Acute EGCG supplementation reverses endothelial dysfunction in patients with coronary artery disease

Abstract

Background: Epidemiological studies demonstrate an inverse relation between dietary flavonoid intake and cardiovascular risk. Recent studies with flavonoid-containing beverages suggest that the benefits of these nutrients may relate, in part, to improved endothelial function.

Objective: We hypothesized that dietary supplementation with epigallocatechin gallate (EGCG), a major catechin in tea, would improve endothelial function in humans.

Design: We examined the effects of EGCG on endothelial function in a double blind, placebo-controlled, crossover design study. We measured brachial artery flow-mediated dilation by vascular ultrasound at six time points: prior to treatment with EGCG or placebo, two hours after an initial dose of EGCG (300 mg) or placebo, and after two weeks of treatment with EGCG (150 mg twice daily) or placebo. The order of treatments (EGCG or placebo) was randomized and there was a one-week washout period between treatments.

Results: A total of 42 subjects completed the study, and brachial artery flow-mediated dilation improved from 7.1 +/- 4.1 to 8.6 +/- 4.7% two hours after the first dose of 300 mg of EGCG (P = 0.01), but was similar to baseline (7.8 +/- 4.2%, P = 0.12) after two weeks of treatment with the final measurements made approximately 14 hours after the last dose. Placebo treatment had no significant effect, and there were no changes in reactive hyperemia or the response to sublingual nitroglycerin. The changes in vascular function paralleled plasma EGCG concentrations, which increased from 2.6 +/- 10.9 to 92.8 +/- 78.7 ng/ml after acute EGCG (P < 0.001), but were unchanged from baseline after two weeks of treatment (3.4 +/- 13.1 ng/ml).

Conclusion: EGCG acutely improves endothelial function in humans with coronary artery disease, and may account for a portion of the beneficial effects of flavonoid-rich food on endothelial function.

Figure 1

Outline of Study Design. Subjects were randomly assigned to either the EGCG or Placebo arm first and then crossed over to the other treatment. Bid = twice daily.

Figure 2

Upper Panel: Changes in brachial artery flow-mediated dilation (FMD) compared to pre-treatment are displayed for Placebo and EGCG. FMD improved two hours after a single 300 mg dose of EGCG (*P=0.01), while FMD was not changed after two weeks of EGCG 150 mg twice daily (P=0.12). Placebo had no effect at the two-hour and two-week time points. Lower Panel: Changes in plasma EGCG concentration compared to pre-treatment concentration are displayed for Placebo and EGCG (n=38). Plasma ECGC concentrations were increased two hours after a single 300 mg dose of EGCG (P<0.001), while trough plasma EGCG concentrations (approximately 14 hours after the last dose) were unchanged after two weeks of EGCG 150 mg twice daily. Data are mean ± SEM.