D2.280 - Biphasic anaphylaxis due to psyllium (Plantago ovata) allergy, the primary component of a plant-based sausage

Psyllium (Plantago ovata) is an emerging allergen frequently used in gluten-free and vegan products. We report a case of biphasic anaphylaxis following the ingestion of a plant-based sausage.

A 21-year-old female with a history of allergic asthma, kiwi anaphylaxis, and prior oropharyngeal pruritus after psyllium ingestion, experienced a severe reaction minutes after consuming a plant-based hot dog. Symptoms included abdominal pain, pharyngeal pruritus, dyspnea, dysphonia, vomiting, diarrhea, and dizziness. She was treated in ER with intramuscular adrenaline, corticosteroids, and antihistamines. After 7 hours of observation and initial resolution, the patient experienced a second wave of symptoms (biphasic reaction).

The implicated vegan sausage listed psyllium fiber as a functional ingredient (41% of the formulation). Other components were: wheat gluten, egg, onion, soy flour, sugar, lemon juice and traces of milk and nuts.

"The patient tolerates an unrestricted diet including dairy, eggs, and gluten-containing flours without reporting adverse symptoms.

• Skin Prick Tests (SPT): Positive for Plantago pollen, Negative for LTPs, profilins, soy, mustard, celery, onion, and a panel of nuts and seds. Prick-prick with Plantago ovata were positive (3x4mm)
• Molecular Diagnosis (ISAC): Confirmed sensitization to Act d 1 (kiwi), various pollens (Cup a 1, Ole e 7/9, Sal k 1). Notably, results were negative for storage proteins (2S, 7S, 11S albumin/globulins) and PR-10 proteins.
• In vitro tests: IgE-Western blot using extracts from the sausage and P. ovata identified matching dominant IgE-binding bands at 27 kDa (non-reducing) and 32/22 kDa (reducing conditions). Inhibition assays demonstrated that P. ovata completely inhibited IgE binding to the sausage extract, whereas Plantago lanceolata pollen showed no inhibition and a distinct profile (10 kDa). Molecular profiling was negative for storage proteins (2S, 7S, 11S) and LTPs.

Plantago ovata, used as a functional fiber in plant-based processed foods, can act as a clinically relevant hidden food allergen.

 Co-sensitization rather than cross-reactivity with P. lanceolata is well documented. These results highlight the need for clinicians to consider psyllium as a potential allergen in reactions to plant-based products.