In vivo antioxidant effect of green tea

Objective: The object of this study was to investigate the in vivo antioxid ant effect of green tea and dosage effect of green tea on antioxidant effec t. Design: We tested 10 healthy subjects (aged 23-25 y, five women and five me n) with overnight fasting. The total antioxidant capacity of plasma was mea sured at baseline and 60 min and 120 min after ingestion of 150 mi green te a. Green tea was prepared by infusing 2.5 g of dried green tea leaves for 2 min at 80 degrees C in 150 mi of water. In the second week, they took 300 mi of tea (5.0 g of green tea leaves) and, in the third week, 450 mi of tea (7.5 g of green tea leaves). The total antioxidant capacities of plasma we re determined with a Total Antioxidant Kit (Randox Laboratories Ltd, UK) us ing a Cobas Mira analyser (Roche Diagnostic Systems Inc., Switzerland). The mean intra-assay coefficient of variation was 1.2%. Results: The total antioxidant capacity of plasma increased by 1.1% at 60 m in and 2.1% at 120 min over baseline value in subjects consuming 150 ml of green tea, which was statistically not significant. However, total antioxid ant capacity of plasma after consuming 300 ml of green tea showed a signifi cant increase of 7.0% after 60 min and 6.2% after 120 min (P < 0.0001), and after consuming 450 ml 12.0% after 60 min and 12.7% after 120 min over bas eline value (P < 0.0001). Conclusions: Total antioxidant capacity of plasma was significantly increas ed after taking green tea in amounts of 300 and 450 mi. A positive incremen t according to green tea dosage was also observed. Sponsorship: This work was funded by the Pacific Corporation (Korea).