Author: Fung, Shing-tack
Title: Plasma and urine polyphenol levels after a single dose and after regular ingestion of green tea
Degree: M.Sc.
Year: 2012
Subject: Green tea -- Health aspects.
Hong Kong Polytechnic University -- Dissertations
Department: Department of Health Technology and Informatics
Pages: xi, 95 leaves : ill. (some col.) ; 30 cm.
Language: English
Abstract: Potential health benefits of consumption of green tea may associate with its content of polyphenols, but their bioavailability is found to be low. The aim of this work was to study the level of catechins, main polyphenols, in plasma and urine after acute intake and after a period of regular intake of green tea. A crossover study was carried out in 16 healthy human volunteers and different timed plasma and urine samples were collected; catehins were identified and quantified in those samples by high-performance liquid chromatography with tandem mass spectrometry with or without enzyme pre-treatment. Among other catechins, free (2)-epigallocatechin-3-gallate (EGCG) was the major catechin found in plasma after acute intake; interestingly, EGCG and epicatechin gallate (ECG) were nearly undetectable in urine, while epigallocatechin (EGC) and epicatechin (EC) were excreted in urine; after 7-days of regular ingestion of green tea, conjugated ECG had accumulated in plasma, followed by conjugated EGC and EGCG. The bioavailability of catechins and their elimination observed for acute intake study are in agreement with previous studies, although the ingested dosage of polyphenols in this project is different. Moreover, this is the first time that a period of 7 days was designed for regular intake study and the results reveal that conjugated ECG, EGC, and EGCG accumulated in plasma but free EGCG did not. This study provides more information such as frequency of oral administration and which type of catechins or their conjugates should be tested for future study.
Rights: All rights reserved
Access: restricted access

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