smoked meat products (salami, ham, sausage)
Beans and pulses (chickpeas, soy)
- Most citrus fruits, including lemon, lime, oranges
- Cocoa and chocolate
- Walnuts, peanuts
- Papaya, pineapples, plums, kiwi, bananas
- Wheat germ
- Most vinegars
- Additives – benzoate, sulfites, nitrites, glutamate, food dyes
Histamine and the DAO deficiency
- HNMT – which requires SAMe as a cofactor (and this requires an effective MTHFR enzyme to help produce SAMe)
- DAO – which requires vitamin B6 and copper
- MAO – which requires vitamin B2 and iron
- NAT2 – which requires CoA which stems from vitamin B5
- Black tea
- Energy drinks
- Green tea
- Mate tea
Histamine and your brain
The histamine-methylation connection
How to treat histamine intolerance
A histamine-free diet is your first step. Cut out fermented and processed foods, citrus, alcohol, aged foods, and cheeses. Increase the intake of healthy fats such as fatty fish, avocado, and nuts.
- DAO supplementation
One study showed that when high-histamine patients took DAO supplements before meals, their symptoms improved significantly.
Avoiding DAO-blocking foods is also advised.
- Methylation support
Many mental health conditions (particularly depression) can be effectively treated with supplementation of the right vitamins, minerals, and amino acids.
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