Journal
JOURNAL OF HYPERTENSION
Volume 21, Issue 12, Pages 2281-2286Publisher
LIPPINCOTT WILLIAMS & WILKINS
DOI: 10.1097/00004872-200312000-00016
Keywords
N-w-nitro-L-arginine methyl ester; nitric oxide synthesis; vasodilation; cocoa; flavonoids; flavanols
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Funding
- NCRR NIH HHS [M01 RR026376] Funding Source: Medline
- NHLBI NIH HHS [T32 HL-07609] Funding Source: Medline
- NIDDK NIH HHS [1 R01 DK5468-01] Funding Source: Medline
- PHS HHS [P01AC00059916, 1P50ML53000-01] Funding Source: Medline
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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, and related procyanidin oligomers]. The specific nitric oxide synthase inhibitor, N-G-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 vasoclilator 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. (c) 2003 Lippincott Williams & Wilkins.
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