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Grape Antioxidants for Heart Health and Diabetes

April 29, 2009 Written by JP    [Font too small?]

Grapes are one of the most scientifically studied foods in the modern diet. Researchers tend to focus on grape seed and grape skin extracts, but juice and red wine frequently get attention as well. The reason for so much interest is that this richly pigmented fruit is chock full of powerful antioxidants and phytochemicals that are known to promote good health. Today’s blog presents an update of the most current findings on these nutritional superstars.

Inside Grape Seeds

New research from the University of Michigan Cardiovascular Center suggests that grape powder may protect the cardiovascular system. (1) Researchers specifically looked at the impact that grapes would have on a group of salt-sensitive, hypertensive rats.

In this study, the rats were provided with either a grape powder or a low dose of a “common blood pressure drug” (hydrazine) for a period of 18 weeks. The grape powder was a mixture of green, red and black grapes and made up 3% of their overall diet. The two sets of rats were fed a high salt diet.

Both groups demonstrated a reduction in blood pressure. But, a significant difference was found between the two treatments: the rats receiving the grape blend also showed signs of better heart function and a decrease in heart muscle damage. Based on diet alone, there was an expectation that the high-salt content would cause heart damage to all of the rats.

The scientists involved believe that the naturally occurring antioxidants in grapes may activate a “protective process in the genes that reduces damage to the heart”.

Two additional studies (2,3) from March 2009 suggest that other mechanisms may also be involved. The first points to the benefits of flavonoids (found in grapes) in promoting elasticity of arteries and, thereby, improving circulation. This allows for greater glucose and oxygen delivery and the “removal of waste products”. Chronic inflammation is now considered a contributing factor in many health concerns, including cardiovascular disease. A recent experiment found that grape seed extract could counter inflammation brought about by an unhealthy diet.

Grape Are Rich in Polyphenols

Grapes have long been associated with heart health. But, there are other seemingly unrelated conditions that also respond to grapes and grape extracts. Here’s a brief overview of a fraction of the potential of this powerful fruit:

  • Alzheimer’s Disease and Brain Health: Oxidative damage is thought to play an important role in neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease and stroke. (4) Antioxidants may prevent such damage, but only if they can cross the “blood brain barrier”. Grape seed extract does just that. (5) This may be part of the reason why evidence points to its role in limiting the build up of Amyloid-beta plaque and inflammation in a mouse model of Alzheimer’s. (6) Both of these processes are considered central to the progression of this debilitating disease. Another recent trial concluded that grape antioxidants could help protect the brain from accelerated cell death in mice with Alzheimer’s disease. (7)
  • Cancer: Many forms of cancer appear to be sensitive to the effects of grape extracts (GE). In the past few months research has emerged showing that GE may help combat breast cancer and its spread to other parts of the body (“metastasis”). (8) A study in January 2009 reported that GE protects against skin cancer and the related inflammation that may play a role in other forms of cancer. (9) That same month, GE was found to decrease the growth and increase the rate of cell death in certain human colorectal cancer cells. (10) Another interesting experiment from February 2009 discovered that both grape skins and seeds had an anti-H. pylori effect. H. pylori is associated with a greater risk of gastric cancer. (11)
  • Diabetes: A paper published in the January issue of Phytotherapy Research describes grape seed extract’s ability to lower blood sugar, both in the short term and over longer periods of time, as measured by HbA1c levels. (12) A Chinese study, also from 2009, noted that grape seed extract helps to reduce diabetic related damage to kidneys, lowers blood pressure and counters the progression of diabetic neuropathy (nerve damage). (13)

I think we’ll continue to see an abundance of research on grapes in the near and distant future. It seems that the more we learn about them, the more promising a natural remedy they become. All you have to do is decide which form is right for you – the whole fruit (with seeds), the juice, nutritional supplements or wine.

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!

Be well!


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Posted in Diabetes, Heart Health, Nutrition

11 Comments & Updates to “Grape Antioxidants for Heart Health and Diabetes”

  1. Robin Thomas Says:

    Thank you for another well researched and written article. I have been very interested in the role of grape extracts in all forms, and have been following the research of the Linus Pauling Institute on resveratrol http://lpi.oregonstate.edu/infocenter/phytochemicals/resveratrol/index.html

    What is your opinion on the relative benefits of resveratrol from red wine vs a tableted supplement?

  2. JP Says:

    Good day, Robin. Thank you for your kind comment!

    My basic position on resveratrol is that in order to get the amounts used in the clinical studies (mostly conducted in an animal model) you’d have to use a concentrated supplement version of this phytochemical.

    Having said that, red wine contains many other health promoting substances besides resveratrol. Those other phytochemicals may promote wellness independently but they may also act synergistically with the naturally occurring resveratrol in red wine.

    Here’s the approach I’m personally taking at the moment: When I drink alcohol, I only drink red wine – preferably organic or biodynamic varieties (that are sulfite-free and possibly higher in resveratrol).

    I also use a red wine supplement that is standardized to contain 3 mg of resveratrol (exclusively from grapes) per capsule three times a day. This is the equivalent of many glasses of red wine – more than I could possibly drink.

    I’m currently in my 30s so I feel as though this dosage is probably adequate. For more intensive anti-aging effects, a higher dosage might be necessary.

    I think there will be many more studies published in the next couple of years that will help clarify what type of dosage range would be most appropriate.

    Be well!


  3. krishibid durlave roy Says:

    where there is life there is hope
    -krishibid durlave roy

  4. JP Says:


    Be well!


  5. Gil Harnois Says:

    Polyphenolics’ MegaNatural-BP Grape Seed Extracts have been in the spotlight recently. Looks like they have gotten an Award from Frost & Sullivan, a leading analyst and market research firm. See link here: http://www.nutritionhorizon.com/news/Polyphenolics-Earns-Frost-Sullivan-Award-for-its-MegaNatural-BP-Grape-Seed-Extract.html

  6. 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!


  7. 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!


  8. 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!


  9. 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!


  10. 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!


  11. JP Says:

    Updated 06/30/17:


    The effect of obesity and repeated exposure on pharmacokinetic response to grape polyphenols in humans.

    SCOPE: Evidence suggests that dietary pattern may affect polyphenol absorption and/or metabolism. Further, obesity is associated with lower circulating nutrients, though the reason is unclear. We investigated the pharmacokinetic (PK) response of polyphenols in obese/overweight vs. lean individuals before and after repeated dosing with of grape polyphenols.

    METHODS AND RESULTS: A pilot study was conducted in which PK challenges were administered before and after 11 days of repeated dosing with polyphenols. Volunteers (6 lean, 6 overweight/obese) consumed resveratrol, grape seed extract, and grape juice (2,125 mg total polyphenols) daily. On days 1 and 11, blood samples were collected for 6 hours after the polyphenol dose and analyzed for deconjugated catechin, epicatechin, resveratrol, and quercetin. Area under the plasma polyphenol mass by time curves (AUCs) were greater for catechin, epicatechin, and quercetin on day 11 vs. day 1 for low BMI individuals (p = 0.039) but not high BMI individuals. Further, AUCs were greater for epicatechin and resveratrol for low vs. high BMI individuals (p = 0.041), with a similar trend for catechin (p = 0.065), on day 11 but not day 1.

    CONCLUSION: These results suggest that that obesity and repeated exposure may modify polyphenol absorption and/or metabolism in humans.

    Be well!


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