Grape Juice Consumption Research Articles

Impact of apple and grape juice consumption on the antioxidant status in healthy subjects

It is reported that consumption of antioxidant-rich foods significantly increased plasma total antioxidant capacity (T-AOC) in humans. Also, it is proved that the antioxidants from plant foods improve the body's antioxidant defence by acting additively and synergistically. As a result, rational combination of antioxidant-rich foods is recommended to population in the prevention of oxidative stress-related diseases. Both apple and grape are antioxidant-rich fruits. In this study, 2 weeks dietary intervention study was carried out in 25 healthy subjects to investigate the influences of apple and grape juices consumption on body antioxidant status. Our results indicated that 2 weeks of apple and grape juice consumption increased the plasma T-AOC and decreased the concentration of malondialdehyde. However, no change was found in the content of plasma carbonyl. Erythrocyte glutathione peroxidase and catalase activities were enhanced by 2 weeks of fruit juice consumption; however, no change was found in the activity of erythrocyte superoxide dismutase. The in vitro comet assay results indicated that apple and grape juice consumption did not influence lymphocyte damage upon hydrogen peroxide treatment. Urinary 8-hydroxy-2-deoxyguanosine content was not affected by 2 weeks of fruit juice intervention. These findings indicated that concomitant intake of apple and grape juice was efficient in enhancing the body's antioxidant status.

Consumption of Purple/Blue Produce Is Associated With Increased Nutrient Intake and Reduced Risk for Metabolic Syndrome: Results From the National Health and Nutrition Examination Survey 1999-2002

To determine the effect of consuming purple/blue fruit and vegetables (P/B) on nutrient intakes and physiological parameters, a secondary analysis of National Health and Nutrition Examination Survey (NHANES) 1999-2002 data for children aged 5 to 18 years (n = 6345) and adults 19+ years (n = 8827) was conducted. Compared with nonconsumers (n = 13 304), P/B consumers (n = 1559) had increased intakes of total fruit (P < .0001), dietary fiber (P ≤ .0001), vitamin C (P < .001), and potassium (P < .0001) and decreased intakes of added sugar (P < .0001). P/B consumers had higher energy intakes (P < .001), but among children, there were no differences in weight or body mass index (BMI) for age between groups; among adults, lower weight and BMI (P < .0001) were found as compared with nonconsumers. Adult P/B consumers had significantly reduced risk for 3 of the 5 risk factors that define the metabolic syndrome (MetS): elevated blood pressure, low HDL cholesterol, and increased waist circumference. An additional analysis for the subgroup of 100% grape juice (GJ) consumers was conducted. GJ consumers (n = 270) also had higher intakes of fruit (P < .001), vitamin C (P < .001), and potassium (P < .005) and lower intakes of added sugar (P < .01) compared with GJ nonconsumers (n = 14 902), with no differences in weight, BMI, or waist circumference. Consumption of P/B produce was associated with increased fruit and nutrient intakes and with reduced risk for MetS. GJ consumption was also associated with increased nutrient intake.

Effects of Red Grape Juice Consumption on High Density Lipoprotein-Cholesterol, Apolipoprotein AI, Apolipoprotein B and Homocysteine in Healthy Human Volunteers

It has suggested that grape juice consumption has lipid- lowering effect and it is associated with a decreased risk of heart disease. We aimed to evaluate the effects of red grape juice (RGj) consumption on high density lipoprotein-cholesterol (HDL-C), apolipoprotein AI (apoAI), apolipoprotein B (apoB) and homocysteine (Hcy) levels in healthy human volunteers. Twenty six healthy and nonsmoking males, aged between 25-60 years, who were under no medication asked to consume 150 ml of RGj twice per day for one month. Serum HDL-C, apoAI, apoB and plasma Hcy levels were measured before and after one month RGj consumption. HDL-C levels after RGj consumption were significantly higher than the corresponding levels before the RGj consumption (41.44 ± 4.50 and 44.37 ± 4.30 mg/dl; P<0.0001). Also, apoB was significantly increased after RGj consumption (149.0 ± 22.35 and 157.19 ± 18.60 mg/dl; P<0.002). But apoAI levels were not changed significantly before and after of RGj consumption (154.27 ± 21.55 and 155.35 ± 21.07 mg/dl; P>0.05). Hcy levels were decreased after RGj consumption (7.70 ± 2.80 and 6.20 ± 2.30 µmol/l; P<0.001). The present study demonstrates that RGj consumption can significantly increase serum HDL-C levels and decrease Hcy levels. These findings may have important implications for the prevention of atherosclerosis in healthy individuals.

Regular Consumption of Concord Grape Juice Benefits Human Immunity

γδ T cells are important immune surveillance cells residing in epithelial layers lining the intestine, lung, and reproductive tract. The main objective of this study was to test the hypothesis that consumption of dietary compounds from grapes would modify γδ T-cell function. Other factors related to immune function after grape juice consumption were also tested. A randomized, double-blind, placebo-controlled, parallel intervention was conducted: 100% grape juice made from Concord grapes or a placebo beverage was consumed by 85 individuals daily for 9 weeks. Subjects were asked not to consume other red, blue, and purple fruits during the study. Blood samples, taken at the beginning and the end, were analyzed for γδ T-cell numbers and proliferation, vitamin C, antioxidant capacity, and the ability to protect DNA from strand breaks. Those consuming the grape juice had significantly greater numbers of circulating γδ T cells and higher serum vitamin C levels compared to the placebo by two-way repeated-measure analysis of variance (P < .05). Individuals consuming the placebo had lower serum antioxidant activity, less γδ T-cell proliferation, and increased DNA strand breaks when challenged with H(2)O(2). Analysis of the data by structural equation modeling confirmed that 61% of the variance in biological functions at 9 weeks was due to grape juice consumption. Based on conventional statistical analyses, as well as on sophisticated modeling techniques, regular consumption of purple grape juice in the absence of other red, blue, or purple fruits benefited immunity in healthy, middle-aged human subjects.

Effects of Concord grape juice on ambulatory blood pressure in prehypertension and stage 1 hypertension

Consumption of flavonoid-containing foods may be useful for the management of hypertension. We investigated whether 100% Concord grape juice lowers blood pressure in patients with prehypertension and stage 1 hypertension. We conducted a double-blind crossover study to compare the effects of grape juice (7 mL · kg⁻¹ · d⁻¹) and matched placebo beverage on 24-h ambulatory blood pressure, stress-induced changes in blood pressure, and biochemical profile. Participants consumed each beverage for 8 wk with a 4-wk rest period between beverages. They ceased consumption of grapes and other flavonoid-containing beverages throughout the study. We enrolled 64 otherwise healthy patients taking no antihypertensive medications (31% women, 42% black, age 43 ± 12 y). Baseline mean (± SD) cuff blood pressure was 138 ± 7 (systolic)/82 ± 7 (diastolic) mm Hg. No effects on the primary endpoint of 24-h mean systolic blood pressure, diastolic blood pressure, or stress-induced changes in blood pressure were observed. A secondary endpoint was nocturnal dip in systolic pressure. At baseline, nocturnal pressure was 8.3 ± 7.1% lower at night than during daytime. The mean nocturnal dip increased 1.4 percentage points after grape juice and decreased 2.3 percentage points after placebo (P = 0.005). Fasting blood glucose was 91 ± 10 mg/dL at baseline for the entire cohort. Glucose decreased 2 mg/dL after consumption of grape juice and increased 1 mg/dL after consuming the placebo (P = 0.03). We observed no effect of grape juice on ambulatory blood pressure in this cohort of relatively healthy individuals with modestly elevated blood pressure. Secondary analyses suggested favorable effects on nocturnal dip and glucose homeostasis that may merit further investigation. This trial was registered at clinicaltrials.gov as NCT00302809.

Atributos sensoriais e aceitação de sucos de uva comerciais

O suco de uva contem compostos fenolicos em quantidades importantes e, portanto, seu consumo e desejavel como aporte de substâncias antioxidantes naturais. Os objetivos do estudo foram investigar os atributos sensoriais e avaliar a aceitacao de sucos de uva comerciais. Foram analisados tres tipos de suco de uva comercializados no Brasil: suco integral, suco concentrado e nectar. Utilizaram-se a Analise Descritiva Quantitativa modificada e o Teste de Aceitacao com escala hedonica estruturada de nove pontos, incluindo questoes sobre consumo e compra. Os resultados apontam que o suco integral apresentou cor e gosto amargo mais intensos; o suco concentrado (reconstituido) apresentou baixa intensidade em todos os atributos; e o nectar de uva apresentou maior intensidade de gosto doce e sabor caracteristico de uva. O teste de aceitacao mostrou que o nectar de uva e o suco integral foram os mais aceitos. A maioria dos consumidores relatou consumir quatro ou mais copos suco de uva por mes. O suco integral recebeu maior intencao de compra e o nectar foi a bebida mais consumida. Concluiu-se que o consumidor aprecia o suco integral da uva, com equilibrada intensidade nos atributos sensoriais investigados, todavia, consume com maior frequencia o nectar, bebida a qual sao adicionadas agua e sacarose.

Acute and long-term effects of grape and pomegranate juice consumption on vascular reactivity in paediatric metabolic syndrome

This study, which to the best of our knowledge is the first of its kind, aimed to determine the acute and long-term effects of the consumption of grape and pomegranate juices on endothelium function in adolescents with metabolic syndrome, and to compare the effects of these two kinds of juices. This randomised controlled clinical trial was conducted in 2008 among 30 adolescents, aged 12-15 years, with metabolic syndrome. Participants were randomly assigned to two groups of equal number; one group was asked to drink 18 millilitre per kilogram per day of natural grape juice and the other group was asked to drink 240 millilitre per day of natural pomegranate juice once daily for 1 month. Juices were homemade without any added sweetener. Basal brachial artery dimension and flow-mediated dilation as an index of endothelial function and endothelial-dependent dilation after receiving nitoglycerin spray were evaluated by high-resolution B mode ultrasonography before juice consumption, 4 hours and 30 days after regular daily consumption. Flow-mediated dilation at 90 seconds and after nitoglycerin significantly improved at 4 hours and at 1 month after drinking both kinds of juices, without significant difference between the two groups. The change at 1 month versus 4 hours was significant only in the grape juice group. Daily consumption of diets rich in antioxidants might improve endothelial function in adolescents with metabolic syndrome. These effects began as soon as 4 hours after juice consumption. Such beneficial effects should be considered in dietary recommendations for the paediatric age group, notably in obese individuals.

The metabolic fate of red wine and grape juice polyphenols in humans assessed by metabolomics

The metabolic impact of polyphenol-rich red wine and grape juice consumption in humans was studied using a metabolomics approach. Fifty-eight men and women participated in a placebo-controlled, double-crossover study in which they consumed during a period of 4 wk, either a polyphenol-rich 2:1 dry mix of red wine and red grape juice extracts (MIX) or only a grape juice extract (GJX). Twenty-four-hour urine samples were collected after each intervention. (1)H NMR spectroscopy was applied for global metabolite profiling, while GC-MS was used for focused profiling of urinary phenolic acids. Urine metabolic profiles after intake of both polyphenol-rich extracts were significantly differentiated from placebo using multilevel partial least squares discriminant analysis. A significant 35% increase in hippuric acid excretion (p<0.001) in urine was measured after the MIX consumption as) or only a red grape juice dry extract (GJX). 24-h urine samples were collected after each intervention. 1H-NMR spectroscopy was applied for global metabolite profiling, while gas chromatography-mass spectrometry (GC-MS) was used for focused profiling of urinary phenolic acids. Urine metabolic profiles after intake of both polyphenol-rich extracts were significantly differentiated from placebo using multilevel partial least squares discriminant analysis (ML-PLS-DA). A significant 35% increase in hippuric acid excretion (p<0.001) in urine was measured after the MIX consumption compared with placebo, whereas no change was found after GJX consumption. GC-MS-based metabolomics of urine allowed identification of 18 different phenolic acids, which were significantly elevated following intake of either extract. Syringic acid, 3- and 4-hydroxyhippuric acid and 4-hydroxymandelic acid were the strongest urinary markers for both extracts. MIX and GJX consumption had a slightly different effect on the excreted phenolic acid profile and on endogenous metabolite excretion, possibly reflecting their different polyphenol composition.

Changes in Antioxidant Status, Blood Pressure, and Lymphocyte DNA Damage from Grape Juice Supplementation

In a placebo-controlled double-blinded study, the effect of 8 weeks of grape juice was compared to the effect of isocaloric placebo juice. Volunteers with a systolic blood pressure > 130 mmHg and diastolic blood pressure > 90 mmHg were recruited. A total of 40 healthy subjects were randomized to receive isocaloric juices for 8 weeks. Twenty-one subjects were instructed to consume 5.5 mL/kg daily of grape juice (GJ), and 19 subjects consumed placebo juice (PJ). Plasma antioxidant vitamin C, total radical trapping antioxidant capacity, blood pressure, and lymphocyte DNA damage were assessed pre- and postsupplementation. Plasma total radical-trapping antioxidant potential showed an increase at the level of 1.31 +/- 0.01 (postsupplementation) versus 1.33 +/- 0.01 (presupplementation) (P < 0.1). Grape juice consumption resulted in a 26% decrease in lymphocyte DNA (both hydrogen peroxide treated or spontaneous) in the grape juice group, while no difference was found in the PJ group. Consuming moderate amounts of daily grape juice may favorably affect antioxidant defense systems and lymphocyte DNA damage in hypertensive individuals.

Effects of red grape juice polyphenols in NADPH oxidase subunit expression in human neutrophils and mononuclear blood cells

The NADPH oxidase enzyme system is the main source of superoxide anions in phagocytic and vascular cells. NADPH oxidase-dependent superoxide generation has been found to be abnormally enhanced in several chronic diseases. Evidence is accumulating that polyphenols may have the potential to improve cardiovascular health, although the mechanism is not fully established. Consumption of concentrated red grape juice, rich in polyphenols, has been recently shown to reduce NADPH oxidase activity in circulating neutrophils from human subjects. In the present work we studied whether red grape juice polyphenols affected NADPH oxidase subunit expression at the transcription level. For this, we used human neutrophils and mononuclear cells from peripheral blood, HL-60-derived neutrophils and the endothelial cell line EA.hy926.Superoxide production was measured with 2'7'-dichlorofluorescein diacetate or lucigenin, mRNA expression by real-time RT-PCR and protein expression by Western blot. Each experiment was performed at least three times. In all cell types tested, red grape juice, dealcoholised red wine and pure polyphenols decreased superoxide anion production. Red grape juice and dealcoholised red wine selectively reduced p47phox, p22phox and gp91phox expression at both mRNA and protein levels, without affecting the expression of p67phox. Pure polyphenols, particularly quercetin, also reduced NADPH oxidase subunit expression, especially p47phox, in all cell types tested. The present results showing that red grape juice polyphenols reduce superoxide anion production provide an alternative mechanism by which consumption of grape derivatives may account for a reduction of oxidative stress associated with cardiovascular and/or inflammatory diseases related to NADPH oxidase superoxide overproduction.

Moderate alcohol consumption increases insulin sensitivity and ADIPOQ expression in postmenopausal women: a randomised, crossover trial

Aims/hypothesisTo determine whether 6 weeks of daily, moderate alcohol consumption increases expression of the gene encoding adiponectin (ADIPOQ) and plasma levels of the protein, and improves insulin sensitivity in postmenopausal women.MethodsIn a randomised, open-label, crossover trial conducted in the Netherlands, 36 apparently healthy postmenopausal women who were habitual alcohol consumers, received 250 ml white wine (∼25 g alcohol/day) or 250 ml of white grape juice (control) daily during dinner for 6 weeks. Randomisation to treatment allocation occurred according to BMI. Insulin sensitivity and ADIPOQ mRNA and plasma adiponectin levels were measured at the end of both periods. Insulin sensitivity was estimated using the homeostasis model assessment of insulin resistance (HOMA-IR). Levels of ADIPOQ mRNA in subcutaneous adipose tissue were determined by RT-PCR.ResultsAll subjects completed the study. Six weeks of white wine consumption reduced fasting insulin (mean ± SEM 40.0 ± 3.4 vs 46.5 ± 3.4 pmol/l; p < 0.01) and HOMA-IR (1.42 ± 0.13 vs 1.64 ± 0.13; p = 0.02) compared with 6 weeks of grape juice consumption. ADIPOQ mRNA levels (1.09 ± 0.15 vs 0.98 ± 0.15; p = 0.04) and plasma levels of total (13.1 ± 0.8 vs 12.0 ± 0.8 μg/ml; p < 0.001) and high molecular weight (HMW) adiponectin (9.9 ± 1.2 vs 8.8 ± 1.2 μg/ml; p = 0.02) significantly increased after alcohol compared with juice consumption. Changes in ADIPOQ mRNA levels correlated with changes in plasma levels of total adiponectin (ρ = 0.46; p < 0.01). Both fasting triacylglycerol (8.2%; p = 0.04) and LDL-cholesterol levels (7.8%; p < 0.0001) decreased, whereas HDL-cholesterol increased (7.0%; p < 0.0001) after prolonged moderate alcohol intake. No notable adverse effects were reported.Conclusions/interpretationModerate alcohol consumption for 6 weeks improves insulin sensitivity, adiponectin levels and lipid profile in postmenopausal women. Furthermore, these data suggest a transcriptional mechanism leading to the alcohol-induced increase in adiponectin plasma levels.Trial registration:ClinicalTrials.gov ID no.: NCT00285909Funding:Partly funded by the Dutch Foundation for Alcohol Research (SAR).

No acute effects of grape juice on appetite, implicit memory and mood

Background: Animal experiments document effects of grape juice on cognitive performance and motor skills, and observational studies in humans suggest an inverse association between flavonoid intake and cognitive decline. These effects may be related to the antioxidant properties of polyphenols. Juice consumption and flavonoid intake may also affect appetite.Objective: To study the acute effects of grape juice consumption on appetite, mood and implicit memory during a time of increased lethargy – the post-lunch dip.Design: Thirty-five participants with a mean age of 26 years who smoked a mean of 11 cigarettes/day for 8 years were included in the study. It included a practice session and two treatment sessions. All sessions involved consumption of grape juice or an energy-matched placebo with lunch followed by assessments of mood, implicit memory, appetite and food intake.Results: Mood decreased over time for both treatments, but there were no differences after lunch between grape juice and placebo for any measure.Conclusion: This study did not document any acute effects of grape juice consumption on mood, implicit memory, appetite or food intake in smokers.

Grape juice consumption is associated with increased nutrient intakes and improved cardiovascular parameters in children and adults

Grape juice consumption is associated with increased nutrient intakes and improved cardiovascular parameters in children and adults

Purple grape juice inhibits 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat mammary tumorigenesis and in vivo DMBA-DNA adduct formation

There has been considerable interest in identifying specific foods and phytochemicals that may have breast cancer preventive properties. Concord grapes are rich in polyphenolic chemicals and anthocyanin pigments that may have biological properties which could suppress cancer such as having antioxidant, antiproliferative, and proapoptotic actions. To determine the potential breast cancer protective action of purple grape juice, we examined the effect of grape juice consumption on the initiation stage of 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat mammary tumorigenesis and on the in vivo formation of rat mammary DNA adducts in female Sprague–Dawley rats. Consumption of grape juice significantly inhibited mammary tumor mass at termination and the growth of tumors for the first 5 weeks of detectable tumor development. Consumption of grape juice phenolics by rats also significantly inhibited in vivo mammary DMBA-DNA adduct formation by 34 and 56% for animals fed phenolics at 346 and 692 mg/dL, respectively, compared to controls. Mammary 8-oxo-deoxyguanosine (8-oxo-dG) levels decreased by 25 and 37%, respectively, but the differences were not statistically significant. Liver DMBA-DNA adducts decreased by 10–30%, while 8-oxo-dG adducts remained unchanged, following grape juice intake. Liver glutathione S-transferase activity was significantly increased following grape juice consumption, but only at the highest level of intake. In addition, liver activities of catalase increased and xanthine oxidase decreased significantly, but only at the highest grape juice dose. Thus, these studies indicate that specific constituents or combinations of phytochemicals in purple grape juice can block the initiation stage of DMBA-induced rat mammary tumorigenesis. This tumor inhibitory effect was associated with a suppression of mammary DMBA-DNA adduct formation, which in part may be explained by increased liver activity of the phase II metabolizing enzyme, glutathione S-transferase. Mammary and liver 8-oxo-dG levels were not significantly altered by grape juice consumption. Thus, grape juice constituents appear to have benefit in decreasing susceptibility of the rat mammary gland to the tumor-initiating action of DMBA.

The Antiinflammatory Effects of Purple Grape Juice Consumption in Subjects with Stable Coronary Artery Disease

To the Editor: Moderate consumption of red wine is associated with a reduction in cardiovascular disease,1–4 and some of the cardioprotective effects have been attributed to the distinct polyphenolic compounds present in red wine and purple grape products. These polyphenols possess multiple biological effects, including antioxidant and free radical–scavenging properties5,6 as well as inhibition of platelet activation.7 The growing interest in the presumed benefits of wine in protecting against coronary heart disease coupled with the inherent limitations in promoting alcohol consumption8,9 has led to the examination of the potential beneficial vascular properties of alternative purple grape products. The effect of these flavonoid-rich substances in subjects with cardiovascular disease taking aspirin is unknown. In addition, their impact on the inflammatory properties of platelets has not been studied. A double blind crossover study was conducted, in which 20 subjects with previously diagnosed coronary disease on standard medications were randomly assigned to drink either placebo or purple grape juice …

Nutritional Study of Copper and Zinc in Grapes and Commercial Grape Juices from Spain

This paper presents the levels of copper and zinc determined in a total of 66 samples of the most widely consumed varieties of white and red grapes in Spain, as well as those of 60 samples of grape juice (39 from white varieties and 21 from red ones) chosen from the main commercial brands in the country. Atomic absorption spectroscopy was used as analytical technique, with electrothermal atomization after digestion of the sample with HNO(3)-H(2)O(2) for grapes and with HNO(3) for grape juice. The mean Zn contents obtained (0.0462 mg/100 g in grapes and 0.0460 mg/100 mL in grape juice) are lower than those provided by most of the more commonly used food composition tables. The mean Cu contents were 0.0515 mg/100 g in grapes and 0.0063 mg/100 mL in grape juice. On the basis of these data and the official data on consumption of grapes and grape juice in Spain, the contribution of both products to the recommended daily intake of zinc (15 and 12 mg/day for healthy adult men and women, respectively) is estimated to be approximately 0.1%, whereas for Cu, this supply represents rather more than 0.25% of the established ESADDI (1.5-3 mg/day in adults). The growing popularity of these products in recent years, on the basis of its nutritional properties and beneficial effects, requires additional data, and the present findings are of potential use to food composition tables.

Concord grape juice supplementation reduces blood pressure in Korean hypertensive men: Double‐blind, placebo controlled intervention trial

Many of the flavonoids found in grapes and grape products such as juice or wine have been known to exert antioxidant, anti-inflammatory, platelet inhibitory and arterial relaxing effects either in vitro, in animal studies and in human trials. This study was designed to test the effect of Concord grape juice consumption on altering blood pressure in hypertensive patients. Forty subjects were given 5.5 ml/kg body weight/day of either Concord grape juice (CGJ) or a calorie-matched placebo drink every day for 8 weeks. Blood pressure (BP) was measured on weeks 0, 4 and 8. Compared to baseline, in the CGJ group systolic BP was reduced on average by 7.2 mm Hg (p = 0.005) and diastolic BP was reduced on average by 6.2 mm Hg (p = 0.001) at the end of 8 weeks. Comparable changes in the group getting the placebo product were -3.5 mm Hg (NS) and -3.2 mm Hg (p = 0.05) Consuming Concord grape juice, which is high in polyphenolic compounds, may favorably affect BP in hypertensive individuals.

Daily grape juice consumption reduces oxidative DNA damage and plasma free radical levels in healthy Koreans

Grape contains flavonoids with antioxidant properties which are believed to be protective against various types of cancer. This antioxidative protection is possibly provided by the effective scavenging of reactive oxygen species (ROS), thus defending cellular DNA from oxidative damage and potential mutations. This study of healthy adults tested whether a daily regimen of grape juice supplementation could reduce cellular DNA damage in peripheral lymphocytes and reduce the amount of free radicals released. Sixty-seven healthy volunteers (16 women and 51 men) aged 19–57 years were given 480 ml of grape juice daily for 8 weeks in addition to their normal diet, and blood samples were drawn before and after the intervention. The DNA damage was determined by using the single cell gel (comet) assay with alkaline electrophoresis and was quantified by measuring tail length (TL). Levels of free radicals were determined by reading the lucigenin-perborate ROS generating source, using the Ultra-Weak Chemiluminescence Analyzer System. Grape juice consumption resulted in a significant decrease in lymphocyte DNA damage expressed by TL (before supplementation: 88.75±1.55 μm versus after supplementation: 70.25±1.31 μm; P=0.000 by paired t-test). Additionally, grape juice consumption for 8 weeks reduced the ROS/photon count by 15%, compared to the beginning of the study. The preventive effect of grape juice against DNA damage was simultaneously shown in both sexes. These results indicate that the consumption of grape juice may increase plasma antioxidant capacity, resulting in reduced DNA damage in peripheral lymphocytes achieved at least partially by a reduced release of ROS. Our findings support the hypothesis that polyphenolic compounds contained in grape juice exert cancer-protective effects on lymphocytes, limiting oxidative DNA damage possibly via a decrease in free radical levels.

Bioavailability of anthocyanidin-3-glucosides following consumption of red wine and red grape juice

Pharmacokinetic parameters and the bioavailability of several dietary anthocyanins following consumption of red wine and red grape juice were compared in nine healthy volunteers. They were given a single oral dose of either 400 mL of red wine (279.6 mg total anthocyanins) or 400 mL of red grape juice (283.5 mg total anthocyanins). Within 7 h, the urinary excretion of total anthocyanins was 0.23 and 0.18% of the administered dose following red grape juice and red wine ingestion, respectively. Pharmacokinetic parameters derived from plasma and urine concentrations exhibited higher variability after ingestion of red grape juice. Compared to red grape juice anthocyanins, the relative bioavailability of red wine anthocyanins was calculated to be 65.7, 61.3, 61.9, 291.5, 57.1, and 76.3% for the glucosides of cyanidin, delphinidin, malvidin, peonidin, petunidin, and its sum (referred to as total anthocyanins), respectively. Bioequivalence was established for none of the anthocyanins. On a low level, urinary excretion of anthocyanins was fast, and the excretion rates seem to exhibit monoexponential characteristics over time after ingestion of both red grape juice and red wine. Due to low bioavailability, any significant contribution of anthocyanins to health protecting properties of red wine or red grape juice seems questionable, but the clinical relevance of these findings awaits further investigation.

Potential health benefits from the flavonoids in grape products on vascular disease.

In the dog, monkey, a nd human we have shown that 5 ml/kg of red wine or 5-10 ml/kg of purple grape juice but not orange or grapefruit juice inhibits platelet activity, and protects against epinephrine activation of platelets. Red wine and purple grape juice enhances platelet and endothelial production of nitric oxide (Fitzpatrick et al., 1993, Parker et al., 2000). This is thought to be one of the mechanisms whereby purple grape juice significantly improved endothelial function in 15 patients with coronary artery disease. The consumption of purple grape juice by the patients also offered increased protection against LDL cholesterol oxidation, even though all the patients were also taking another antioxidant vitamin E, 400 IU/day. The number of people and animals in these studies was small; however, each one acted as their own control as measurements were made in each before, and then after consumption of red wine or purple grape juice. Thus these studies are thought to be significant. We feel that the results of these studies are encouraging and justify further research on larger numbers of subjects. This suggests that the flavonoids in purple grape juice and red wine may inhibit the initiation of atherosclerosis by one or more of the mechanisms described above. It will take years to fully characterize the potential benefits of daily consumption of red wine or purple grape juice for maintaining a healthy heart. Based on the existing evidence of antiplatelet and antioxidant benefits and improved endothelial function from red wine and purple grape juice, it seems reasonable to suggest that moderate amounts of red wine or purple grape juice be included among the 5-7 daily servings of fruits and vegetables per day as recommended by the American Heart Association to help reduce the risk of developing cardiovascular disease.