MCAS and Histamine - Diet isn't the ONLY Answer

Mast Cell Activation Syndrome is a beast of a condition that can impact every part of your life. The good news is there are many things you can do on your own to improve symptoms and reduce flares.

Welcome all my fellow masties, suspected masties and anyone who’s struggling with a form of Mast Cell disease. This is Part Two of a Three Part series on MCAS (mast cell activation syndrome). If you missed the introduction post - you can read it below:

When You're Allergic to Everything and Nothing... That's MCAS

The goal of these posts is to help patients feel empowered to do things on their own - outside of the medical system - to help improve symptoms and quality of life.

Today we’re going to focus first on diet - and then on the myriad of non food related things you can do to decrease reactions and lower your overall ‘bucket’. I’m noticing that a lot of people focus exclusively on diet when diagnosed with MCAS - often drastically overhauling their food to include only low histamine options. It’s an important step - but histamine is ONE of 200 mediators that mast cells secrete. The histamine content in food only tells part of the story. How the food is prepared, how it’s stored and when you eat it can all change the levels of histamine.

What ends up happening to many patients is that they eliminate a ton of foods from their diet that they were tolerating well - only to notice no measurable improvement in symptoms. This can be quite disastrous because when we eliminate a food - we can struggle to get it back.

Optimal nutrition and health requires a varied diet filled with essential vitamins, minerals and amino acids. If you become too restrictive you could inadvertently be robbing your body of something it needs for survival (and malnutrition can worsen the symptoms of MCAS).

MCAS Diet - It’s not JUST Histamine

First things first - I’m not going to spend much time on low histamine foods as there are a ton of excellent guides on the web where you can find this information. When I got my MCAS diagnosis I eliminated some foods which were obvious triggers (spinach, eggplant, pineapple and bananas) but my overall goal was to focus on eating an anti-inflammatory and nutrient dense diet. MCAS can cause a LOT of inflammation in the body - so I wanted to make sure I wasn’t adding more inflammation through my food.

I was following a whole food and vegan diet when I first received my mast cell diagnosis. I had never heard of the condition but it instantly made sense. I had always had a lot of ‘allergies’ but didn’t test positive on traditional allergy testing. It was an AHA! moment for me.

I ate sauerkraut daily (trying to help fix my gut), and eggplant, overripe bananas and avocado were staples in my diet. Yet every time I ate them I would get a pesky cough, my nose would run and I would have a slight wheeze. I never considered it was allergies because my airway didn’t feel impacted and there was no swelling or blistering in my mouth.

When I learned that these foods are big no-no’s for most people with MCAS - it all made sense. I removed them from my diet and a lot of those symptoms went away. Unfortunately I quickly learned that elimination will only take you so far.

Preparation and Storage Matters

Food should be cooked fresh and consumed immediately if at all possible - if it sits in the fridge it grows histamine. You could have a low histamine ‘safe’ food trigger a horrible MCAS reaction if you wait three days to eat it.

Freezing food can help with this issue - though you have to be mindful of how you thaw it. If you leave it on the counter or in the fridge to thaw you will get the same overgrowth of histamine. I tend to freeze food immediately after cooking and thaw as quickly as possible in a high powered microwave.

How you STORE your food matters. If you’re storing in plastic containers there’s a higher risk of reaction as chemicals from the plastic can leech into the food. All my storage containers are glass - though that represents a whole other problem given my propensity for fainting in the kitchen (more on that when I write my series on POTS/Dysautonomia).

Where you get your food and how it was handled prior to reaching you needs to be factored in - especially if you consume meat and fish. Ideally you want these to be flash frozen as soon as the animal is caught/killed - because the more time that passes the more histamine grows. This is why aged beef will often make us sick - but other types of meat may not.

I do best with local and organic produce that I get delivered from nearby farms - because it hasn’t sat on trucks or in the supermarket for weeks before I consume it.

There’s SO many considerations beyond the histamine content - it really can be exhausting.

Photo by NordWood Themes on Unsplash

Image Description: A black and green stool sits in front of a grey wall. On top is a farmhouse style bucket with red and green flowers and root vegetables inside.

Inflammation is Key

There’s little point in eliminating all the sources of histamine in your diet if you’re going to eat food that’s known to promote inflammation. MCAS is an inflammatory condition - so anything we can do to lower our overall levels will help with symptoms.

For me this meant eating a whole food, plant based diet. I focus on foods which are as nutrient dense as possible and have good ratios of fat, protein and carbs. I optimize my healthy fats and try and avoid unhealthy ones that are known to cause inflammation. I blend a lot of food for easy absorption and have a few key ‘superfoods’ in my diet to help cover my mineral and amino acid bases.

It’s important not to fall for marketing schemes that promise a certain superfood will ‘cure’ you - but rather I looked at my lab work to see what I was deficient in and tried to purposefully choose foods that would help. Iron is a big issue for me - so I consume spirulina and blended hemp seeds. I also cook in cast iron whenever possible. I eat mushrooms for vitamin D and turmeric to reduce pain and inflammation. I used to consume two brazil nuts a day for selenium - but started to react to them and have yet to find another source.

A good dietician can be an excellent resource to help you maximize your nutrition - if you have the opportunity to consult with one I highly recommend it. You can also check out

Build Up Dietitians Newsletter

here on Substack for loads of great nutritional information.

It’s a lot of trial and error - but it is worth remembering that you’re eating for health. You’re eating to stop the condition from progressing. You’re eating to try and give yourself the best quality of life possible. Get curious, read up on food and nutrition and try and have fun experimenting! The less it feels like a chore the more likely we are to do it.

If there’s interest - I would be happy to write a series of articles on the dietary changes I made that helped the most (including recipes - before my MCAS became severe I was quite creative in the kitchen). Feel free to send me a message or drop a comment if you would like more diet related content!

Unfortunately - adjusting one’s diet is often not enough to stop the symptoms that come with this dreadful condition. There’s a litany of triggers outside of food.

How Else Do We Keep Our Mast Cells Happy?

Indoor air quality is the biggest issue for me. Even the best diet can only do so much if your air is full of triggers. Pollen is a trigger for people with MCAS - but there’s tons of others. Chemicals, scents, smoke, VOCs (volatile organic compounds) … all these things can trigger symptoms.

As a result - I recommend monitoring your indoor air quality if you can.

I’ve got a QingPing Pro indoor air monitor that I received as a gift. It measures PM 2.5 (particulate matter), VOCs, CO2, temperature and humidity. When the PMs or VOCs are high I’m noticeably more symptomatic. This information is key because different triggers are mitigated in different ways. 

For PMs (particulate matter) I have HEPA filters. I took a long time to finally break down and buy one as I didn’t think it would make much of a difference. Imagine my surprise when the morning after putting it in my bedroom my tongue and lip swelling were reduced!

It made such a difference that I ended up getting more so that I could maximize the CADR (clean air delivery rate) in my space. Thankfully my condo is so small it doesn’t take much to get maximum benefit - but I recommend people slightly oversize their air purifiers for their square footage. These days my particulate matter is almost always zero - and my mast cells are happier for it! When I notice the PMs start to creep up - it’s a good indication I need to change filters.

VOCs (volatile organic compounds) are trickier to mitigate. HEPA filters don’t remove them but charcoal can help. I’ve got bags of charcoal placed around my condo - but mainly I try to minimize using products that generate VOCs. I don’t use chemical cleaners, I don’t cook with non-stick cookware and if at all possible I ventilate whenever the VOCs are high by running exhaust fans and opening doors and windows.

MCAS is a condition that constantly surprises me - I’m always learning. This year I’ve been extra reactive since my AC turned on. I was stumped as to why and then realized my unit has unusually high humidity. Turns out the type of HVAC I have actually ADDS humidity to the air.

I can’t change the HVAC system -so I purchased a large dehumidifier to offset the humidity and keep it at a more manageable level. Ironically both humidity AND dryness can trigger an MCAS response - so many patients find they may need a humidifer for winter and a dehumidifer for summer. It’s worth experimenting to find what’s best for your body (and since mold is a huge trigger - try and keep your home under 60% relative humidity).

Personal Care, Cooking and Cleaning Products

Personal care products are another area that people often overlook. Everything I use is scent free with minimal ingredients and no chemicals if at all possible. This is a privilege as these products are more expensive - but I’ve found a huge difference in skin reactions as a result.

Speaking of skin reactions - I find the drier my skin is the more reactions I get. Dust, pollen and other crap gets into micro tears in my skin and causes painful hives. Finding a good lotion that a) I can tolerate and b) actually works has been quite the struggle. 

I finally found a local shop that makes whipped body butter with tallow and coconut oil. Sometimes I smell a bit “beefy” but it’s a small price to pay for the HUGE reduction in skin reactions. Tallow can also be used as a cooking oil and it’s very well tolerated among patients with mast cell (though not vegan).

Photo by Max van den Oetelaar on Unsplash

Image Description: A wall of greenery with a pink neon sign that reads ‘and breathe’.

For toothpaste I use baking soda and coconut oil with a bit of activated charcoal, haircare is unscented shampoo and conditioner and I gave up styling products as they were triggering and largely unnecessary. I can’t tolerate any mouthwashes but gargling three times daily with saltwater keeps my mouth from drying out and helps prevent ulcers, tonsil stones and infections.

How to safely cook food was a challenge. Make sure you’ve got a good exhaust fan and (ideally) non toxic cookware. I use stainless steel and cast iron and cook as quickly as possible. Electric stoves are safer than gas (I’ve not had a chance to try induction but I imagine it would be a safe option as well).

Many MCAS patients react to the smells, smoke and chemicals from cooking more than the actual food - and in my case I find if I react to the cooking - my immune system gets confused and thinks the food is also a trigger. 

If something is particularly smelly or taking a long time to cook I will wear a respirator while I do it - especially if the outdoor air is bad and I can’t ventilate. I also highly recommend cooking in the microwave for speed and smell reduction and consuming food immediately or freezing leftovers to stall histamine growth. 

Don’t Neglect Your Water, Minimalism and Cleaning Tips

I live in Canada and am fortunate that we have relatively safe tap water - but I can’t tolerate fluoride or chlorine. I’ve got a filter on my shower, I close the toilet lid when flushing and use a Berkey or bottled spring water for drinking. Note if you’re allergic to coconut the Berkey filters won’t work for you.

I live a minimalist lifestyle - my home is very small with no carpet or throw rugs, few knick knacks and a small wardrobe. My clothes are all natural fibres and I buy organic cotton when possible. Thrift shopping is a fantastic option as newer clothes seem to be treated in all kinds of chemicals and dyes - buying second hand reduced my reactions considerably (and saves money!).

My minimalist lifestyle reduces the effort it takes to clean as well as provides less places for allergens to get trapped. The lack of throw rugs meant I could get a super cheap robotic vacuum to help me save spoons (another thing I wish I had done sooner - I love my robot friend!).

Clutter free spaces lower stress and promote a sense of peace and calm. I can’t have indoor plants because of my allergies and lack of direct sunlight - so I create ‘cozy corners’ with fake plants and gentle lighting to help my brain feel more at ease.

Image Description: My ‘cozy corner’. A beige couch arm is seen with a dark end table next to it. On it is a farmhouse style vase with purple lavender flowers and a mason jar with fairy lights. Behind it are white curtains with twinkle lights and a wooden coatrack.

Cleaning is something that can also trigger your mast cells - which seems a bit nonsensical considering dust and dirt will make you sick as well. Unfortunately vacuuming and dusting can temporarily increase VOCs. If possible have a HEPA on your vacuum and wear a respirator while doing these activities. I turn my purifiers on high and open windows whenever dust is being kicked up.

A Few Final Food Tips

Here’s a few bonus tips I learned the hard way - if there’s something you’ve found that helps (or hurts) please feel free to leave a comment! We can help one another by sharing our stories as MCAS has a steep learning curve:

• You HAVE to learn to read labels and be your own investigator. Triggers hide in all kinds of foods which is one of the reasons I stick to a whole food diet as much as possible. I can’t tolerate any oat milk produced in North America - but I CAN tolerate oat milk from the UK. The reason? The UK doesn’t fortify with vitamin D3. I’m wildly allergic to the type that’s added to plant milks in North America

• Avoid food dyes whenever possible

• Experiment with preparation styles and speeds of cooking - you may find you can tolerate higher histamine foods that are cooked quickly and consumed instantly - whereas low histamine foods that are ‘slow cooked’ may provoke a reaction

• Don’t cut out a food just because it’s on a list - if you’re doing well with it you should keep it in your diet. Our systems are so sensitive that once we cut out a food we often can’t get it back

• Remember that histamine is not the only factor. Many patients with MCAS are sensitive to oxalates and/or salicylates. You can find food lists and apps to help you sort out levels of each in various foods.

MCAS can be an absolute beast to manage - but keeping an open mind and remaining curious can go a long way. Experiment, keep notes and learn what hurts you versus what helps you. Connect with other patients and support groups to learn from those who came before.

Also - this condition can be VERY expensive. I recognize I have a degree of privilege in that I live in Canada where healthcare is free and I have excellent prescription drug coverage. Despite this - you will find that you often have to make financial sacrifices to keep the mast cells happy. Once upon a time I would be excited about purchasing a new outfit or taking a trip - and now my ‘excitement’ comes from air purifiers and organic food. Chronic illness has a way of changing your priorities - and I wish more people could understand just how costly the ‘crip tax’ can be.

Things WILL get better - but there’s a learning curve and it takes time. It’s easy to get frustrated and throw in the towel but give yourself grace. It’s hard work being chronically ill. It’s ok to make mistakes. We start fresh each day and better days will come.

For an extensive guide on all things MCAS - check out

Jodi Ettenberg

’s fantastic Mast Cell Activation Syndrome Resource Page. She also writes a wonderful monthly substack if you’re not subscribed!