Assessing the respective contributions of dietary flavanol monomers and procyanidins in mediating cardiovascular effects in humans: randomized, controlled, double-masked intervention trial

Am J Clin Nutr. 2018 Dec 1;108(6):1229-1237. doi: 10.1093/ajcn/nqy229.


Background: Flavanols are an important class of food bioactives that can improve vascular function even in healthy subjects. Cocoa flavanols (CFs) are composed principally of the monomer (-)-epicatechin (∼20%), with a degree of polymerisation (DP) of 1 (DP1), and oligomeric procyanidins (∼80%, DP2-10).

Objective: Our objective was to investigate the relative contribution of procyanidins and (-)-epicatechin to CF intake-related improvements in vascular function in healthy volunteers.

Design: In a randomized, controlled, double-masked, parallel-group dietary intervention trial, 45 healthy men (aged 18-35 y) consumed the following once daily for 1 mo: 1) a DP1-10 cocoa extract containing 130 mg (-)-epicatechin and 560 mg procyanidins, 2) a DP2-10 cocoa extract containing 20 mg (-)-epicatechin and 540 mg procyanidins, or 3) a control capsule, which was flavanol-free but had identical micro- and macronutrient composition.

Results: Consumption of DP1-10, but not of either DP2-10 or the control capsule, significantly increased flow-mediated vasodilation (primary endpoint) and the concentration of structurally related (-)-epicatechin metabolites (SREMs) in the circulatory system while decreasing pulse wave velocity and blood pressure. Total cholesterol significantly decreased after daily intake of both DP1-10 and DP2-10 as compared with the control.

Conclusions: CF-related improvements in vascular function are predominantly related to the intake of flavanol monomers and circulating SREMs in healthy humans but not to the more abundant procyanidins and gut microbiome-derived CF catabolites. Reduction in total cholesterol was linked to consumption of procyanidins but not necessarily to that of (-)-epicatechin. This trial was registered at as NCT02728466.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Pressure / drug effects
  • Cacao / chemistry*
  • Cardiovascular Physiological Phenomena / drug effects*
  • Catechin / administration & dosage*
  • Catechin / blood
  • Catechin / pharmacokinetics
  • Cholesterol / blood
  • Diet*
  • Double-Blind Method
  • Endothelium, Vascular / drug effects
  • Endothelium, Vascular / physiology
  • Flavonols / administration & dosage*
  • Humans
  • Male
  • Plant Extracts / chemistry
  • Proanthocyanidins / administration & dosage*
  • Young Adult


  • Flavonols
  • Plant Extracts
  • Proanthocyanidins
  • Catechin
  • Cholesterol

Associated data