Daily Consumption of an Aqueous Green Tea Extract Supplement Does Not Impair Liver Function or Alter Cardiovascular Disease Risk Biomarkers in Healthy Men

Abstract

Regular consumption of green tea polyphenols (GTP) is thought to reduce the risk of cardiovascular disease (CVD) but has also been associated with liver toxicity. The present trial aimed to assess the safety and potential CVD health beneficial effects of daily GTP consumption. We conducted a placebo-controlled parallel study to evaluate the chronic effects of GTP on liver function and CVD risk biomarkers in healthy men. Volunteers (treatment: n = 17, BMI 26.7 +/- 3.3 kg/m(2), age 41 +/- 9 y; placebo, n = 16, BMI 25.4 +/- 3.3 kg/m(2), age 40 +/- 10 y) consumed for 3 wk 6 capsules per day (2 before each principal meal) containing green tea extracts (equivalent to 714 mg/d GTP) or placebo. At the beginning and end of the intervention period, we collected blood samples from fasting subjects and measured vascular tone using Laser Doppler Iontophoresis. Biomarkers of liver function and CVD risk (including blood pressure, plasma lipids, and asymmetric dimethylarginine) were unaffected by GTP consumption. After treatment, the ratio of total:HDL cholesterol was significantly reduced in participants taking GTP capsules compared with baseline. Endothelial-dependent and -independent vascular reactivity did not significantly differ between treatments. In conclusion, the present data suggests that the daily consumption of high doses of GTP by healthy men for 3 wk is safe but without effects on CVD risk biomarkers other than the total:HDL cholesterol ratio.

Antibacterial Activity and Bond Strength to Enamel of Catechin-Incorporated 4-META/MMA-TBB Resin as an Orthodontic Adhesive Resin

“…Daily consumption of a high dose of green tea polyphenols, equivalent to 6-8 cups of green tea 34) , for 3 wk did not affect markers of liver and kidney function in healthy men 33) , consistent with a comparable trial in healthy Japanese men who consumed 690 mg/d catechins for 12 weeks 35) .…”

“…Frank et al 33) reported that supplementation by healthy men with a high daily dose of 714 mg green tea polyphenols for 3 wk did not cause adverse effects or impair liver and kidney function and did not improve cardiovascular disease risk biomarkers other than the ratio of total HDL cholesterol. Daily consumption of a high dose of green tea polyphenols, equivalent to 6-8 cups of green tea 34) , for 3 wk did not affect markers of liver and kidney function in healthy men 33) , consistent with a comparable trial in healthy Japanese men who consumed 690 mg/d catechins for 12 weeks 35) .…”

Effects of a beverage rich in (poly)phenols on established and novel risk markers for vascular disease in medically uncomplicated overweight or obese subjects: A four week randomized placebo-controlled trial

“…These are convenient to measure at time-points before and after an intervention but it should be stressed that they are not a replacement for true cardiovascular outcomes such as myocardial infarction and stroke. This pilot study has shown no convincing evidence for beneficial effects on cardiovascular risk markers and joins a very limited number of mainly negative studies in similar populations (33). That noted, pilot evidence for an effect on a urinary proteomic-derived coronary artery disease biomarker was noted after 2 weeks with the active beverage in this study (34), similar to another study in healthy volunteers taking olive oil for an equivalent duration ( For the purposes of this short-term study examining the effects of a nutritional interventional in isolation, it was necessary for subjects to maintain their usual diet and no significant weight loss was desired or observed during the study.…”

Limited Sampling Estimates of Epigallocatechin Gallate Exposures in Cirrhotic and Noncirrhotic Patients With Hepatitis C After Single Oral Doses of Green Tea Extract

“…28 However, chronic moderate to high dose daily GTE and EGCG use in healthy human volunteers was not shown to cause severe adverse effects or impair liver function. [29][30][31][32] Prior pharmacokinetic studies have established peak blood concentrations and exposures of EGCG associated with its safety and tolerability in healthy subjects. [30][31][32][33][34] In a study by Chow et al, following a single 800mg dose of EGCG in five healthy volunteers, AUC (min·µg/ml) ±SD was 167.1 ± 57.0, C max (ng/mL) was 438.5 ± 28.4 and t 1/2 (min) was 114.0 ± 33.3.…”