Acute effects of tea on fasting and postprandial vascular function and blood pressure in humans

Background Effects of regular exposure to polyphenolic compounds found in tea, leading to improved endothelial function and blood pressure, may reduce cardiovascular disease risk. Controlled trials in humans have found that ingestion of tea can improve endothelial function, but also cause a rapid onset acute increase in blood pressure. Objective To examine the acute effects of tea consumption on fasting and postprandial vascular function and blood pressure. Methods Endothelium-dependent dilatation of the brachial artery, assessed using ultrasound and blood pressure were measured in 20 participants with a history of coronary artery disease. Measurements were performed at baseline and at 3.5 h (blood pressure) and 4 h (endothelial function) after drinking three cups of black tea or hot water (consumed at time = 0, 1.5 and 3 h) with and without a high-fat (50 g) meal: a total of four treatments administered in random order. Results The high-fat meal did not impair endothelial function. In comparison to water alone, endothelium-dependent dilatation was increased by the meal with tea (1.7 (0.4, 3.0)%, P = 0.02), but was not significantly altered by the tea alone (0.7 (-0.6, 2.0)%, P = 0.32). Systolic blood pressure was significantly increased by tea alone in comparison to each of the other three groups: water alone (9.3 (4.5, 14.1) mmHg, P = 0.0003), meal with water (9.8 (5.0, 14.6) mmHg, P = 0.0001) and meal with tea (7.2 (2.4, 12.0) mmHg, P = 0.004). Consumption of a meal negated the acute increase in systolic blood pressure found with tea in the fasting state. Conclusion Consumption of food may alter the acute effects of tea on vascular function and blood pressure. (C) 2005 Lippincott Williams Wilkins.