Novel Research Investigates Dose Dependency and Causal Relationship Between Diet and Cardiac Function

Cocoa StudyIt has become an accepted belief that “dark chocolate is good for the heart.” While myriad data support the link between cocoa ingestion and improved heart health, what is less clear is the amount of cocoa and the reason. Research being conducted at Penn State Hershey Heart and Vascular Institute seeks to clarify these important points.

Kevin D. Monahan, Ph.D., associate professor at Penn State College of Medicine, examined dose-dependent increases in brachial artery flow-mediated dilation (FMD) acutely with responses measured over two hours after older adults in good health ingested cocoa. The study hypothesized that the favorable effects of flavonoids, such as those found in cocoa, on the endothelium may result in positive cardiovascular effects. A dose-dependent relationship was seen between cocoa ingestion and an increase in endothelium-dependent vasodilation measured by FMD.1 Positive cardiovascular effects were observed with ingestion of between five and twenty-six grams of cocoa.1

Although many studies of the cocoa-heart health relationship exist, less is known of the correlation between heart health and grape consumption. “Grapes are often included in the larger category of ‘fruits and vegetables’ in the questionnaire-type studies most often conducted of patient diet,” says Monahan. These studies, he continues, specialize in identifying risk factors, and influence recommendations on risk reduction, while a study currently being conducted by his team examines the ways such substances are beneficial.

Study participants are coronary artery disease (CAD) patients who have undergone coronary artery bypass graft (CABG) surgery. While CABG can correct blockages of the large coronary vessels, Monahan believes that downstream smaller arteries may become dysfunctional and remain dysfunctional even after surgery, and is investigating the effect grape consumption can have on the small coronary vessel vasodilator function in these patients.2 This randomized, double-blinded, placebo-controlled study drawn from the pool of CAD patients utilizes the novel intervention of grape consumption to address this question of pathophysiologic and clinical significance.2

By showing evidence for the novel role of cocoa and grapes in improving cardiovascular health, particularly in at-risk patient groups, these studies may influence specific dietary recommendations by the medical establishment.

Kevin Monahan, Ph.D.Kevin D. Monahan, Ph.D.
Associate Professor, Medicine
Phone: 717-531-8407
Graduate Study: Doctorate, Kinesiology, University of Colorado, Boulder, Colorado

1. Monahan KD, Feehan RP, Kunselman, AR, et al. Dose-dependent increases in flow-mediated dilation following acute cocoa ingestion in healthy older adults. J Appl Physiol 111:1568–1574, 2011.
2. Monahan KD. Research proposal: Does grape consumption improve coronary vascular regulation in coronary artery disease patients after coronary artery bypass graft surgery? Grant application submitted to the California Table Grape Commission, January 2013.

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