What do headaches, itchy skin and hives, anxiety, acid reflux, and sinus congestion have in common?

You might be surprised to hear that these symptoms may be brought on by the apple cider vinegar you’re swigging, all the fresh citrus and dried fruits you’re eating, nuts and seeds you’re snacking on and green tea you’re drinking.

All healthy foods, right?

Yes, they sure are. But they are also high in the neurotransmitter histamine. The inability to break down this naturally occurring molecule, which is most often associated with seasonal allergies, may be the single cause of this great variety of symptoms.

The condition has been labeled “histamine intolerance.”

The culprit is usually lack of diamine oxidase (DAO), an enzyme that breaks down histamine in the digestive tract and neutralizes allergic reactions. Histamine N-methyltransferase (HMT) is the other enzyme that metabolizes histamine in the body. Both are genetic variations, and both can lead to allergy-like misery. The tricky thing about identifying histamine intolerance is that the response to foods is cumulative and not immediate. Here’s why.

When eating a high histamine diet, even a single serving can trigger symptoms because the system is overloaded with histamines. If the diet is lower in histamine-rich foods, more servings are needed to trigger a response. This makes it very difficult to identify the cause of the reactions because one can eat the same food on different days and react one day but not the next, depending on what the “total load,” or sum total consumption, of histamines is at any given time. Plus, with an increase in airborne allergens, such as seasonal pollens, the histamine response will flare due to the additive effect of the environmental assault on top of food-caused irritants.

Here’s an example:
You have two glasses of wine with a seafood entree, a strawberry-spinach salad with walnuts and balsamic vinaigrette, and chocolate mousse for dessert. No problem. Until you add a third glass of wine or top that salad with goat cheese. Or it’s springtime and the grasses you are allergic to are blooming, raising your histamine load so high that you feel a headache coming on or a stuffy nose starting to develop.

What to choose instead?

Substituting a house salad for the strawberry spinach salad and apple pie for the chocolate mousse may make the difference between having an allergy reaction or not, even with the pollens in full force. Or you could manage the entire meal with spinach, strawberries, and chocolate in winter without any problems, because there are no pollens to add to your total load.

So why do people develop histamine intolerance?

Functional nutritionist Chris Kresser, M.S., L.Ac., posits that it’s