Two weeks of cocoa consumption enhances insulin-mediated vasodilatation, but does not improve blood pressure or insulin resistance in essential hypertension, according to a recent study published in the American Journal of Clinical Nutrition.

For this randomized, placebo-controlled, double-blind, crossover trial, individuals with essential hypertension (n = 20) received 150 ml of a flavanol-rich cocoa drink twice a day. Antihypertensive medications were discontinued before study enrollment. After a seven-day cocoa-free run-in period, cocoa or flavanol-poor placebo treatment for two weeks was followed by a one-week washout and then crossover to the other treatment arm.

Blood pressure was measured three times per week. At baseline and after each treatment period, researchers 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 indicate cocoa treatment over the two-week period increased insulin-stimulated changes in brachial artery diameter when compared with placebo. However, 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.