Cocoa flavanols and cardioprotective effects

Peer-reviewed | Manuscript received: February27, 2014 | Revision accepted: June 23, 2014

Which flavanols may contribute to cardiovascular health?

Introduction

Studies on the cardioprotective effect of cocoa

Meta-analyses of controlled intervention studies have shown a reduction in blood pressure [1–4] and an increase in flow-mediated dilatation (FMD), which is an indicator of vascular elasticity [3, 4]. Moreover, a decline in LDL-cholesterol [4, 5], triglycerides and insulin in serum as well as an improvement in insulin sensitivity [3, 4] was ascertained. The meta-analysis of Shrime et al. showed the same effects whether or not studies with industrial support were considered [4], while Hooper et al. found only evidence for an increase in FMD [3].

The cardioprotective effects of cocoa are attributed to flavanols, in particular to epicatechin [6]. After a bolus administration (one-time administration) of a flavanol-rich cocoa drink to healthy volunteers, the increase in FMD was dependent on the concentration of epicatechin and its metabolite epicatechin-7-O-glucuronide in plasma [7]. A meta-regression analysis of intervention studies showed that the extent of blood pressure reduction depends on the intake of epicatechin ingested by regular consumption of cocoa products.

Summary

Regular cocoa consumption decreases blood pressure, improves vascular elasticity, and exerts beneficial effects on carbohydrate and lipid metabolism. These effects are attributed to flavanols. However, the question which flavanols in cocoa may be responsible for these effects has not been clarified yet. The flavanols’ bioavailability differs strongly: procyanidins are rarely bioavailable; catechin is bioavailable, but much less than epicatechin. Only the administration of isolated epicatechin, but not catechin, enhanced vascular elasticity in rats. Regression analyses have shown that blood pressure reduction depends on epicatechin intake with the cocoa product and improvement in vascular elasticity on the concentration of epicatechin in plasma, but not on those of catechin. Therefore, epicatechin seems to be responsible for the cardioprotective effects of cocoa. This should be investigated by intervention studies administrating isolated epicatechin and other flavanols in doses that can be ingested with cocoa products.

Keywords: cocoa, flavanols, epictechin, phytochemicals, cardiovascular effects

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