What is cross allergy?
Why should I give up apples if I'm allergic to birch pollen? About 70% of sufferers of a tree pollen allergy (e.g. birch, alder, hazel) have cross-allergies, also called cross-reactions with food because their proteins are very similar. Our immune system can't distinguish whether the proteins are those of birch or apple. It only recognises the allergen as dangerous - and a cross-reaction occurs.
Symptoms of cross-allergy
Anyone suffering from hay fever and experiencing the following symptoms while eating should avoid these foods, at least during the pollen season.
itching in mouth and throat
puffiness of the eyelids
swelling of the mouth, tongue and lips
The following cross-allergies are typical
Many proteins, and thus allergens, are destroyed when cooking or heating and can therefore still be eaten.
January–April: birch, alder, hazel
Pome and stone fruit (apples, pears, plums, apricots, cherries, etc.), hazelnuts, walnuts, almonds, tomatoes, carrots, celery, mango, avocado, fennel, kiwi, lychee.
Celery, carrots, fennel, artichokes, chamomile, pepper, mustard, dill, parsley, coriander, caraway, aniseed, sunflower seeds.
Allergy to grasses can cause sensitivity to certain foods, such as peanuts, potatoes, soya, kiwi, tomatoes, melon, cereals, peppermint. However, these don't usually cause an allergic reaction when eating these foods.
Latex or house dust mites
But cross-reactions with food aren't always triggered by pollen alone. An allergy to latex or house dust mites can also cause a reaction.
- House dust mites: shrimps, lobsters, crawfish, crabs, snails
- Latex: avocado, banana, sweet chestnut (vermicelli, chestnut), kiwi, papaya, fig, paprika
- Heating foods: certain allergenic foods are tolerated after being baked or cooked, as the heat destroys many of the allergens they contain. But be careful: while most people can safely eat an apple pie, for example, allergens in hazelnuts, peanuts, celery or spices such as cinnamon or coriander are heat-resistant and should therefore be avoided.
- Desensitisation: pollen therapy – consisting of several small injections under the skin – also relieves the cross-allergy in many cases.
- Medication: antihistamines, mast cell stabilisers or glucocorticoids – taken in the form of tablets or nasal sprays, for example, and used to treat pollen allergies – can stop the symptoms of a cross-allergy.
Risk of anaphylactic shock
In the worst case, the allergy triggers respiratory distress or circulatory arrest. In the case of a so-called anaphylaxis, it's vital that allergy sufferers know the most important rules of behaviour and emergency measures, but also how to avoid potential allergens. CSS has joined forces with the aha! Swiss Allergy Centre to offer a course for adults, young people, and parents of affected children.