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Concord Grapes in the News

Healthy Heart, Healthy Circulation

Clinical Study Suggests Drinking Concord Grape Juice Helps Support Healthy Circulation

October 20, 2014

Nearly 20 years of research suggests that, thanks to the Concord grape, 100% grape juice helps support a healthy heart.1-7 A new study,8 presented at the American College of Nutrition’s annual conference in San Antonio (Oct. 15-18, 2014), adds to this body of work and suggests that Concord grape juice supports heart health by promoting healthy circulation.

This new research – a randomized, double-blind, placebo-controlled study in 51 overweight but otherwise healthy adult men and women – was led by Dr. Joseph A. Vita and Robert T. Eberhardt of Boston University Medical Center. Researchers found that circulation was improved when subjects consumed Concord grape juice daily versus the placebo control.8

During this crossover study, each participant drank 12 ounces (1½ cups) of Concord grape juice or a grape-flavored, sugar-sweetened drink (the placebo) daily for 4 weeks. At the conclusion of the study, the researchers found that drinking Concord grape juice resulted in a significant improvement in flow-mediated dilation, a measure of vascular function and blood vessel health versus drinking the placebo. However, drinking the 100% juice had no effect on arterial stiffness or blood pressure, nor did it have an acute effect on vascular function, suggesting that routine consumption may be important for healthy circulation. Moreover, drinking Concord grape juice daily did not negatively affect weight, glucose (blood sugar) or insulin levels versus placebo.

This new study suggests that drinking moderate amounts of Concord grape juice regularly contributes to cardiovascular health by promoting healthy circulation.

Expert Outlook:
According to Dr. Vita: “This research is exciting as it builds on the previous body of work showing the beneficial effect of Concord grape juice consumption on important markers of heart health, including blood vessel function and circulation.”

1Vislocky LM and Fernandez ML. Biomedical effects of grape products. Nutr Rev. 2010. 68(11):656-670.

2Vislocky LM and Fernandez ML. Grapes and grape products their role in health. Nutr Today. 2013. 48(1):47-51.

3Freedman JE, Parker C, 3rd, Li L, Perlman JA, Frei B, Ivanov V, Deak LR, Iafrati MD and Folts JD. Select flavonoids and whole juice from purple grapes inhibit platelet function and enhance nitric oxide release. Circulation. 2001. 103(23):2792-2798.

4Anselm E, Chataigneau M, Ndiaye M, Chataigneau T and Schini-Kerth VB. Grape juice causes endothelium-dependent relaxation via a redox-sensitive Src- and Akt-dependent activation of eNOS. Cardiovasc Res. 2007. 73(2):404-413.

5Chou EJ, Keevil JG, Aeschlimann S, Wiebe DA, Folts JD and Stein JH. Effect of ingestion of purple grape juice on endothelial function in patients with coronary heart disease. Am J Cardiol. 2001.88(5):553-555.

6Fitzpatrick DF, Hirschfield SL and Coffey RG. Endothelium-dependent vasorelaxing activity of wine and other grape products. Am J Physiol Heart Circ Physiol. 1993. 265(2):H774-H778.

7Stein JH, Keevil JG, Wiebe DA, Aeschlimann S and Folts JD. Purple grape juice improves endothelial function and reduces the susceptibility of LDL cholesterol to oxidation in patients with coronary artery disease. Circulation. 1999. 100(10):1050-1055.

8Dorsey PG, Holbrook M, Carey M, LeLeiko RM, Flint N, Rodrigues I, Aasen J, Eberhardt RT and Vita JA. Concord grape juice improves endothelial function in overweight, older adults. Presented at the 55th Annual Conference of the American College of Nutrition. San Antonio, TX. October 15-18, 2014. PDF download

Grape Research Overview

For nearly 20 years, researchers have been exploring an important mix of plant nutrients – polyphenols – found in Concord grapes and the effects they have on the body, including possible benefits in supporting cardiovascular health. In addition, emerging research is being conducted to determine whether Concord grapes play a role in supporting a healthy mind and immune system. See the research.


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An observational study, usually a retrospective study (a study that looks backward in time) that compares two groups of people: 1) those with the specific condition (e.g., disease) being studied (cases) and, 2) a similar group of people without that condition (controls). Researchers compare these two groups of people and important characteristics, such as certain lifestyle choices, to determine what factors may be associated with the condition under investigation.

A type of study that often includes patients with specific health conditions who could benefit from receiving a new treatment. These studies can also be performed in healthy subjects. The end goal of a clinical study (also called clinical research or clinical trial) is to determine effectiveness and safety of a health intervention in humans.

An observational study, usually prospective (looking forward), that follows a group of similar people over time. The goal is to determine which factors and exposures affect the development of a specific outcome or health condition (e.g., disease) during the study’s time period.

A type of observational study, often given as a survey, that examines a group of subjects during a single occasion, or over a very short period of time. This type of study aims to describe the relationship between health-related conditions (e.g., metabolic syndrome, hypertension) and other factors that exist in the general population (e.g., dietary intake, physical activity levels), during a particular time period.

A type of study in which researchers simply observe subjects and measure the associations between certain characteristics (e.g., fruit/vegetable intake) and specific outcomes (e.g., obesity). Examples of observational studies include case-control studies, cross-sectional studies, and cohort studies. While these studies gather important information, they cannot prove that a specific treatment or factor affects health.

A small scale, preliminary study that is conducted to determine the potential for a larger study.

A stage of research that often occurs prior to trials involving humans. This type of research can help determine mechanisms of action of a treatment, or how the treatment is causing the effect, as well as help ensure the safety of treatment in subsequent human trials.

In vitro
Testing performed in a controlled environment, such as a test tube or a Petri dish, instead of living organisms. In vitro literally means "within the glass" in Latin.

Ex vivo
These experiments are performed on tissue (e.g., animal or human cells) taking place outside of the organism, such as in a laboratory setting. In Latin, this means "out of the living."

In vivo
These tests are done on whole, living organisms. Technically, animal and human testing are two forms of in vivo research, which means "within the living." These experiments may be performed outside of a laboratory setting.

A study designed to provide the most credible information about the cause and effects of treatment. These types of studies are recognized as unbiased because they involve the random assignment of treatments to subjects being studied.

The tendency throughout any stage of research to generate findings that may not reflect "true values." In clinical trials, researchers try to avoid many kinds of bias, including selection by randomizing subjects, measurement by creating placebos and performing blind trials, and confounding by carefully designing the study and analyzing the findings.

Study in which subjects do not know whether they receive the treatment or the placebo, which assists in prevention of bias. Double-blinded studies are a higher level of scientific rigor because neither the participants nor the investigators know who is receiving the treatment or the placebo. A double-blind crossover study means each participant undergoes both the treatment and control scenario, typically with a wash-out period in between.

Study that allows researchers to isolate the effect size of the treatment by comparing a group given a simulated treatment (e.g., grape flavored drink) to those with the real treatment (e.g., Concord grape juice), which reduces measurement bias. The placebo should match as closely as possible to the treatment without containing the active ingredients.

Study involving participants who are randomly assigned to either the treatment or the placebo group, reducing selection bias.