A team of international researchers claims to have ‘direct evidence’ for a cocoa flavanol improving blood vessel relaxation.Flavonols are found naturally in chocolate, fruit, red wine and teas, and have previously been linked to improvements in heart health.The new study, sponsored by confectionary giant Mars, examined the effect on blood vessel relaxation of chocolate flavanols in the form of a specially prepared cocoa drink, and then a drink containing isolated, cocoa-derived (-)epicatechin.“Applying accepted causality criteria and gold standard methodologies, we have been able to advance our understanding of the relationship between the intake of certain flavanols present in cocoa, their absorption into the circulation, and their effects on cardiovascular function,” said lead author Hagen Schroeter, from the University of California, Davis.The initial randomised, double-blind, cross-over study gave volunteers a specially prepared cocoa drink containing either high or low concentrations of specific cocoa flavanols. Only the group that consumed the flavanol rich drink showed blood vessel relaxation.A follow-on “proof-of-concept” study gave volunteers either a placebo drink or a drink containing isolated, cocoa-derived (-)epicatechin. The latter test group experienced similar blood vessel relaxation as for the flavanol-rich cocoa drink.The role of (-)epicatechin was directly linked to nitric oxide, a molecule used by the endothelium to signal surrounding muscle to relax, thereby dilating the blood vessels and increasing blood flow. This supports previous research by individual team members suggesting a link between nitric oxide and cocoa flavanols.
