A hidden food allergen : soy

Abstract

Background: Soy products are widely used in a variety of processed foods such as meet products, sausages, chocolate and breakfast cereals. The prevalence of soy allergy in adults is unknown. The development of soy allergy in the late adulthood is rare. In most of the reports birch pollen sensitisation was determined to be a risk factor for developing food allergy to soy due to cross-reactivity between the major birch polen allergen (Bet v 1) and soy allergen (Gly m4). A 38-year-old female referred to Allergy Unit with a history of oral allergy syndrome (OAS), itching of the scalp and palms, generalised urticaria, rhinitis and dyspnea necessitating intervention in the emergency department in few minutes after ingestion of meat with sauce and meatball at the restaurant for 10 years. She also reported to experience OAS after ingesting ready soup, chocolate, pastry and cookies. The personal history did not reveal allergic rhinitis, asthma, atopic dermatitis, drug or venom allergy. Method: The skin prick test (SPT) with common food allergens and aeroallergens (Stallargenes, Paris, France) was performed. Soy-specific IgE was measured by using the CAP system (Phadia, Uppsala, Sweeden). Food challange test with soy was not carried out due to convincing anaphylaxis history. Results: The repeated SPT with soy revealed a remarkable wheal which is greater than the positive control (soy; 7 mm, histamine; 5 mm). The SPT with aeroallargens including birch was found to be negative. The soy-specific IgE was noticeably positive (82.30 IU/l, normal range: 0-0.10 IU/l). Conclusion: Here we present an adult case experiencing anaphylaxis to soy in the absence of birch sensitivity. Taking into consider the wide use of this protein it can be regarded as an hidden allergen responsible for food-related systemic allergic reactions or OAS in adults.