Food-Dependent, Non-Allergic Mast Cell Activation

Pathology: Symptoms result froman unpredictable release of inflammatory mediators. Food triggers some patients, but the mechanism is unknown.

Trigger-Symptom Interval: Some clients experience immediate, anaphylactic-like symptoms, and others experience delayed symptoms.

Diagnosis: The physician considers clinical symptoms, laboratory results, medication response, etc. Unfortunately, no precise diagnostic tools exist for mast cell activation syndrome, and a definitive diagnosis is not always possible. Specific food triggers are determined by observation and experimentation but are often inconsistent and difficult to pinpoint.

Treatment: Mast cell disease is managed with medication, lifestyle changes (e.g., stress reduction) and trigger avoidance (including food). A low histamine diet may improve symptoms for a subset of patients.

Mast cell activation syndrome (MCAS) is a recently recognized condition characterized by abnormal mast cell activation. As discussed in IgE Food Allergy (Module #3: Above the Water), mast cells are like tiny balloons filled with inflammatory chemicals. They activate and release their chemicals as part of our innate immunity (the first line of defence against pathogens). In MCAS, various other events (e.g., stress, heat, vibration, pressure, food, and temperature changes) activate mast cells.

Mast cell activation can impact every organ, so the symptoms vary tremendously from patient to patient and within a patient. Unpredictable allergic-like symptoms are common (especially with food-related triggers).

The disease is not organ-specific, so various physician specialists have developed expertise – including allergists, dermatologists, hematologists, gastroenterologists, etc.

Laboratory testing is primarily based on detecting inflammatory chemicals in the blood or urine. However, these chemicals are unstable and difficult to catch. As a result, there are no definitive (easy to administer) tests. Many patients are treated based on suspicion of the disease.

This comic captures the challenges.

MCAS can usually be managed with medication, lifestyle changes and trigger avoidance. Unfortunately, the best treatments are individual; clients must experiment to determine what works for them. This journey can be frustrating and tedious, so professional support is crucial.

Medication:  Physicians use various treatments depending on the patient’s symptoms. Typical medications:

  • Stabilize mast cells (so they are less likely to activate)
  • Block inflammatory mediators (e.g., antihistamines)
  • Treat the effect of mediators (e.g., epinephrine)

Lifestyle: Mast cells are more likely to activate when the body is under physical or emotional stress. Therefore, stress management is essential for this client population. When talking with a client, I emphasize that their body is more sensitive to stress, rather than they do not handle stress well. I speak further about this concept in module #8: Counselling Skills.

Trigger avoidance: Many events trigger mast cells (e.g., stress, heat, vibration, pressure, food, and temperature changes). Inconsistent triggers are very challenging. A client may have symptoms with a specific meal but be okay with the same foods on another day. There are several explanations, including:

  • The client incorrectly assumes their symptoms are food-related.
  • Co-triggers impact the client’s sensitivity to the food. For example, the food only bothers the client if they are stressed.
  • Digestion may be the culprit rather than a specific food sensitivity. A possible explanation is that pressure inside the gastrointestinal tract during digestion activates mast cells. Dermographism (mast cell activation and hives from pressure on the skin) is a common symptom. Mast cell activation during digestion would be similar but internal, so it would be difficult to see the connection.
  • A variable food component is a trigger (e.g., salicylates).

The benefit of a low histamine diet in this patient population has not been researched, but there are anecdotal reports that some clients benefit. Clients who want to try a low histamine diet should be encouraged to do so systematically (module #10: Experiment Plans & module #11: Elimination Diet and Challenge). If the diet is beneficial, the client will see the improvement within a few weeks (often in a few days).

Mast cell clients are often on a limited diet because:

  1. Online support groups offer a sense of community with people who understand what they are going through. Unfortunately, the discussions tend to be fear-focused. I have spoken with several clients who restricted their diet after online conversations, even though they had never experienced a problem with the food.
  2. Symptom triggers are inconsistent (as discussed above). If clients associate their symptoms with food, they may progressively become more restricted. For example, reviewing their intake and pinpointing a potential culprit.  “It must have been the carrots.”
  3. A mysterious disease (like MCAS) creates uncertainty, and food restrictions can make patients feel more in control.