Grape Seed (Extract) Kills Germs

(Updated April 20, 2020)

Grapes have been around for a long time, their attributes being praised by the Egyptians six thousand years ago. The healing powers of grapes had been tapped by the ancient Greeks, usually in the form of wine. Folk healers in Europe used the leaves and sap from the vines to treat skin and eye diseases and to stop the inflammation and pain from hemorrhoids. The substances inside the grape, oligomeric proanthocyanidin compounds (OPCs), are powerful anti-oxidants believed to be able to treat a number of human maladies, from heart disease to cancer to aging skin. Regardless of whatever research can support these uses, there is considerable evidence that grape seed extract is able to address venous insufficiency and edema (Kalus, 2004) (Schaefer, 2003) (Kiesewetter, 2000).

The seeds of grapes are loaded with vitamin E, linoleic acid (an omega-6 fatty acid), various flavonoids (including epicatechin, epicatechin gallate, epigallocatechin gallate, quercitin, kaempferol, and luteolin, among others) and OPCs (USDA, 2003). These compounds are also found in the juice, skins and wine, but in lower concentrations.   Related to the OPCs, resveratrol is the most recently heralded of the grape compounds, and is the subject of several human clinical trials (U.S. NIH), where it’s being studied for use in Alzheimer’s disease, type 2 diabetes, obesity, vascular health, and a raft of other conditions. Only recently announced is that grape seed extract has antimicrobial properties that appear to be more successful than some (or even all) drugs of that class.

One of the most ubiquitous microbes, which causes more than ninety percent of gastrointestinal illnesses worldwide, is the Norovirus. Norovirus-induced gastroenteritis is often called intestinal flu, although the influenza virus is not associated with this illness. Norovirus is transmitted by fecal contamination of food or water, by person-to-person contact, or by airborne means, where it may land on doorknobs, computer keyboards and other surfaces. The flush of a toilet can do this. A disgusting thought is that some of this virus can land on a toothbrush if it’s kept close enough to the toilet when the silver handle is depressed while the seat is up. Long-term care facilities are notorious venues for transmission (Said, 2008). You’ve seen the sign on the mirror in the public lavatory that reminds employees to wash their hands before returning to work. Some pay attention, some do not. Maybe this is a legitimate reason to pray over your food.

Norovirus may be inactivated with bleach (Tuladhar, 2012), but that’s not something you carry around. Because the virus is not girded by a lipid coat, neither alcohol nor detergents are effective biocides. That possibly includes those little moist towels that come in foil packets. As odd as it may seem, grape seed extract (GSE) has shown itself effective against Norovirus. The shell that protects the nucleic acid of a virus is called a capsid, which is a protein. GSE has the uncanny ability to denature that protein and to render the virus inactive. In laboratory tests, Norovirus cells that were exposed to GSE clumped together, deformed and inflated, reducing the virus’ binding capability and infectivity (Li, 2012). When GSE-treated water was used to wash freshly cut lettuce, similar results were noted. But GSE’s potential doesn’t stop here.

Staphylococcus denotes a group of spherical bacteria that aggregate in clusters, like grapes. They’re part of the normal micro-organisms that congregate on the skin and upper respiratory tract. Being gram-positive, they endure on dry surfaces. The strain of this bacterium most significant to humans is S. aureus, which forms a large yellow colony in its host and exhibits a facultative character, meaning that it can survive either with or without oxygen. Most of us carry S. aureus as a ubiquitous flora located in the armpits (axillary), groin (inguinal), the outer section of the nostrils (anterior nares), and the anus (perineum). Some of us carry this bacterium intermittently with changing strains; a minority not at all. Many, if not most, cases of S. aureus illness originate from nasal colonies (von Eiff, 2001). Oddly, this circumstance, identified as MRSA (methicillin-resistant S. aureus), may be attenuated by drinking coffee or tea. It was found that coffee and tea drinkers were fifty percent less likely to carry the bacterium in their nostrils than those who did not imbibe (Matheson, 2011).

Seeking compounds against S. aureus is an ongoing challenge. However, there is hope in GSE, a complex able to inhibit the enzyme needed by the bacterium to grow. In a Taiwanese experiment, fish that were exposed to the pathogen in their environment were spared infection when pre-incubated with GSE, prompting the scientists to foresee the extract as a viable means to prevent food poisoning caused by this bacterium (Kao, 2010). Electron microscopy examination of S. aureus after exposure to GSE noted disruption of the cell wall and a distinct bactericide effect (Al-Habib, 2010). In bacterial skin conditions, S. aureus was found to be most susceptible to the bactericidal nature of GSE (Abtahi, 2011).

In an era where bacteria are learning to resist the drugs designed to eliminate them, research is looking to add natural sources to its armamentarium. Some believe that a natural villain cannot escape a natural hero, regardless of villainous mutations. Hospital-acquired (nosocomial) MRSA infections have increased in recent decades, becoming the leading cause of pneumonia and operative wound infections, and the second most common cause of bloodstream infections. Antibiotic resistance is disturbing, particularly among children (Frei, 2010), but there is evidence that blood and skin infections are on the wane (Landrum, 012). With increasing signs that GSE (and now pomegranate polyphenols) alters S. aureus cell walls to the point of destruction, the only aspect left to be investigated is safety (Su, 2012). This is usually not a major concern with ingredients found in common foods, but may be an issue with the more exotic and foreign elements.  Grape seed extract is held to be safe when used in appropriate dosages (ECFR) (Food Navigator, 2001) (Kiesewetter, 2000). From treating E. coli (Quinones, 2011) to Listeria (Sivarooban, 2007) to Campylobacter (Silvan, 2013) to a collection of enteric pathogens (Su, 2011) (Xiaowei, 2011), the compounds in grape seed extract have earned a place of honor in the medicine cabinet.

Cytokine Storm and COVID-19

Of late, we are inundated with news of a cytokine storm initiated by a strain of the corona virus.  This type incites a vigorous inflammatory response that overwhelms the immune system with interleukins, notably the pro-inflammatory IL-1β, IL-2 and IL-8.  Recent Korean research found that GSE reduces the transcription of pro-inflammatory cytokines in airway epithelial cells, thus forestalling a disease outcome (Kim, 2019).  These syncytial viruses almost always result in pneumonia, and even COPD.  With no reliable vaccines available, we reach for straws. Here, GSE suppresses viral signaling capacity by hindering activity of the prototypical pro-inflammatory signaling compound, nuclear factor kappa B, NF-kB (Lee, 2017).



Abtahi H., Ghazavi A. and Karimi M.

Antimicrobial activities of ethanol extract of black grape

African Journal of Microbiology Research Vol. 5(25), pp. 4446-4448, 9 November, 2011


Al-Habib A, Al-Saleh E, Safer AM, Afzal M.

Bactericidal effect of grape seed extract on methicillin-resistant Staphylococcus aureus (MRSA).

J Toxicol Sci. 2010 Jun;35(3):357-64.


Anastasiadi M, Chorianopoulos NG, Nychas GJ, Haroutounian SA.

Antilisterial activities of polyphenol-rich extracts of grapes and vinification byproducts.

J Agric Food Chem. 2009 Jan 28;57(2):457-63.


Bernstein DI, Bernstein CK, Deng C, Murphy KJ, Bernstein IL, Bernstein JA, Shukla R.

Evaluation of the clinical efficacy and safety of grapeseed extract in the treatment of fall seasonal allergic 

rhinitis: a pilot study.

Ann Allergy Asthma Immunol. 2002 Mar;88(3):272-8.


ECFR--Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: 


Food Navigator

GRAS status for grapeseed extract

8 Jun 2001


Frei CR, Makos BR, Daniels KR, Oramasionwu CU.

Emergence of community-acquired methicillin-resistant Staphylococcus aureus skin and soft tissue infections as a common cause of hospitalization in United States children.

J Pediatr Surg. 2010 Oct;45(10):1967-74.


Kalus U, Koscielny J, Grigorov A, Schaefer E, Peil H, Kiesewetter H.

Improvement of cutaneous microcirculation and oxygen supply in patients with chronic venous insufficiency by orally administered extract of red vine leaves AS 195: a randomised, double-blind, placebo-controlled, crossover study.

Drugs R D. 2004;5(2):63-71.


Kao TT, Tu HC, Chang WN, Chen BH, Shi YY, Chang TC, Fu TF.

Grape seed extract inhibits the growth and pathogenicity of Staphylococcus aureus by interfering with dihydrofolate reductase activity and folate-mediated one-carbon metabolism.

Int J Food Microbiol. 2010 Jun 30;141(1-2):17-27. Epub 2010 May 11.


Kiesewetter H, Koscielny J, Kalus U, Vix JM, Peil H, Petrini O, van Toor BS, de Mey C.

Efficacy of orally administered extract of red vine leaf AS 195 (folia vitis viniferae) in chronic venous insufficiency (stages I-II). A randomized, double-blind, placebo-controlled trial.

Arzneimittelforschung. 2000 Feb;50(2):109-17.


Kim SJ, Lee JW, Eun YG, Lee KH, Yeo SG, Kim SW.

Pretreatment with a grape seed proanthocyanidin extract downregulates proinflammatory cytokine expression in airway epithelial cells infected with respiratory syncytial virus.

Mol Med Rep. 2019 Apr;19(4):3330-3336.


Landrum ML, Neumann C, Cook C, Chukwuma U, Ellis MW, Hospenthal DR, Murray CK.

Epidemiology of Staphylococcus aureus blood and skin and soft tissue infections in the US military health system, 2005-2010.

JAMA. 2012 Jul 4;308(1):50-9.


Lee JW, Kim YI, Im CN, Kim SW, Kim SJ, Min S, Joo YH, Yim SV, Chung N.

Grape Seed Proanthocyanidin Inhibits Mucin Synthesis and Viral Replication by Suppression of AP-1 and NF-κB via p38 MAPKs/JNK Signaling Pathways in Respiratory Syncytial Virus-Infected A549 Cells.

J Agric Food Chem. 2017 Jun 7;65(22):4472-4483.


Dan Li, Leen Baert, Dongsheng Zhang, Ming Xia, Weiming Zhong, Els Van Coillie, Xi Jiang and Mieke Uyttendaele

Effect of Grape Seed Extract on Human Norovirus GII.4 and Murine Norovirus 1 in Viral Suspensions, on Stainless Steel Discs, and in Lettuce Wash Water

Appl. Environ. Microbiol. November 2012 vol. 78 no. 21 7572-7578 



Matheson EM, Mainous AG 3rd, Everett CJ, King DE.

Tea and coffee consumption and MRSA nasal carriage

Ann Fam Med. 2011 Jul-Aug;9(4):299-304.


Quiñones B, Massey S, Friedman M, Swimley MS, Teter K. 

Novel cell-based method to detect Shiga toxin 2 from Escherichia coli O157:H7 and inhibitors of toxin activity. 

Appl Environ Microbiol.   2011 March  75(5): 1410–1416. 


Said MA, Perl TM, Sears CL.

Healthcare epidemiology: gastrointestinal flu: norovirus in health care and long-term care facilities.

Clin Infect Dis. 2008 Nov 1;47(9):1202-8.


Schaefer E, Peil H, Ambrosetti L, Petrini O.

Oedema protective properties of the red vine leaf extract AS 195 (Folia vitis viniferae) in the treatment of chronic venous insufficiency. A 6-week observational clinical trial.

Arzneimittelforschung. 2003;53(4):243-6.


Jose Manuel Silván, Elisa Mingo, Maria Hidalgo, Sonia de Pascual-Teresa, Alfonso V. Carrascosa, Adolfo J. Martinez-Rodrigueza

Antibacterial activity of a grapeseed extract and its fractions against Campylobacterspp.

Food Control. Volume 29, Issue 1, January 2013, Pages 25–31


Sivarooban T, Hettiarachchy NS, Johnson MG.

Inhibition of Listeria monocytogenes using nisin with grape seed extract on turkey frankfurters stored at 4 and 10 degrees C.

J Food Prot. 2007 Apr;70(4):1017-20.

Su X, D'Souza DH.

Grape seed extract for control of human enteric viruses.

Appl Environ Microbiol. 2011 Jun;77(12):3982-7. Epub 2011 Apr 15.


Su X, Howell AB, D'Souza DH.

Antibacterial effects of plant-derived extracts on methicillin-resistant Staphylococcus aureus.

Foodborne Pathog Dis. 2012 Jun;9(6):573-8.



Tuladhar E, Hazeleger WC, Koopmans M, Zwietering MH, Beumer RR, Duizer E.

Residual viral and bacterial contamination of surfaces after cleaning and disinfection.

Appl Environ Microbiol. 2012 Nov;78(21):7769-75. doi: 10.1128/AEM.02144-12. Epub 2012 Aug 31.


U.S. Department of Agriculture; Agricultural Research Service

USDA Database for the Flavonoid Content of Selected Foods

March, 2003


U.S. National Institutes of Health


A service of the U.S. National Institutes of Health


von Eiff C, Becker K, Machka K, Stammer H, Peters G.

Nasal carriage as a source of Staphylococcus aureus bacteremia. Study Group.

N Engl J Med. 2001 Jan 4;344(1):11-6.


Xiaowei Su and Doris H. D'Souza

Grape Seed Extract for Control of Human Enteric Viruses

Appl Environ Microbiol. 2011 June; 77(12): 3982–3987.