Cocoa consumption for 2 wk enhances insulin-mediated vasodilatation without improving blood pressure or insulin resistance in essential hypertension.
BACKGROUND
Essential hypertension is characterized by reciprocal relations between endothelial dysfunction and insulin resistance. Cocoa flavanols stimulate production of the vasodilator nitric oxide from vascular endothelium.


OBJECTIVE
The objective was to test the hypothesis that consumption of cocoa may simultaneously lower blood pressure, improve endothelial dysfunction, and ameliorate insulin resistance in subjects with essential hypertension.


METHODS
We conducted a randomized, placebo-controlled, double-blind, crossover trial of a flavanol-rich cocoa drink (150 mL twice a day, approximately 900 mg flavanols/d) in individuals with essential hypertension (n = 20). Antihypertensive medications were discontinued before study enrollment. After a 7-d cocoa-free run-in period, cocoa or flavanol-poor placebo (approximately 28 mg flavanols/d) treatment for 2 wk was followed by a 1-wk washout and then crossover to the other treatment arm. Blood pressure was measured thrice weekly. At baseline and after each treatment period, we assessed insulin sensitivity (hyperinsulinemic-isoglycemic glucose clamp) and insulin-stimulated changes in brachial artery diameter and forearm skeletal muscle capillary recruitment (Doppler ultrasound with or without microbubble contrast).


RESULTS
Cocoa treatment for 2 wk increased insulin-stimulated changes in brachial artery diameter when compared with placebo [median percentage increase from baseline (25th-75th percentile): 8.3 (4.2-11.3) compared with 5.9 (-0.3 to 9.6); P < 0.04]. Nevertheless, cocoa treatment did not significantly reduce blood pressure or improve insulin resistance and had no significant effects on skeletal muscle capillary recruitment, circulating plasma concentrations of adipocytokines, or endothelial adhesion molecules.


CONCLUSIONS
Daily consumption of flavanol-rich cocoa for 2 wk is not sufficient to reduce blood pressure or improve insulin resistance in human subjects with essential hypertension. This trial was registered at clinicaltrials.gov as NCT00099476.
Muniyappa
Ranganath
R
Diabetes Unit, National Center for Complementary and Alternative Medicine, National Institutes of Health, Bethesda, MD, USA.
Hall
Gail
G
Kolodziej
Terrie L
TL
Karne
Rajaram J
RJ
Crandon
Sonja K
SK
Quon
Michael J
MJ
D000328:Adult; D000368:Aged; D001628:Beverages; D001916:Brachial Artery; D002099:Cacao / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004730:Endothelium, Vascular / Q000187:drug effects*; D005260:Female; D044948:Flavonols / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D015309:Glucose Clamp Technique; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000188:drug therapy*; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow; D016896:Treatment Outcome; D055815:Young Adult
D044948:Flavonols; D007328:Insulin