The Effects Of Acute Consumption Of A Brewed Cocoa Beverage On Endothelial Function

Abstract

Previous studies have shown that the polyphenol components of cocoa can improve the health and function of blood vessels. It is currently unknown whether consuming a brewed drink made from roasted cocoa beans has the same beneficial effects on blood vessel function. PURPOSE: The purpose of this study was to assess the acute effects of consuming brewed cocoa on resting blood pressure and endothelial function using near-infrared spectroscopy (NIRS) to evaluate changes in tissue oxygen saturation (StO2) following blood vessel occlusion. METHODS: A total of 15 healthy college-aged adults participated in this study. StO2 levels were monitored continuously throughout the test using a NIRS device placed on the flexor digitorum profundus of the dominant arm. Baseline StO2 levels were measured for 5 minutes following 10 minutes of supine rest, after which blood flow to the forearm was occluded for 3 minutes using a blood pressure cuff inflated to 50mmHg above resting systolic pressure, followed by a 5-minute period of reperfusion following release of the cuff. Subjects then consumed either plain water, or the cocoa treatment (40g of roasted cocoa brewed for 10 minutes), and all testing was repeated 90 minutes later. Subjects returned to the lab on a separate day to repeat the test using the opposite beverage. RESULTS: The change from baseline was not significantly different between water (W) and cocoa (C) for resting heart rate (C= -6.6+6.5 bpm, W= -4.4+7.0 bpm; p=0.29), resting systolic blood pressure (C= 0.9+4.5 mmHg, W= -2.2+7.4 mmHg; p=0.10), resting diastolic blood pressure (C= -1.1+6.7 mmHg, W= 0.8+4.5 mmHg; p=0.39), pre-occlusion StO2 (C= 1.6+5.6 %, W= -1.9+6.9%; p=0.06), minimum StO2 during occlusion (C= -0.6+10.5 %, W= -0.7+12.8%; p=0.98), reperfusion maximum StO2 (C= 0.5+3.6 %, W= -0.8+5.0 %; p=0.40), or reperfusion rate quantified as the slope of the StO2 during the first 10 seconds of reperfusion (C= 0.1+0.4 % s-1, W= 0.06+0.4 % s-1; p=0.79). CONCLUSION: Consumption of a brewed cocoa drink does not significantly affect markers of endothelial function or blood pressure in healthy college-aged adults.