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Is Grape Juice Healthy?

April 16, 2012 Written by JP    [Font too small?]

Fruit juice isn’t something that I normally recommend. Most bottled and fresh juices simply contain too much sugar – a dietary component that is already too plentiful in many diets. Then, there’s the issue of dietary fiber. The process of making juice removes the fibrous portion of fruits and vegetables, and concentrates the sweet liquid contained therein. This yields both negative and positive effects. On the one hand, the antioxidants, nutrients and phytochemicals that naturally occur in juice are often better absorbed when fiber is absent from the equation. But, without fiber, fruits and vegetable juices become more concentrated reservoirs of high glycemic carbohydrates which generally result in large fluctuations in blood sugar and insulin.

The one constant rule in nutrition is that there is an exception and nuance to be found in almost every rule. Purple grape juice is positively loaded with sugar – about 30 to 40 grams per 8 oz serving. However, several recent studies in adults and children have discovered that daily consumption of purple grape juice may positively influence cardiovascular health and neurocognitive functioning without causing significant blood sugar spikes or weight gain.

Here’s what the research tells us: Two studies in older patients with mild dementia or memory decline reveal that drinking 2 to 3 cups of Concord grape juice daily for up to 16 weeks increases “activation in the anterior and posterior regions” of the brain. These changes in brain activity resulted in improvements in cognitive functioning as indicated by improved spatial recall and verbal learning. A study in children with metabolic syndrome suggests that a combination of pomegranate and purple grape juice supports healthier circulation by enhancing endothelial functioning and lowering inflammation. Elevated inflammation and poor blood flow are frequently implicated in cases of age related cognitive decline, heart disease and type-2 diabetes. In addition, patients with dementia and metabolic syndrome tend to have higher levels of oxidative stress. According to current studies, the antioxidants in purple grapes, including anthocyanins, quercetin and resveratrol, are capable of counteracting such oxidative imbalances

Before rushing out to buy just any grape juice, keep several factors in mind. First and foremost, you should always look for 100% pure, purple grape juice. Grape juice with added sweeteners or white grape juice that lacks the same phenolic antioxidants are not health promoting and may result in weight gain. Also, researchers from Brazil have noted that organic grape juice is more potent in protecting against brain and liver damage in rats than conventional grape juice. So, seeking out the organic variety may be worthwhile. However, there are two downsides to drinking even organic, purple grape juice on a regular basis: 1) it’s quite expensive when used at a therapeutic level of 2 to 3 glasses/day; 2) grape juice is very acidogenic and can cause tooth decay. The latter point can easily be remedied by rinsing well after drinking. If availability or cost is a problem, other purple grape options exist, such as using concentrated grape seed and grape skin supplements. These have also shown some promise and are much lower in price and sugar.

Note: Please check out the “Comments & Updates” section of this blog – at the bottom of the page. You can find the latest research about this topic there!

To learn more about the studies referenced in today’s column, please click on the following links:

Study 1 – Concord Grape Juice Supplementation and Neurocognitive Function (link)

Study 2 – Concord Grape Juice Supplementation Improves Memory Function in (link)

Study 3 – Acute and Long term Effects of Grape and Pomegranate Juice (link)

Study 4 – Impact of Apple and Grape Juice Consumption on the Antioxidant (link)

Study 5 – Effects of Concord Grape Juice on Appetite, Diet, Body Weight … (link)

Study 6 – Grape Seed Extract Supplementation Prevents High-Fructose Diet (link)

Study 7 – Neuroprotective and Anticonvulsant Effects of Organic and (link)

Study 8 – Antioxidant and Antigenotoxic Activities of Purple Grape Juice (link)

Study 9 – Plaque and Salivary pH Changes After Consumption of Fresh Fruit (link)

Study 10 – Pleiotropic Benefit of Monomeric and Oligomeric Flavanols on (link)

Purple Grape Juice Supports Healthier Cognitive Functioning

Source: British Journal of Nutrition (2010),103 : pp 730-734 (link)

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Posted in Food and Drink, Heart Health, Memory

11 Comments & Updates to “Is Grape Juice Healthy?”

  1. JP Says:

    Update: Grape juice benefits antioxidant status, blood pressure and protects DNA in smokers …


    J Clin Biochem Nutr. 2015 Jan;56(1):49-56.

    Purple grape juice supplementation in smokers and antioxidant status according to different types of GST polymorphisms.

    DNA damages and antioxidant status was assessed after 8 weeks of purple grape juice supplementation in male smokers depending on the glutathione S-transferase polymorphisms. Ninety-five smokers consumed 480 ml of purple grape juice for 8 weeks. The blood samples were collected before and after supplementation to measure lymphocyte DNA damages, plasma antioxidants, conjugated diene, and the erythrocyte antioxidant enzymes. The diastolic pressure, lymphocyte DNA damage, and plasma conjugated diene were significantly decreased but the plasma γ-tocopherol was increased in GSTM1-null genotype, while increased blood glutathione and decreased lymphocyte DNA damage were observed in GSTM1-present genotype. In case of GSTT1 on the other hand, the decrease in diastolic pressure and lymphocyte DNA damage was observed in both null types and present types, but the erythrocyte catalase activity was decreased in GSTT1-null type and the plasma vitamin C level was increased in GSTT1-present type, suggesting that, the antioxidant effect of grape juice was greater in GSTT1-present type compared to GSTT1-null type. The intakes of 8-week purple grape juice affected diastolic blood pressures, DNA damage reductions and antioxidant status in smokers, mainly greater in GSTM1-null type and GSTT1-present type.

    Be well!


  2. JP Says:

    Update: A study that failed to find cardiovascular benefits in a group of cancer survivors …


    Pediatr Blood Cancer. 2014 Dec;61(12):2290-6.

    Feasibility and preliminary efficacy of the effects of flavanoid-rich purple grape juice on the vascular health of childhood cancer survivors: a randomized, controlled crossover trial.

    BACKGROUND: Childhood cancer survivors have an increased risk of developing cardiovascular disease following treatment, yet few interventions have been evaluated to reduce this risk. Purple grape juice (pGJ), a rich source of flavonoids with antioxidant properties, has been shown in adults to reduce oxidative stress and improve endothelial function. We examined the effects of supplementing meals with pGJ on microvascular endothelial function and markers of oxidative stress and inflammation in 24 cancer survivors (ages 10-21 years).

    PROCEDURE: In a randomized controlled crossover trial consisting of two, 4 week intervention periods, each preceded by a 4 week washout period, subjects received in random order 6 ounces twice daily of pGJ and clear apple juice (cAJ; similar in calories but lower in flavonoids). Measurements were obtained before and after each supplementation period; change was evaluated using mixed effects ANOVA.

    RESULTS: pGJ did not improve endothelial function, measured using digital reactive hyperemia, compared with cAJ (mean change: pGJ 0.06, cAJ 0.22; difference of mean change [95% CI]: -0.16 [-0.42 – 0.11], P = 0.25). No significant changes in plasma concentrations of oxidized-LDL, myeloperoxidase, or high sensitivity C-reactive protein were observed.

    CONCLUSION: After 4 weeks of daily consumption of flavonoid-rich pGJ, no measurable change in vascular function was observed in these childhood cancer survivors.

    Be well!


  3. JP Says:

    Update 05/27/15:


    Glob J Health Sci. 2014 Oct 29;7(3):40015.

    The topical effect of grape seed extract 2% cream on surgery wound healing.

    BACKGROUND: Reducing the wound healing time is crucial in wound as it lowers the chance of infection and decreases complications and cost. Grape seed extract has the ability to release endothelial growth factor and its topical application results in contraction and closure of the skin wound. Furthermore, it possesses antioxidant and antibacterial properties. In several studies it has been proved effective in animals. Therefore, due to low side effects and recognition of herbal medicine, we decided to evaluate the effect of grape seed extract 2% herbal cream on human skin lesions.

    MATERIALS: This study is a double blind clinical trial conducted on two groups of treatment and placebo. Surgery was performed on skin lesions such as skin tags and moles which were found on the neck, trunk and limbs (except for face). After enrollment and obtaining informed consent from participants, they were randomized into two groups of treatment and placebo. Excision of the lesions was done by surgical scissors. The lesions got restored by secondary intention method. After the first day of treatment, the patients were visited on the 3rd, 7th, 10th, 14th, and 21st day. Grape seed extract cream 2% was produced and coded by the Faculty of Pharmacy, Ahvaz University of Medical Sciences. In order to compare the two groups, T-test was used. For time assessing, analysis of variance with repeated measures was employed.

    RESULTS: The results showed complete repair of wounds averagely on day 8 for the treatment group and on day 14 for the placebo group, which was clearly significant in terms of statistical difference (p=0.00).

    CONCLUSION: Proanthocyanidins in grape seed extract trigger the release of vascular endothelial growth factor and its topical application causes wound contraction and closure. Curing skin lesions with grape seed extract caused proliferation areas with protected boundaries in epithelium, increased cell density and increased deposition of connective tissue at the wound site which in general improves cellular structure in wound. In addition, its anti-inflammatory and anti-microbial properties are effective in wound healing.

    Be well!


  4. JP Says:

    Update 05/31/15:


    Food Funct. 2015 May 26.

    Comparative effects of red and white grapes on oxidative markers and lipidemic parameters in adult hypercholesterolemic humans.

    The present study compared the effects of consuming red versus white whole grapes on oxidative and lipidemic indices in people with hypercholesterolemia. Sixty nine patients were randomized into three groups. The two treatment groups consumed 500 g of either Condori red grapes or Shahroodi white grapes daily for 8 weeks, and the third group served as a control. Plasma glucose, triacylglycerol (TG), cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), thiobarbituric acid reactive substances (TBARS) and total antioxidant capacity (TAC) were determined by colorimetric methods at baseline and at the end of the study. In addition, the polyphenol and fiber content of the two grape varieties was measured. TBARS was reduced in both study groups compared to the control group, and the reduction was greater in the group that consumed red grapes compared to the white grapes. TAC was increased significantly in both red and white grape consuming groups compared to the control group. Total cholesterol and LDL-C were decreased in the red grape group compared to the control group. No significant changes in fasting blood glucose, TG or HDL-C were observed among the groups. The results of this study suggest that consumption of the whole fruit of red grapes has more potent anti-oxidative and hypolipidemic effects compared to the white grapes in hyperlipidemic adult humans. Hence, the whole fruit of red grapes may be an excellent fruit choice not only to prevent oxidative stress related metabolic disorders but also cholesterol related cardiovascular diseases, particularly in hyperlipidemic adult humans.

    Be well!


  5. JP Says:

    Update 06/21/15:


    Nutr J. 2015 Jun 19;14(1):62.

    Effects of a grape-supplemented diet on proliferation and Wnt signaling in the colonic mucosa are greatest for those over age 50 and with high arginine consumption.

    A diet rich in fruits and vegetables, and a grape-derived compound, resveratrol, have been linked to a reduced incidence of colon cancer. In vitro and in vivo, resveratrol suppresses Wnt signaling, a pathway constitutively activated in over 85 % of colon cancers.Thirty participants were placed on a low resveratrol diet and subsequently allocated to one of three groups ingesting 1/3-to-1 lb (0.15-0.45 kg) of grapes per day for 2 weeks. Dietary information was collected via 24-h recall. Colon biopsies for biomarker analysis were obtained pre- and post-grape and evaluated for the expression of Wnt pathway target genes and for markers of proliferation by RT-PCR and immunohistochemistry.Participants lost an average of 2 · 6 lb (1.2 kg, p = 0 · 0018) during the period of grape ingestion. The expression of CyclinD1 (p < 0 · 01), AXIN2, CD133 (p = 0 · 02) and Ki67 (p = 0 · 002) were all reduced after grape ingestion. Individuals over 50 years of age and those with high dietary arginine consumption had increased basal expression of CyclinD1, AXIN2, cMYC and CD133 (p value range 0 · 04 to <0 · 001) that, following grape ingestion, were reduced to levels seen in younger participants.The reduction in Wnt signaling and mucosal proliferation seen following short-term ingestion of 1/3-1 lb (0.15-0.45 kg) of grapes per day may reduce the risk of mutational events that can facilitate colon carcinogenesis. The potential benefit is most marked for high-risk older individuals and individuals whose diet is high in arginine intake. Dietary grape supplementation may play a role in colon cancer prevention for high-risk individuals. Be well! JP

  6. JP Says:

    Updated 09/05/15:


    Biol Res. 2015 Sep 4;48:49.

    Wine grape pomace flour improves blood pressure, fasting glucose and protein damage in humans: a randomized controlled trial.

    BACKGROUND: The Mediterranean diet is a healthy diet with positive scientific evidence of preventing chronic diseases. Bioactive components support the healthy properties of the Mediterranean diet. Antioxidants and fiber, two components of the Mediterranean diet, are key functional nutrients for healthy eating and nutrition. Wine grape pomace is a rich source of these dietary constituents and may be beneficial for human health. Our hypothesis was that the intake of red wine grape pomace flour (WGPF) prepared from red wine grapes (Cabernet Sauvignon variety) reduced the metabolic syndrome in humans. To evaluate the effect of WGPF on components of metabolic syndrome we design a 16-week longitudinal intervention study. Thirty-eight males, 30-65 years of age, with at least one component of metabolic syndrome, were randomly assigned to either the intervention group (n = 25) or the control group (n = 13). At lunch, the intervention group was given 20 g of WGPF per day, which contained 10 g of dietary fiber, 822 mg of polyphenols and an antioxidant capacity of 7258 ORAC units. Both groups were asked to maintain their regular eating habits and lifestyles. Clinical evaluation, anthropometric measurements and biochemical blood analyses were done at the beginning and the end of the study.

    RESULTS: WGPF intake significantly decreased systolic and diastolic blood pressure as well as fasting glucose levels. Plasma γ-tocopherol and δ-tocopherol increased and carbonyl group in plasma protein decreased in WGPT group, significantly. No significant effect was observed for waist circumference, HDL cholesterol, triglycerides, total antioxidant capacity and vitamin C in and between groups. The group-dependent magnitude of the differences between the baseline and final postprandial insulin values and γ-tocopherol concentrations was statistically significant.

    CONCLUSIONS: The consumption of WGPF-rich in fiber and polyphenol antioxidants, as a food supplement in a regular diet improves blood pressure, glycaemia and postprandial insulin. In addition, increased antioxidant defenses and decreased oxidative protein damage indicating attenuation of oxidative stress. WGPF might be a useful food ingredient for health promotion and chronic disease prevention.

    Be well!


  7. JP Says:

    Updated 10/15/15:


    Nutr J. 2015 Sep 9;14:94.

    Effect of consuming a grape seed supplement with abundant phenolic compounds on the oxidative status of healthy human volunteers.

    BACKGROUND: Diverse enzymatic and non-enzymatic antioxidants provide protection against reactive oxygen species in humans and other organisms. The nonenzymatic antioxidants include low molecular mass molecules such as plant-derived phenols.

    AIM OF STUDY: This study identified the major phenolic compounds of a grape seed extract by HPLC and analyzed the effect of consumption of biscuits enriched with this extract on the urinary oxidative status of healthy subjects by measurement of urine redox potential.

    METHODS: The major phenolic compounds were characterized in a red grape seed extract separated by HPLC with detection by a photodiode array (PDA), fluorescence (FL) and quadrupole mass spectrometer (MS). A nutritional study in a healthy volunteers group was done. Each volunteer ate eight traditional biscuits with no red grape seed extract supplementation. The second day each volunteer ate eight traditional biscuits supplemented with 0.6% (wt/wt) of grape seed extract. An overnight urine sample was obtained for each treatment. The redox potential was measured at 25 °C using a potentiometer in each urine sample.

    RESULTS: Epicatechin, catechin, procyanidin dimers B1 to B4, and the procyanidin trimer C2 were the major phenolic components in the extract. Epicatechin gallate and procyanidin dimers B1-3-G and B2-3′-G were the major galloylated flavan-3-ols. The forty-six healthy volunteers each shown a reduction of the urine redox potential after the treatment by traditional biscuits supplemented with the grape seed extract.

    CONCLUSIONS: This simple dietary intervention significantly reduced (33%) the urine redox potential, reflecting an overall increase in antioxidant status. Incorporation of plant-derived phenols in the diet may increase anti-oxidative status.

    Be well!


  8. JP Says:

    Updated 1/8/16:


    Nutrients. 2015 Dec 2;7(12):10032-52.

    Concord Grape Juice Polyphenols and Cardiovascular Risk Factors: Dose-Response Relationships.

    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 low density lipoprotein cholesterol (LDL) 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.

    Be well!


  9. JP Says:

    Updated 02/14/16:


    Am J Clin Nutr. 2016 Feb 10.

    Concord grape juice, cognitive function, and driving performance: a 12-wk, placebo-controlled, randomized crossover trial in mothers of preteen children.

    BACKGROUND: Daily consumption of Concord grape juice (CGJ) over 3-4 mo has been shown to improve memory function in adults with mild cognitive impairment and reduce blood pressure in hypertensive adults. These benefits likely result from the high concentration of polyphenols in CGJ. Increased stress can impair cognitive function and elevate blood pressure. Thus, we examined the potential beneficial effect of CGJ in individuals with somewhat stressful and demanding lifestyles.

    OBJECTIVE: We sought to examine the effects of the daily consumption of CGJ for 12 wk on cognitive function, driving performance, and blood pressure in healthy, middle-aged working mothers.

    DESIGN: Twenty-five healthy mothers (aged 40-50 y) of preteen children who were employed for ≥30 h/wk consumed 12 ounces (355 mL) of either CGJ (containing 777 mg total polyphenols) or an energy-, taste-, and appearance-matched placebo daily for 12 wk according to a randomized crossover design with a 4-wk washout. Verbal and spatial memory, executive function, attention, blood pressure, and mood were assessed at baseline and at 6 and 12 wk. Immediately after the cognitive battery, a subsample of 17 women completed a driving performance assessment at the University of Leeds Driving Simulator. The 25-min driving task required participants to match the speed and direction of a lead vehicle.

    RESULTS: Significant improvements in immediate spatial memory and driving performance were observed after CGJ relative to placebo. There was evidence of an enduring effect of CGJ such that participants who received CGJ in arm 1 maintained better performance in the placebo arm.

    CONCLUSIONS: Cognitive benefits associated with the long-term consumption of flavonoid-rich grape juice are not exclusive to adults with mild cognitive impairment. Moreover, these cognitive benefits are apparent in complex everyday tasks such as driving. Effects may persist beyond the cessation of flavonoid consumption, and future studies should carefully consider the length of washout within crossover designs.

    Be well!


  10. JP Says:

    Updated 07/19/16:


    Atherosclerosis. 2016 Jul 1;251:266-272.

    The impact of dietary flavonoid supplementation on smoking-induced inflammatory process and fibrinolytic impairment.

    BACKGROUND AND AIMS: Smoking is associated with increased inflammatory process and impairment of fibrinolytic status. Concord grape juice (CGJ), a rich source of flavonoids, can modify cardiovascular risk factors. We aimed to evaluate the impact of CGJ on smoking-induced impairment of inflammatory and fibrinolytic status in healthy smokers.

    METHODS: We studied the effect of a 2-week oral treatment with CGJ in 26 healthy smokers on three occasions (day 0: baseline, day 7 and day 14) in a randomized, placebo-controlled, double-blind, cross-over design. Measurements were carried out before (pSm) and 20 min after (Sm20) cigarette smoking. Serum levels of intercellular adhesion molecule-1 (sICAM-1) and plasminogen activator inhibitor 1 (PAI-1) were measured as markers of inflammatory and fibrinolytic status, respectively.

    RESULTS: Treatment with CGJ reduced pSm sICAM-1 levels (p < 0.001), while placebo had no impact on ICAM-1 levels (p = 0.31). Moreover, treatment with CGJ decreased pSm values of PAI-1 (p < 0.001) while placebo had no impact on PAI-1 levels (p = 0.89). Smoking induced an elevation in PAI-1 levels after smoking compared to pro-smoking levels in all study days and in both arms (CGJ and placebo) of the study (p < 0.001 for all). Interestingly, CGJ compared to placebo, attenuated the acute smoking increase in sICAM-1 and PAI-1 levels (p < 0.001 and p = 0.005 respectively). CONCLUSIONS: CGJ consumption improved inflammatory and fibrinolytic status in healthy smokers and attenuated acute smoking induced increase in ICAM-1 and PAI-1 levels. These findings shed further light on the favorable effects of flavonoids in cardiovascular health. Be well! JP

  11. JP Says:

    Updated 11/20/16:


    Exp Gerontol. 2016 Nov 14.

    Examining the impact of grape consumption on brain metabolism and cognitive function in patients with mild decline in cognition: Adouble-blinded placebo controlled pilot study.

    BACKGROUND: Natural compounds in grapes such as resveratrol are known for their antioxidant and anti-inflammatory properties. Some studies have shown a potential role for grapes or wine in slowing cognitive decline and other effects of aging. However, well-controlled experimental data obtained in human subjects are still in need of further development. Here we aimed to systemically assess effects of grapes on regional cerebral metabolism.

    METHODS: Ten subjects with mild decline in cognition (mean, 72.2±4.7years; 50% female) were included in this analysis. Participants were randomized into an active grape formulation arm or a placebo arm which consumed a formulation free of polyphenols for six months. Cognitive performance was measured through neuropsychological assessments performed at baseline and 6months after initiation of therapy. Changes in brain metabolism occurring with each therapy regimen were assessed by brain PET scans with the radiotracer [F-18] fluorodeoxyglucose (FDG), obtained during initial evaluation and 6months. Standardized volumes of interest (sVOI) and statistical parametric mapping (SPM) methods were applied to FDG-PET scans to identify significant regional cerebral metabolic changes.

    RESULTS: In contrast to participants taking the active grape formulation, who displayed no significant decline in metabolism, the placebo arm underwent significant metabolic decline in sVOI’s of the right posterior cingulate cortex (p=0.01), and left superior posterolateral temporal cortex (p=0.04). SPM analyses also found significant declines in the placebo group, particularly in left prefrontal, cingulate, and left superior posterolateral temporal cortex (p<0.01) with stable brain metabolism in the active formulation arm. No significant differences were seen in scores on the neuropsychological battery of tests between the two groups. However, metabolism in right superior parietal cortex and left inferior anterior temporal cortex was correlated with improvements in attention/working memory, as measured with WAIS-III Digital Span within the active formulation group (r=-0.69, p=0.04).

    CONCLUSIONS: The placebo arm had declines in regions of the brain known to be significantly affected in the early stages of Alzheimer's disease, while the active formulation group was spared such decline. This suggests a protective effect of grapes against early pathologic metabolic decline.

    Be well!


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