Tea, flavonoids, and cardiovascular health: endothelial protection

Several studies have suggested that tea consumption might protect against the development and progression of cardiovascular disease, one of the leading causes of morbidity and mortality worldwide. The endothelium plays a pivotal role in arterial homeostasis. Reduced nitric oxide (NO) bioavailability with endothelial dysfunction is considered the earliest step in the pathogenesis of atherosclerosis. Endothelial dysfunction has been considered an important and independent predictor of future development of cardiovascular risk and events. The association between brachial NO-dependent flow-mediated dilation (FMD) and cardiovascular disease risk has been investigated in several prospective studies, suggesting that FMD is inversely associated with future cardiovascular events. Dietary flavonoids and tea consumption have been described to improve endothelial function and FMD. A proposed mechanism by which dietary flavonoids could affect FMD is that they improve the bioactivity of the endothelium-derived vasodilator NO by enhancing NO synthesis or by decreasing superoxide-mediated NO breakdown. This could be of clinical relevance and may suggest a mechanistic explanation for the reduced risk of cardiovascular events and stroke observed among tea drinkers in the different studies. The purpose of this article is to provide an overview of the relation between tea consumption and cardiovascular disease, with a focus on clinical implications resulting from the beneficial effects of tea consumption on endothelial function.