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 yr; 8 M, 9 F) participated in five trials using 250-mL drinks containing 0, 2, 5, 13, or 26 g of cocoa, whereas 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 h 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 RR 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 with 0 g (12.1 ± 5.7 vs. 18.2 ± 7.7 ms/mmHg, post hoc test, P = 0.018). In addition, 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.NEW & NOTEWORTHY Evidence suggests that regular consumption of cocoa products reduces the risk of cardiovascular disease. However, the present study demonstrates that acute cocoa ingestion decreases cardiac baroreflex sensitivity (CBRS) in a dose-dependent manner in healthy older adults. Because low CBRS may be associated with adverse cardiovascular events, the effects of cocoa on reducing CBRS warrant attention, particularly in individuals with compromised cardiovascular regulation.