Acute cocoa ingestion decreases spontaneous cardiac baroreflex sensitivity in healthy older adults

Prior reports suggested the beneficial effects of cocoa intake on cardiovascular system. However, the effects of cocoa on cardiac baroreflex sensitivity (CBRS) remain poorly understood. In this study, we hypothesized that cocoa ingestion would increase CBRS in a dose-dependent manner. Seventeen healthy older adults (61 ± 8 yrs; 8 M, 9 F) participated in five trials using 250 ml drinks containing 0, 2, 5, 13, or 26 grams of cocoa, while the drinks had a similar appearance and taste. The trials were conducted in a randomized, double-blind design, at the same time each morning, with at least 72 hours between sessions. Two hours after ingesting the experimental drink, beat-by-beat heart rate (HR) and blood pressure (BP) were recorded in a supine position. Spontaneous CBRS was calculated from the beat-by-beat systolic BP and R-R interval data using a sequence method. There were no significant differences in BP and HR after ingesting the drink across all visits (repeated measures ANOVA; P > 0.05). Cocoa ingestion dose-dependently decreased CBRS (repeated measures ANOVA, P = 0.009). CBRS was significantly lower following 26 g of cocoa compared to 0 g (12.1 ± 5.7 vs. 18.2 ± 7.7 ms/mmHg, post-hoc test, P = 0.018). Addtionally, CBRS was significantly and negatively correlated with cocoa dose (R= -0.35, P = 0.003). The data suggest that acute cocoa ingestion dose-dependently reduces CBRS in healthy older adults. As reduced CBRS may be associated with increased cardiovascular risks, this potential effect of cocoa warrants attention despite its known cardiovascular benefits.