Tea, Cardiovascular Disease and Endothelial Cell Function





Joseph A. Vita

Boston University School of Medicine, Boston, MA



Epidemiological studies suggest that consumption of tea and other flavonoid-containing foods is associated with reduced risk of cardiovascular disease events including myocardial infarction and stroke. There also are data to suggest that tea consumption reduces extent of atherosclerosis in the aorta and the risk of recurrent complications following myocardial infarction. The mechanisms responsible for these beneficial effects remain uncertain. Studies that attempted to demonstrate that tea has an antioxidant effect in vivo in human subjects have had mixed and largely negative. These findings have prompted investigators to consider other possible explanations.

One area of particular interest has been the vascular endothelium. Recent studies have emphasized that the endothelium plays a central role in the regulation of vascular homeostasis. Loss of normal endothelial function may promote the development of atherosclerotic lesions and the conversion of quiescent plaques to active plaques that are responsible for acute ischemic syndromes, including myocardial infarction and stroke. There recently has been considerable interest in the effects of certain water-soluble antioxidants on endothelial function. For example, studies indicate that short and long term exposure to ascorbic acid enhance endothelium-dependent vasodilation in patients with coronary artery disease. These studies prompted us to examine the effects of tea consumption on endothelial function. In a randomized crossover clinical trial, we observed that tea consumption improves endothelial function in patients with coronary artery disease. These findings were not attributable to the effects of caffeine and appear to be specific for the endothelium, rather than vascular smooth muscle. Similar findings have been reported for patients with mild hypercholesterolemia, and for other flavonoid-containing beverages. Ongoing studies will exam the effects of specific components in tea in an attempt to determine how tea is exerting this effect. Tea consumption has beneficial effects on other clinically relevant aspects of the cardiovascular system. For example, tea consumption has been shown to reduce systemic markers of platelet activity and collagen-induced platelet aggregation.

Thus, there is growing evidence that tea consumption has effects on endothelial function and possibly platelet function that would tend to reduce the risk of cardiovascular disease. While there are insufficient data to specifically recommend tea consumption for treatment or prevention of coronary artery disease, the evidence is growing. As tea is a vegetable-derived beverage, however, a recommendation to drink tea would be consistent the dietary guidelines of the American Heart Association to increase consumption of fruits and vegetables as a strategy to reduce the risk of heart disease.




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