Green tea and heart health.

The adherence of monocytes to vascular endothelial cells is an important early event in atherogenesis. Monocyte adherence to endothelial cells is induced by oxidized low-density lipoprotein (LDL) and mediated by multiple cell-adhesion molecules, including vascular cell-adhesion molecule 1 and intercellular cell-adhesion molecule 1. Enhanced endothelial expression of these molecules by oxidized LDL has been shown to be a critical step in foam cell formation and the development of atherosclerosis. Recent studies have demonstrated that tea catechin, especially (-)-epigallocatechin-3-gallate, inhibits the expression of these molecules by endothelial cells in response to stimulation with oxidized LDL or inflammatory cytokines and the expression of CD11b by monocytic leukocytes. An in vivo study using apolipoprotein E-deficient mice has demonstrated that tea catechin extracts prevent the development of atherosclerosis and that (-)-epigallocatechin-3-gallate effectively reduces the progression of accelerated atherosclerotic plaque formation induced by cuff injury. These data suggest that tea catechin may provide a unique approach to reduce atherosclerosis, although further studies will be necessary to clarify the precise mechanism of these effects, especially the role of metabolites of catechin and the target sites of these compounds.