title: Comparison of catechin profiles in human plasma and urine after single dosing and regular intake of green tea (Camellia sinensis).
abstract: Green tea (Camellia sinensis) catechin profiles in plasma and urine following single dosing and regular ingestion of green tea are not clear. We performed a placebo-controlled intervention study with sixteen healthy volunteers to determine changes in total and free catechins after a single dose and following 1 week of twice-daily green tea. Blood and urine samples were collected before (fasting) and after (60 and 120 min for blood; 90 and 180 min for urine) drinking 200 ml of 1.5% (w/v) green tea or water (n 8 each), and fasting samples were again collected after 7 d of 150 ml of 1% (w/v) supplemental green tea or water twice daily. After a 4-week washout, subjects were crossed onto the other treatment and procedures repeated. Plasma results at 1 h post-ingestion showed elevated (P < 0.05) mean epigallocatechin gallate (EGCG; 310 (SD 117) nmol/l; all in free form), epigallocatechin (EGC; 192 (SD 67) nmol/l; 30% free) and epicatechin gallate (ECG; 134 (SD 51) nmol/l; 75% free). Fasting plasma after 7 d of regular intake showed increased (P < 0.05) EGCG (80 v. 15 nmol/l at baseline) and ECG (120 v. 40 nmol/l), with > or =90% of both in their conjugated forms. Total EGC was < 10 nmol/l. Post-ingestion conjugation and renal loss of EGC and epicatechin were rapid and high, but were negligible for EGCG and ECG. In the green tea consumed, the content was EGCG > EGC > ECG, and the acute plasma response mirrored this. However, after chronic consumption there was almost no EGC found in fasting plasma, some EGCG was present, but a rather high level of ECG was maintained.
authors.affiliation: Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong.
authors.forename: Shing-Tack
authors.initials: ST
authors.lastname: Fung
authors.forename: Cyrus K
authors.initials: CK
authors.lastname: Ho
authors.forename: Siu-Wai
authors.initials: SW
authors.lastname: Choi
authors.forename: Wai-Yuen
authors.initials: WY
authors.lastname: Chung
authors.forename: Iris F F
authors.initials: IF
authors.lastname: Benzie
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000975:Antioxidants / Q000008:administration & dosage / Q000378:metabolism*; D001682:Biological Availability; D028241:Camellia sinensis / Q000378:metabolism*; D002392:Catechin / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism* / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D000975:Antioxidants; D002392:Catechin