Flavonoid reduce platelet aggregation

Platelets and leukocytes contribute to arterial thrombosis and to inflammatory processes. An increasing number of foods have been reported to have platelet-inhibitory actions, and research with a number of (-) epicatechin and (+)-catechin, flavan-3-ols (flavanols) rich foods, including cocoa and chocolate, suggests that these foods may provide some protection against thrombosis.

Flavanols are also commonly found in other foods and beverages including grapes and tea.

Procyanidins with as many as 10 flavanol subunits have been identified in cocoa and chocolate. Studies with subjects given flavanol- and procyanidin-rich foods have reported positive vascular effects including increased plasma antioxidant status, improved endothelium function, and reduced platelet reactivity.

Regular consumption of flavanols and procyanidins from cocoa, in a range easily accommodated in a normal diet, increased plasma concentrations of epicatechin and catechin, but there were no effects on markers of oxidation.

Similarly, study found that after the consumption of 25 g chocolate, supplying 220 mg flavanols and procyanidins, there was a decrease in primary hemostasis (as measured by the time to occlude an aperture in a collagen membrane) 2 h after consumption. (JAMA 2002;287:2212–3)
Flavonoid reduces platelet aggregation