Differential effect of polyphenol-rich dark chocolate on biomarkers of glucose metabolism and cardiovascular risk factors in healthy, overweight and obese subjects: a randomized clinical trial.

摘要

Association between excess cortisol and various parameters of metabolic syndrome including hypertension, insulin resistance and dyslipidaemia is increasingly recognized. A single-blind randomized placebo-controlled cross-over study compared the effect of polyphenols-rich dark chocolate (DC) on biomarkers of glucose metabolism, lipid profile and blood pressure (BP) in females with BMI >=25 kg m--2 (n = 21) and females with BMI <25 kg m--2 (n = 21). Volunteers consumed 20 g of DC containing 500 mg polyphenols or a placebo DC with negligible polyphenols-content daily for 4 wk, separated by a 2 wk washout period. Systolic BP and diastolic BP decreased after 4 wk of polyphenols-rich DC. Placebo raised fasting insulin, homeostasis model assessment of insulin resistance (HOMA-IR) and salivary cortisol, an effect that was markedly different from polyphenols-rich DC which had a negligible effect on fasting insulin, HOMA-IR and salivary cortisol. Females with BMI >=25 kg m--2 responded less favourably to placebo than lean females and consequently had higher fasting insulin and HOMA-IR, in addition to a lower quantitative sensitivity check index (QUICKI) after ingestion of placebo compared to polyphenols-rich DC. No significant changes in lipid profile were observed. Results provide evidence for the metabolic benefits of consuming polyphenols-rich dark chocolate while demonstrating the possibility of adverse effects occurring with polyphenols-poor chocolate placebo.