Wissenswertes

Cross-allergies and histamine intolerance

An allergic reaction always involves an immunological reaction to a (glyco)protein , which in turn becomes an allergen . The number of protein families that act as allergens is manageable; however, so-called cross-reactions are common because the proteins within an allergen family are related .

Allergen-specific immunoglobulin (Ig)E antibodies are bound in the body. And how does all this relate to histamine intolerance? We'll explain it all in this blog post.

Is a food allergy always a cross-allergy?

Not all food allergies are cross-reactions. However, according to estimates from allergological societies , nearly 60% of all food allergies in older children, adolescents, and adults are cross-reactions . If a pollen allergy has existed for an extended period, there is a high probability of a cross-reaction to certain foods.

Many people find it puzzling: they don't suffer from food intolerances like fructose intolerance , yet they can't tolerate apples, for example. The culprit behind these intolerance symptoms is the similarity between the allergen in the food and the pollen to which humans normally react. The structures of the allergen sources are almost identical .

Allergens are often fragments of specific proteins , also called epitopes. The same is true for cross-reactive allergens. In cross-reactivity, the body mistakes the protein fragment for the allergen, triggering an antigen-antibody reaction .

In allergies, including food allergies and cross-allergies, certain triggers play a major role. For example, spicy foods, alcohol , caffeine ( coffee ), stress, and physical exertion can increase the permeability of the mucous membranes, allowing protein fragments to pass through the intestinal wall more easily. This explains why, for instance, someone allergic to mugwort might tolerate celery on some days and not at all on others.

It's striking that these triggers are precisely the ones that are also counterproductive and cause symptoms in cases of histamine intolerance . Often, foods that cause intolerances are better tolerated on stress-free days.

Allergies rarely come alone!

There are countless cross-allergies, so we will only highlight three selected examples to give you a better understanding. Most allergy sufferers are affected by a birch pollen-associated food allergy, also known as birch pollen-nut-stone fruit syndrome.

Birch cross-allergy

Birch pollen carries the main allergen, which is related to the allergens of hornbeam, chestnut, walnut, and hazelnut. Cross-reacting allergens are also found in apples, peaches, cherries, peas, soy, parsley, and carrots. These are known as plant defense proteins . When stress or injury occurs, their release is increased. Tolerance also varies depending on the production method and variety , which is why, for example, apple variety A is often better tolerated than apple variety B.

Therefore, a birch pollen-associated food allergy is also called a fresh fruit allergy . In connection with birch pollen cross-allergies, the term Oral Allergy Symptoms (OAS) is used, which describes the symptoms that occur as a result of consuming allergenic foods. These include complaints such as swelling or burning in the mouth and throat, or itching.

Cross-allergy grasses

People with grass pollen allergies often react sensitively to various types of grain . However, they usually don't experience any symptoms when consuming grains, as these are often cooked thoroughly. This is because the allergens contained in grasses are extremely heat-sensitive . Nevertheless, raw grain sprouts or fresh grain muesli should ideally be avoided altogether.

Cross-allergy of house dust mites

Certain muscle proteins (tropomyosins) of house dust mites are very similar to those of crustaceans and molluscs , which is why people allergic to house dust mites also experience symptoms after eating crabs, shrimp, lobsters, snails or mussels.

What can be done about histamine intolerance symptoms resulting from a cross-allergy?

Your body releases histamine during any allergic reaction , including pollen and cross-allergies. It's therefore not surprising that the symptoms of allergies are very similar to those of histamine intolerance . These include, for example, shortness of breath, skin problems , and a runny nose.

If you already have a histamine intolerance problem, your histamine reserves can quickly become overloaded due to a cross-allergy , exacerbating your histamine intolerance. But what measures can be taken to alleviate the symptoms of a cross-allergy and prevent histamine-related symptoms?

Spring is the peak season for pollen, while in autumn the air is pollen-free and fresh. Unlike in spring, histamine levels in the colder months are not constantly driven to new heights by pollen. An exception is those with allergies to early-blooming plants, who suffer even earlier, in the first months of the year. It is advisable for severe allergy sufferers to avoid fields and forests during this time and to eat seasonal fruit , as the air is rich in allergy-triggering pollen outside of the season.
Creating a list of foods you can tolerate and keeping a food and symptom diary can make your life easier. For example, you can list which apple varieties you can tolerate and which you can't.
During pollen season, it is advisable to follow a strict low-histamine diet .
Avoid certain triggers such as caffeine, spicy foods and alcohol, and try to keep your stress level as low as possible.
Since cross-allergens are located under the skin of grains and fruits, peeling the grain or fruit can help.
Friction and juicing of fruits and vegetables release phenolic compounds that structurally alter proteins. Therefore, the allergenic potential of grated or juiced fruits and vegetables is lower than that of freshly harvested ones.
Allergens cannot withstand heat, which is why allergy sufferers usually tolerate cooked fruits and vegetables well. However, this does not apply to nuts . Prolonged simmering destroys the IgE-binding epitopes, but this also results in the loss of many nutrients. Therefore, steaming is recommended, as it preserves heat-sensitive vitamins.