Vasculoprotective Effects of Dietary Cocoa Flavanols in Patients on Hemodialysis: A Double-Blind, Randomized, Placebo-Controlled Trial

Clin J Am Soc Nephrol. 2016 Jan 7;11(1):108-18. doi: 10.2215/CJN.05560515. Epub 2015 Dec 17.


Background and objectives: Hemodialysis (HD) per se entails vascular dysfunction in patients with ESRD. Endothelial dysfunction is a key step in atherosclerosis and is characterized by impaired flow-mediated dilation (FMD). Interventional studies have shown that cocoa flavanol (CF)-rich supplements improve vascular function. Aim of this study was to investigate the effect of flavanol-rich bioactive food ingredients on acute and chronic HD-induced vascular dysfunction in ESRD.

Design, setting, participants, & measurements: We conducted a randomized, double-blind, placebo-controlled trial from 2012 to 2013. Fifty-seven participants were enrolled, ingested CF-rich beverages (900 mg CF per study day), and were compared with those ingesting CF-free placebo. This included (1) a baseline cross-over acute study to determine safety and efficacy of CF and (2) a subsequent chronic parallel group study with a 30-day follow-up period to study effects of CF on HD-mediated vascular dysfunction entailing (3) an acute substudy during HD in flavanol-naive patients and (4) an acute on chronic study during HD. Primary and secondary outcome measures included changes in FMD and hemodynamics.

Results: CF ingestion was well tolerated. Acute ingestion improved FMD by 53% (3.2±0.6% to 4.8±0.9% versus placebo, 3.2±0.7% to 3.3±0.8%; P<0.001), with no effects on BP or heart rate. A 30-day ingestion of CF led to an increase in baseline FMD by 18% (3.4±0.9% to 3.9±0.8% versus placebo, 3.5±0.7% to 3.5±0.7%; P<0.001), with reduced diastolic BP (73±12 to 69±11 mmHg versus placebo, 70±11 to 73±13 mmHg; P=0.03) and increased heart rate (70±12 to 74±13 bpm versus placebo, 75±15 to 74±13 bpm; P=0.01). No effects were observed for placebo. Acute ingestion of CF during HD alleviated HD-induced vascular dysfunction (3.4±0.9% to 2.7±0.6% versus placebo, 3.5±0.7% to 2.0±0.6%; P<0.001). This effect was sustained throughout the study (acute on chronic, 3.9±0.9% to 3.0±0.7% versus placebo, 3.5±0.7% to 2.2±0.6; P=0.01).

Conclusions: Dietary CF ingestion mitigates acute HD-induced and chronic endothelial dysfunction in patients with ESRD and thus, improves vascular function in this high-risk population. Larger clinical trials are warranted to test whether this translates into an improved cardiovascular prognosis in patients with ESRD.

Keywords: blood pressure; cocoa-flavanols; double-blind method; endothelial function; heart rate; hemodialysis; hemodynamics; humans; kidney failure, chronic; nutrition; vascular functions.

Publication types

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

MeSH terms

  • Adult
  • Aged
  • Cacao / chemistry*
  • Catechin / pharmacology
  • Cross-Over Studies
  • Dietary Supplements
  • Double-Blind Method
  • Endothelium, Vascular / drug effects
  • Endothelium, Vascular / physiopathology
  • Female
  • Humans
  • Kidney Failure, Chronic / physiopathology*
  • Kidney Failure, Chronic / therapy
  • Male
  • Middle Aged
  • Polyphenols / pharmacology*
  • Protective Agents / pharmacology
  • Renal Dialysis / adverse effects*
  • Vasodilation / drug effects*


  • Polyphenols
  • Protective Agents
  • Catechin