Davis, CA - Researchers in the US and Germany have identified a flavanol found in cocoa, red wine, and green tea that improves vascular relaxation, potentially explaining why these foods appear to improve cardiovascular health. Their study, which focused on flavanols in cocoa—and was partially funded by Mars Inc—provides the first direct evidence that the flavanol (-)epicatechin is an important mediator of vascular function. The finding has implications for dietary and pharmaceutical approaches to treating and preventing cardiovascular disease (CVD), the authors say.

The study, by Dr Hagen Schroeter (University of California, Davis) and colleagues, was published online January 17, 2006 in the Proceedings of the National Academy of Sciences [1].

[Source: Cocoapro]

In the first of several experiments described in the paper, Schroeter and colleagues performed a randomized, double-blind, crossover study in healthy male volunteers, demonstrating that a cocoa drink high in flavanols produced a significant transient increase in flow-mediated dilation within one to four hours after consumption, while a cocoa drink low in flavanols produced no such response. To confirm that the vascular effects were caused by flavanol content and not another compound in cocoa, the investigators gave study subjects a drink containing cocoa-derived (-)epicatechin or a placebo beverage and observed that only those receiving the (-)epicatechin-rich drink experienced vessel relaxation and an increase in circulating nitric oxide. Next, the investigators inhibited nitric-oxide synthase and found that flavonoid-induced relaxation did not occur, underscoring the importance of nitric oxide as a key mechanistic component controlling endothelial response to flavanols.

In yet another series of experiments described in the paper, the authors studied two groups of Panama Kuna Indians—a population whose people traditionally drink an average of three to four cups of flavanol-rich cocoa every day. Indigenous island-dwelling Kuna Indians still consume the traditional high amounts of cocoa, but those who have moved to the mainland city suburbs drink substantially less. Previous studies have demonstrated that the island-dwelling Kuna Indians also have lower blood pressure than their city-dwelling counterparts. Now, in an observation that helps link the new flavanol findings to the earlier research, Schroeter et al report that the islanders have higher circulating levels of both flavanols and nitric-oxide metabolites, while mainland Kuna Indians have lower circulating levels of both.

"These findings suggest that frequent intake of cocoa flavanols can have biological effects with important implications for long-term cardiovascular health," coauthor Dr Norman K Hollenberg (Brigham and Women's Hospital, Boston, MA) commented in a press statement.

While the focus of the current research was cocoa, the authors emphasize that other plant foods with high epicatechin content would likely have similar vascular effects and as such, epicatechin content may be responsible for the well-described cardiovascular benefits of purple grape juice, tea, and red wine.

"Thus, the findings in the current paper may provide new avenues to dietary or therapeutic interventions aimed at improving and maintaining cardiovascular health," the authors write.

As well, the data provide a possible mechanism by which diets that emphasize fruits and vegetables reduce CVD. "Although it has been argued that the inverse relationship between plant-based diets and CVD may be the result of the absence of dietary components associated with vascular risk (eg, high fat and high cholesterol) in such diets, our data support the notion that it is, at least in part, the presence of beneficial components, such as flavanols, that drive these positive inverse correlations," the authors conclude.