Flavonol-rich cocoa can help blood blow

Consumption of cocoa rich in flavonols, a sub-group of naturally occurring flavonoids, may be associated with the modulation of nitric oxide, according to new research from a team of scientists at Brigham and Women's Hospital and Harvard Medical School.

Nitric oxide is a compound critical for healthy blood flow and blood pressure and has been identified by scientists as an important compound in the area of cardiovascular health. It is produced in the lining of blood vessels and its major functions include opening up the arteries to increase blood flow, maintain elasticity and prevent platelets from adhering to artery walls.

The new 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 Norman Hollenberg, lead investigator of the cocoa study. "If our research results continue to support a link between consumption of flavonol-rich cocoa and nitric oxide synthesis, there could be significant implications for public health."​

Dr Hollenberg's research began as an investigation into the difference between the isolated, island-dwelling Kuna Amerinds in Central America, who have a low tendency toward developing age-related hypertension, and Kuna who had migrated to the mainland, who do develop hypertension with age.

It was observed that the island-dwelling Kuna had significantly higher nitrite/nitrate excretion than those on the mainland, which suggested that the nitric oxide pathway might be involved. The team learned that the Kuna consume large quantities of cocoa and pursued the idea that the flavonol-rich food might be one of the reasons for the differences.

To test their hypothesis, Dr Hollenberg's team fed Boston volunteers cocoa with either a high amount or low amount of flavonols. The cocoa was made by US confectionery giant Mars. In the Boston study, subjects who consumed the high-flavonol cocoa 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-flavonol cocoa used in the study was comparable to that consumed by the Kuna.

Researchers at the University of California, Davis, led by Dr Carl Keen, have conducted numerous studies that suggest that consumption of certain flavonol-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 flavonol-rich cocoa beverage and found reductions in platelet aggregation with both. The researchers hypothesised 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.