What Is Histamine Intolerance

Holistic nutritionists are taking to social media to spread the word about histamine intolerance (HIT). This is a somewhat controversial proposed diagnosis in which a person may have difficulty breaking down the compound histamine in food, leading to a range of symptoms, from bloating to brain fog.

Read on to learn more about what histamine intolerance is, what mainstream medicine has to say about it, and whether a low-histamine diet can make a difference.

What Is Histamine Intolerance?

Histamine intolerance is not an official diagnosis in mainstream medicine, but some complementary and integrative medicine practitioners support it. They define it as a condition in which a person has difficulty metabolizing histamine in food, leading to stomach problems, allergy-like reactions like hives, and other issues.

Histamine is a naturally occurring molecule in the body that plays a key role in the immune system and digestion. Foods can also contain histamine. The thinking goes, if you eat too much high-histamine food (such as aged Parmesan, tomatoes, or processed meats), or your body can’t properly break down histamine, it can lead to problems.

“When we balance the body and lower the histamine, these symptoms become more in control, and you just feel better,” explained Lisa Kilgour, a registered holistic nutritionist, on TikTok.

“When patients first come to me to find out whether or not they have histamine intolerance, I explain that histamine intolerance is not a well-established disease, and there are no clear diagnostic criteria,” says Ross Tanis, MD, an allergist and immunologist who practices at Allergy & Asthma Physicians in Hinsdale, Illinois.

“I also discuss the fact that most food intolerances do not have clear diagnostic criteria, unlike food allergies that do,” says Dr. Tanis.

The proposed symptoms of histamine intolerance can vary widely, and they may overlap with those of other conditions. Some nutritionists and advocates for the field assert that the following symptoms are potentially linked to histamine intolerance:

• Gastrointestinal (stomach) issues, including bloating, diarrhea, and nausea
• Skin symptoms, such as itchy skin, flushing, hives, and swelling
• Headaches or migraines
• Respiratory symptoms, including shortness of breath, stuffy or runny nose, sneezing, wheezing, or tightness in the chest
• Swelling of the lips, tongue, or throat
• Heart irregularities, such as racing heart or palpitations
• Low blood pressure or dizziness

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“Often people perceive having increased symptoms, particularly GI-related symptoms, after consumption of histamine-rich foods. However, the symptoms often do not abate [decrease or stop] when histamine rich foods are avoided, which would suggest against this diagnosis,” says Tanis.

Additionally, there is a normal resting amount of histamine that the body naturally produces every day, so you could never eliminate all the histamine completely, he adds.

If symptoms worsen or you experience severe reactions, consult your doctor immediately.

If DAO problems are responsible for histamine intolerance symptoms, possible causes and risk factors include:

Genetics Some people are born with genetic mutations that result in lower levels of or less effective DAO.

GI Disorders People with inflammatory bowel disease may have suppressed DAO activity.

“To the best of my knowledge, there is no propensity for people with other existing allergies such as asthma, allergic rhinitis, or IgE-mediated food allergies to have a higher reported incidence of histamine intolerance,” says Tanis.

• Aged cheese, such as Parmesan, manchego, and Gruyere
• Fermented foods, including sauerkraut, kimchi, and soy sauce
• Alcoholic beverages, including wine, beer, Champagne
• Processed meats, such as salami, pepperoni, and hot dogs
• Fish and shellfish, for example, mackerel, sardines, tuna, and herring
• Some vegetables, including tomatoes, spinach, and eggplant
• Tropical fruits, including bananas, pineapples, papayas, and citrus fruits
• Chocolate
• Nuts and peanuts
• Strawberries
• Avocados
• Food additives like colorants and preservatives

Working with a nutritionist can help you craft a balanced, low-histamine diet trial that will still meet your nutritional needs to see if it helps your symptoms.

To help determine if histamine intolerance may be at play, a healthcare provider will typically start by reviewing a patient’s symptoms and medical history. “It’s important to rule out all other medical conditions, including GI pathology [diseases affecting the digestive tract], celiac disease, and GERD [acid reflux], to name a few,” says Tanis.

There are no reliable tests for identifying histamine intolerance, he adds. A histamine skin prick test and DAO activity test have been proposed as markers. “Unfortunately, the results are variable and histamine skin prick tests do not show differences in people without histamine intolerance and those with plausible or possible histamine intolerance,” says Tanis.

In a prick test, a small amount of a suspected allergen is inserted into the skin to see if a person has any kind of negative reaction.

When Tanis has patients who appear to have a food intolerance, he recommends they try eliminating potentially triggering foods to see if symptoms improve.

“The best way to do this is to eliminate one food at a time, but this may be more difficult in the case of suspected histamine intolerance,” he says, because so many foods have some level of histamine.

“There should be objective improvement in symptoms when eliminating these foods; otherwise you generally assume that it is not the culprit and we recommend these foods are reintroduced, particularly if not eating them impacts quality of life,” he says.

Food elimination for suspected histamine intolerance in any child or adolescent requires caution due to the risk of developing food allergies or malnutrition, adds Tanis.

In addition to dietary changes, your healthcare provider or nutritionist may recommend certain medications to try for a period of time to see if they help with your symptoms.

Medications

Antihistamines These medications block histamine receptors in the body. Both H1 and H2 antihistamines may be helpful, with H1 antihistamines (like cetirizine and loratadine) targeting allergic reactions and H2 blockers (like ranitidine) helping with digestive symptoms.

There is little downside to trying antihistamines due to their excellent safety profile, but keep in mind that improvement of symptoms after taking oral antihistamines doesn’t confirm you have histamine intolerance. “Additionally, there aren’t well=controlled randomized trials that show they are effective,” says Tanis.

Complementary and Integrative Therapies

Supplements Some research suggests that nutrients like quercetin, and N-acetylcysteine (NAC) may help stabilize mast cells or support histamine breakdown. Supplements specifically tailored to DAO may help people with DAO deficiency.

It’s important to discuss any supplements with your provider before you start taking them, and to recognize that this is an active area of research where the current evidence is lacking.

Because histamine intolerance hasn’t been established as a formal condition with a clear cause, there aren’t expert recommendations for avoiding it.

Many people with histamine intolerance are able to manage their symptoms with diet changes. If symptoms remain, medications may help.

In some cases, symptoms can improve over time, and some people may even be able to go back to eating the foods they’ve been avoiding.

Histamine intolerance also shares symptoms with mast cell activation syndrome.

Mast Cell Activation Syndrome

Mast cell activation syndrome (MCAS) is a condition that causes intense episodes of swelling, shortness of breath, hives, diarrhea, vomiting, and other symptoms. In severe episodes, it can cause life-threatening anaphylaxis (an extreme allergic reaction). It’s caused by mast cells mistakenly alerting the immune system that there’s something harmful in your body, which leads to an overreaction.

• Histamine intolerance (HIT) is a controversial proposed diagnosis involving difficulty metabolizing histamine from foods, leading to symptoms like bloating, headaches, skin rashes, and digestive issues.
• Histamine intolerance is not officially recognized by mainstream medical professionals, and some research suggests other conditions are responsible for symptoms.
• Managing histamine intolerance typically involves avoiding high-histamine foods and beverages like aged cheeses, alcohol, and fermented items like soy sauce.
• If you think you have symptoms that fit with those of histamine intolerance, it’s best to see a specialist like an allergist-immunologist or gastroenterologist to evaluate you and guide your next step, which may include consulting with a nutritionist.