A Quick Guide To Understanding and Managing Mast Cell Activation Syndrome and Histamine Intolerance

By Maggie Yu. MD IFMCP
Mast cells have a protective function in your body, as they are designed to detect foreign substances such as allergens…

And respond by producing and releasing histamines.

While this release is a natural and necessary part of your body’s defense mechanism, things can take an adverse turn when there is an overproduction of histamines, leading to what is known as Mast Cell Activation Syndrome (MCAS).

There are also other allergy-related syndromes, such as Histamine Intolerance, where you have a hyperactive response to the histamines produced, resulting in an overwhelming level of allergy symptoms.

If you suffer from MCAS or Histamine Intolerance, you’re most likely familiar with classic symptoms of allergies like:
  • Itchy eyes
  • Runny nose
  • Hives
  • ​Asthma
  • ​Swelling of eyes, mouth, lips, throat, sinus, and bronchial
  • Uterine cramping and bleeding
  • Headaches
  • Migraines
  • ​Irritable Bowel Syndrome such as gas, bloating, diarrhea, and constipation
  • ​Insomnia
  • Fatigue
  • Crippling anxiety
  • Vertigo
  • ​Brain fog
  • And more severe allergic responses like anaphylactic shock and respiratory failure.
It’s not uncommon for allergists to dismiss these symptoms because they don’t understand or specialize in them.

However, there are 8 ways you can effectively manage your MCAS/Histamine Intolerance from the comfort of your home…

But before you read any further, you should know that there are many health diagnoses and symptoms that go hand in hand with your allergic reactions, and they include:
  • Autoimmune Disorders of every type, including Rheumatoid arthritis, Lupus, Hashimoto’s, Celiac, Sjogren’s, Crohn’s, and Ulcerative Colitis.

    An autoimmune disorder indicates a dysregulated immune system, which contributes to the dysregulation of the allergy branch of the immune system.
  • Chronic Infections including COVID-19, Lyme, EBV, SIBO, candida, H.pylori, and C.difficile. Having these infections long-term makes one susceptible to also having many allergy-related issues.
  • POTS and Dysautonomia: These two syndromes dysregulate the autonomic nervous system responsible for regulating the fight vs. fight response and allergy system.
  • Hormones: Dysregulated individuals, including those with fibroids, endometriosis, heavy periods, PCOS, early menopause, and increased symptoms from menopausal changes, are all victims of abnormal levels of histamine. The histamine pathways affect estrogen metabolism pathways, leading to an imbalance of hormones. 

8 Out The Box Ways To Manage Mast Cell Activation Syndrome And Histamine Intolerance

Quick reference links:

1. Blood Sugar Mastery

Maintaining stable blood sugar levels is crucial for managing MCAS and histamine intolerance because frequent fluctuations in blood sugar can trigger mast cell activation and worsen symptoms.

6 Strategies for Blood Sugar Mastery:

  • Eat balanced meals like complex carbohydrates, healthy fats, and protein to slow down the release of glucose into the bloodstream and prevent blood sugar spikes.
  • Avoid refined sugars and processed foods to reduce the number of bacteria in the body that triggers the overproduction of histamines. Opt for whole, unprocessed foods instead.
  • Eat smaller, frequent meals throughout the day to stabilize blood sugar levels and prevent large fluctuations.
  • Choose low glycemic index foods like whole grains, legumes, non-starchy vegetables, and lean proteins to help release glucose slowly into the bloodstream and prevent sudden spikes.
  • Exercise regularly to improve insulin sensitivity and help regulate blood sugar levels. Aim for a combination of cardiovascular exercise and strength training.
  • ​Stay hydrated throughout the day to prevent sudden blood sugar spikes.

2. Nutrient Density

Consuming a nutrient-dense diet is essential for supporting overall health and managing MCAS and histamine intolerance…

And most individuals with MCAS or histamine intolerance show labs with functional values that are low, i.e., their nutrient absorption rate is severely hampered…

And vital nutrients like vitamin D, calcium, zinc, and magnesium all critical to stabilizing allergies are typically critically low.

Nutrient-dense foods provide the body with a wide range of essential vitamins, minerals, antioxidants, and phytochemicals.

Here are some tips for maximizing nutrient density in your diet:
  • Include a variety of fruits and vegetables like leafy greens, cruciferous vegetables, berries, citrus fruits, and other colorful produce to ensure a diverse range of nutrients.
  • Choose high-quality proteins such as poultry, fish, legumes, tofu, and tempeh for cell repair and immune function.
  • Incorporate healthy fats like avocados, nuts, seeds, olive oil, and fatty fish to support anti-inflammatory processes. I highly recommend at least 3000mg of a high-quality omega supplement like Pro-Omega 1000 daily because omega 3 deficiency is rampant in those with allergic-related health issues.
  • Focus on whole grains such as quinoa, brown rice, oats, and whole wheat bread over refined grains to retain more nutrients and fiber.
  • Consider supplementation to ensure adequate nutrient intake. Consult with a healthcare professional to determine if any specific supplements are suitable for you.

3. Data-Driven Identification of Food Allergens

A large aspect of mast cell activation is that, often, it’s the food you consume that acts as the trigger. The complexity lies in identifying which specific food or ingredients are responsible for setting off the mast cells.

This can be a daunting task as individual reactions to foods can be extremely diverse and inconsistent.

The problem is people assume that the list of the most commonly allergenic list of foods (huge list) is the right list for every individual.

This is the basis for elimination diets.

This creates a bigger problem as you may feel some relief but then symptoms return and overall they’re feeling sicker and sicker adding more and more symptoms while only eating this short list of foods.
It also creates huge digestion, absorption, and nutrient density issues creating long-term chronic illness and other hormone-related symptoms like fatigue, vertigo, pain, and irritable bowel syndrome.

A while ago, I created a system, called Food Mapping, to accurately identify specific trigger foods…

And it involves testing based on your blood data and training you to understand the false positive and negative results which is common for those with MCAS or histamine intolerance.

Utilizing the data, you can finally identify which foods may be contributing to your mast cell activation and histamine release.

Helpful ways to understand food reactions: 

  • Keep a food diary to record everything you eat and drink, including ingredients and portion sizes. Note any symptoms or reactions you experience after consuming certain foods.
  • Look for patterns between the consumption of certain foods and the onset of symptoms. This can help you pinpoint potential trigger foods.
  • Be careful with long-term elimination diets: Once you suspect a specific food as a trigger, eliminate it from your diet for a while, typically 2-4 weeks. Monitor your symptoms during this elimination phase, but do not continue to eliminate more and more foods or prolong eliminating large food groups based on “shoulds.”

    Food decisions not to be consumed should be 100% based on a known reaction by you or by accurate testing via the Food Mapping System. Long-term elimination diet contributes to severe nutrient deficiencies and worsening allergic reactions.
  • Reintroduce foods systematically: After the elimination phase, reintroduce the eliminated food one at a time in small quantities. Observe your body's response and note any changes in symptoms.
  • Document reactions: Record any reactions or symptoms that occur upon reintroduction of a previously eliminated food. This will help you determine if the food is indeed a trigger.

4. Hormone Balance

When there is an overabundance of hormones during perimenopause, menstruation, childbirth, or even Polycystic Ovary Syndrome (PCOS), the liver has trouble breaking down histamines.

Hormone imbalances not only make histamine-related problems worse, but they also cause other health problems including insomnia, brain fog, and anxiety making the allergic reactions even worse to tolerate.

Achieving hormone balance is crucial for managing MCAS and histamine intolerance…

And since hormone replacement therapy (HRT) can make the problem worse…
I always encourage everyone to test their hormones accurately with a saliva hormone test panel available at www.mymdshop.com.

I also recommend you get educated about the scientific patterns of hormone disruption that your doctors do not know about.

Strategies to promote hormone balance:

  • Support your liver’s health by consuming liver-friendly foods such as cruciferous vegetables, leafy greens, garlic, and turmeric, as it plays a crucial role in metabolizing hormones. Also, avoid excessive alcohol consumption and minimize exposure to toxins.
  • Manage stress through meditation, deep breathing exercises, regular exercise, and adequate sleep to promote hormonal equilibrium.
  • Eat 6 cups of cruciferous vegetables like broccoli, cauliflower, and Brussels sprouts per day as they help hormones break down.
  • Balance blood sugar levels by following the blood sugar mastery strategies mentioned earlier to maintain stable hormone levels.
  • Consider accurate hormone testing if you suspect hormonal imbalances.
  • Support gut health by consuming fiber-rich foods, probiotics, and prebiotics, and avoid inflammatory foods – as the gut and hormones have a complex relationship. 
  • Take a helpful probiotic for hormone metabolism and histamine management.
  • Engage in regular movement like walking to break down and balance hormones.

5. Gut Health

Having a diverse population of good bacteria in your gut is crucial for maintaining a healthy microbiome. The term "microbiome diversity" refers to the variety of different types of microorganisms that reside in your gastrointestinal tract.

When your gut microbiome lacks diversity and is dominated by a limited number of bacterial strains…

The limited range of capabilities and strategies makes it difficult to fight off a wide array of threats effectively.
Similarly, a less diverse microbiome may struggle to maintain a balanced environment and combat various health issues, such as inflammation, immune dysregulation, and digestive disorders.

However, by increasing the diversity of good bacteria in your gut, you equip your body with a broader range of capabilities to defend itself…

As your body's microbiome becomes more resilient and adaptable.

A healthy gut plays a crucial role in immune function, histamine metabolism, and overall well-being.

Here are some strategies to support gut health:

  • Eat a fiber-rich diet i.e. plenty of fruits, vegetables, whole grains, and legumes to nourish beneficial gut bacteria.
  • Consume fermented foods like sauerkraut, kimchi, kefir, and yogurt contain probiotics that support a healthy gut microbiome. These beneficial bacteria can help regulate immune function and reduce inflammation…
  • Avoid trigger foods: Identify and eliminate foods that trigger gut symptoms or worsen MCAS and histamine intolerance. This can be done through food mapping or guidance from a healthcare professional.
  • Support digestion: Chew your food thoroughly, eat in a relaxed environment, and consider digestive aids such as enzymes or probiotics if needed. Proper digestion reduces the chances of allergen presentation and inflammation.
  • Manage stress: Chronic stress can disrupt gut health. Incorporate stress management techniques, such as meditation, yoga, or mindfulness practices, to support a healthy gut-brain connection.
  • Stay hydrated: Drinking enough water helps maintain optimal digestive function and prevents constipation. Aim to drink an adequate amount of water throughout the day.
  • Minimize antibiotic use: While antibiotics can be necessary in certain situations, overuse can disrupt the gut microbiome. Use antibiotics judiciously and consider probiotic supplementation during and after antibiotic treatment.

6. Mindset

A positive mindset and emotional well-being play an important role in managing MCAS and histamine intolerance. Stress, negative emotions, and especially past traumas play a huge role in the onset of histamine reactions. Unresolved trauma can exacerbate symptoms, while a proactive mindset can empower you in your journey.

Stress can have a big impact on how your immune system works and can make the symptoms of MCAS and histamine intolerance worse or even trigger them in the first place.

Here are some strategies to cultivate a positive mindset:

  • Education and understanding: Learn about MCAS and histamine intolerance to gain a deeper understanding of your condition. Knowledge empowers you to make informed decisions and take control of your health.
  • Self-compassion: Be kind to yourself and practice self-compassion. Accept that managing MCAS and histamine intolerance can be challenging, and give yourself grace during setbacks or flare-ups.
  • Stress management: Implement stress reduction techniques that work for you. This may include mindfulness, meditation, journaling, deep breathing exercises, or engaging in hobbies and activities you enjoy.
  • Support network: Surround yourself with a supportive network of family, friends, or online communities who understand your condition and provide encouragement. Share experiences, seek advice, and offer support to others facing similar challenges.
  • Focus on what you can control: While you may not have full control over your symptoms, focus on the aspects of your health that you can influence. This includes dietary choices, lifestyle habits, and self-care practices.
  • Celebrate small victories: Acknowledge and celebrate your progress, no matter how small. Each step forward is a win and demonstrates your resilience and commitment to managing your condition.
  • Learn about polyvagal theory and somatic therapy, both we have found to be critical for recovery from trauma, stress, and MCAS and histamine intolerance.
  • Prioritize sleep: Sufficient sleep supports the balance of gut bacteria. Aim for quality sleep and establish a consistent sleep schedule. There are many trainings available on our Youtube channel including an insomnia workshop. Check out and subscribe to our YouTube channel.

7. Proper Digestion

When food is digested properly, it reduces the chances of allergen presentation, decreases inflammation, and supports a healthy gut environment.

Here are some tips for promoting proper digestion:

  • Chew your food thoroughly: Take your time to chew each bite thoroughly. Chewing breaks down food into smaller particles, aiding digestion and nutrient absorption.
  • Eat in a relaxed environment: Create a calm and peaceful eating environment. Avoid distractions, such as screens or stressful conversations, while eating to support optimal digestion.
  • Support stomach acid production: Adequate stomach acid is essential for proper digestion. Consider incorporating foods or supplements that support stomach acid production, such as apple cider vinegar or digestive bitters. One Digest-it is recommended for small meals, while two are recommended for large meals.
  • Consider digestive enzymes: In some cases, digestive enzyme supplements may be helpful for individuals with compromised digestion.
  • Manage portion sizes: Avoid overeating, as it can put a strain on digestion. Opt for smaller, more frequent meals to support optimal digestion and nutrient absorption.
  • Avoid trigger foods: Identify and eliminate foods that trigger digestive symptoms or worsen MCAS and histamine intolerance. Food mapping can help identify these trigger foods.
  • Support gut health: Prioritize gut health strategies mentioned earlier, such as consuming a fiber-rich diet, including fermented foods, and staying hydrated. A healthy gut promotes proper digestion.

8. Microbiome Diversity

A diverse and balanced gut microbiome is essential for managing MCAS and histamine intolerance. The gut microbiome influences immune function, histamine metabolism, and overall health.

Here are some strategies to promote microbiome diversity:

  • Include fiber-rich foods: Consume a variety of fruits, vegetables, whole grains, legumes, and other fiber-rich foods. These provide prebiotic fibers that nourish beneficial gut bacteria.
  • Limit processed foods and added sugars: Processed foods and added sugars can negatively impact the gut microbiome. Minimize their consumption to support a healthy microbial balance.
  • Consider probiotic supplements: In some cases, probiotic supplements may be beneficial in promoting microbiome diversity. I recommend a rotation of Pro-flora AI+ and Pro-flora GI from our line to provide the specific species for specific needs I always advocate. Pro-flora AI+ contains specific strains to aid in reactions from histamines and Pro-flora GI specifically has a strain shown to decrease gut-related symptoms from food reactions and infections.

If you’re ready to take control of your health and uncover real solutions for your MCAS and histamine intolerance, I urge you to schedule a private call with me now.

Maggie Yu MD, IFMCP is a highly respected family practice physician and certified functional medicine physician. Over the past 16+ years, she has been provided education and training on topics related to longevity and reversing chronic diseases through various media platforms. With over 25 years of experience, she is deeply committed to promoting wellness and helping her clients achieve optimal health and longevity.

Dr. Yu is an expert in the field of functional medicine, which involves identifying and treating the root causes of chronic diseases. She has helped thousands of patients overcome chronic symptoms such as pain, fatigue, POTS, MCAS, autoimmune conditions, hormone imbalances, irritable bowel, depression, anxiety, and brain fog. Her success stories include hundreds of case studies demonstrating her approach's effectiveness in alleviating these symptoms and more.

Dr. Maggie Yu has firsthand experience in reversing her symptoms. At the age of 36, she suffered from a range of chronic conditions, including fibromyalgia, early menopause, Hashimoto's, chronic pain, depression, TMJ, and Mixed Connective Tissue Disorder. However, she was able to completely reverse her symptoms through a combination of hard work, years of additional training, and her medical expertise.

Since then, Dr. Yu has developed the Transform protocol, which has helped thousands of people reverse their symptoms through a healing-centric education system. Her programs are tailored to meet the individual needs of each person, and she focuses on reversing symptoms of any chronic disease. She has successfully helped people with hormone imbalances, chronic pain, autoimmune diseases, IBS, neurological and mental health conditions (including ADD/ADHD, autism spectrum disorder, and sensory processing disorders), and more.

Dr. Yu is a mother of two grown children and currently resides in Oregon. Her programs have delivered results to clients from over 14+ countries. She received her medical degree from the University of California, Los Angeles (UCLA) and has specialized in hormone balance, chronic disease, autoimmune diseases, and functional medicine, incorporating a personalized root cause approach to patient care. With her extensive education and decades of experience, Dr. Yu has developed a unique and innovative system to help clients and their families reverse chronic disease symptoms.


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