What is the Best Diet for MCAS (Mast Cell Activation)?

This post discusses factors in determining the best diet for MCAS. Each patient will have different tolerated foods, unique triggers, and individual susceptibility to particular mast cell mediators. So the answer to this question is going to be unique to each person.

Along my healing journey, I’ve tried intermittent fasting, the GAPS Protocol, low histamine diet, gluten-free, dairy-free, nightshade-free, grain-free, soy-free, sugar-free, Primal diet, Paleo diet, low histamine diet, low oxalate diet, low salicylate, low FODMAP, Specific Carbohydrate Diet (SCD), anti-inflammatory diet, Supergut diet*, and Keto diet. This post covers these options

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Mast cell mediators

When you think of MCAS you likely think of histamine, because it is probably the most well-known mast cell mediator. But many other mast cell mediators can cause mast cell activation besides histamine, including leukotrienes, cytokines chemokines, and neutral proteases (chymase and tryptase). – source

The following graphic describes the symptoms associated with each type of mast cell mediator.

This post addresses mast cell mediators. The remainder of this post is focused primarily on the mediator histamine.

Reducing histamine

One major part of an MCAS diet is reducing histamine. That can mean eating foods that are generally lower in histamine, eating foods that actually reduce histamine, taking medications and supplements that control histamine in the body, and controlling the histamine your body creates.

This post discusses how to figure out what foods you tolerate.

This post gives a list of generally tolerated lower histamine foods.

This post provides information on anti-histamine foods.

Reducing inflammation

Another important part of an MCAS diet is reducing inflammation. Inflammation causes mast cells to congregate in an area of the body where they perceive a threat. So, by reducing overall inflammation you can reduce the overall mast cell activation in your body.

The biggest inflammatory food sources are gluten, dairy, and refined sugar, so most low-histamine food lists advocate eliminating some combination of those three. Gluten is my biggest trigger for inflammation, so I have been gluten-free for decades.

Refined sugars are a major source of inflammation in the western diet. This post discusses alternative sweeteners for MCAS.

Dairy products are another big source of inflammation, and this post uncovers the issues with dairy and MCAS.

Fasting

Besides eliminating food sources of inflammation, fasting in the morning can also help to reduce overall inflammation and pain. Giving your gut a rest between periods of digesting food, or intermittent fasting, has been shown to reduce inflammation, improve immune function, and help blood sugar issues:

“… periods of fasting can limit inflammation, (7) attenuate proinflammatory cytokines and immune cells, (8) improve circulating glucose (9) and lipid levels (10) and reduce blood pressure. (11) In addition to that, studies undertaken in animals and humans have suggested that fuel selection is altered and efficiency of metabolism is improved while oxidative stress is reduced.” NIHReduce mast cell activity

In addition, fasting has been shown to reduce mast cell degranulation and histamine release. So, you can reap multiple benefits from fasting: reduced inflammation, better blood sugar regulation, and less histamine release.

Fasting also helps you maintain a healthy weight, improves gut health and immune function, enhances brain health, and helps in the treatment of insulin resistance. – Newbridge Clinic

Of course, you should ease into intermittent fasting under the care of a doctor or functional provider. There is a lot of good advice for beginning fasters online, but you will want to avoid packaged foods marketed under the title “fasting-mimicking diet” because they are typically highly processed and likely to cause mast cell activation and/or histamine issues.

However, fasting can also cause mast cell reactions due to:

1. Blood Sugar Fluctuations

• Fasting can lead to drops in blood glucose levels, which the body perceives as a stressor.

• Low blood sugar can trigger the release of stress hormones like cortisol and adrenaline, which are known to activate mast cells and promote histamine release.

• For people with MCAS, this may result in symptoms like flushing, itching, or gastrointestinal distress.

2. Stress Response Activation

• Prolonged fasting activates the hypothalamic-pituitary-adrenal (HPA) axis, leading to the release of corticotropin-releasing hormone (CRH).

• CRH directly stimulates mast cells, increasing histamine and inflammatory cytokine release, which can exacerbate mast cell-related symptoms.

3. Histamine Buildup

• During fasting, the body’s ability to metabolize and break down histamine may be impaired due to lower enzymatic activity (e.g., reduced levels of diamine oxidase (DAO), an enzyme responsible for histamine breakdown).

• This can lead to histamine accumulation, resulting in symptoms like headaches, rashes, or gastrointestinal issues.

4. Prolonged Fasting as a Trigger

• For some individuals, prolonged fasting can cause physical stress and inflammation, which may worsen mast cell instability.

• Fasting for too long may also increase gut acidity, irritating the stomach lining and activating mast cells in the process.

The Keto diet

Combining fasting with the Keto diet is one way to reduce overall inflammation and maintain a healthy weight, though it is a rigorous protocol, and not for everyone. I have struggled myself to maintain especially the Keto portion of this combination. You will see that many of my recipes are compatible with the keto diet, but I readily acknowledge that it doesn’t suit everyone. When I am experiencing extra stress in my life like when I am treating infections, I stop the Keto diet and just focus on eating a lower histamine diet.

So what is a Keto diet? A Keto diet is high in fat and low in carbohydrates. When you follow a Keto diet you rely on fat for your fuel, not sugars or carbohydrates (or glycogen stores). By consuming a diet high in fat, you are more likely to get into a metabolic state called Ketosis and burn fat as your fuel, making it easier to avoid carbohydrates. But why would you want to avoid carbs, you ask? Carbohydrates often cause inflammation, especially sugars, and grains. Foods higher in fat don’t cause inflammation, and the Keto diet itself can be helpful in reducing inflammation.

What I mean by “Keto diet” in the mast cell and histamine intolerance context is not what you will likely find online. Many of the so-called Keto diet foods on the market are packaged, processed, and can be high in histamine-containing foods, or cause histamine to be released by the body. Many of the foods commonly prescribed on a Keto diet include fermented foods, aged cheeses, cured meats like bacon, nuts, dried fruits, and vegetables such as those from the nightshade family (tomatoes, eggplant, peppers, potatoes), and avocadoes. All of these foods might be healthy for the typical person on a Keto diet, but for those with MCAS or histamine intolerance, they could be deadly.

The Keto diet did not work for me, and I discuss why in this post.

Before you jump into a Keto diet or fasting it is good to consult with your healthcare practitioner. A Keto diet itself can be a stressor on your digestive system. Any time you make a drastic change to your diet it can cause you to feel worse. So, if you are interested in making a change to a high-fat diet, get guidance from your doctor, ease into it, go slow, and listen to your body.

Low FODMAP Diet

The best mast cell activation syndrome diet is the one that helps relieve your unique symptoms. A low FODMAP diet can be helpful if you are experiencing gut dysbiosis. 

FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) are fermentable carbohydrates. Many people eat these carbohydrates without any issues, but some people are unable to break them down, and/or the carbohydrates ferment too much, often because of gut bacterial dysbiosis such as SIBO (small intestinal bacterial overgrowth). Gut dysbiosis can cause stomach pain, bloating, and diarrhea.  

High FODMAP diets can increase urinary histamine, whereas the low FODMAP diets reduce it. – source

For more about low FODMAP diets see this post.

Oxalates

Oxalic acid is an organic compound found in many plants, including leafy greens, vegetables, fruits, cocoa, nuts, and seeds (1Trusted Source).

In plants, it’s usually bound to minerals, forming oxalate. The terms “oxalic acid” and “oxalate” are used interchangeably in nutrition science.

Your body can produce oxalate on its own or obtain it from food. Vitamin C can also be converted into oxalate when it’s metabolized source.

Once consumed, oxalate can bind to minerals to form compounds, including calcium oxalate and iron oxalate. This mostly occurs in the colon, but can also take place in the kidneys and other parts of the urinary tract.

In most people, these compounds are then eliminated in the stool or urine source.

However, in sensitive individuals, high oxalate diets have been linked to an increased risk of kidney stones and other health problems. – source

I discuss oxalates in this post, this post, and this post.

Salicylates

Salicylates are natural chemicals made by plants. They are found in fruits and vegetables and help protect plants against disease and insects.

Salicylate extracts have been used medicinally for thousands of years. Salicylic acid, more commonly known as aspirin, relieves pain and inflammation and lowers fevers. However, salicylates can also cause health problems for people who take them. Learn about what salicylate does in the body and when you should avoid it.

I tried a low salicylate diet but found it was not causing my MCAS issues.

Why You Should Avoid Salicylates

For many, salicylates provide the same protective effects in your body as they do for the plants that produce them. High salicylate diets generally afford lower risks of cancer, heart disease, and diabetes.

Medicinally, salicylate derivatives like white willow bark, methyl salicylate, and salicylic acid provide anti-inflammatory and pain-relieving benefits. Aspirin is often used to manage heart disease and has contributed to lowering heart disease death rates.

However, for others, salicylates in the diet can lead to health problems. Such issues include insensitivities, allergies, and swelling of different organs. – source

I discuss salicylates in this post, this post, and this post.

Other ways to support a lower histamine diet

This post discusses helpful apps that can support you in eating a special diet.

This post covers my favorite ten cooking tools to support a lower histamine diet.

This post provides survival tips for eating a lower histamine diet away from home.

The bucket theory

The bucket theory offers a helpful analogy for understanding symptom reactions with MCAS.

Think of your body as an empty bucket that you want to keep from overflowing. Different foods and activities fill your histamine bucket at different speeds but they combine to form the total level of histamine in your body (how full your bucket is). A fuller bucket means you have more histamine symptoms. When you manage triggers, reduce exposure to known triggers, and take medications and supplements to reduce histamine, you can manage the level of your bucket.

Know your typical symptom progression

Knowing your symptom progression in a symptom flare is the key to developing your own rescue plan. In this post, I discuss how to determine your own symptom progression. Once you know what typically happens in your symptom progression you can design a rescue plan to address those symptoms.

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Sign up for the SSP!

The Safe and Sound Protocol (SSP) is a listening therapy based on Polyvagal Theory that helps heal nervous system regulation. Many people with MCAS have nervous system dysregulation stemming from infections, toxic exposures, concussions, and trauma. The SSP is an easy-to-use app where you listen to specially filtered music for 30 minutes each day for a 5-hour cycle. Studies show the SSP has a profound effect on mental health and chronic conditions

You can sign up for the SSP here!

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Healy is an individualized microcurrent device I use to reduce inflammation. Check out this post for more about Healy.

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Disclaimer

The preceding material does not constitute medical advice. This information is for information purposes only and is not intended to be a substitute for professional medical advice, diagnosis, cure or treatment. Always seek advice from your medical doctor.