Why do some summer fruits itch, even if you’re not allergic

It may have happened to you: you eat a piece of an apple, a kiwi, or some berries and you suddenly feel itchy around your mouth, even though you’re pretty sure you’re not allergic to the fruit you just ate. Why does this happen?

Experts refer to this phenomenon as Oral Allergy Syndrome (OAS), also known as Pollen Syndrome (PFT). Unwellness is very common and is the result of cross-reactivity. Quite simply: your body recognizes the proteins in the fresh fruit you just ate as being similar to those in pollen, to which you are allergic.

What is allergic mouth syndrome?

According to the American Academy of Allergy, Asthma, and Immunology, OAS is “a form of contact allergic reaction that occurs upon mouth and throat contact with raw fruits and vegetables.” The most common symptoms, which usually occur immediately after ingestion, are ‘itching or swelling of the mouth, face, lips, tongue and throat’.

“It’s usually a reaction to fresh fruits, nuts, or vegetables seen in patients with hay fever, and it’s an allergy to tree, grass, or wheat pollen,” explains Dr. Svetlana Kriegel, a certified allergist from the University of Toledo. College of Medicine and Life Sciences and University of Toledo Medical Center. “About 15% of patients have a reaction to fresh fruits and vegetables because the immune system mistakes the fruit protein as a pollen protein.” Your body totally thinks you just ate the type of pollen you’re allergic to.

Dr. Katie Marks Kogan, Head of Allergology at Ready, ready, food! “But when talking about these foods specifically, the reaction is usually caused by a cross-reactivity and this syndrome.”

The expert noted that the most common pollen allergies associated with OAS are birch trees, grasses, and certain types of wheat.

What are cross reactors?

In general, there are four classes of environmental allergens that interact with the types of fruits, vegetables, and nuts that cause allergic-like reactions.

This chart from the American Academy of Allergy, Asthma, and Immunology is very helpful in keeping track of foods that trigger reactions.

Just as some fruits are in season during certain times of the year, certain types of pollen are more visible during certain months. This means that the reaction that many people associate with summer fruits is not limited to that season, but simply refers to an allergy to one type of pollen. Some people deal with allergy-like symptoms during the winter, spring, and fall, as well as after eating foods that don’t appear in the summer months.

What are the symptoms of allergic mouth syndrome?

There are some important things to keep in mind when analyzing the symptoms of PAS.

Cooking the fruit changes its composition, often making it less likely to provoke a reaction.

David Bishop Inc. via Getty Images

Cooking the fruit changes its composition, often making it less likely to provoke a reaction.

First of all, symptoms usually go down to the mouth. “When we digest fruits, vegetables, and nuts, the protein in our system breaks down and doesn’t seem to have happened when it first caused the reaction,” Marks Kogan explains. As a result, the most common symptoms include itching, tingling and possibly burning of the mouth, lips, and throat. Sometimes, runny eyes and nose and some sneezing may occur.

If you’ve had an allergic-like reaction to consuming any of these foods, you may actually be allergic to the fruits, vegetables, or nuts themselves — not just an allergy to cross-reactive pollen.

Is there a way to prevent the reaction?

The easiest way to avoid having a reaction to any of these fruits, vegetables, and nuts, of course, is to avoid eating them altogether. Cooking it or even putting it in the microwave for a few seconds may help you avoid symptoms, too.

Interestingly, reactions usually do not occur when people consume foods that are not in a raw state, such as canned or cooked. This is because cooking fruits, vegetables, and nuts actually changes the composition of the protein and the immune system will not attach said protein to various other allergens. So if you’re allergic to raw peaches, for example, you may not experience the same symptoms when eating a baked peach pie.

“All of these allergens are affected by heat,” Kriegel explains. You can’t eat fresh apples but you can have apple jam for example. You can’t have an apricot but you can keep it. This is because, once cooked, its composition changes.”

Eaters should also keep in mind that the main allergens are in the skin and core (besides the seeds) of fruits, vegetables or nuts, according to Kriegel. Not eating those specific parts of the fruit may also ease your discomfort.

The most discussed treatment is allergen immunotherapy, which mainly consists of getting regular allergen injections. Once you identify the fruits or vegetables you interact with, you can do a skin test to check your allergy to pollen. The injections will then desensitize your body to the allergens in the environment, and hopefully, teach your immune system not to react to them.

“Once you stop reacting to pollen, your sensitivity to fruits and vegetables also goes down,” Kriegel says. “We use pollen extract in injections to make the body tolerate the exposure to the protein without causing the reaction. The body will then say, ‘I have a lot of pollen in the My body already, so why do I have a reaction when I experience more of it when I eat, say, a cucumber or an apple?”

It has not been proven that simply “getting rid” of the syndrome by eating more fruits, nuts, and vegetables that causes a reaction rather than undergoing treatment is successful.

“There was anecdotal evidence,” Marx Kogan admits. “But, as adults, it is difficult to know how much extract your body needs to ‘get used to.’ With young children, the immune system is forming and so we advise exposure to potential allergens but as you get older it is difficult to determine.”

What do we do after the reaction?

Since this is not a “true food allergy,” as experts note, symptoms usually subside on their own within minutes. However, taking an antihistamine (Benadryl, for example) will help soothe any kind of itching or burning relatively quickly.

In general, doctors recommend sensitization. After you know what kind of fruit, vegetables, and nuts are causing a reaction, consider getting a skin test to see which pollen you’re actually allergic to.

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