The cardiovascular benefits of dark chocolate
Asimina Kerimi and Gary Williamson from the University of Leeds (UK) have found that human intervention studies analysing chocolate consumption are complicated by metabolic dysfunction amongst participants and limited molecular knowledge of flavanols. Their review concluded that future research on chocolate should focus on the effects of individual components on human health.
Dark chocolate (70% cocoa solids or greater) contains many biologically active components, such as catechins, procyanidins and theobromine from cocoa, together with sucrose and lipids. All of these compounds can affect the cardiovascular system directly or indirectly through multiple mechanisms.
Intervention studies on healthy and metabolically dysfunctional volunteers suggest that cocoa improves blood pressure, platelet aggregation and endothelial function. However, the effects of chocolate are not clear because sucrose and fat affect endothelial function negatively in the short-term, through insulin signalling and nitric oxide bioavailability. Understanding this is further complicated by interactions between some components of chocolate that can oppose or complement one another. For example, sugar opposes the impact of epicatechin on flow-mediated dilation (FMD) of blood vessels whilst theobromine and epicatechin act synergistically on the same biomarker.
Studying these effects in human intervention studies is difficult as some benefits might only be observed in individuals with specific characteristics, and often no suitable placebos are available. Thus, whilst many health benefits have been observed, for dark chocolate to receive a health claim, the confounding factors identified in this review need to be addressed first.
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- The impact of components in chocolate on biomarkers, such as flow-mediated dilation (FMD), can oppose or complement one another
- The direct effects of theobromine and epicatechin from chocolate will be short-lived, but any changes in gene expression or cell signalling could last much longer
- The complexities of molecular interactions amongst the various bioactive components in chocolate make human intervention studies using this food very difficult