Acute consumption of flavanol-rich cocoa and the reversal of endothelial dysfunction in smokers

J Am Coll Cardiol. 2005 Oct 4;46(7):1276-83. doi: 10.1016/j.jacc.2005.06.055.


Objectives: This study was designed to assess the effect of flavanol-rich food on the circulating pool of bioactive nitric oxide (NO) and endothelial dysfunction in smokers.

Background: Studies suggest that smoking-related vascular disease is caused by impaired NO synthesis and that diets rich in flavanols can increase bioactive NO in plasma.

Methods: In smokers (n = 11), the effects of flavanol-rich cocoa on circulating NO species in plasma (RXNO) measured by reductive gas-phase chemiluminescence and endothelial function as assessed by flow-mediated dilation (FMD) were characterized in a dose-finding study orally administering cocoa containing 88 to 370 mg flavanols and in a randomized double-blind crossover study using 100 ml cocoa drink with high (176 to 185 mg) or low (<11 mg) flavanol content on two separate days. In addition to cocoa drink, ascorbic acid and NO-synthase inhibitor L-NMMA (n = 4) were applied.

Results: There were significant increases in RXNO (21 +/- 3 nmol/l to 29 +/- 5 nmol/l) and FMD (4.5 +/- 0.8% to 6.9 +/- 0.9%, each p < 0.05) at 2 h after ingestion of 176 to 185 mg flavanols, a dose potentially exerting maximal effects. These changes correlated with increases in flavanol metabolites. Cocoa-associated increases in RXNO and FMD were reversed by L-NMMA. Ascorbic acid had no effect.

Conclusions: The circulating pool of bioactive NO and endothelium-dependent vasodilation is acutely increased in smokers following the oral ingestion of a flavanol-rich cocoa drink. The increase in circulating NO pool may contribute to beneficial vascular health effects of flavanol-rich food.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Beverages*
  • Cacao*
  • Cross-Over Studies
  • Double-Blind Method
  • Endothelium, Vascular / drug effects*
  • Endothelium, Vascular / physiopathology*
  • Female
  • Flavonoids / pharmacology*
  • Humans
  • Male
  • Nitric Oxide / blood
  • Smoking / blood
  • Smoking / physiopathology*


  • Flavonoids
  • Nitric Oxide
  • flavan-3-ol