Concord grape juice polyphenols and cardiovascular risk factors: dose-response relationships

Authors: BLUMBERG, JEFFREY - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; VITA, JOSEPH - Boston University; CHEN, CHEN-YEN OLIVER - Jean Mayer Human Nutrition Research Center On Aging At Tufts University

Submitted to: Nutrients
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/23/2015
Publication Date: 12/2/2015
Citation: Blumberg, J.B., Vita, J.A., Chen, C. 2015. Concord grape juice polyphenols and cardiovascular risk factors: dose-response relationships. Nutrients. 7(12):10032-10052. doi:10.3390/nu7125519.

Interpretive Summary: The consumption of 100% fruit juice is positively associated with improved diet quality in children and adults and so can contribute to a healthy diet. However, this association does not account for the phytonutrient composition of fruits, including polyphenols, which may also contribute importantly to several of the functional benefits associated with their consumption. Polyphenols in Concord grape juice (CGJ) have been demonstrated to increase antioxidant defenses, reduce inflammation, promote vascular reactivity, and inhibit the progression of indices of heart disease. However, as these studies rarely tested more than a single dose, data are lacking that show the relationship between the amount of CGJ polyphenols consumed and the magnitude of their putative benefit. Thus, we undertook a quantitative analysis of results from randomized clinical trials of CGJ investigating its impact on risk factors for heart disease (blood pressure, platelet aggregation, vascular reactivity, and oxidation of the bad cholesterol) in the context of similar studies of other polyphenol-rich foods to determine the minimum and maximum doses of CGJ that might provide benefit. Taking advantage of these other studies suggests a new approach to evaluating the relationship between the consumption of phytonutrient ingredients in a single food and health outcomes when a data from a broad range of intakes is not available. This analysis of human intervention studies shows a positive relationship between the total polyphenol content of Concord grape juice and several biological responses associated with risk factors of cardiovascular disease.

Technical Abstract: Pure fruit juices provide nutritional value with evidence suggesting some of their benefits on biomarkers of cardiovascular disease risk may be derived from their constituent polyphenols, particularly flavonoids. However, few data from clinical trials are available on the dose-response relationship of fruit juice flavonoids to these outcomes. Utilizing the results of clinical trials testing single doses, we have analyzed data from studies of 100% Concord grape juice by placing its flavonoid content in the context of results from randomized clinical trials of other polyphenol-rich foods and beverages describing the same outcomes but covering a broader range of intake. We selected established biomarkers determined by similar methods for measuring flow-mediated vasodilation (FMD), blood pressure, platelet aggregation, and the resistance of LDL-cholesterol to oxidation. Despite differences among the clinical trials in the treatment, subjects, and duration, correlations were observed between the dose and FMD. Inverse dose-response relationships, albeit with lower correlation coefficients, were also noted for the other outcomes. These results suggest a clear relationship between consumption of even modest serving sizes of Concord grape juice, flavonoid intake, and effects on risk factors for cardiovascular disease. This approach to dose-response relationships may prove useful for testing other individual foods and beverages.