Fruit and Vegetable Allergies: Symptoms, Diagnosis and Treatment

The techical name for these allergies is 'oral allergy syndrome'

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The most common type of food allergy in adults involves tingling and swelling in and around your mouth, and it's triggered by fruits and vegetables, not peanuts, tree nuts, or even shellfish. Although peanut and nut allergies tend to get the most attention, you're actually more likely to be allergic to nectarines and apples than you are to the best-known allergens.

These reactions to fruits and vegetables stem from what's called oral allergy syndrome (OAS). When you have oral allergy syndrome, you begin to react to foods that are related to allergenic pollens.

If you have a runny nose during pollen season, you are more likely to develop oral allergy syndrome as an adult. Virtually all adults with OAS have a history of allergic rhinitis (a runny nose) due to pollen allergies.

Oral allergy syndrome sometimes is referred to as pollen-food syndrome, or as a "class 2 food allergy."

Symptoms

If you have oral allergy syndrome, you shouldn't expect a runny nose. Instead, your symptoms will involve your digestive tract and skin. These symptoms may include:

  • itching or tingling of the mouth, tongue or lips
  • swelling of the mouth, tongue, and/or throat (this is known as angioedema)
  • increased eczema skin symptoms in patients with eczema
  • rarely: vomiting, stomach cramps, or diarrhea
  • very rarely: anaphylaxis

Often, people with OAS will react to certain raw fruits or vegetables but will be able to tolerate them when well-cooked. For example, your mouth may itch after eating a raw apple, but you will be able to eat applesauce. This is because some of the proteins that cause pollen-related reactions break down when heated.

Diagnosis

Diagnosis of oral allergy syndrome relies on a history of reactions and allergy testing and can prove to be a bit of a challenge for you and your doctor.

Your doctor will ask you about your history of immediate reactions after eating certain fruits or vegetables, and also will ask about your history of seasonal allergies, hay fever, or a runny nose. To identify the specific pollens and foods that are causing your symptoms, your doctor may order skin-prick testing or RAST blood testing.

Unlike other types of food allergy, a double-blind, placebo-controlled food challenge (where you don't know if you're consuming the suspect food) probably won't be helpful in diagnosing OAS.

Because reactions vary depending on the freshness of the food, and with the direct contact of that food with the skin of your mouth and tongue, testing results may not be accurate. For example, a capsule of prepared apple may not cause a reaction even if you have a reaction to eating a raw apple.

Cause

OAS is caused by a cross-reactivity between an inhaled pollen allergen and the proteins found in certain fruits and vegetables. While the pollen plant and the foods are not biologically related, the structures of their proteins are so similar that the body reacts to both.

The most common type of OAS in Northern Europe is birch pollen allergy. One study found that 70% of people with a birch pollen allergy also have some sort of OAS. Because birch pollen allergy is so common, it is the most widely studied of all OAS associations. People sensitized to birch pollen may have OAS symptoms when they eat the following foods (in order of frequency):

  • Apple (80%)
  • Hazelnut (59%)
  • Nectarine/peach (51%)
  • Kiwi (48%)
  • Walnut (41%)
  • Carrot (35%)
  • Apricot (33%)
  • Cherry (32%)
  • Pear (32%)
  • Almond (32%)
  • Peanut (24%)
  • Plum (24%)
  • Tomato (21%)
  • Potato (19%)
  • Celery (16%)
  • Soybean (14%)

Grass pollen allergies are associated with sensitivities to:

  • Melon
  • Tomato
  • Orange
  • Cherry

Ragweed allergies are associated with sensitivities to:

  • Melon
  • Chamomile
  • Honey
  • Banana
  • Sunflower seeds
  • Cucumber
  • Zucchini

Mugwort allergies are associated with sensitivities to:

  • Celery
  • Carrot
  • Spices
  • Melon
  • Apple
  • Hazelnut
  • Chestnut

Treatment and Management

As with most food allergies, the main method of managing oral allergy syndrome is avoiding trigger foods. Some people may only need to avoid their triggers in their raw form.

You may find that your symptoms are worse when pollen counts are high. During pollen season, you may need to avoid foods that you can tolerate at other times of the year. Talk to your doctor about taking antihistamines or other allergy medication to help control your allergic rhinitis symptoms.

There have been some studies of birch pollen and apple allergies that have found that people who receive immunotherapy for birch pollen allergy are later able to tolerate raw apples. These studies were small, however, and there have not been studies done on other specific pollen-food interactions in immunotherapy.

A Word from Verywell

Oral allergy syndrome is a serious condition, and you'll need to manage your symptoms and watch your reactions carefully. You'll likely need to cut back on foods you enjoy, especially at certain times of the year.

Most adults with this condition do not need to carry an epinephrine auto-injector (commonly referred to by the brand name Epi-Pen). However, some people do have reactions that are severe enough or have the potential to be severe enough, that they should be prescribed an auto-injector. Talk to your doctor about the type and severity of your reactions to your trigger foods.

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