Everything You Need To Know About Histamine Intolerance & Low-Histamine Diets

To understand histamine intolerance, it's helpful to have a background on histamine first. Histamine is a chemical compound that's involved in immune function. When you're exposed to an allergen or harmful substance, your body releases histamine to fight off the potential harm. 

Histamine has other roles too, like helping with digestion, wound healing, and nerve signaling in the brain1. Because of this, it's important to have some, but problems arise when you're exposed to too much or develop a reaction to normal amounts.

A histamine intolerance develops when the amount of histamine that accumulates in your body is greater than the amount of histamine your body can eliminate. Having a histamine intolerance doesn't mean that you're allergic or sensitive to histamine; it simply means that there's too much in your body.

But while there are several possible underlying root causes, the most common cause of histamine intolerance1 is a problem with the way an enzyme called diamine oxidase, or DAO, works in your body. 

Normally, histamine travels to the gut, where DAO breaks it down and prevents it from entering the bloodstream. However, if you don't have adequate levels of DAO, histamine passes through the small intestine, where it gets into your blood. Over time, this can lead to high levels of histamine that cause the uncomfortable symptoms associated with histamine intolerance.

Because histamine is one of the main chemicals involved in allergic reactions, the symptoms of histamine intolerance closely mimic an allergy (even though it isn't a true allergy).

Some researchers have recommended standard allergy testing or skin prick tests to diagnose histamine intolerance, but since it's not a true allergy and histamine can take a while to accumulate in the body, these tests are not the ideal choice. 

The biggest difference between a histamine intolerance and an allergy is how much it takes to trigger a reaction. In a true allergy, even a small amount of the allergen can cause a severe reaction. However, with histamine intolerance, symptoms generally develop only after a large enough amount of histamine has accumulated2. That's why a low-histamine diet is so effective.

Your body naturally produces histamine, but the chemical compound also comes from the food you eat. The goal of a low-histamine diet is to drop your body's histamine levels. This is done through a combination of avoiding foods that are high in histamine (and foods that trigger your body to release histamine) and using proper food preparation and storage techniques.

Although a low-histamine diet can feel overwhelming at first, it's highly effective and worth the effort if you have histamine intolerance. In one study, participants with chronic hives were put on a low-histamine diet. After four weeks, all participants saw significant reductions in blood histamine levels3 and body distribution of hives.

It's not just the food itself that's important, though. How you prepare it matters too. Some foods might not have a high histamine concentration when they're fresh, but as they sit in your refrigerator, their histamine levels go up. 

For example, functional medicine doctor Frank Lipman, M.D., explains that raw meats, poultry, and fish have a high bacterial count, and as the bacteria ferment the food, they create histamine as a byproduct.

While it's best to cook everything fresh, there are times when you'll likely have leftovers. Because the histamine content of cooked food can increase as it sits in the refrigerator, there are certain precautions you should take when dealing with leftovers on a low-histamine diet.

A low-histamine diet is pretty restrictive, but the good news is that it's not meant to be a long-term solution. It's a short-term fix that can help alleviate symptoms so that you can improve your quality of life while working toward correcting the underlying cause.

While you may start to see results within one week of following the diet, Zibdeh says that the goal is to stay on it for about a month to reap the full benefits.

You can increase your intake of these nutrients either through diet changes or supplements (or a combination of both), but be sure to talk to your health care provider before adding new supplements to your routine.

Supplemental DAO is also available in capsule form. You can take DAO when you eat histamine-containing foods to help break them down so your body can handle them better. However, DAO supplements only work in your gut, so they can't help with the histamine that your body naturally produces, according to Zibdeh.

Another downside is that DAO supplements only work while you take them. Researchers from one study5 instructed 28 participants with histamine intolerance to take DAO capsules for four weeks and then report the severity of their symptoms. All of the participants had improvements in their symptoms, but as soon as they stopped taking the supplements, the symptoms came back.

Histamine intolerance, or an inability to properly break down a chemical called histamine, can cause nonspecific yet widespread symptoms. If you have unexplained anxiety, frequent headaches, dizziness, and regular gastrointestinal symptoms, you may have a histamine intolerance.