Acute effect of oral flavonoid-rich dark chocolate intake on coronary circulation, as compared with non-flavonoid white chocolate, by transthoracic Doppler echocardiography in healthy adults

Abstract 

Purpose

To assess the effects of the oral intake of flavonoid-rich dark chocolate on coronary circulation, we measured coronary flow velocity reserve (CFVR) by noninvasive transthoracic Doppler echocardiography (TTDE) in healthy adult subjects.

Materials and methods

The study was a randomized, single-blind design conducted for 2 weeks in 39 healthy men (mean age 29.7±3.9 years, range 23–40 years). Subjects were randomly assigned a daily intake of either flavonoid-rich dark chocolate (Meiji Black Chocolate 45 g, Meiji Seika kaisya Ltd, including cacao polyphenol 550 mg/day, 200 kcal) or non-flavonoid white chocolate (Meiji White Chocolate 35 g, Meiji Seika kaisya Ltd, including cacao polyphenol 0 mg/day, 140 kcal) as a control. CFVR was recorded by TTDE, and assessed before and after 2 weeks of intake. At the same time, we also assessed serum asymmetric dimethylarginine, 8-isoprostanes, and malondialdehyde-modified low-density lipoprotein (MDA-LDL) as markers of oxidative stress.

Results

Flavonoid-rich dark chocolate consumption significantly improved CFVR (3.38±0.49 before intake, 4.28±0.85 after intake; p<0.01), whereas non-flavonoid white chocolate consumption did not (3.28±0.49 before intake, 3.16±0.49 after intake; p=0.44). All predictor variables were used as dependent variables in a multiple regression model of the incremental change in CFVR after 2 weeks of chocolate intake. Intake of dark (but not white) chocolate, MDA-LDL, triglyceride (TG) and heart rate (HR) significantly influenced the change of CFVR after 2 weeks of intake (p<0.01) according to the multiple regression formula: Y=1.01X₁−0.005X₂−0.003X₃−0.017X₄ (Y=change in CFVR after 2 weeks of chocolate intake, X₁=intake of dark (but not white) chocolate, X₂=MDA-LDL, X₃=TG, X₄=HR).

Conclusion

Flavonoid-rich dark chocolate intake significantly improved coronary circulation in healthy adults, independent of changes in oxidative stress parameters, blood pressure and lipid profile, whereas non-flavonoid white chocolate had no such effects.

Keywords: Acute effect, Oral flavonoid-rich dark chocolate intake, Coronary circulation, Non-flavonoid white chocolate, Transthoracic Doppler echocardiography, Healthy adults