Spring’s arrival is often accompanied by pollen and seasonal allergies! In addition to the usual symptoms, people affected by these allergies can sometimes experience similar symptoms when consuming certain foods, even though they’re not allergic to them at all. This is called oral allergy syndrome or pollen-food syndrome. Let's shed some light on this phenomenon.
Food allergy, seasonal allergy or oral allergy syndrome?
A food allergy is a hypersensitivity reaction of the immune system in response to a protein found in certain foods. According to recent data from a Health Canada report in 2013, food allergies affect between 5% and 6% of children and about 3% to 4% of adults. A seasonal allergy is caused by exposure to pollen and is estimated to affect nearly 17% of Canadians. Symptoms are usually triggered by birch pollen, but other types of pollen, such as ragweed, grass, and mugwort (alder) pollen, may have the same effects.
Oral allergy syndrome only occurs in people who suffer from seasonal allergies and predominantly affects older children as well as adults. Some proteins in food have a structure similar to those of various pollens. Thus, by consuming fruits and vegetables that have proteins with structures similar to the structure of a pollen to which a person is allergic, the person's immune system kicks in, causing inflammation as well as some unpleasant symptoms. This is called cross-reactivity. Antigens, which would normally only react in the presence of a pollen protein, activate upon contact with a specific food even though there’s no real link between the two.
Symptoms of oral allergy syndrome
Between 50 and 70% of people with birch pollen allergy also suffer from cross-reactivity. Different symptoms can appear in oral allergy syndrome. Symptoms usually appear a few minutes after eating the food and are typically concentrated in the mouth and throat areas. The most common are:
- Swelling and burning of the lips, mouth and throat
- Runny, itchy eyes
- Nasal discharge
Symptoms may be amplified during allergy season due to the increase in specific antibodies to pollen. For this type of allergy, there’s a low risk of nausea, vomiting, diarrhea or asthma. It’s estimated that about 10% of people will have a generalized reaction and 1.7% of people can even go as far as anaphylaxis. Among the foods most likely to cause anaphylactic reactions are celery, peach, walnuts, and peanuts.
Foods to avoid during the allergy season, depending on the type of associated pollen
|Type de pollen||Fruits||Vegetables and herbs||Nuts, seeds and legumes|
Apples, cherries, peaches, kiwi fruit, plums, nectarines, apricots, pears
Celery, carrots, tomatoes, potatoes, parsnip, green peppers, peas, fennel, dill, cumin
Almonds, hazelnuts, walnuts, lentils, beans
Kiwi fruit, melon, oranges, tomatoes, watermelon
Apples, melon, watermelon
Carrots, celery, fennel, dill, parsley, coriander, cumin
Bananas, cantaloupe, honeydew melon, watermelon
Adapted from: Zarkadas M, Scott FW, Salminen J, Ham Pong A. Common Allergenic Foods and Their Labelling in Canada - A Review. Canadian Journal Allergy & Clinical Immunology 1999; 4: 118-141. And Sussman, G., Sussman, A., & Sussman, D. (2010). Oral allergy syndrome. Canadian Medical Association Journal, 182 (11), 1210-1211.
Cooking food generally helps prevent an allergic reaction. Also, it seems that a greater concentration of the allergenic protein is located in the peel. Peeling fruits and vegetables could therefore help limit allergic reactions while allowing people who don’t have too severe a reaction to continue to consume their favourite fruits and vegetables. When it comes to different nuts and seeds, cooking the nuts doesn’t always turn off the protein that is causing the allergic reaction. You should therefore avoid consuming them, even if they’re cooked or roasted.
In conclusion, it’s important to continue to consume foods that don’t cause an allergic reaction in order to promote a diversified and balanced diet. Although this information can help people understand their allergies, it’s recommended that you see an allergist when symptoms of an allergic reaction occur, since they’ll be able to perform the necessary tests in order to make a diagnosis and thus provide specific recommendations depending on the type of allergy.
Familiprix in collaboration with Hubert Cormier
- Saunders, S., & Platt, MP (2015). Oral allergy syndrome. Current opinion in otolaryngology & head and neck surgery, 23 (3), 230-234.
- Poncet, P., & Sénéchal, H. (2019). Actualités des reactions croisés pollen-aliment. Revue Française d’Allergologie.
- Nguyen, M. (2009). Le syndrome d’allergie orale. Médecin Qué, 44 (5).
- Government of Canada, A. Canadian Food Inspection. (nd). Oral allergy syndrome [Fact sheet, reference material].
- Sussman, G., Sussman, A., & Sussman, D. (2010). Le syndrome d’allergie oral. Canadian Medical Association Journal, 182 (11), 1210-1211.
- Association des allergologues et immunologues du Québec. Le syndrome pollen-aliment. http://www.allerg.qc.ca/Information_allergique/3_2_pollen_aliment.html (consulted on January 9, 2020)