BACKGROUND: Consumption of flavonoid-rich beverages, including tea and red wine, has been associated with a reduction in coronary events, but the physiological mechanism remains obscure. Cocoa can contain extraordinary concentrations of flavanols, a flavonoid subclass shown to activate nitric oxide synthase in vitro. OBJECTIVE: To test the hypothesis that flavanol-rich cocoa induces nitric-oxide-dependent vasodilation in humans. DESIGN: The study prospectively assessed the effects of Flavanol-rich cocoa, using both time and beverage controls. Participants were blinded to intervention; the endpoint was objective and blinded. METHODS: Pulse wave amplitude was measured on the finger in 27 healthy people with a volume-sensitive validated calibrated plethysmograph, before and after 5 days of consumption of Flavanol-rich cocoa [821 mg of flavanols/day, quantitated as (-)-epicatechin, (+)-catechin, and related procyanidin oligomers]. The specific nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) was infused intravenously on day 1, before cocoa, and on day 5, after an acute ingestion of cocoa. RESULTS: Four days of flavanol-rich cocoa induced consistent and striking peripheral vasodilation (P = 0.009). On day 5, pulse wave amplitude exhibited a large additional acute response to cocoa (P = 0.01). L-NAME completely reversed this vasodilation (P = 0.004). In addition, intake of flavanol-rich cocoa augmented the vasodilator response to ischemia. Flavanol-poor cocoa induced much smaller responses (P = 0.005), and none was induced in the time-control study. Flavanol-rich cocoa also amplified the systemic pressor effects of L-NAME (P = 0.005). CONCLUSION: In healthy humans, flavanol-rich cocoa induced vasodilation via activation of the nitric oxide system, providing a plausible mechanism for the protection that flavanol-rich foods induce against coronary events.
BACKGROUND: Consumption of flavonoid-rich beverages, including tea and red wine, has been associated with a reduction in coronary events, but the physiological mechanism remains obscure. Cocoa can contain extraordinary concentrations of flavanols, a flavonoid subclass shown to activate nitric oxide synthase in vitro. OBJECTIVE: To test the hypothesis that flavanol-rich cocoa induces nitric-oxide-dependent vasodilation in humans. DESIGN: The study prospectively assessed the effects of Flavanol-rich cocoa, using both time and beverage controls. Participants were blinded to intervention; the endpoint was objective and blinded. METHODS: Pulse wave amplitude was measured on the finger in 27 healthy people with a volume-sensitive validated calibrated plethysmograph, before and after 5 days of consumption of Flavanol-rich cocoa [821 mg of flavanols/day, quantitated as (-)-epicatechin, (+)-catechin, and related procyanidin oligomers]. The specific nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) was infused intravenously on day 1, before cocoa, and on day 5, after an acute ingestion of cocoa. RESULTS: Four days of flavanol-rich cocoa induced consistent and striking peripheral vasodilation (P = 0.009). On day 5, pulse wave amplitude exhibited a large additional acute response to cocoa (P = 0.01). L-NAME completely reversed this vasodilation (P = 0.004). In addition, intake of flavanol-rich cocoa augmented the vasodilator response to ischemia. Flavanol-poor cocoa induced much smaller responses (P = 0.005), and none was induced in the time-control study. Flavanol-rich cocoa also amplified the systemic pressor effects of L-NAME (P = 0.005). CONCLUSION: In healthy humans, flavanol-rich cocoa induced vasodilation via activation of the nitric oxide system, providing a plausible mechanism for the protection that flavanol-rich foods induce against coronary events.
Authors: Hagen Schroeter; Christian Heiss; Jan Balzer; Petra Kleinbongard; Carl L Keen; Norman K Hollenberg; Helmut Sies; Catherine Kwik-Uribe; Harold H Schmitz; Malte Kelm Journal: Proc Natl Acad Sci U S A Date: 2006-01-17 Impact factor: 11.205
Authors: Katrina Go Yamazaki; Diego Romero-Perez; Maraliz Barraza-Hidalgo; Michelle Cruz; Maria Rivas; Brenda Cortez-Gomez; Guillermo Ceballos; Francisco Villarreal Journal: Am J Physiol Heart Circ Physiol Date: 2008-06-20 Impact factor: 4.733