Grape Science Center

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Concord Grapes in the News

Weighing the Facts on Concord Grape Juice

Study revealed that daily, moderate consumption of Concord grape juice did not impact weight.

June 1, 2010

A recent study published in the Journal of the American College of Nutrition showed that drinking 100% Concord grape juice did not lead to significant changes in appetite, energy intake or body weight.1

Weighty Matter
The health benefits offered by fruits are sometimes overlooked when they are consumed in the form of a juice. Evidence suggests that for most children and adults, drinking moderate amounts of 100% fruit juice is not associated with overweight. 2-5 However, some have remained concerned that juice may impact weight gain, mainly because compared to whole fruit, juice can be consumed with less effort and thus could provide more calories with less satiety (sense of fullness).6

100% Concord Grape Juice and Body Weight
In a study published by the Journal of the American College of Nutrition, Director of the Ingestive Behavior Research Center and Professor in the Department of Foods and Nutrition at Purdue University, Dr. Richard Mattes and his team showed that drinking 100% Concord grape juice did not lead to significant changes in appetite or to increased energy intake; in fact, it was associated with reduced waist circumference.1

This double-blind, placebo-controlled trial was composed of 76 overweight men and women who were divided into three groups and studied for 12 weeks. The intervention group drank eight ounces of 100% Concord grape juice twice daily, the placebo group drank a grape-flavored drink and the final group was a non-treatment control group. Unlike the Concord grape juice drinkers, those in the placebo group felt less full, experienced moderate yet significant weight gain, and did not experience a significant decrease in waist circumference.

While it is too early to draw any conclusions on Concord grape juice and body weight, this work builds on other research that has shown that daily, moderate consumption of Concord grape juice does not significantly impact weight.7-10

Expert Opinion
This study showed that those who drank 100% Concord grape juice compensated for its calories by taking in fewer calories from other foods and drinks throughout the day and thus avoided a positive calorie balance and significant weight gain. According to Dr. Mattes, “These results are in sharp contrast to other published evidence suggesting little or no compensation for energy-containing beverages.”  With that said, Dr. Mattes added, “Energy compensation may not fully explain why the Concord grape juice group exhibited a significant decline in waist circumference and no significant weight gain, while the placebo group did gain a significant amount of weight. The differences in weight may be attributable to the beneficial effects of grape polyphenols on thermogenesis or fat oxidation.”

1 Hollis JH, Houchins JA, Blumberg JB and Mattes RD. Effects of concord grape juice on appetite, diet, body weight, lipid profile, and antioxidant status of adults. J Am Coll Nutr. 2009. 28(5):574-582.
2 O’Neil CE. A Review of the Relationship Between 100% Fruit Juice Consumption and Weight in Children and Adolescents.  American Journal of Lifestyle Medicine. 2008. 2(4):315-354.
3 Nicklas TA, O'Neil CE, Kleinman R. Association between 100% juice consumption and nutrient intake and weight of children aged 2 to 11 years. Arch Pediatr Adolesc Med. 2008.162(6):557-565.
4 O'Neil CE, Nicklas TA and Kleinman R. Relationship between 100% juice consumption and nutrient intake and weight of adolescents. Am J Health Promot. 2010. 24(4):231-237.
5 Fulgoni VL and Pereira MA. Consumption of 100% Fruit Juice and Risk of Obesity and Metabolic Syndrome: Findings from the National Health and Nutrition Examination Survey 1999-2004.  Presented at Experimental Biology, 2009. New Orleans, LA.
6 Mourao DM, Bressan J, Campbell WW, Mattes RD: Effects of food form on appetite and energy intake in lean and obese young adults. Int J Obes (Lond) 31:1688–1695, 2007.
7 Krikorian R, Nash TA, Shidler MD, Shukitt-Hale B and Joseph JA. Concord grape juice supplementation improves memory function in older adults with mild cognitive impairment. Br J Nutr. 2010. 103(5):730-734.
8 Park YK, Kim JS and Kang MH. Concord grape juice supplementation reduces blood pressure in Korean hypertensive men: double-blind, placebo controlled intervention trial. Biofactors. 2004. 22(1-4):145-147.
9 Dohadwala MM, Hamburg NM, Holbrook M, Kim BH, Duess M-A, Levit A and Titas M. Effects of Concord grape juice on ambulatory blood pressure in prehypertension and stage 1 hypertension. Am J Clin Nutr, Am J Clin Nutr. 2010. 92(5):1052-1059.
10 Mark D and Maki K. Concord grape juice reduces blood pressure in mean with high systolic blood pressure. Presented at Experimental Biology. San Diego CA. April 11-15, 2003.

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.