Critique 031: Wine polyphenols have a variety of beneficial effects on health. 30 January 2011
Rodrigo R, Miranda A, Vergara L. Modulation of endogenous antioxidant system by wine polyphenols in human disease. Clin Chim Acta 2011;412:410-424.
Numerous studies indicate that moderate red wine consumption is associated with a protective effect against all-cause mortality. Since oxidative stress constitutes a unifying mechanism of injury of many types of disease processes, it should be expected that polyphenolic antioxidants account for this beneficial effect. Nevertheless, beyond the well-known antioxidant properties of these compounds, they may exert several other protective mechanisms. Indeed, the overall protective effect of polyphenols is due to their large array of biological actions, such as free radical-scavenging, metal chelation, enzyme modulation, cell signalling pathways modulation and gene expression effects, among others.
Wine possesses a variety of polyphenols, with resveratrol its most outstanding representative, due to its pleiotropic biological properties. The presence of ethanol in wine aids to polyphenol absorption, thereby contributing to their bioavailability. Before absorption, polyphenols must be hydrolyzed by intestinal enzymes or by colonic microflora. Then, they undergo intestinal and liver metabolism. There have been no reported polyphenol adverse effects derived from intakes currently associated with the normal diet. However, supplements for health-protection should be cautiously used as no level definition has been given to make sure the dose is safe. The role of oxidative stress and the beneficial effects of wine polyphenols against cardiovascular, cancer, diabetes, microbial, inflammatory, neurodegenerative and kidney diseases and ageing are reviewed. Future large scale randomized clinical trials should be conducted to fully establish the therapeutic use of each individual wine polyphenol against human disease
Much of the protection against cardiovascular disease attributed to wine intake may relate not only to the alcohol in wine, but to its polyphenolic constituents. This review article summarizes research into the chemistry, bioavailability, metabolism and excretion of polyphenols as well as mechanisms of their action. The authors describe their cardioprotective effects, effects on vascular function and atherosclerosis, anti-platelet effects, effects on myocardial ischemia, and anti cancer and anti-diabetic effects.
The authors conclude that “Polyphenols are the most abundant antioxidants in the diet and are widespread constituents of wine, fruits and vegetables. Red wine is protective against all-cause mortality. These protective effects could be due to one or many components of the complex mixture of bioavailable and bioactive compounds present in red wine including ethanol, resveratrol, flavonols, flavan-3-ols, anthocyanins, phenolic acids as well as their metabolites formed either in the tissues or in the colon by the microflora.”
Forum members thought this was a very thorough review that can stand as a valuable and durable reference. It appeared to be dispassionate and sensible. Members appreciated the fact that the authors presented their own opinions and advice throughout the article. For example they warn the reader that it is important to bear in mind that taking supplements may have detrimental effects on the body since no data are available today regarding the potential toxicity. The authors are always cautious in this very readable article.
Another Forum member stated that while this review summarizes a large amount of research on wine polyphenols, it does not provide a critical review of what is realistic and what is not. Not all of the effects observed in vitro could be extended to humans, and a critical discussion about this is not included. Moreover, some terms — although widely used in the scientific literature — are seen today to be obsolete and somehow misleading. Against the concept of “oxidative stress” argues the notion that redox couples are not in equilibrium to each other. Thus, a better definition of electrofiles and nucleofiles is needed. The same for ROS: which are the species we are talking about? It is not thought that hydroxyl radical could be pathologically relevant.
Forum Summary: This review article summarizes research into the chemistry, bioavailability, metabolism and excretion of wine polyphenols as well as mechanisms of their action. The authors describe their cardioprotective effects, effects on vascular function and atherosclerosis, anti-platelet effects, effects on myocardial ischemia, and anti cancer and anti-diabetic effects. The authors conclude that “Polyphenols are the most abundant antioxidants in the diet and are widespread constituents of wine, fruits and vegetables.” Their review provides an extensive scientific literature on polyphenols in wine; it suggests multiple mechanisms by which such substances may have beneficial effects on health.
* * * *
Contributions to this critique by the International Scientific Forum on Alcohol Research were made by the following members:
R. Curtis Ellison, MD, Section of Preventive Medicine & Epidemiology, Boston University School of Medicine, Boston, MA, USA
David Vauzour, PhD, Dept. of Food and Nutritional Sciences, The University of Reading, UK
Fulvio Ursini, MD, Dept. of Biological Chemistry, University of Padova, Padova, Italy
Harvey Finkel, MD, Hematology/Oncology, Boston University Medical Center, Boston, MA, USA