When I think about histamines, I think about anti-histamines, AKA OTC allergy meds, and how itchy my face gets whenever I’m around my aunt’s cats. But histamine in food? That has never crossed my mind.

Or, at least, it didn’t until an appointment with a naturopathic doctor revealed that I had high levels of histamine in my blood—and that my healthy diet was apparently chock-full with high-histamine foods.

Confused? Yeah, so was I. But apparently there’s more to histamines than pet dander and pollen—and some of us may need to tweak our daily menu to keep from feeling itchy and puffy 24/7.

What are histamines?

Let’s back up for a sec: “Histamines are a compound naturally produced by the body—mostly by the immune system—in response to injury or allergic reaction,” explains Rebekah Blakely, RDN, dietitian for The Vitamin Shoppe. You know how pollen in the springtime makes your nose run and your eyes itch? Those symptoms are caused by histamines at work, trying to rid your body of the pollen.

Histamines can increase blood flow, heart rate, and contractions in the lungs and digestive tract, Blakely says. The result: symptoms like runny nose, watery or itchy eyes, sinus congestion, wheezing, or stomach cramps we often associate with allergies. When you pop an OTC anti-histamine, you essentially block these annoying—but potentially necessary—effects.

Histamines have other jobs in the body, too. “They communicate with the brain and support digestion, by triggering the release of stomach acids that help us break down our food,” says functional medicine practitioner Keren Day, DC, of New York City’s Eleven Eleven Wellness Center.

And they’re in food?

“Almost all foods contain some histamines,” says Blakely. “However, certain foods contain a lot more than others.” And the longer that a food is stored or aged before being consumed, it generates more histamines.

Since foods’ histamine content increases with time, aged and fermented foods tend to be some of the highest in histamines, says Blakely. Even certain fresh foods are known to contain more of these compounds, though.

Some of the foods highest in histamine (brace yourself) include:

• Alcohol
• Kombucha
• Vinegar
• Fermented dairy (buttermilk, yogurt)
• Fermented or pickled vegetables (kimchi, sauerkraut)
• Soy products (miso, tempeh, soy sauce)
• Wheat
• Canned foods
• Processed meats
• Aged cheese
• Legumes
• Tomatoes
• Spinach

Here are the foods you should always make sure to buy organic, according to a dietitian: 

How much do the histamines in food matter?

For most healthy people, not much at all. “People with healthy immune responses can eat these foods in moderation and have no reaction at all,” says Dr. Day. That’s because our bodies produce an enzyme called DAO that breaks down excess histamine from the foods we consume.

However, there are a few small groups of people who can potentially experience a histamine intolerance, where they either have too much histamine in their systems or can’t break it down properly:

1. People with compromised gut health: Since poor gut function can impact DAO production and impede histamine breakdown, people with celiac, IBS, Crohn’s, colitis, or other digestive issues may react to the histamines in foods, says Blakely.

2. People with a DAO deficiency: Whether because of genetics or certain medications (like metformin, NSAIDs, certain antibiotics, and more), other people may also have impaired DAO production and, as a result, excess histamine in their system, Blakely says.

3. Those with certain nutrient deficiencies: Finally, people deficient in vitamin B6, vitamin C, zinc, or copper may also react to the histamines in foods, says Blakely, since each of these nutrients plays a role in histamine breakdown.

In these small groups of people, eating foods high in histamine can make them experience allergy-like reactions—think sneezing, congestion, itchiness, the whole nine yards.

How to address histamine issues

Again, having issues with histamine in food is pretty rare; reportedly only 1 percent of the population has a histamine intolerance. If any of the above describes you and you’re concerned, be sure to talk with your health practitioner. They may check your body’s DAO levels or perform a skin prick test to evaluate your histamine tolerance, says Blakely.

Generally, a person with histamine intolerance will be told to try a temporary low-histamine diet. “A low-histamine diet can help rebuild the immune system and gut health, so that the body can better handle histamines in the future,” Dr. Day says. For four weeks, Blakely says a person will have to eliminate all high-histamine foods (so, all the things listed above), as well as avoiding foods that can inhibit the DAO enzyme, like cocoa, tea, and coffee.

After four weeks, a person would slowly reintroduce high-histamine foods one at a time, Blakely says. They’ll eat one high-histamine food a few times in one day and monitor their symptoms for three days before testing another food.

If that sounds restrictive, well, that’s because it is. Cutting out such a vast amount of foods can lead to nutrient deficiencies, especially since histamine is present in so many healthy foods, like legumes, produce, and fermented foods. It’s definitely not safe to just casually try eating exclusively low-histamine foods just because—not only is there no reason to for healthy adults, it’s pretty unsafe.

The bottom line: consider histamine in food another wellness myth, much like lectins and other “anti-nutrients.” For the majority of us, they’re fake news. (Which is good, because what kind of a life is it where you can’t even drink kombucha?)

Don’t stress about histamines—instead, follow these simple golden rules for healthy eating and you can’t go wrong. And you’re not alone in feeling confused AF about food.