Cocoa Flavanols Protect Dialysis Patients' Cardiovascular System

Researchers observe significant improvements chronic and hemodialysis-induced vascular dysfunction.
Researchers observe significant improvements chronic and hemodialysis-induced vascular dysfunction.

Dietary cocoa flavanols may improve vascular function in patients on hemodialysis (HD), according to a new study.

In a randomized, double-blind study that enrolled 57 HD patients, Tienush Rassaf, MD, of the West German Heart and Vascular Center Essen, University Hospital, Essen, Germany, and colleagues found that acute and chronic ingestion of a cocoa flavanol (CF)-rich beverage (900 mg/day) improved flow-mediated dilation (FMD) compared with placebo.

The researchers concluded that their results demonstrate that CF ingestion is well tolerated and improves endothelial functions in patients with end-stage renal disease (ESRD). “CFs mitigate chronic and HD-induced vascular dysfunction in ESRD,” they wrote in a paper published online ahead of print in the Clinical Journal of the American Society of Nephrology. “CFs may, thus, have the potential to ameliorate vascular dysfunction in this high-risk population.”

The trial consisted of 2 parts: a baseline cross-over acute study to determine safety and efficacy of CF (11 patients) and a subsequent chronic parallel group study with a 30-day follow-up period (52 patients) to study effects of CF on HD-mediated vascular dysfunction.

Acute ingestion of the cocoa flavanols improved FMD by a significant 53% (from 3.2% to 4.8%); 30-day (chronic) ingestion increased FMD by a significant 18% (from 3.4% to 3.9%), and this increase was accompanied by a significant reduction in diastolic blood pressure (from 73 to 69 mm Hg) and increase in heart rate (from 70 to 74 beats per minute) compared with placebo. Placebo recipients experienced no significant increase in FMD.

“Impressively, the degree of reversion of vessel dysfunction was comparable to the effects observed through administering statins or making dietary and lifestyle changes,” Dr. Rassaf said in a press release from the American Society of Nephrology. “Whether this approach also leads to a reduction in mortality is not clear and has to be investigated.”

In an accompanying editorial, Carmine Zoccali, MD, and Francesca Mallamaci, MD, of Ospedali Riuniti, Calabria, Italy, said the findings by Dr. Rassaf's group, if confirmed by other studies, “may be a turning point” in the management of cardiovascular (CV) disease in patients on dialysis.

“Cocoa flavanols seem to be remarkably beneficial for the endothelium in these patients,” they wrote.

Study findings suggest that endothelial dysfunction and perhaps atherosclerosis should not be considered non-modifiable alterations in patients with chronic kidney disease, they noted. “Patients with heart failure were excluded from the trial, but a beneficial effect in these patients seems likely,” they stated.

Drs. Zoccali and Mallamaci observed that some caveats remain. They pointed out, for example, that FMD has not been established as a valid surrogate biomarker in ESRD patients. In spite of the caveats, “the burden of CV disease in patients on dialysis is so devastating that a promising intervention like cocoa flavanols deserves full attention by the nephrology community,” they wrote.

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