Mast Cell Activation Syndrome (MCAS) and Histamine Intolerance (HI) are both conditions related to histamine dysregulation, but they have different underlying mechanisms and clinical features.
Key points:
Definition: MCAS is primarily an immune system disorder where mast cells, which are a type of immune cell, are activated and release excessive amounts of chemical mediators, including histamine. HI is a metabolic issue where the body has difficulty breaking down and eliminating histamine; related to histamine levels exceeding the body’s capacity.
Mechanism: In MCAS, mast cells become hyperresponsive and release their contents inappropriately, even in the absence of a real threat. In HI, there is a deficiency or dysfunction of enzymes involved in histamine metabolism, such as diamine oxidase (DAO).
Symptoms: MCAS can cause a diverse array of symptoms, and can be unpredictable and vary from person to person. HI symptoms often resemble an allergic reaction, and typically occur after consuming histamine-rich foods or substances that inhibit DAO.
Triggers: MCAS triggers can include stress, infections, certain foods, medications, and environmental exposures. HI triggers are typically allergens, or medications that interfere with DAO function.
Treatment: MCAS treatment involves a combination of antihistamines, mast cell stabilizers, and medications that target specific symptoms. HI treatment involves avoiding histamine-rich foods, minimizing triggers, and possibly taking DAO supplements.