Despite its frequent consumption, allergy due to consumption of tea (Camellia sinensis) is extremely rare and is limited to individual case reports. Most frequently, food allergy to green tea is seen in patients with a history of occupational asthma, although it has been reported occasionally without prior sensitization (2, 3).
A 20-year-old woman with no history of asthma, anxiety, or occupational exposure to green tea presented with allergy symptoms after consuming brewed green tea. Approximately 15 minutes after consuming green tea, she began to experience throat swelling, itching and soreness, hoarse voice, shortness of breath, and nasal congestion, all lasting up to 3 hours. She had imbibed green tea in the past without any reaction; however, she then had a second episode more severe than the first. A skin prick test (SPT) to green tea elicited a 6-mm wheal with a 61-mm flare, whereas green tea SPT were negative in the 5 control subjects. Further SPT performed to food allergens based on her food history were non-reactive, including to chocolate and coffee. IgE testing to fermented black tea or a blend of several black teas were negative (3).
Occupational asthma caused by inhalation of green dust has been reported in 11 patients, 5 of which also developed food allergy to green tea. These patients had worked for several years at different green tea factories in Japan. They developed food allergy to green tea simultaneously with the onset of occupational asthma or subsequently. Allergic symptoms, including cough, dyspnea and, in a severe case, loss of consciousness, occurred soon after ingestion of black, green and oolong teas, as well as after ingestion of cakes and noodles containing green tea powder. The diagnosis of green tea–induced asthma was confirmed with SPT and inhalation challenges using green tea dust (2).
Asthma
The catechin epigallocatechin gallate (EGCg) from green tea has been shown to inhibit mast cell degranulation and suppress allergen- and non-allergen-specific IgE production in asthmatic patients. This suggests that green tea may have beneficial immunoregulatory effects on IgE responses in asthmatics (5).
Atopic Dermatitis
Cases of immediate and delayed contact sensitization to Camellia sinensis have been described in occupational settings. A 49-year-old female wine and tea merchant with no personal history of atopy or skin disease experienced symptoms of contact sensitization within 5 minutes of exposure to tea dust. The patient tolerated drinking tea infusions both before and after this incident. Symptoms included itching of the face, neck and mouth, periorbital edema and rhinitis. The rash lasted for 3–4 days, with antihistamine treatment having some effect. Histamine release (HR) testing showed sensitivity to 3 out of the 5 tea blends tested. Skin prick tests to standard inhalant allergens were positive to birch, grass, and mugwort pollen as well as to house dust mites and, to a lesser degree, dog and Alternaria alternata. The report concluded that the history, clinical tests and HR tests were suggestive of concomitant immediate and delayed hypersensitivity reactions to tea (6).
