AN INTERVENTIONAL STUDY OF THE RELATIONSHIP BETWEEN GREEN TEA CONSUMPTION AND THE PREVALENCE OF ALLERGIC DISEASES (FINAL REPORT)

INTRODUCTION and PBJECTIVE: Allergic diseases, including allergic rhinitis, are becoming increasingly more prevalent nowadays in Japan. However, no definite etiology is currently known. Our observational study demonstrated a significant negative association between green tea consumption and the prevalence of allergic diseases. This interventional study was conducted to investigate the protective effect of green tea consumption with respect to allergic diseases. METHODS: The subjects were 2,412 elementary and junior high school pupils in Japan. We provided 1,140 pupils each with two bags of green tea leaves (one litter of green tea, when prepared) per day, for three months in 2013-2015. The pupils were asked to drink the green tea while at school. We observed another age- and sex- matched group of 1,272 pupils, as the control. For both, average age was 9.742.13 years old (meanSD). The questionnaire was distributed by City Municipal Boards of Education. Questions covered age, sex, medical history of allergic diseases including bronchial asthma, allergic rhinitis, urticaria, atopic dermatitis, and food allergy. The severity of each reported disease was assessed compared with the previous year. Student’s t-test was used for these comparisons. RESULTS and CONCLUSION: The severity of allergic rhinitis was significantly lower among pupils who were provided green tea compared to control (t=2.35, p=0.019). There were no significant differences with respect to other allergic diseases in terms of severity. Green tea may indeed have a protective effect with respect to allergic rhinitis.