Consumption of diets rich in plant-based products protects against the development of CVD. Such effects have been ascribed in part to polyphenols, which are non-nutritive but, potentially bioactive secondary metabolites ubiquitous found in fruits, vegetables, herbs, spices, teas and wines. The beneficial effects of polyphenols on CVD is believed to be mediated, at least in part, though improving platelet function. At least 10 human intervention studies found a consistent and robust beneficial effect of cocoa products on platelet function, but unfortunately all of these studies used only one or two methods to assess platelet function, therefore only getting limited insights into the complex physiological behavior of platelets. In addition, none of these studies assessed potential mechanisms by which flavan-3-ols may inhibit platelet function. Schramm et al. have shown that consumption of chocolate rich in flavan-3-ols and their oligomers (procyanidins) lead to increased production of prostacyclin, a strong platelet inhibitor. This finding has also been observed when aortic endothelial cells are treated with procyanidins in vitro. Thus the stimulation of prostacyclin production in endothelial cells may reflect one pathway by which flavan-3-ols indirectly inhibit platelet activation. Many other potential mechanisms are discussed in the literature but so far the evidence for such mechanisms is limited or non-existing.