An apple a day…turning apples into allergy treatment
Published online July 7, 2025
Birch pollen allergy is one of the most common causes of seasonal hay fever, and many affected individuals also develop what is called pollen food allergy syndrome (PFAS). This condition occurs because the immune system confuses Betula vulgaris 1 (Bet v1) homologue proteins in certain foods, such as apples, with the main birch pollen allergen Bet v 1. The result is itching, burning, or mild swelling in the mouth after eating raw fruits, vegetables or nuts. Standard immunotherapy with birch pollen extracts works well for the birch pollen allergy itself, but has limited benefit for PFAS. For this reason, Mueller et al. developed a new treatment approach using carefully selected apple cultivars for the treatment of PFAS. Their research, called “Structured fresh apple consumption for birch pollen food allergy syndrome in an uncontrolled Phase II/III trial”, was recently published in The Journal of Allergy and Clinical Immunology: In Practice.
The clinical study was conducted in three phases. First, the researchers tested 42 different apple cultivars ranging from typical commercial supermarket varieties like Golden Delicious to traditional regional apples like Boskoop using skin prick tests and food challenges. Based on these results, they created a structured treatment plan in which patients consumed fresh apples in gradually increasing amounts. The apple-based therapy was first tested in a small pilot study with 16 patients over eight months and was investigated further in a larger follow-up study with 36 patients over one year. The participants started in late summer mostly with an eighth of freshly harvested, well-tolerated, low-allergenic apple cultivar (e.g. Granny Smith or Boskoop) and slowly increased their daily dose doubling the amount every two weeks until one full apple daily was reached. Following this, they switched to a medium-allergenic variety (e.g. Pink Lady or Jonagold) during the winter, and then to a high-allergenic cultivar (e.g. Golden Delicious or Kanzi) in the spring, after the birch pollen season had ended, following the same stepwise approach. The therapy was monitored with patient diaries, blood tests, allergy skin prick tests, basophil inhibition tests and questionnaires to ensure safety and effectiveness.
The results were promising. After one year of therapy, patients were able to eat much larger portions of raw apples without symptoms, the amount tolerated increased by an average of 82%. Patients were able to safely consume at least three-quarters of a high-allergenic Golden Delicious apple, compared to only a sugar-cube-sized piece before therapy. Tolerance also significantly improved for other cross-reactive foods such as cherries, carrots and hazelnuts. Blood tests showed a significant increase in protective antibodies (IgG4) and a decrease in allergy-driving antibodies (specific IgE) and a decrease in skin prick test and basophil reactivity. Patients reported better quality of life and fewer hay fever symptoms, while side effects of treatment such as itching in the mouth and throat were generally mild, short-lived, and decreased over time. The therapy was safe and well accepted, fewer than 5% interrupted the treatment. Overall, the study suggests that structured apple consumption is a natural, practical, and low-cost option to treat birch pollen-related pollen food allergy syndrome.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.
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