A single dose of dark chocolate increases parasympathetic modulation and heart rate variability in healthy subjects

Ana Amélia Machado Duarte,Katya Rigatto,Cristiano Mostarda,Maria Claudia Irigoyen

doi:10.1590/1678-98652016000600002

Abstract

ABSTRACT Objective: The aim of this study was to investigate the acute effect of a single dose of dark chocolate (70% cocoa) on blood pressure and heart rate variability. Methods: Thirty-one healthy subjects (aged 18-25 years; both sexes) were divided into two groups: 10 subjects in the white chocolate (7.4 g) group and 21 in the dark chocolate (10 g) group; measurements were performed at the university's physiology lab. An electrocardiogram measured the sympathovagal balance by spectral and symbolic analysis. Results: A single dose of dark chocolate significantly reduced systolic blood pressure and heart rate. After consuming 10 g of dark chocolate, significant increases were observed for heart rate variability, standard deviation of RR intervals standard deviation of all NN intervals, square root of the mean squared differences between adjacent normal RR intervals root mean square of successive differences, and an increase in the high frequency component in absolute values, representing the parasympathetic modulation. Conclusion: In conclusion the importance of our results lies in the magnitude of the response provoked by a single dose of cocoa. Just 10 g of cocoa triggered a significant increase in parasympathetic modulation and heart rate variability. These combined effects can potentially increase life expectancy because a reduction in heart rate variability is associated with several cardiovascular diseases and higher mortality.

Highlights

Studies indicate that consumption of foods rich in polyphenols is associated with lower risk of disease[1,2] and with a decreased risk of morbidity and mortality[3]
Just 10 g of cocoa triggered a significant increase in parasympathetic modulation and heart rate variability
Diastolic Blood Pressure (DBP), MAP, and Pulse Pressure (PP) did not change in either group (Table 1)

Summary

Introduction

Studies indicate that consumption of foods rich in polyphenols is associated with lower risk of disease[1,2] and with a decreased risk of morbidity and mortality[3] Cocoa products, such as dark chocolate, which are rich in polyphenols, have demonstrated beneficial effects, on the cardiovascular system[4,5]. DARK CHOCOLATE AND HEART RATE VARIABILITY | 767 with the peripheral afferent nerve fibers that carry BP information to the central nervous system. This mechanism includes the sympathetic and/or parasympathetic activation that changes Heart Rate (HR) to promote BP stabilization[17]. Good BP adaptation is an indication of high HRV, whereas lower HRV is frequently an indicator of abnormal and/or insufficient adaptation of cardiac Autonomic Nervous System (ANS) modulation[21]

Methods

Results

Discussion

Conclusion