Understanding Mast Cell Activation Syndrome (MCAS): The Role of Histamines, Sensitivity, and Diet

by Lucia Stansbie

Mast Cell Activation Syndrome (MCAS) is a condition in which the body’s mast cells—a type of white blood cell that plays a role in immune response—become overactive. When triggered, these cells release chemical mediators like histamines, which can lead to widespread inflammatory symptoms. Many people with MCAS experience histamine intolerance or sensitivity, which often exacerbates digestive issues, including Small Intestinal Bacterial Overgrowth (SIBO). Understanding the connection between MCAS, histamine sensitivity, and gut health is essential for managing symptoms and optimizing nutrition.

What Is Mast Cell Activation Syndrome?

In MCAS, mast cells are easily triggered by common allergens, environmental factors, stress, and certain foods, resulting in the release of histamines and other mediators. Symptoms of MCAS can vary widely and may include hives, headaches, gastrointestinal discomfort, flushing, fatigue, and more. Because of its impact on multiple body systems, MCAS can be challenging to diagnose and manage.

People with MCAS are often sensitive to histamines, which are naturally produced by the body but are also found in many foods. In people with histamine intolerance, the body struggles to break down excess histamines, leading to symptoms similar to those of an allergic reaction.

The Link Between Histamine Sensitivity and MCAS

Histamines play a crucial role in the body’s immune response, helping fight off pathogens. However, when mast cells release too many histamines, or when histamines are not broken down effectively, they can lead to an array of symptoms. For individuals with MCAS, this overactivity can cause heightened histamine sensitivity, making them more prone to reactions when consuming histamine-rich foods.

The main enzyme responsible for breaking down histamine is diamine oxidase (DAO), which is produced in the gut. When DAO levels are low, histamines from both the body and diet may accumulate, exacerbating MCAS symptoms. Supporting DAO activity through diet and supplements can help alleviate some of this sensitivity.

MCAS, Histamine Sensitivity, and SIBO

Small Intestinal Bacterial Overgrowth (SIBO) is a condition in which bacteria overgrow in the small intestine, causing gas, bloating, diarrhea, and abdominal discomfort. There is a connection between MCAS, histamine sensitivity, and SIBO. In individuals with SIBO, bacteria can produce histamine and other biogenic amines, which may worsen histamine intolerance and aggravate MCAS symptoms.

Additionally, chronic inflammation from MCAS can lead to poor gut motility, making it easier for bacteria to proliferate in the small intestine, increasing the risk of SIBO. Thus, addressing both SIBO and histamine sensitivity is essential for managing MCAS symptoms.

Dietary Tips for Managing MCAS, Histamine Sensitivity, and SIBO

• Follow a Low-Histamine Diet: Many common foods are high in histamine and can trigger symptoms. Avoid aged cheeses, fermented foods, alcohol, smoked meats, and certain fruits and vegetables (such as tomatoes and spinach). Instead, focus on fresh, minimally processed foods.
• Include DAO-Boosting Foods: Foods rich in vitamin C (like bell peppers, strawberries, and citrus) and vitamin B6 (such as chicken, turkey, and bananas) can help support DAO activity, aiding in histamine breakdown.
• Incorporate Anti-Inflammatory Foods: Turmeric, ginger, and leafy greens may help reduce inflammation, supporting a balanced immune response.
• Limit Foods that Promote SIBO: Avoid simple carbohydrates and refined sugars, as they can feed bacteria in the small intestine. Instead, focus on complex carbohydrates like brown rice and quinoa in moderation.
• Consider Probiotic Supplements Carefully: Some probiotics can increase histamine levels. Look for strains that are known to be histamine-friendly, such as Bifidobacterium infantis.

Those are just some tips and referring to a nutritional therapist experienced in MCAS can provide you a highly personalised nutrition plan to enable you to manage this condition and its symptoms.