Blood Pressure Is Reduced and Insulin Sensitivity Increased in Glucose-Intolerant, Hypertensive Subjects after 15 Days of Consuming High-Polyphenol Dark Chocolate1 3

Abstract

Flavanols from chocolate appear to increase nitric oxide bioavailability, protect vascular endothelium, and decrease cardiovascular disease (CVD) risk factors. We sought to test the effect of flavanol-rich dark chocolate (FRDC) on endothelial function, insulin sensitivity, β-cell function, and blood pressure (BP) in hypertensive patients with impaired glucose tolerance (IGT). After a run-in phase, 19 hypertensives with IGT (11 males, 8 females; 44.8 ± 8.0 y) were randomized to receive isocalorically either FRDC or flavanol-free white chocolate (FFWC) at 100 g/d for 15 d. After a wash-out period, patients were switched to the other treatment. Clinical and 24-h ambulatory BP was determined by sphygmometry and oscillometry, respectively, flow-mediated dilation (FMD), oral glucose tolerance test, serum cholesterol and C-reactive protein, and plasma homocysteine were evaluated after each treatment phase. FRDC but not FFWC ingestion decreased insulin resistance (homeostasis model assessment of insulin resistance; P < 0.0001) and increased insulin sensitivity (quantitative insulin sensitivity check index, insulin sensitivity index (ISI), ISI0; P < 0.05) and β-cell function (corrected insulin response CIR120; P = 0.035). Systolic (S) and diastolic (D) BP decreased (P < 0.0001) after FRDC (SBP, −3.82 ± 2.40 mm Hg; DBP, −3.92 ± 1.98 mm Hg; 24-h SBP, −4.52 ± 3.94 mm Hg; 24-h DBP, −4.17 ± 3.29 mm Hg) but not after FFWC. Further, FRDC increased FMD (P < 0.0001) and decreased total cholesterol (−6.5%; P < 0.0001), and LDL cholesterol (−7.5%; P < 0.0001). Changes in insulin sensitivity (Δ ISI − Δ FMD: r = 0.510, P = 0.001; Δ QUICKI − Δ FMD: r = 0.502, P = 0.001) and β-cell function (Δ CIR120 − Δ FMD: r = 0.400, P = 0.012) were directly correlated with increases in FMD and inversely correlated with decreases in BP (Δ ISI − Δ 24-h SBP: r = −0.368, P = 0.022; Δ ISI − Δ 24-h DBP r = −0.384, P = 0.017). Thus, FRDC ameliorated insulin sensitivity and β-cell function, decreased BP, and increased FMD in IGT hypertensive patients. These findings suggest flavanol-rich, low-energy cocoa food products may have a positive impact on CVD risk factors.