The relation between single/double or repeated tea catechin ingestions and plasma antioxidant activity in humans

Abstract

Objective: The purpose of this study was to investigate the effects of single=double or repeated intake of a normal amount of tea catechin on plasma catechin concentrations and antioxidant activity in young women. Design: First, after an overnight fast, five healthy subjects were given water or single=double dose(s) of tea polyphenol extract (164 mg tea catechins containing 61% epigallocatechin gallate in 190 ml water). Blood samples were taken before and 30, 60 and 180 min after the ingestion. Second, 16 healthy subjects ingested the tea polyphenol extract three times a day at mealtimes for 7 days followed by withdrawal of tea polyphenol extract for 7 days. Blood samples were taken before and after ingestion, and 7 days after the withdrawal of tea catechin. Subjects were prohibited from drinking any beverages containing polyphenols or antioxidant supplements during the study period. Catechin and other antioxidant concentrations in the plasma were measured, and changes in antioxidant activity were evaluated by ferric reducing ability of plasma assay. Results: Single=double ingestion of tea polyphenol extract did not cause an increase in the antioxidant activity. There was no also change in antioxidant activity after the ingestion of tea polyphenol extract for 7 days. Plasma-free epigallocatechin gallate concentration remained at the pre-study level; however, the plasma FRAP value decreased significantly at 7 days after the withdrawal of tea polyphenol extract. Decreases in endogenous antioxidants in the plasma, including vitamin C and bilirubin, were also observed 7 days after withdrawal of tea polyphenol. Conclusions:The results suggest that continuous daily intake of tea catechins affects the concentrations of endogenous antioxidants in the plasma and has the potential to maintain total antioxidant activity.

Changes in Epigallocatechin-3-0- (3-0-methyl) Gallate and Strictinin Contents of Tea (Camellia sinensis L.) Cultivar 'Benifuki' in Various Degrees of Maturity and Leaf Order

“…anti-carcinogenetic (Kuroda & Hara, 1999;Lin et ul., 1999;Suganuma et ul., 1999, 200_3;Ahmad et a!., 2000;Cao & Cao, 1999;Lambert & Yan_~, 2003), anti-metastatic (Sazuka et a/., 1997; Maeda-Yamamoto et a/., 1999; Isemura et a!., 199_3; Sazuka et a/., 1995), anti-oxidative (Bors & Saran, 1987;Hashimoto et a!., 2003;Okuda et al, 1983;Kimura et a!., 2002), anti-hypertensive (Yokozawa et a!., 1994), anti-hypercholesterolemic (Murase et al, 2002;Chlsaka et a/., 1988; Matsumoto et a!., 1998), anti-dental caries (Sakanaka et a/., 1992;Hattori et a!., 1990), antl-bacterial (Fukai et al, 1991), and intestinal fiora amelioration activity (Okubo et a/., 1992).…”

Binding Energy of Tea Catechin/Caffeine Complexes in Water Evaluated by Titration Experiments with1H-NMR

“…They have recently been discovered to have various physiologically modulating effects such as anti-carcinogenic, [1][2][3][4][5][6][7] anti-metastatic, [8][9][10][11] anti-oxidative, [12][13][14][15] antihypertensive, 16) anti-hypercholesterolemic, [17][18][19] antibacterial, 20) anti-dental caries, [21][22][23] and intestinal flora amelioration activities. 24) Caffeine (1, Fig.…”

Genotoxic Effects of Green Tea Extract on Human Laryngeal Carcinoma Cells In Vitro

“…It is possible that EGCG in nanomolar concentrations causes hydrogen peroxide production in physiological concentrations, which mediates cell signalling pathways, proliferation, and differentiation (30). A study in humans by Kimura et al (31) revealed that ingestion of a single (164 mg) and a double (328 mg) catechin dose in green tea did not change its antioxidant activity because they were conjugated or methylated after absorption by the digestive system. However, antioxidant activity in cells decreased signifi cantly seven days after tea catechin consumption stopped (31).…”

“…A study in humans by Kimura et al (31) revealed that ingestion of a single (164 mg) and a double (328 mg) catechin dose in green tea did not change its antioxidant activity because they were conjugated or methylated after absorption by the digestive system. However, antioxidant activity in cells decreased signifi cantly seven days after tea catechin consumption stopped (31).…”