An enormous number of studies in the last two decades have been devoted to investigating the role of the endothelium in cardiovascular diseases. Nonetheless, the optimal methodology for investigating the multifaceted aspects of endothelial dysfunction is still under debate. Biochemical markers, molecular genetic tests and invasive and non-invasive tools with and without pharmacological and physiological stimuli have been introduced. Furthermore newer pharmacological tools have been proposed. However, the application of these methodologies should fulfil a number of requirements in order to provide conclusive answers in this area of research. Thus, the most relevant methodological issues in the research on endothelial function and dysfunction are summarized in this paper.

Consumption of flavanol-rich dark chocolate (DC) has been shown to decrease blood pressure (BP) and insulin resistance in healthy subjects, suggesting similar benefits in patients with essential hypertension (EH). Therefore, we tested the effect of DC on 24-hour ambulatory BP, flow-mediated dilation (FMD), and oral glucose tolerance tests (OGTTs) in patients with EH. After a 7-day chocolate-free run-in phase, 20 never-treated, grade I patients with EH (10 males; 43.7±7.8 years) were randomized to receive either 100 g per day DC (containing 88 mg flavanols) or 90 g per day flavanol-free white chocolate (WC) in an isocaloric manner for 15 days. After a second 7-day chocolate-free period, patients were crossed over to the other treatment. Noninvasive 24-hour ambulatory BP, FMD, OGTT, serum cholesterol, and markers of vascular inflammation were evaluated at the end of each treatment. The homeostasis model assessment of insulin resistance (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), and insulin sensitivity index (ISI) were calculated from OGTT values. Ambulatory BP decreased after DC (24-hour systolic BP −11.9±7.7 mm Hg, P <0.0001; 24-hour diastolic BP −8.5±5.0 mm Hg, P <0.0001) but not WC. DC but not WC decreased HOMA-IR ( P <0.0001), but it improved QUICKI, ISI, and FMD. DC also decreased serum LDL cholesterol (from 3.4±0.5 to 3.0±0.6 mmol/L; P <0.05). In summary, DC decreased BP and serum LDL cholesterol, improved FMD, and ameliorated insulin sensitivity in hypertensives. These results suggest that, while balancing total calorie intake, flavanols from cocoa products may provide some cardiovascular benefit if included as part of a healthy diet for patients with EH.

Background: Numerous studies indicate that flavanols may exert significant vascular protection because of their antioxidant properties and increased nitric oxide bioavailability. In turn, nitric oxide bioavailability deeply influences insulin-stimulated glucose uptake and vascular tone. Thus, flavanols may also exert positive metabolic and pressor effects. Objective: The objective was to compare the effects of either dark or white chocolate bars on blood pressure and glucose and insulin responses to an oral-glucose-tolerance test in healthy subjects. Design: After a 7-d cocoa-free run-in phase, 15 healthy subjects were randomly assigned to receive for 15 d either 100 g dark chocolate bars, which contained ≈500 mg polyphenols, or 90 g white chocolate bars, which presumably contained no polyphenols. Successively, subjects entered a further cocoa-free washout phase of 7 d and then were crossed over to the other condition. Oral-glucose-tolerance tests were performed at the end of each period to calculate the homeostasis model assessment of insulin resistance (HOMA-IR) and the quantitative insulin sensitivity check index (QUICKI); blood pressure was measured daily. Results: HOMA-IR was significantly lower after dark than after white chocolate ingestion (0.94 ± 0.42 compared with 1.72 ± 0.62; P < 0.001), and QUICKI was significantly higher after dark than after white chocolate ingestion (0.398 ± 0.039 compared with 0356 ± 0.023; P = 0.001). Although within normal values, systolic blood pressure was lower after dark than after white chocolate ingestion (107.5 ± 8.6 compared with 113.9 ± 8.4 mm Hg; P < 0.05). Conclusion: Dark, but not white, chocolate decreases blood pressure and improves insulin sensitivity in healthy persons.

Primary aldosteronism (PA) has been associated with cardiovascular hypertrophy and fibrosis, in part independent of the blood pressure level, but deleterious effects on the kidneys are less clear. Likewise, it remains unknown if the kidney can be diversely involved in PA caused by aldosterone-producing adenoma (APA) and idiopathic hyperaldosteronism (IHA). Hence, in the Primary Aldosteronism Prevalence in Italy (PAPY) Study, a prospective survey of newly diagnosed consecutive patients referred to hypertension centers nationwide, we sought signs of renal damage in patients with PA and in comparable patients with primary hypertension (PH). Patients (n=1180) underwent a predefined screening protocol followed by tests for confirming PA and identifying the underlying adrenocortical pathology. Renal damage was assessed by 24-hour urine albumin excretion (UAE) rate and glomerular filtration rate (GFR). UAE rate was measured in 490 patients; all had a normal GFR. Of them, 31 (6.4%) had APA, 33 (6.7%) had IHA, and the rest (86.9%) had PH. UAE rate was predicted ( P <0.001) by body mass index, age, urinary Na ⁺ excretion, serum K ⁺ , and mean blood pressure. Covariate-adjusted UAE rate was significantly higher in APA and IHA than in PH patients; there were more patients with microalbuminuria in the APA and IHA than in the PH group ( P =0.007). Among the hypertensive patients with a preserved GFR, those with APA or IHA have a higher UAE rate than comparable PH patients. Thus, hypertension because of excess autonomous aldosterone secretion features an early and more prominent renal damage than PH.

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.