The top eight food allergens (milk, eggs, peanuts, tree nuts, fish, shellfish, wheat and soy) account for about 90 percent of food-allergic reactions. Other foods, ranging from meat to fruit to spices, make up the remaining food allergens.
One group of food allergies that is becoming more common are fruit allergies. But while there are people who are actually allergic to fruit, in most of the cases where people think they are allergic to fruit they are actually experiencing what is known as oral allergy syndrome.
Oral allergy syndrome (OAS) is a reaction that sometimes occurs when a person who has hay fever, or is allergic to pollen, eats fruits or vegetables (most often fresh) that contain prolifins. Prolifins are proteins found in grass, weeds and pollen; they are also found on fruits and vegetables. This triggers a cross-reaction, usually an itchy feeling in the mouth or throat, tingling in the lips or tongue, and sometimes swelling. Vomiting, diarrhea and even anaphylaxis may also occur. The reaction usually happens within minutes, but it can sometimes take up to two hours for symptoms to occur.
OAS can happen at any time of the year, but it is at its peak during pollen season. A reaction may occur to only one specific fruit or vegetable, or several fruits and vegetables may trigger reactions. Also, not everyone who suffers from pollen allergies will experience OAS.
Below is a list of pollen allergens and fruits, vegetables, herbs and nuts that may cross react with one other.
- Alder pollen: almonds, apples, celery, cherries, hazelnuts, peaches, pears, strawberries, raspberries, parsley
- Birch pollen: almonds, apples, apricots, avocados, bananas, carrots, celery, cherries, fig, hazelnuts, kiwi, nectarines, peaches, pears, peppers, plums, potatoes, prunes, soy, strawberries, walnuts, wheat, chicory, coriander, fennel, parsley, parsnips
- Grass pollen: figs, melons, tomatoes, oranges, celery, peaches
- Mugwort pollen: carrots, peppers, sunflower, coriander, fennel, parsley
- Ragweed pollen: bananas, cucumber, green peppers, sunflower seeds and oil, melon, watermelon, zucchini, artichoke, paprika
The following may cross react to ANY of the above pollens: berries including but not limited to strawberries, blueberries and raspberries; citrus fruits such oranges and lemon, grapes, mango, figs, peanuts, pineapple, pomegranates and watermelon.
Age and Other Factors
Adults are more likely to experience OAS, however there have been children as young as three who were diagnosed with hay fever and then went on to have reactions to fruit.
Also, because the protein is richer in the skin of the fruits and vegetables than in the flesh, reactions don’t occur as frequently when these foods have been peeled. Furthermore, people who suffer from OAS usually only react to raw fruits. Since heat destroys the proteins that cause the allergic reactions, people who suffer from OAS may be able to eat cooked fruits and vegetables that usually cause them to react while they are in a raw state.
Individuals who suffer from pollen allergies, hay fever, asthma and atopic diseases such as eczema are the ones usually affected by OAS. Again, this does not necessarily mean everyone who experiences these allergies will also experience OAS—they are just at risk for it. OAS is diagnosed if a pollen allergy is already present and the individual goes on to have allergic symptoms or a reaction to raw fruit or vegetables.
If any allergy is suspected, you should consult your physician and/or an allergist. Allergy testing may be necessary to determine what exactly you are allergic to.
We would love to hear from you! Have you or anyone you know experienced OAS? Let us know. We would also love to connect with you on social media. We are on Instagram as @mykidsfoodallergies, as well as Facebook, Twitter and Pinterest.