Histamine intolerance (HIT) happens when there is a buildup of histamine in the body, rather than a reaction to or intolerance to histamine itself. Our body depends on histamine for many functions. Our immune system depends on histamine to help rid the body of allergens. Our body’s release of histamine is an inflammatory response to a pathogen, virus or allergy. Our body sees this response and sends white blood cells to fight the intruder. Afterwards, our body’s enzymes break down the histamine that was released.
Histamine also regulates stomach acid, stimulates the brain, boosts libido and plays a key role in ovulation and female reproduction. Because of all its roles in the immune system and beyond, we don’t want to get rid of the histamine response altogether, but instead figure out what is causing the overproduction of histamine.
Too much histamine can effect many systems including the brain, gut, lungs and cardiovascular systems. Histamine symptoms are widespread since it travels in the blood, so it can reach anywhere in the body. Symptoms can be similar to seasonal allergies but it’s not necessary to have traditional allergy symptoms or to get positive allergy test results, since those test are only looking for a specific reaction.
Here are a list of symptoms that can be caused be HIT:
Itchy skin, eyes, ears and nose, seasonal allergies, runny nose and congestion, red eyes
Headaches, migraines
Asthma attacks
Eczema or other types of dermatitis, facial flushing, psoriasis, hives
Facial swelling or other tissues swelling
Throat tightness
Difficulty regulating body temperature
Drop in blood pressure when standing up quickly, low blood pressure
Vertigo or dizziness
Fast heart rate, heart palpitations
Difficulty falling asleep
Confusion, irritability
Anxiety or panic attacks
Acid reflux or other digestive issues, food allergies or intolerances
Hormone symptoms such as PMS, acne, period pain and heavy periods
We all have a histamine threshold - meaning that you will be ok with a little histamine but after your histamine levels surpass a certain threshold you’ll experience symptoms. Often times the metaphor of a bucket is used, where you can add histamine responses to the bucket without many symptoms until the bucket fills up and overflows. This makes it harder to figure out your triggers, since it can be cumulative. It can also be hard to pinpoint that what you’re experiencing is a histamine issue since the symptoms can be across so many different body symptoms.
What might cause your body to release more histamine, contributing to your histamine load and your histamine bucket overflowing? Any inflammation in the body can impede DAO function. Stress increases inflammation and releases cortisol. Cortisol causes an increase in release of mast cells, which break open dumping more histamine into the blood. Dr Becky Campell says that stress is the #1 cause of a HIT flare up. Estrogen also triggers histamine to be released, and histamine causes an increase in estrogen. So it’s a vicious cycle. Many women (and even men) struggle with estrogen dominance, either due to an excess of estrogen or not enough progesterone to balance the estrogen. And there are times when our bodies are more sensitive to histamine, like around ovulation when estrogen is naturally higher. Therefore, excess histamine can increase your hormonal symptoms, either around ovulation or with PMS. Environmental allergens, certain foods and food sensitivities will all cause a histamine response.
What can predispose or cause you to have issues with histamine? Very simply put: your body makes histamine, food sensitives will also stimulate histamine production, and many foods contain histamine. Then your body’s enzymes need to be working to break it down and clear it. Many people who have HIT have certain genetic mutations or variations that put them more at risk. These specific variations are quite common. The two main ones are with DAO, the enzyme that breaks down ingested histamine, and HNMT, the enzyme that breaks down histamine within the cells. Other genetic variations that can increase HIT risk include MTHFR and MAO. If this is an area you’re interested in finding out more about, I highly recommend the work of Dr. Ben Lynch and his book Dirty Genes.
Other conditions or issues that can make you more susceptible to having HIT include Mast Cell Activation Syndrome, gut issues, gluten intolerance, certain medications, nutrient deficiencies, thyroid dysfunction and adrenal fatigue.
Why won’t antihistamines, such as allergy medications, solve this problem? There are a few reasons. Different types of antihistamines block receptors in different cells/areas of the body. Antihistamines just block receptors, they don’t actually reduce your histamine load. So when the medication wears off, the symptoms and histamine reaction starts back up again because the receptor isn’t blocked anymore. Long term use of some antihistamines can cause the body to make less DAO enzyme to break down histamine, and to digestive issues. If you're having a bad flare up, using antihistamines for a short period of time can be a good solution to help ease symptoms. However, regular, long term antihistamine use isn’t going to help address your histamine load and can lead to other health issues. My two favorite supplements for histamine support can be found in my supplement portal here. One is comprehensive vitamin and herbal histamine support (Designs for Health Histaeze) and the other is a histamine specific probiotic.
In the words of Dr. Ben Lych: “Can you maintain and support your body’s ability to balance histamine levels? Absolutely! By addressing a variety of pathways and mechanisms.” For a more comprehensive guide to histamine intolerance, testing and treatment contact me for my full handout, check out Dr Becky Campbell’s website or her book The 4-Phase Histamine Reset Plan.