Some patients react allergically to certain allergens (substances), such as pollen, mold, foods, pet dander and medicines. The immune system responds to a harmless substance when it comes into contact with the body.
A fruit allergy is a type of food allergy. About ten percent of all food-related allergies are fruit allergies. Allergic reactions to fruit are often relatively mild with symptoms limited to the mouth and throat. In some patients the symptoms are more severe and there is an anaphylactic reaction.
It is best for patients to avoid triggering fruits, although it is also possible to prepare the fruits differently. Medicines treat allergic reactions to fruit.
- Different types of allergens in fruits
- Present in fruits
- Added to fruits
- Common allergic reaction to fruit
- Common signs
- Severe signs (anaphylaxis)
- Diagnosis and investigations
- Treatment of fruit allergy
Different types of allergens in fruits
Allergens are substances to which the body may react allergically, because the body regards these substances as ‘foreign’. The body will attack these substances. This causes the immune system to release histamine so that the allergen can be cleared. Histamine is responsible for the signs of an allergy.
Present in fruits
Because fruits often contain allergens from different classes of food allergens, patients with a fruit allergy exhibit different reactions to the same fruit. Stone fruits belonging to the Rosaceae family (apricots, peaches, nectarines, cherries, etc.) contain the LTP allergen (thaumatin-like protein) for lipid transfer, both in the pulp and in the peel of the fruits. Other allergens that may cause problems are the PR-5 thaumatin-like proteins TLP, profilins and various enzymes (Î²1,3 glucanase, chitinase). However, drupes consist of another source of major allergens in the fruit seed, namely the cupin and 2S albumin allergens.
Added to fruits
An allergy to fruit may also be due to added chemical sprays that increase the allergens. For example, some chemicals used to ripen bananas induce allergens, increasing the number of allergens people can have an allergic reaction to.
Common allergic reaction to fruit
There are many different fruits that cause an allergic reaction, but the most common are reactions to apple, peach and kiwifruit.
Allergic reactions to apple may present in two different forms, depending on the apple allergen involved. Patients sensitive to birch pollen often react to a heat labile (after heating they are tolerable for patients) apple allergen that usually causes some milder local symptoms in the oral cavity (oral allergy syndrome). These allergies are mainly found in areas where birch can grow. Other patients react allergically to another, heat-stable (after heat they are still intolerable) allergen that is located under the skin of the apple and cross-reacts with peach allergens, causing severe reactions and is mainly present in the Mediterranean region.
An allergy to kiwifruit appears by direct sensitization to kiwi allergens or by cross-reaction to other allergens (such as birch pollen or latex). A kiwi allergy (direct or associated with latex allergy) may lead to serious skin, stomach and systemic reactions.
A peach allergy is most commonly manifested in Mediterranean countries and is often accompanied by allergies to other Rosacaic fruits (such as apples, apricots, plums, cherries), hazelnuts and walnuts). The major peach allergen is heat stable and highly concentrated under the fruit peel and therefore avoidance of fresh and processed fruits is necessary for patients who have an allergic reaction to peaches.
The signs of this type of food allergy are variable and depend on the patient, the severity of the allergy and the type of fruit. Patients who have an allergic reaction to one or more fruits do not always experience signs when they eat another type of fruit. Most fruit allergies are oral syndrome allergies because they are consumed, but sometimes an external allergy occurs when the fruit touches the skin. Symptoms usually occur within minutes to hours. The duration of symptoms varies from four hours to seven days.
Raw fruit with or without peel may cause an allergic reaction. Allergic reactions to fruit are usually mild. In most patients, only the mouth is affected. They suffer from symptoms that arise at the location where the food has touched the lips and mouth. These symptoms are known as oral allergy syndrome. A number of patients who react in this way to fruit or vegetables also react to pollen from some trees and weeds (pollen food allergy). For example, patients who are allergic to birch pollen are often also allergic to apples. The following symptoms may be manifested:A pollen-food syndrome usually causes one or more of the following signs:
- skin : itching, a rash or blistering
- throat : itching and mild swelling of the throat, causing a tight and stuffy feeling in the throat
- stomach and intestines : constipation, diarrhea, abdominal pain, nausea, vomiting
- mouth : redness, mild swelling or itching of the lips, tongue, inside of the mouth, soft palate
- nose : a runny nose, a stuffy nose
- eye problems
The patient is not experiencing breathing problems, so the symptoms are not life-threatening.A fruit allergy may cause hives / Source: Hans, Pixabay
Severe signs (anaphylaxis)
Less commonly, patients who are allergic to fruit suffer from another, more severe type of allergy. In some cases, patients are also allergic to latex. Furthermore, an allergy to vegetable proteins is sometimes also present (lipid transfer protein (LTP) allergy). These conditions may cause more severe symptoms which increase the risk of a serious allergic reaction (anaphylactic shock, anaphylaxis).Some patients suffer a severe allergic reaction (anaphylaxis, anaphylactic shock). The symptoms then consist of:
- loss of consciousness
- a severely swollen throat
- low blood pressure
- an airway narrowing
- a shock
- a rapid pulse
- swallowing problems
Accompanying symptoms of anaphylaxis include:
- abdominal pain, nausea and vomiting
- swelling of the deeper layers of the skin (angioedema) anywhere on the body
- swelling of the lips
- hives (urticaria)
- widespread flushing of the skin
Diagnosis and examinations
Medical advice is required when a patient eats fruit and experiences symptoms. The doctor determines which type of allergy the patient has (pollen-food syndrome or a more serious category). The symptoms may have a non-allergic cause such as food intolerance. The doctor notes the symptoms and tries to identify the suspected trigger foods. A skin prick test is a common way to test for allergies. Other ways to detect a fruit allergy is an oral challenge test. The doctor gives the patient a very small and measured amount of the allergen (substance that triggers an allergic reaction) and the patient’s reaction is closely monitored. This examination always takes place under the supervision of a doctor. Furthermore, a blood test is useful for analyzing immunoglobulin E (IgE), an allergy-related antibody.Medicines treat fruit allergies / Source: Stevepb, Pixabay
Treatment of fruit allergy
Patients who are allergic to fruit should avoid the raw version of these fruits. Sometimes they experience less severe signs or else the symptoms disappear when they cook, bake or pasteurize fruits. A doctor may also prescribe antihistamines (medications that treat an allergic reaction). In severe cases, treatment with adrenaline (epinephrine) is necessary. Patients at high risk of anaphylactic shock always carry an auto-injector pen with them.
- Antihistamines: Medicines against allergic reactions
- Allergies and allergic reaction: Contact with allergens
- Anaphylaxis: Severe allergic reaction
- Oral allergy syndrome: Symptoms in the mouth after eating food
- Food allergy and food intolerance: Symptoms