Food Reactions or MCAS?
Histamine Intolerance or MCAS?
Have you ever eaten a piece of aged cheese or had a glass of red wine and suddenly your face flushed? Maybe you started itching. Maybe you felt bloated out of nowhere.
It feels exactly like an allergic reaction. So you go to the doctor. They do the skin prick test. And they tell you, “You are fine. It is not an allergy.”
But you know something is wrong. So what is going on?
In my experience, there are usually two culprits behind this kind of reaction.
Culprit One: A Breakdown Problem
Your gut lining makes an enzyme called DAO, which stands for diamine oxidase. Its job is to break down the histamine that comes in with your food.
But if your gut lining is damaged, that enzyme factory is not working well. You cannot make enough DAO to keep up. So when you eat foods that are high in histamine, your body cannot break them down fast enough. Your histamine bucket fills up and eventually overflows. That is when the symptoms hit.
The good news is that this problem often improves when you heal the gut lining. As your gut heals, your DAO levels can naturally rise again.
Culprit Two: Mast Cell Activation Syndrome
This one is different and seems to be showing up more and more.
Your mast cells are part of your immune system. They are full of stored histamine. Normally, they hold onto it until there is a real threat, like an infection or an injury.
But in mast cell activation syndrome, or MCAS, those cells become trigger-happy. They start dumping histamine into your system for no good reason.
You end up with the same symptoms. The flushing. The itching. The misery. But the cause is not food coming in. It is your own body releasing histamine on its own.
Two Problems, Same Symptoms
At the end of the day, both of these conditions can look and feel exactly the same. But the path to feeling better depends on knowing which one is driving your symptoms.
Here is a simple question to start with. Do you notice your reactions mostly after eating certain foods? That may point to a DAO issue. Or do your symptoms seem to come out of nowhere, even when you have not eaten anything obvious? That may point more toward MCAS.
Figuring out the pattern is the first step toward finding the right answers.
Authored by Gerard Guillory, MD
Gerard Guillory, MD, is a board-certified internist who practiced for nearly four decades with a focus on functional, root-cause medicine. He is the author of three books on irritable bowel syndrome and the founder of It’s My Health, where he and his team put current health news in context and help members understand the underlying causes of chronic symptoms.
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