Explaining Mast Cell Activation Syndrome and Histamine Intolerance

by Dr. Martin Hart DC, NASM-CES, TFT/EFT

Are you having unexplainable reactions? Seemingly allergic to the world around you? Food intolerances that come and go? One day a strawberry makes your lips swell and the next day it’s fine. Will the wrong thing touching your skin create hives and rashes for days? Maybe it is worse than that; maybe it’s not just rashes, but your reactions include heart palpitations, lightheadedness, intense acid reflux, and intense bladder pains. If this is starting to sound like you, then hopefully I can shed some light on your situation by explaining Histamine Intolerance (HIT) and Mast Cell Activation Syndrome (MCAS).

You may know a little about histamine and mast cells and their connection to seasonal allergies, but do you know the other roles they play in the human body? Histamine is a compound made from histidine; an amino acid found in food. A short list of its functions includes:

  • Vasodilation (opening blood vessels and regulating blood pressure)
  • Vascular hyperpermeability (makes blood vessels leaky to help transport)
  • Glandular secretions (mucus, etc.)
  • Regulates the sleep-wake cycle
  • Releases stomach acid for digestion
  • Stimulates neurons
  • Regulates appetite
  • Smooth muscle (in the organs) contraction
  • Sexual function
  • Pain perception
  • Inflammation and immune function
  • Helps move mast cells for immune function
  • Neurotransmitter (serotonin, dopamine, norepinephrine, etc.) regulation

Mast Cells

Mast Cells are part of the immune system. Most often they are factors in fighting off parasites, fungus, and bacteria. They do this by releasing many different substances, including histamine, leukotrienes, prostaglandins, tryptase, and serotonin. These cells originated in the bone marrow but later migrate heavily to the connective tissue of the lungs, digestive tract, bladder, and other regions.

Mast cells:

  • Fight infections
  • Aid in communication for the immune system
  • Regulate inflammation
  • Support detoxification, especially with venom (such as bug bites)
  • Balance blood flow
  • Mediate pain
  • Aid in wound healing

Dysregulated Histamine and Mast Cells

Looking at these lists, you can see that histamine and mast cells have many jobs throughout the body. This makes it evident that when histamine and mast cells go haywire, the effects can be intense and happen all over the body. This is known as Histamine Intolerance or Mast Cell Activation Syndrome. HIT is when the body accumulates an excessive amount of histamine, creating a sort of toxicity. While HIT is an overload of histamine, MCAS is when the body has either more mast cells than it needs, or they are being triggered (degranulated) to release their contents too often. In these syndromes, each of the roles they play becomes a symptom. If you don’t know that these symptoms are coming from HIT or MCAS, they can seem random and unpredictable.

Why Reactions Are Not Always Consistent

Your load of histamine and mast cell mediators will determine if you react or not and how intensely you react. One day a seemingly healthy avocado might make your face swell and leave you lightheaded, while two days later it might leave you with just a little extra mucus in your throat. This is because your histamine load in the body has shifted, or your mast cells are less reactive. Symptoms of increased histamine load and MCAS include swelling, inflammation, hives, rashes, flushing, welts, food reactions, increased pain, heart palpitations, sexual dysfunction, loose stools, bloating, poor sleep, feeling wired or overstimulated, anger, irritability, neuro-psychiatric symptoms, increased mucus production, congestion, low blood pressure, racing heartbeat, and any symptom related to the areas regulated by histamine receptors.

Histamine Receptors

Histamine works on our cells through receptors. Histamine locks into these receptors to do its job. There are 4 types of histamine receptors throughout the body called H1, H2, H3, and H4 (not creative but easy to remember). They are in areas such as blood vessels, nerves, the brain, digestive tract, gonads, skin, and lungs. Antihistamine medications have varying effects or make you drowsy depending on which receptor they block.

Where did all this histamine come from? As mentioned above, some of the histamine in the body comes from the foods we eat. Certain foods, such as pickled or fermented products, smoked or processed meats, and leftovers contain high amounts of histamine. A diet full of these foods can create HIT; but more often than not, it needs another catalyst. We need certain enzymes and probiotics to help us breakdown histamine in the body. These enzymes include diamine oxidase (DAO), histamine n-methyl transferase (HNMT), and monoamine oxidase-B (MAO-B). They function to clear and process histamine through various means. You can have a genetic polymorphism (meaning a mutation) that lowers your ability to make these enzymes, or you can have functional issues (such as nutritional deficiencies or infections) that decrease the ability of the enzymes to work well.

Co-Factors for DAO, HNMT, and MAOB:

  • Copper
  • Vitamin C
  • Methyl donors
  • B-vitamins (especially B-6)
  • Iron
  • Magnesium

Mast Cell Locations

Mast cells are located throughout the body in the loose connective tissue, especially near blood vessels. They are most concentrated in the lungs, digestive tract, bladder, skin, and the brain. These locations will often be the sight of the most intense symptoms. Because the brain is a major hub of mast cells and the role of histamine as a neurochemical, MCAS and HIT can mimic or contribute to many neuropsychiatric disorders.

Causes of MCAS

The number one of cause of MCAS that I have seen is mold exposure. This has been consistent across my patients dealing with mast cell activation syndrome and even histamine intolerance. The body will trigger mast cells to release their contents in order to fight the fungal spores being inhaled as well mounting an immune response to the mold toxins.

Next, parasite infestations can also lead to MCAS or HIT due to the immune system trying to expel these critters. After that I see various chronic infections such as Lyme, Bartonella, and SIBO impacting MCAS. Lastly, glyphosate toxicity (herbicide) and vaccine reactions play a role in these issues.

Role of our Gut in MCAS/HIT

Our microbiome, the good bacteria in our gut, also works to break down histamine and other inflammatory molecules. The strains Bifidobacterium infantis, Bifidobacterium longum, and Bifidobacterium breve have been shown to lower histamine. Other strains are also involved, such as Lactobacillus rhamnosus; but these first listed are the primary three strains that support our good bugs as they work for us. A person who lacks these critters will find it is more difficult to break down histamine. Mast cells are intimately involved with our gut-brain connection as well.

Whereas in our microbiome the absence of good bacteria can lead to excess histamine, some pathogens directly promote excess histamine by their presence. A major source includes SIBO, small intestine bacterial overgrowth. Our small intestine is not meant to host as much bacteria as our colons, so when it migrates up north or we become infected with bacteria in that region, we end up with gas, bloating, various other symptoms, but especially excess histamine. Other infections in the gut, such as parasites, can provoke increased histamine and mast cell activation, as it is one of the main ways our immune systems fight these pathogens. Any factor that triggers a chronic immune response or inflammatory response, such as mold toxicity, can also trigger chronic histamine release and mast cell activation.

What To Do

Any good practitioner learns to become a good detective in working with issues such as Histamine Intolerance and Mast Cell Activation. Solving HIT/MCAS requires removing the root cause, such as SIBO or parasites, improving the body’s ability to process histamine, and providing immediate support to relieve the suffering of the patient. The detective work becomes important because many patients dealing with this will react to treatments if the doctor only guesses at how best to help. Instead, the doctor needs to be specific and work with the patient’s biochemical individuality to create the best solutions.

For those at home who believe themselves to be suffering from HIT and MCAS, first test your home for mold (EC3 Mold Plates). If you have mold toxicity, you want to create a safe environment and start a gentle detox, we use the EC3 fogger in our home and office to keep them clean. Detoxing the mold toxins is your next priority. Then I recommend eliminating the largest sources of excess histamine from your diet as well as highly inflammatory foods. Controlling histamine and mast cells through nutraceuticals goes a long way to bringing some relief. There are plenty of herbs and supplements that are mast cell stabilizing and antihistamine including quercetin, vitamin C, stinging nettle, and black cumin seed.

After you stabilize the inflammation, you can begin to support the immune system in clearing infections such as parasites or Lyme. Sinus Defense 2.0 is a very gentle way to help your body do that.

Living with Histamine Intolerance or Mast Cell Activation Syndrome can be overwhelming. The experience can be equated to walking through a live minefield, never knowing when you are going to have a reaction. Please know that there is hope for you out there. Learning about Histamine Intolerance and working with a qualified practitioner can offer you a path to health and healing. Don’t give up, don’t give in, and keep looking for the answers you seek.

Questions and comments are always welcome. Please write to us below or email us at newsletter@sinusitiswellness.com. Dr. Hart and his team may be contacted through his practice website for Keystone Total Health.