"In addition to HDL levels increasing, we saw significant decreases in the production of superoxide, a free radical, and soluble CD40 ligand, an inflammatory marker about which there is growing interest," explains Jane E. Freedman, M.D., Associate Professor of Medicine and Pharmacology, Boston University School of Medicine and an author of the study. "Platelet release of soluble CD40 ligand is thought to contribute to the development of atherosclerosis and vascular inflammation. We have seen in previous studies of healthy subjects that drinking grape juice decreases superoxide production and inhibits platelet aggregation, yet its impact on the inflammatory properties of platelets had not been previously studied. The soluble CD40 ligand information is new and particularly interesting, given the growing interest in the link between this inflammatory marker and cardiovascular disease."
The positive increase in HDL levels is also noteworthy, according to Freedman. Historically, HDL increases have been linked to drinking red wine and attributed to the alcohol found in the wine. Given that Concord grape juice does not contain alcohol, researchers may now be looking more closely at the polyphenolic compounds found in both wine and grape juice as potential contributors to this effect.
"There has been great interest in the possible benefits of drinking red wine for people with cardiovascular disease," notes Freedman. "But it has been offset, to a certain extent, by concerns about promoting alcohol consumption. This has led to the exploration of non-alcoholic grape products. In the past, we have seen that Concord grape juice has shown strong antioxidant and platelet-inhibitory effects. This is the first study to show its positive effect on soluble CD40 ligand, an emerging marker of cardiovascular inflammation, even in subjects on a daily aspirin regimen."
The double blind, placebo-controlled study looked at 20 subjects, with a mean age of 63 years, who had previously been diagnosed with coronary artery disease and were on standard medications, including aspirin. "Because the patients were already on aspirin therapy, we didn't see the significant platelet inhibition we typically get in subjects drinking the grape juice. This is not surprising, however, given aspirin's potent effect on platelets."
Freedman cautions that her study is preliminary and that more work needs to be done in this area. Nonetheless, she notes that consumption of purple grape juice may suppress inflammatory indices that have been recently linked to cardiovascular disease.
The study comes on the heels of the release of the new USDA proanthocyanidin database in which purple grape juice made from Concord grapes tested higher in total proanthocyanidins than any other beverage tested on a per serving basis, including red wine, tea, cranberry juice cocktail and apple juice. Proanthocyanidins, a subset of polyphenols, are natural plant compounds that function as antioxidants and that have been linked to good health in a variety of ways.
The study was underwritten, in part, by the NIH and Welch Foods Inc.