Blood pressure is reduced and insulin sensitivity increased in glucose-intolerant, hypertensive subjects after 15 days of consuming high-polyphenol dark chocolate

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, b-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 6 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 washout 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 b-cell function (corrected insulin response CIR120; P ¼ 0.035). Systolic (S) and diastolic (D) BP decreased (P ,0.0001) after FRDC (SBP, 23.82 6 2.40 mm Hg; DBP, 23.92 6 1.98 mm Hg; 24-h SBP, 24.52 6 3.94 mm Hg; 24-h DBP, 24.17 6 3.29 mm Hg) but not after FFWC. Further, FRDC increased FMD (P , 0.0001) and decreased total cholesterol (26.5%; P , 0.0001), and LDL cholesterol (27.5%; P , 0.0001). Changes in insulin sensitivity (D ISI 2 D FMD: r ¼ 0.510, P ¼ 0.001; D QUICKI 2 D FMD: r ¼ 0.502, P ¼ 0.001) and b-cell function (D CIR120 2 D FMD: r ¼ 0.400, P ¼ 0.012) were directly correlated with increases in FMD and inversely correlated with decreases in BP (D ISI 2 D 24-h SBP: r ¼ 20.368, P ¼ 0.022; D ISI 2 D 24-h DBP r ¼ 20.384, P ¼ 0.017). Thus, FRDC ameliorated insulin sensitivity and b-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.