New research suggests that consumption of a cocoa rich in flavanols, a sub-group of naturally occurring flavonoids, may be associated with the modulation of nitric oxide, the compound essential to healthy hearts.
This new preliminary research was presented during a symposium at the annual meeting of the American Association for the Advancement of Science (AAAS).
"Nitric oxide plays such an important role in the maintenance of healthy blood pressure and, in turn, cardiovascular health," said lead investigator Norman Hollenberg, professor of medicine at Brigham and Women's Hospital and Harvard Medical School. "If our research results continue to support a link between consumption of flavanol-rich cocoa and nitric oxide synthesis, there could be significant implications for public health."
Dr Hollenberg's research began as an inquiry into the difference between the isolated, island-dwelling Kuna Amerinds in Central America, who had a low tendency toward developing age-related hypertension, and Kuna who had migrated to the mainland, who did develop hypertension with age. It was observed that the island-dwelling Kuna had significantly higher nitrite/nitrate excretion than those on the mainland, which suggests that the nitric oxide pathway may be involved.
The team learned that the Kuna consume large quantities of cocoa, findings that are published in the most recent issue of the Journal of Food Composition and Analysis, and they pursued the idea that this flavanol-rich food may play a part.
To test this hypothesis, they fed Boston volunteers cocoa with either a high amount or low amount of flavanols, each of which was made for this study by Mars. In the Boston study, subjects who consumed the high-flavanol cocoa, but not the low-flavanol version, displayed a renal plasma flow response that was consistent with the hypothesis that the nitric oxide pathway may play a role.
Research is currently underway that will conclusively determine whether or not modulation of nitric oxide synthesis is the responsible mechanism for these positive observations. The high-flavanol cocoa used in the study was comparable to that consumed by the Kuna.
The nitric oxide mechanism of action may be similar to the method of action in certain pharmaceuticals products, like nitroglycerin. Nitric oxide is produced in the lining of blood vessels. Its major functions include opening up the arteries to increase blood flow, maintain elasticity and prevent platelets from adhering to artery walls. These protective mechanisms are important for good cardiovascular health.
Researchers at the University of California, Davis, led by Dr Carl Keen, have conducted numerous studies that suggest that consumption of certain flavanol-rich cocoa and chocolate may positively affect cardiovascular biomarkers.
The latest research, which also was presented at the AAAS symposium for the first time, simultaneously compared low-dose aspirin and a flavanol-rich cocoa beverage and found reductions in platelet aggregation with both. The researchers hypothesize that the responsible mechanism for the favourable platelet effects may well be related to the nitric oxide mechanism suggested by the on-going research of Dr Hollenberg at Harvard.