The effect of polyphenol-rich dark chocolate on fasting capillary whole blood glucose, total cholesterol, blood pressure and glucocorticoids in healthy overweight and obese subjects

Abstract

Numerous studies indicate that polyphenol-rich chocolate reduces fasting blood glucose, blood pressure (BP) and total cholesterol in healthy individuals and hypertensives with or without glucose intolerance. The aim of the present study was to investigate the effect of two doses of polyphenol-rich dark chocolate (DC) on fasting capillary whole blood glucose, total cholesterol and BP and to examine whether improvements in these parameters are associated with changes in adrenocorticoid excretion in overweight and obese individuals. The study used a randomised, single-blind, cross-over design where fourteen overweight and obese subjects were randomised to either take 20 g DC with 500 mg polyphenols then 20 g DC with 1000 mg polyphenols or vice-versa. Participants followed each diet for 2 weeks separated by a 1-week washout period. It was observed that the 500 mg polyphenol dose was equally effective in reducing fasting blood glucose levels, systolic BP (SBP) and diastolic BP (DBP) as the 1000 mg polyphenol dose suggesting that a saturation effect might occur with increasing dose of polyphenols. There was also a trend towards a reduction in urinary free cortisone levels with both groups although it did not reach statistical significance. No changes in anthropometrical measurements were seen. We suggest that more research is required to investigate the mechanism(s) by which polyphenol-rich foods influence health.Dark chocolate: Glucose: Blood pressure: Cholesterol: Glucocorticoids: Obesity Epidemiological studies link high polyphenol intake with reduced risk of oxidative stress-related diseases like diabetes, hypertension and CVD (1 -3) . In particular, consumption of cocoa and dark chocolate (DC) has been shown to improve endothelium function, insulin sensitivity, blood pressure (BP) in healthy individuals, hypertensives with or without glucose intolerance (4 -6) and obese subjects (7) . Cocoa and DC are rich sources of polyphenols providing on average more polyphenols per serving than red wine, green tea or black tea (8) . These polyphenols confer potent antioxidant properties to cocoa and DC (8,9) in addition to the ability to regulate NO (4 -7) .Obesity is known to be associated with insulin resistance and elevated BP (10) . One of the underlying factors linked to these cardiovascular risk factors is abnormal cortisol metabolism (11,12) . Cortisol is a counterregulatory hormone that is essential in the long-term maintenance of blood glucose (13) and which could also unfavourably influence BP and lipid profile (12 -15) . When present in excess, cortisol induces overproduction of reactive oxygen species (16,17) leading to reduced endothelial NO synthase expression (18) . In obesity, particularly abdominal obesity, postprandial hypercortisolism and enhanced peripheral metabolism of cortisol, characterised by increased urinary cortisone-to-cortisol ratio, are observed which are linked to insulin resistance and increased fasting insulin (11) . Increased expression of subcutaneous adipose tissue 11b-hydroxysteroid ...

Oxidised LDL levels decreases after the consumption of ready-to-eat meals supplemented with cocoa extract within a hypocaloric diet

“…The improvements were observed in both groups, indicating that cocoa supplementation did not have additional effect on those variables and attributing the observed changes to the hypocaloric diet followed by the volunteers. Our results are in agreement with two previous studies and one meta-analysis, in which no changes were observed in body size and composition of overweight/obese subjects after the cocoa supplementation (9,16,17). Golomb et al observed a negative correlation between the frequency of dark chocolate consumption and BMI (18).…”

“…Several studies have observed a strong link between their consumption and a decrease of blood pressure (BP) levels (9). Moreover, cocoa flavanols can influence blood lipid levels by decreasing lowdensity lipoprotein-cholesterol (LDL-c), increasing high-density lipoprotein-cholesterol (HDL-c) and inhibiting oxidized LDL-c production (oxLDL), which is one of the most important triggers implicated in atherosclerosis (10,11).…”

Use of dark chocolate for diabetic patients: a review of the literature and current evidence

“…Cocoa’s effects on insulin resistance may be dependent on its continual consumption over a longer period of time. Two studies have indicated improvements within two weeks of insulin-mediated vasodilation (through increased NOS levels) and fasting capillary whole blood glucose, but the two week trial period did not demonstrate improved measures of insulin resistance [20,25]. …”

Nutritional recommendations for individuals with Flammer syndrome

“…This is due to the action of flavan-3-ols which augment endothelial NOS and thereby enhance the production of nitric oxide (NO), thereby improving endothelium-dependant vasorelaxation [95]. Cacao decreases blood pressure [96,97], increases insulin sensitivity [96], increases HDL cholesterol concentrations [98] and reduces blood platelet stickiness and clotting [91,92].…”