Researchers Report Mechanism For Anti-clotting Effects Of Purple Grape Juice Unrelated to Alcohol
Flavonoids found in purple grape juice thought to increase nitric oxide levels while reducing free radical production
DALLAS, Texas, November 10, 1998
The so-called French Paradox seems a little less mysterious today as researchers reported that flavonoids found in purple grape juice, also found in red wine, stimulate platelet production of nitric oxide—a chemical which plays a role in inhibiting platelet aggregation and thrombus formation. Preliminary studies in both humans and animals have previously reported the effects of drinking purple grape juice on platelet aggregation. Studies have reported similar anti-platelet effects for red wine. The mechanisms behind these potentially beneficial effects, however, are not fully understood.
In a laboratory study presented today at the 71st Scientific Sessions of the American Heart Association, Jane E. Freedman, M.D., assistant professor of medicine and pharmacology at Georgetown University Medical Center, found that blood platelets bathed in a dilute solution of purple grape juice released three times more nitric oxide (NO) than those in a control group.
"The process by which coronary artery disease progresses is multifactorial and extremely complicated. Nonetheless, these findings are significant for a number of reasons," Freedman explains. "First, there is a growing understanding that a reduction in nitric oxide production, which normally comes from both the platelets and from the endothelial lining of the blood vessel, contributes to platelet aggregation and thrombus formation. In patients with coronary artery disease, for example, their platelet and blood vessel nitric oxide production appears to be lower than in healthy subjects."
At the same time, Freedman found that platelets bathed in purple grape juice also released 55% less superoxide—a free radical—than platelets in the control solution.
"We also believe that the release of superoxide contributes to thrombus formation as well, by rendering the nitric oxide ineffective. Thus, a patient with coronary artery disease who has low levels of nitric oxide and high levels of superoxide may be likelier to experience a potentially dangerous thrombus formation than a person with normal levels. Seeing the ability of purple grape juice to increase nitric oxide production combined with its ability to suppress superoxide production gives us a better understanding of why drinking purple grape juice may support healthy cardiovascular function."
Finally, Freedman was able to show the beneficial effects of a specific flavonoid called quercetin, one of many polyphenolic compounds found in purple grape juice. She found that platelet incubation with quercetin inhibited PMA-induced stimulation of protein kinase C – a pathway by which platelet aggregation is increased.
"There have always been questions about the role of alcohol in the health benefits of drinking red wine," says Freedman. "However, it carries with it its own set of problems and concerns. Isolating the effects of quercetin is important because it suggests that purple grape juice may be a legitimate, non-alcoholic alternative to red wine."
Freedman’s co-authors on the study are Ryan Sauter, B.S., Georgetown University Medical Center, and John D. Folts, Ph.D., University of Wisconsin Medical School.
Choose a Category.
Valuable health news for you
