title: Protective effects of flavanol-rich dark chocolate on endothelial function and wave reflection during acute hyperglycemia.
abstract: 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-PGF(2α) 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-PGF(2α) (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-PGF(2α) 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.
authors.affiliation: University of L'Aquila, Department of Internal Medicine and Public Health, Viale S Salvatore, Delta 6 Medicina, 67100 Coppito, L'Aquila, Italy. davide.grassi@cc.univaq.it
authors.forename: Davide
authors.initials: D
authors.lastname: Grassi
authors.forename: Giovambattista
authors.initials: G
authors.lastname: Desideri
authors.forename: Stefano
authors.initials: S
authors.lastname: Necozione
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Ruggieri
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Blumberg
authors.forename: Michele
authors.initials: M
authors.lastname: Stornello
authors.forename: Claudio
authors.initials: C
authors.lastname: Ferri
mesh_terms: D000208:Acute Disease; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002099:Cacao; D015237:Dinoprost / Q000031:analogs & derivatives / Q000097:blood; D019332:Endothelin-1 / Q000097:blood; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology*; D005260:Female; D044950:Flavanones / Q000494:pharmacology*; D005951:Glucose Tolerance Test; D006801:Humans; D006943:Hyperglycemia / Q000503:physiopathology*; D007333:Insulin Resistance / Q000502:physiology; D050417:Insulin-Secreting Cells / Q000502:physiology; D008297:Male; D063177:Pulse Wave Analysis
chemical_list: D019332:Endothelin-1; D044950:Flavanones; C075750:8-epi-prostaglandin F2alpha; D015237:Dinoprost