You have probably heard about resveratrol, a powerful antioxidant found in grapes. But did you know that extracts from grape seeds also have very high levels of another powerful antioxidant? These disease-fighting compounds are called oligomeric proanthocyanidins (also known as OPCs), and are a combination of polyphenols.1 Polyphenol antioxidant activity is believed to be the source of their many health benefits.2 It was documentation about Native American use of tea from pine tree bark and needles from French explorers who used it to treat scurvy in the 1500s that culminated in research to extract the biologically active OPC compounds hundreds of years later.3 In 1970 these same scientists extracted OPCs from grape seeds,3 and later studies confirmed that the grape seed waste (pomace) from wineries is an abundant raw material source of multiple good quality OPCs and other beneficial polyphenols.4 Agricultural and nutritional experts continue to explore the best methods and solvents to extract the greatest yield of these powerful antioxidant compounds from grape seeds.5
Scientists have conducted many experiments on grape seed extract (GSE), both in vitro and in vivo (animals and human), that suggest an astounding array of benefits for a variety of health conditions. Even though there has been some question about the bioavailability of OPCs in grape seed extract,6 in vivo studies have demonstrated that GSE’s antioxidant protection from free radicals is actually better than other well-known antioxidants—including vitamins C and E.3 The three most important antioxidant mechanisms2 of OPCs are:
- free radical scavenging2
- preventing metals naturally in the body, like copper and iron, from reacting with other substances and forming harmful hydroxyl radicals2,7
- inhibition of enzymes that form free radicals2,8
Some of the antioxidant benefits that grape seed extract may provide include:
- Alzheimer’s disease: GSE has neuro-protective effects that may help prevent Alzheimer’s; in vivo studies with rats suggest that the OPCs from GSE were bioavailable in the brain with repeated dosing.9
- Cancer: Research continues to show that GSE exhibits cancer chemopreventive activity,10 including inhibiting proliferation while promoting death of prostate cancer cells11, bladder cancer,12 and non-small cell lung cancer.13
- Cardiovascular Disease: As fats in our diets are digested and oxidize, they can cause physiological reactions that promote cardiovascular disease. In vivo and in vitro experiments demonstrated that GSE added to meat inhibited oxidized lipid production during digestion of that meat, suggesting a preventive effect from cardiovascular disease.18
- HIV: GSE OPCs have been shown to inhibit the receptors that allow entry of the HIV virus into cells.21
- Liver Health: GSE antioxidants seemed to provide enhanced antioxidant protection of liver cells against free radical damage produced by high blood sugar in one in vivo animal study.15
- Obesity: An in vivo study with hamsters suggests that GSE can help prevent obesity, even in a high-fat diet, probably due to helping prevent the insulin resistance, higher blood glucose levels, and increased abdominal fat found in test subjects not given GSE.14
- Oral Health: Based on comparative measurements of antioxidants and free radicals in the saliva of patients with periodontal diseases in one study, researchers linked these diseases to an imbalance between oxidants and antioxidants;16 in vitro studies suggest that GSE’s antioxidant and antimicrobial properties can help prevent periodontitis.17
- Rheumatoid Arthritis: Interleukin 17 (IL-17) and tumor necrosis factor alpha (TNF-α) are both inflammatory cytokines involved in the development of rheumatoid arthritis.19 An animal study of rats with collagen-induced arthritis showed that those injected with grape seed extract had much lower levels of both IL-17 and TNF-α, suggesting possible therapeutic uses for rheumatoid arthritis in humans.20
The Best Way to Ingest Grape Seed Extract
Grape seed extract is most commonly available in capsule, tablet, or liquid form. When buying grape seed extract supplements, look for a formula that is labeled as having at least 95% OPCs; recommended dosage is 25 - 150 mg up to 3 times a day. As for drinking your grape seed extracts in the form of wine, scientists are still unsure whether it is the flavonoids, the alcohol, or the combination of both that offers the most protective and preventative results. Since alcoholic beverages may represent health risks to some, it is important to discuss the risks and benefits of drinking wine with your health care provider, especially if you are pregnant, breastfeeding, or trying to become pregnant.22
Possible Risks Associated with Grape Seed Extract Consumption
Grape seed extract is generally well tolerated by most individuals when taken in an oral form. Rare cases of side effects may involve headache, itchiness, dizziness, and/or nausea.23 Due to the action of proanthocyanidins, which reduce blood platelet adhesion, this extract may increase the clotting time for blood. Interactions between grape seed extract and allopathic medicines have not been carefully studied, so as with any supplement, always consult with a doctor before taking grape seed extract, especially if you are currently taking any other form of medication.22
References and Other Resources:
- Veluri, Ravikanth, et al. Fractionation of grape seed extract and identification of gallic acid as one of the major active constituents causing growth inhibition and apoptotic death of DU145 human prostate carcinoma cells. Oxford Journals: Carcinogenesis. [Online] 2006.
- Cos, P., et al. Curr Med Chem.: Proanthocyanidins in health care: current and new trends. PubMed: U.S. National Library of Medicine and the National Institutes of Health. [Online] May 2004.
- Fine, Anne Marie. Oligomeric Proanthocyanidin Complexes:History, Structure, and Phytopharmaceutical Applications. Thorne Research, Inc.: Alternative Medicine Review. [Online] 2001.
- Hurst, W. Jeffrey. Methods of Analysis for Functional Foods and Nutraceuticals. s.l. : CRC Press, 2007. ISBN 084937314X, 9780849373145.
- Residues of grape (Vitis vinifera L.) seed oil production as a valuable source of phenolic antioxidants. ScienceDirect: Food Chemistry. [Online] February 2009. http://dx.doi.org/10.1016/j.foodchem.2008.06.005.
- Braun, Lesley and Cohen, Marc. Herbs & Natural Supplements: An Evidence-Based Guide. s.l. : Elsevier Australia, 2007. ISBN 072953796X, 9780729537964.
- Akhlaghia, Masoumeh and Bandy, Brian. Mechanisms of flavonoid protection against myocardial ischemia–reperfusion injury. ScienceDirect: Journal of Molecular and Cellular Cardiology. [Online] 2008.
- Watson, Ronald R. Handbook of Nutrition in the Aged. s.l. : CRC Press, 2008. ISBN 1420059718, 9781420059717.
- Lobo, Jessica Kathleen, et al. Bioavailability of gallic acid and catechins from neuroprotective grape seed extract is improved by repeated dosing in rats. The FASEB Journal. [Online] 2009.
- Kaur, Manjinder, Agarwal, Chapla and Agarwal, Rajesh. Anticancer and Cancer Chemopreventive Potential of Grape Seed Extract and Other Grape-Based Products. American Society for Nutrition: Journal of Nutrition. [Online] July 29, 2009.
- Neuwirt, Hannes, et al. Oligomeric proanthocyanidin complexes (OPC) exert anti-proliferative and pro-apoptotic effects on prostate cancer cells. Wiley InterScience: The Prostate. [Online] July 28, 2008.
- Liu, Jie, et al. Role of survivin in apoptosis induced by grape seed procyanidin extract in human bladder cancer BIU87 cells. SpringerLink: The Chinese-German Journal of Clinical Oncology. [Online] July 24, 2009.
- Akhtar, Suhail, et al. Grape Seed Proanthocyanidins Inhibit the Growth of Human Non-Small Cell Lung Cancer Xenografts by Targeting Insulin-Like Growth Factor Binding Protein-3, Tumor Cell Proliferation, and Angiogenic Factors. Clinical Cancer Research. [Online] September 1, 2009.
- Décordé, Kelly, et al. Chardonnay grape seed procyanidin extract supplementation prevents high-fat diet-induced obesity in hamsters by improving adipokine imbalance and oxidative stress markers. Wiley InterScience: Molecular Nutrition & Food Research. [Online] November 26, 2008.
- Chis, Irina C., et al. Antioxidant effects of a grape seed extract in a rat model of diabetes mellitus. Sage Journals Online: Diabetes and Vascular Disease Research. [Online] 2009.
- Diab-Ladki, Randa, Pellat, Bernard and Chahine, Ramez. Decrease in the total antioxidant activity of saliva in patients with periodontal diseases. SpringerLink: Clinical Oral Investigations. [Online] February 19, 2004.
- Furigaa, Aurelie, Lonvaud-Funelb, Aline and Badeta, Cecile. In vitro study of antioxidant capacity and antibacterial activity on oral anaerobes of a grape seed extract. ScienceDirect: Food Chemistry. [Online] August 29, 2008.
- Kuffaa, Matthew, et al. Ability of dietary antioxidants to affect lipid oxidation of cooked turkey meat in a simulated stomach and blood lipids after a meal. ScienceDirect: Journal of Functional Foods. [Online] April 2009.
- Tokuda, Haruhiko, et al. Interleukin (IL)-17 enhances tumor necrosis factor-a-stimulated IL-6 synthesis via p38 mitogen-activated protein kinase in osteoblasts. Wiley InterScience: Journal of Cellular Biochemistry. [Online] February 25, 2004.
- Cho, Mi-La, et al. Grape seed proanthocyanidin extract (GSPE) attenuates collagen-induced arthritis. ScienceDirect: Immunology Letters. [Online] May 24, 2009.
- Ullah, Mohd Fahad and Khan, Md Wasim. Food as Medicine: Potential Therapeutic Tendencies of Plant Derived Polyphenolic Compounds.Asian Pacific Journal of Cancer Prevention: Therapeutic Properties of Plant Derived Polyphenolic Compounds. [Online] 2008.
- Hawkins, Ernest B. and Ehrlich, Steven D. Grape seed. University of Maryland Medical Center Medical Reference: Complementary Medicine. [Online] January 24, 2007.
- National Center for Complementary and Alternative Medicine. Grape Seed Extract. Dept. of Health and Human Services: National Institutes of Health. [Online] May 2008.
Biologically active plant compounds that have antioxidant properties.
In vitro studies are conducted in the laboratory, not in a living human/animal test subject; in vivo studies are done using human/animal test subjects.
How much of a substance becomes biologically available, through absorption, for cellular action.
Small proteins excreted from cells.
Fats and waxy substances soluble in alcohol (not water).
An animal model of rheumatoid arthritis in humans.