Data from; Concentration-Dependent Impact of Green Tea Catechin Gargling on Acute Upper Respiratory Tract Infections: An Exploratory Randomized Controlled Trial

We conducted an open-label randomized study (UMIN000045060). The target population consisted of 209 students from the University of Shizuoka and Meiji University, who were randomly assigned to high-catechin (70 participants, approximate catechin concentration: 76.4 mg/dL), low-catechin (69 participants, approximate catechin concentration: 30.8 mg/dL), and a control water gargling (70 participants, catechin concentration: 0 mg/dL) groups. All participants gargled water or GT thrice daily for 12 weeks between December 2021 and February 2022. The symptoms experienced by participants who developed URTI during the study period were recorded on a survey form. The primary endpoint of URTI occurred in 6 (9.1%), 7 (10.8%), and 11 (15.7%) participants in the high-catechin, low-catechin, and water groups, respectively (Fisher's exact test for the overall group: p=0.482). Cox proportional hazards analysis, using background factors and prevention status as covariates, revealed a hazard ratio of 0.57 (95% CI: 0.21–1.55, p=0.261) for the high-catechin vs. water group and 0.54 (95% CI: 0.20–1.50, p=0.341) for the low-catechin vs. water group.