These results were announced in the November issue of the journal Arteriosclerosis, Thrombosis and Vascular Biology by researchers from Boston University School of Medicine.
Jane Freedman, associate professor of medicine and pharmacology at the university and one of the authors of the study, said that in addition to an increase in HDL (good cholesterol) levels, they saw a significant decrease in the production of superoxide, a free radical, and soluble CD40 ligand, an inflammatory marker that is provoking growing interest
"Platelet release of soluble CD40 ligand is thought to contribute to the development of atherosclerosis and vascular inflammation," said Freedman, noting that previous studies of healthy subjects have shown that drinking grape juice decreases superoxide production and inhibits platelet aggregation. However, 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," said Freedman.
The positive increase in HDL levels is also interesting, according to Freedman, as historically this phenomenon has been linked to drinking red wine and attributed to the alcohol found in the wine.
Freedman noted that to a certain extent interest in the possible benefits of drinking red wine have been offset by concern about promoting alcohol consumption. Concord grape juice obviously does not contain alcohol, meaning that researchers may now look more closely at the polyphenolic compounds found in grape juice, as well as wine.
"In the past, we have seen that Concord grape juice has shown strong antioxidant and platelet-inhibitory effects," said Freedman. "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," said Freedman.
She concluded that consumption of purple grape juice may suppress inflammatory indices that have been recently linked to cardiovascular disease, though cautioned that her study is preliminary and more work needs to be done in this area.