Protective Effects of Flavanol-Rich Dark Chocolate on Endothelial Function and Wave Reflection During Acute Hyperglycemia

• Published in: Hypertension (Dallas, Tex. 1979) Vol. 60; no. 3; pp. 827 - 832
• Main Authors: Grassi, Davide, Desideri, Giovambattista, Necozione, Stefano, Ruggieri, Fabrizio, Blumberg, Jeffrey B., Stornello, Michele, Ferri, Claudio
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD American Heart Association, Inc 01.09.2012; Lippincott Williams & Wilkins
• Subjects: Acute Disease; Adult; Antihypertensive agents; Arterial hypertension. Arterial hypotension; Biological and medical sciences; Blood and lymphatic vessels; Blood Pressure - drug effects; Blood Pressure - physiology; Cacao; Cardiology. Vascular system; Cardiovascular system; Dinoprost - analogs & derivatives; Dinoprost - blood; Endothelin-1 - blood; Endothelium, Vascular - drug effects; Endothelium, Vascular - physiology; Female; Flavanones - pharmacology; Glucose Tolerance Test; Humans; Hyperglycemia - physiopathology; Insulin Resistance - physiology; Insulin-Secreting Cells - physiology; Male; Medical sciences; Pharmacology. Drug treatments; Pulse Wave Analysis; Hypertension; endothelial function; Oxidative stress; wave reflections; Cardiovascular disease; Flavonoid; cocoa; Prevention; Polyphenol; Hyperglycemia; Nitric oxide; Phenols; flavonoids
• ISSN: 0194-911X; 1524-4563; 1524-4563
• DOI: 10.1161/HYPERTENSIONAHA.112.193995

Nitric oxide plays a pivotal role in regulating vascular tone. Different studies show endothelial function is impaired during hyperglycemia. Dark chocolate increases flow-mediated dilation in healthy and hypertensive subjects with and without glucose intolerance; however, the effect of pretreatment with dark chocolate on endothelial function and other vascular responses to hyperglycemia has not been examined. Therefore, we aimed to investigate the effects of flavanol-rich dark chocolate administration on (1) flow-mediated dilation and wave reflections; (2) blood pressure, endothelin-1 and oxidative stress, before and after oral glucose tolerance test (OGTT). Twelve healthy volunteers (5 males, 28.2±2.7 years) randomly received either 100 g/d dark chocolate or flavanol-free white chocolate for 3 days. After 7 days washout period, volunteers were switched to the other treatment. Flow-mediated dilation, stiffness index, reflection index, peak-to–peak time, blood pressure, endothelin-1 and 8-iso-PGF2α were evaluated after each treatment phase and OGTT. Compared with white chocolate, dark chocolate ingestion improved flow-mediated dilation (P=0.03), wave reflections, endothelin-1 and 8-iso-PGF2α (P<0.05). After white chocolate ingestion, flow-mediated dilation was reduced after OGTT from 7.88±0.68 to 6.07±0.76 (P=0.027), 6.74±0.51 (P=0.046) at 1 and 2 h after the glucose load, respectively. Similarly, after white chocolate but not after dark chocolate, wave reflections, blood pressure, and endothelin-1 and 8-iso-PGF2α increased after OGTT. OGTT causes acute, transient impairment of endothelial function and oxidative stress, which is attenuated by flavanol-rich dark chocolate. These results suggest cocoa flavanols may contribute to vascular health by reducing the postprandial impairment of arterial function associated with the pathogenesis of atherosclerosis.