Platelet activity and platelet-endothelial cell interactions are important in
the acute development of thrombosis, as well as in the pathogenesis of
cardiovascular disease. An increasing number of foods have been reported to
have platelet-inhibitory actions, and research with a number of flavanol-rich foods,
including, grape juice, cocoa and chocolate, suggests that these foods may provide
some protection against thrombosis. In the present report, we review a series of in
vivo studies on the effects of flavanol-rich cocoa and chocolate on platelet activation
and platelet-dependent primary hemostasis. Consumption of flavanol-rich cocoa
inhibited several measures of platelet activity including, epinephrine- and
ADP-induced glycoprotein (GP) IIb/IIIa and P-Selectin expression, platelet
microparticle formation, and epinephrine-collagen and ADP-collagen induced
primary hemostasis. The epinephrine-induced inhibitory effects on GP IIb/IIIa and
primary hemostasis were similar to, though less robust than those associated with
the use of low dose (81 mg) aspirin. These data, coupled with information from
other studies, support the concept that flavanols present in
cocoa and chocolate can modulate platelet function through a multitude of
pathways.