Short- and long-term black tea consumption reverses endothelial dysfunction in patients with coronary artery disease

Background-Epidemiological studies suggest that tea consumption decreases c ardiovascular risk, but the mechanisms of benefit remain undefined. Endothe lial dysfunction has been associated with coronary artery disease and incre ased oxidative stress. Some antioxidants have been shown to reverse endothe lial dysfunction, and tea contains antioxidant flavonoids, Methods and Results-To test the hypothesis that tea consumption will revers e endothelial dysfunction, we randomized 66 patients with proven coronary a rtery disease to consume black tea and water in a crossover design. Short-t erm effects were examined 2 hours after consumption of 450 mt tea or water. Long-term effects were examined after consumption of 900 mt tea or water d aily for 4 weeks. Vasomotor function of the brachial artery was examined at baseline and after each intervention with vascular ultrasound. Fifty patie nts completed the protocol and had technically suitable ultrasound measurem ents. Both short- and long-term tea consumption improved endothelium-depend ent flow-mediated dilation of the brachial artery, whereas consumption of w ater had no effect (P <0.001 by repeated-measures ANOVA). Tea consumption h ad no effect on endothelium-independent nitroglycerin-induced dilation. An equivalent oral dose of caffeine (200 mg) had no short-term effect on flow- mediated dilation. Plasma flavonoids increased after short- and long-term t ea consumption. Conclusions-Short- and long-term black tea consumption reverses endothelial vasomotor dysfunction in patients with coronary artery disease. This findi ng may partly explain the association between tea intake and decreased card iovascular disease events.