Cross-reactivity can cause additional complaints

“This means that if someone with a pollen allergy eats, for example, nuts that contain similar proteins to pollen, they could have an immunological allergic reaction,” explains Dr Krista Ress, head of the Centre for Allergology and Immunology at East Tallinn Central Hospital.

Raw fruit and vegetables as common allergens

Cross-reactivity is often confusing at first because the person notices their eyes watering or nose dripping when peeling a potato or carrot. “This may be the first symptom of pollen allergy,” says Dr Ress. “In spring, you may not even notice a mild runny nose because everyone has colds from time to time. But because raw potatoes and carrots contain proteins similar to those in the pollen of spring trees, a reaction occurs when handling them.”

In Estonia, carrots, potatoes, nuts, apples and stone fruits (e.g. plums and cherries) as well as peas are the most common allergens that can cause cross-reactivity. “Fruits and vegetables mainly cause reactions in their raw form,” says Dr Ress. “When they are heated or cooked, the high heat changes the structure of the light and they usually no longer cause complaints.” “However, with nuts, cooking often does not alter the proteins that cause allergies; therefore, nuts can still cause complaints even if they are cooked.”

In some cases, people experience cross-reactivity symptoms year-round, especially if the pollen allergy is severe. “However, for some people, cross-reactivity symptoms only occur during the flowering season and they can eat apples in winter with no issues,” adds the allergist-immunologist.

What to do if you suspect cross-reactivity

If a person with a pollen allergy develops symptoms when eating a certain food, it is important to discuss this with a doctor to see if the specific allergen should be avoided in the future and if any allergy medications are needed. However, the doctor does not recommend setting unreasonable restrictions on yourself.

“You should make your life easier and only avoid eating foods that really cause discomfort,” advises Dr Ress. “Food restrictions should not be imposed just in case or as a preventive measure. Why spoil our already short summer season with unreasonably harsh food restrictions?”

In addition, skin tests and blood tests can diagnose cross-reactivity. “When a person talks about their complaints, we can identify which pollen allergy to look for based on the protein groups of different foods, fruits, vegetables or nuts,” notes Dr Ress.

Cross-reactivity does not usually cause severe symptoms; rinsing the mouth and taking an antihistamine if necessary is usually enough.