"We know that high levels of LDL cholesterol in the body contribute to heart disease," explains Ishwarlal Jialal, M.D., Ph.D., Professor, Department of Pathology and Internal Medicine, University of California, Davis. "What is also important to understand is that the LDL is relatively harmless unless it oxidizes within the arterial wall. So on one hand, we should strive to maintain healthy LDL levels in the body. At the same time, taking steps to impede the oxidation of LDL is a complementary pathway to cardiovascular health."
Subjects that drank Concord grape juice for two weeks showed a marked increase in the resistance of their LDL cholesterol to oxidation. The study is published in the December issue of the American Journal of Clinical Nutrition.
As LDL cholesterol (the so-called "bad" cholesterol) circulates in the blood stream, it will occasionally penetrate the lining of the artery and occupy space within the arterial wall. In normal circumstances, it returns to the blood stream and continues to circulate. However, there is growing evidence that when the LDL oxidizes while in the arterial wall, it can initiate a cascade of events that lead to atherosclerosis and, eventually, arterial blockage that can lead to a heart attack or stroke. The more resistant the LDL is to oxidation--as in this study with people drinking Concord grape juice--the less likely the LDL is to contribute to this process.
"We compared subjects who drank Concord grape juice with similar individuals consuming vitamin E and found comparable effects on resistance to LDL oxidation--an important indicator of oxidative stress--and on ORAC capacity," says Jialal. "We also found that the juice decreased plasma protein oxidation--another oxidative stress marker--better than the vitamin E."
Dr. Jialal goes on to suggest that consuming Concord grape juice for longer periods of time--the subjects participated in the study for only two weeks--may provide increased protection from oxidative stress and inflammation.
"The take-away of this study is that we saw a potent antioxidant effect in both plasma protein and LDL cholesterol while seeing no corresponding increase in levels of vitamin E or C," explains Dr. Jialal. "This means that we can attribute the antioxidant effect directly to absorbed flavonoids found in the Concord grape juice,"
The research was funded by the National Institutes of Health and Welch Foods, Inc.
Editors' Note: Dr. Jialal is available for interviews, photos available via email, b-roll with animation available.
Journal
American Journal of Clinical Nutrition