What Is a Low-Histamine Diet?

What is a low-histamine diet and should you try it? We talked to NYC-based dietitian Isabel Smith, M.S., R.D., C.D.N. to get the details.

Most people who suffer from allergies are familiar with antihistamine medications, which reduce the body's inflammatory response to pollen, dust mites or animal allergies and help keep sneezing, watery eyes, hives or runny nose at bay. But you may not know that the body makes its own histamines, which are chemicals your immune system releases in response to a "trigger" or allergen.

When the body encounters an allergen—whether pollen, dander, dust or a food allergen—it sends a signal to mast cells to release histamine, which prompts a cascade of reactions to help clear the allergen. When histamine leaves the mast cells, it boosts blood flow and causes inflammation (in this case, the good kind of inflammation) in the area of the body being affected by the allergen. That inflammation prompts other chemicals from your immune system to kick into action to help counteract the perceived threat. For example, with seasonal allergies you may get a runny nose or itchy eyes. That's one way histamine is trying to get rid of the trigger—by prompting membranes to make more mucus. That mucus then leads to a runny nose, itchy eyes, a cough or sneezing.

What is histamine intolerance?

Your cells already have all the histamine you need, but foods and drinks contain histamine too. If too much histamine builds up in the body, it can cause histamine intolerance. Two enzymes break down histamine—diamine oxidase (DAO) and histamine N-methyltransferase (HNMT). Histamine intolerance is thought to be a result of DAO not working properly. Genetics, gastrointestinal (GI) diseases, alcohol and drugs can cause reduced DAO activity. And if you have impaired DAO and you're eating too many histamine-rich foods, it may lead to high histamine levels.

Symptoms of histamine intolerance are similar to those of an allergic reaction—like hives and itchiness. But other symptoms can present also, like bloating, diarrhea, gas and headaches. This makes it difficult to diagnose histamine intolerance. There is no easy test for it, and it's fairly uncommon: only 1-3% of the population has histamine intolerance. But if other allergies and GI conditions are ruled out and your symptoms remain, it may be worthwhile to try a low-histamine diet.

What is a low-histamine diet?

"A low-histamine diet consists of limiting or removing high-histamine foods for a week or two (though many people see benefit sooner), then adding back a few of the foods one at a time, looking for symptoms like hives, itchiness or heat," says Isabel Smith, M.S., RD, CDN, a registered dietitian at Isabel Smith Nutrition in New York City. "We can learn so much about a patient's individual tolerance to foods containing histamine and overall histamine levels from trialing this kind of eating."

According to a 2018 study published in Allergy, a histamine-free diet is the method of choice to figure out if someone has an intolerance to histamine. That said, Smith notes that it's a difficult diet to follow—even for a dietitian—and highly recommends working with a nutrition professional if you want to give it a try.

Who should follow a low-histamine diet?

"People who might experiment with a low-histamine diet are ones that experience some of the classic symptoms [of histamine intolerance], such as constant headaches/migraines, sinus issues, hives, skin irritations, digestive issues, irregular menstrual cycle, tissue swelling, anxiety, abdominal cramping, nausea and difficulty regulating body temperature," Smith says.

Some of the most common symptoms of histamine intolerance listed in the aforementioned study included diarrhea, nausea and vomiting, headache, itchy skin and oral allergy syndrome, as well as red eyes and swollen eyelids. Often people with histamine intolerance have other food intolerances too, like lactose or fructose intolerance.

Foods to avoid on a low-histamine diet

The following foods are high in histamine. According to Smith, for someone with a histamine intolerance or an overabundance of histamine in their bodies, eating these foods could trigger some of the symptoms mentioned above.

Another thing to note: Freshness is also a factor in a food's histamine levels. The longer foods sit, the higher the histamine levels, so meat and fish should be cooked soon after buying. A 2017 study in the Annals of Dermatology also found that frying and grilling increased histamine in foods—but boiling did not.

Foods to avoid:

Fermented foods, such as kombucha, kefir, sauerkraut, kimchi, miso, tempeh, yogurt

Alcohol

Vinegars

Cured meats, such as bacon, salami, pepperoni, deli meats, hot dogs

Aged cheese

Milk

Specific nuts, including walnuts, cashews, peanuts

Dried fruit

Most citrus fruits

Grapes

Bananas

Strawberries

Avocados

Eggplant

Spinach

Tomatoes

Some fish, including mahi-mahi, tuna, sardines, mackerel, anchovies, smoked fish

Mayonnaise

Ketchup

Chocolate

Additionally, alcohol, black tea, and mate tea can block DAO activity, and should also be avoided on a low-histamine diet.

Foods allowed on a low-histamine diet

Pictured recipe: Gluten-Free Teriyaki Chicken with Broccoli (skip the rice vinegar in this recipe)

"Anyone working through a low-histamine diet should focus on anti-inflammatory foods that are high in omega 3s—salmon and chia seeds/flaxseeds—as well as foods that contain quercetin (note that many of them also contain histamine!), like berries, broccoli, onions, apples, buckwheat, kale, grapes and cherries," Smith says. Quercetin inhibits histamine release.

Foods allowed

Fresh fruits and vegetables (except those listed above)

Dark leafy greens (except spinach)

Meat and fish (except those listed above)

Cooked eggs

Salmon

Gluten-free grains

Herbs & herbal teas

Mango

Apples

Watermelon

Pear

Kiwi

Grapes

Cantaloupe

Nondairy milks

Olive oil

Coconut oil

Here's what a day of eating low-histamine looks like:

Breakfast:

2 scrambled eggs with gluten-free toast & pear

Lunch:

Kale salad with chicken, peppers, cucumbers and flaxseed

Snack:

Apple with almond butter

Dinner:

Grilled salmon with broccoli and quinoa

Bottom line:

Too much histamine in the body can lead to histamine intolerance. If you have hives, itchiness, headaches, diarrhea, nausea or vomiting, and you test negative for other allergies or GI conditions, consider working with a registered dietitian to follow a low-histamine diet to relieve symptoms.