London Clinic of Nutrition
Google 4.7 220+

Mast Cell Activation Syndrome

We have a wealth of experience across our practitioners in working with Mast Cell Activation Syndrome; helping people to manage their condition, and in some cases, to live a symptom-free life.


Book a Discovery Call


Mast Cell Activation Syndrome (MCAS) is a rare condition caused by an excess number of mast cells gathering in the body’s tissues. Mast cells are special immune cells that hang out in all of your body’s tissues, but they particularly like to congregate where your body comes into contact with the environment—such as in your gut and on your skin.

Mast cells are constantly on alert for danger, so they carry around sacs of inflammatory substances. When you’re exposed to stress or a threat, they break open these sacs and release the pro-inflammatory substances to protect you. This abnormal growth of mast cells causes a range of symptoms, including itchy bumps on the skin, gastrointestinal issues such as diarrhea, and bone pain. MCAS is not contagious.

There are two main types of Mast Cell Activation Syndrome

Cutaneous: This type of MCAS affects the skin only. It occurs more often in children. Mast cells build up in the skin, causing red or brown lesions that itch. By itself, cutaneous MCAS isn’t life-threatening. But people with the disorder have significant symptoms and have a much higher risk of a severe allergic reaction, which can be fatal.

Systemic: Occurring mainly in adults, systemic MCAS affects parts of the body other than the skin. Mast cells accumulate in the bone marrow and organs, such as the intestines. In cases of aggressive systemic MCAS , it can be life-threatening. Systemic MCAS includes two rare forms: mast cell leukemia and mast cell sarcoma. Mast cell sarcoma occurs when a tumor made up of mast cells forms somewhere in the body. Mast cell leukemia is a very aggressive form of the disease where large numbers of mast cells are found in the blood and bone marrow.

What Causes Mast Cell Activation Syndrome?

The cause or causes of MCAS are not fully known, but there’s thought to be an association with a change in genes known as the KIT mutation. The KIT mutation makes the mast cells more sensitive to the effects of a signalling protein called stem cell factor (SCF). The change happens after conception. In most cases, it is not inherited (passed down from one generation to another). If you have MCAS, certain activities and factors can trigger an attack. What causes an attack for one person may not affect someone else.

MCAS has also been associated with obesity, IBS, depression and diabetes [2]. We don’t yet know if MCAS plays a role in the development of these conditions, or if it’s the other way around, but we do know they’re connected.

What are the symptoms of mast cell activation syndrome?

  • Brown or red blotches on the skin, or bumps or spots that itch
  • Nausea, stomach pain, diarrhea and vomiting
  • Bone pain
  • Flushing (when skin all over the body turns red)
  • A drop in blood pressure
  • Fainting
  • Shortness of breath
  • Wheezing
  • Low blood pressure
  • Rapid heart rate
  • Diarrhoea
  • Abdominal cramps
  • Headaches
  • Fatigue

What can trigger Mast Cell Activation Syndrome?

  • Stress: emotional, physical, including pain, or environmental (i.e., weather changes, pollution, pollen, pet hair, etc.)
  • Exercise
  • Fatigue
  • Food or beverages, including alcohol
  • Drugs (opioids, NSAIDs, antibiotics and some local anaesthetics) and contrast dyes
  • Natural odours, chemical odours, perfumes and scents
  • Venoms (bee, wasp, mixed vespids, spiders, fire ants, jelly fish, snakes, biting insects, such as flies, mosquitos and fleas, etc.)
  • Infections (viral, bacterial or fungal)
  • Mechanical irritation, friction, vibration
  • Sun/sunlight
  • Heat, cold or sudden temperature changes

For patients who develop MCAS, their mast cells have already be irritated by something more prolonged.

We have identified three common factors which have been known to exasperate mast cells:

Heavy metals. Metals such as aluminium and mercury destabilise mast cells.

Gut dysbiosis. More than 70% of your immune system is clustered around you gut, which means an imbalance of bacteria can activate mast cells.

Mycotoxins. Chronic exposure to environmental pathogens activates mast cells. This one is huge. In our clinical experience, mould exposure or sick building syndrome is at the root of 90% of MCAS cases.

How do we assess Mast Cell Activation Syndrome?

During an initial consultation, one of our Functional Medicine practitioners will conduct a clinical assessment. Symptoms such as childhood allergies and asthma may seem relatively benign and unrelated but with MCAS, they are often the first indicator. Our practitioner will also explore whether you’ve suffered from exposure to mould or heavy metals toxicity


How do we support Mast Cell Activation Syndrome?

Diet. Based on our assessment, we will devise a suitable dietary plan.

Stress. Corticotropin hormone, released when you’re under stress, destabilises mast cells. This means a stress-reduction practice is an essential part of tackling MCAS.

Sleep. Research suggests your mast cells have a sleep-wake cycle too. By supporting your circadian rhythm, you can help to bring them back into balance.

Supplements. Certain nutrients provide natural mast cell stabilisers.

Additionally, we will help you to establish a solid routine, implement stress reduction, and heal and support the gut to give your body the best chance at reversing any evidence of this disease. By supporting your gut health, your immune system and your body’s detoxification processes, you can bring your mast cells back into balance. The process requires time and dedication and is best done with the support of your designated Functional Medicine Practitioner.

While our goal is always to prevent or reverse disease, we recognise that it is not always possible. However, it is certainly possible to live a fulfilling and functional life with a chronic condition such as MCAS – and although it may take some work, including dietary and lifestyle changes, you do not have to do it alone.


Finding a Functional Medicine Practitioner that specialises in Mast Cell Activation Syndrome

Chronic, complicated illnesses, such as Mast Cell Activation Syndrome, often send people from clinic to clinic searching for solutions for what can turn into years. It can be a discouraging and seemingly hopeless situation. Too often widespread, confusing symptoms are dismissed by medical professionals because they don’t seem to fit any of the criteria associated with the acute infections and chronic illnesses they are used to treating.

We live in an age where chronic illnesses run rampant. Their complicated nature can leave a lot of practitioners at a loss for what’s going on. Sometimes clients are even turned away – or worse, told that their symptoms are in their head.

Here at The London Clinic Of Nutrition we have a wealth of experience across our practitioners in working with many different complicated diseases; helping people to manage their conditions, and in some cases, to live a symptom-free life.

Suspect you have mast cell activation syndrome or want to learn more? Please give us a call today on 020 3332 0030.

Health and Nutrition Resources

Do I have mast cell activation syndrome?

Heavy Metals

Sun exposure – how much sun do we need?

Sign up to receive free recipes, health tips and more