Mast Cell Activation Syndrome (MCAS)
MCAS is a syndrome with symptoms related to overactive mast cells. Mast cells are part of your immune system. They are found in most parts of your body, especially your skin and intestines. They protect you by releasing chemicals like histamine when a foreign substance enters your body. In MCAS, mast cells release histamine and chemical signals when they detect generally harmless substances entering your body and trigger an allergic reaction.
Symptoms
MCAS reactions include two or more organ systems in your body.
Skin
Hives
Swelling under the skin
Skin flushing
Itchy skin
Red eyes
Intestines
Nausea
Vomiting
Diarrhea
Belly cramping
Heart
Fainting
Fast heart rate
Respiratory
Wheezing
Hoarseness
Nasal congestion
Headache
You have a positive blood and urine test of MCAS that is collected while you are having symptoms.
You have a clear decrease in symptoms while on medicines that target MCAS.
Nutrition can be Part of Treatment
In some people with MCAS, specific food ingredients may trigger symptoms, you may not be able to eat the same amount of food you used to, or you may have unwanted weight loss/gain and poor nutritional quality of life. A dietitian can help you:
Reach and maintain a balanced diet.
Maintain a healthy weight.
Address gaps with certain vitamins and minerals.
Special Diets for MCAS
Current guidelines do not suggest any special diet for people with MCAS. However, reducing the histamine in your diet may help.
A Low Histamine Diet
Your provider may suggest a histamine gentle diet to help improve symptoms. This diet reduces foods considered higher in histamine. Foods higher in histamine include:
Avocado
Citrus/citric acid
Dried Fruit
Tomatoes
Spinach
Canned or smoked fish
Aged/hard cheese
Alcohol
Eggs
Nuts
Cured meats
Chocolate
Leftovers (especially ones with meat)
Broadly speaking, a low histamine diet emphasizes fresh, non-fermented, and minimally processed foods. Your provider may also suggest ways to prepare food that will not promote histamine, such as baking, boiling or air frying. Freezing leftovers can delay histamine build-up in prepared foods.
It is still not known if following a low histamine diet will help if you have MCAS. You may not feel better after taking these foods out of your diet. Eliminations of entire food groups and over restriction of foods is NOT recommended.
We suggest you work with a dietitian to find safe foods to eat as part of a balanced diet.
Maintaining as much diet variety as possible.
A variety of foods such as meats, fish, eggs, vegetables, fruits, grains, dairy, and oils.
Enough calories to support a healthy weight.
Limited added sugar, trans fat, saturated fat, and salt.
Other Nutrition Tips
Avoid diets that take many foods out of your diet to see if your symptoms improve.
Follow the “Rule of Threes”
Eat 3 meals a day and up to 3 snacks.
Eat at least every 3 hours.
Eat at least 3 food groups at each meal.
If you are not able to eat enough, you may need a multivitamin.
Liquid nutrition shakes may help if you need more calories. (Boost®, Ensure®, and Orgain®).
If you feel limited in what you can eat, a dietitian can help you choose the best foods to add back into your diet at your own pace.
Resources
https://www.aaaai.org/conditions-and-treatments/library/allergy-library/food-intolerance
https://www.mastcellaction.org/diet-and-mcas
https://tmsforacure.org/nutrition/
Who to Call
If you are a UW Health patient and have more questions, please contact UW Health at one of the phone numbers listed below. You can also visit our website at www.uwhealth.org/nutrition.
Nutrition clinics for UW Hospital and Clinics (UWHC) and American Family Children’s Hospital (AFCH) can be reached: (608) 890-5500.