Polyphenolic compounds health benefits

At one time polyphenolics were regarded as antinutrients since they can complex with proteins and reduce protein quality. Today s heightened interest in these compounds is due to possible health benefits that are attributed to their antioxidant properties. The possible health benefits include reduced risk of coronary heart disease, cancer, stroke, and diabetes. In addition to these health-related findings, it has been long recognized that... 

In association with well-known health benefits related to the consumption of fruit- and vegetable-rich diets, research on the protective effects of plant-derived phenolic compounds (polyphenols) has developed notably in recent years. In particular, their antioxidant properties have been the objective of extensive research. However these phenolics are the target of an array of chemical reactions that, if confirmed to occur in vivo, would contribute to their health promoting effects. It is now emerging that both parent compounds and their metabolites produced after ingestion can regulate cell and tissue functions by both antioxidant and nonantioxidant mechanisms. This volume provides the latest evidence supporting these concepts. 

We must be cautious about what conclusions we draw from new research on polyphenols in relation to superfruits. The polyphenol class as a whole is a highly productive research topic in food and medical science. While scientists are continually adding to what we know about the possible impact of these plant compounds on human health, we need to be wary about the use of unconfirmed results for marketing by manufacturers eager to have a competitive edge in selling superfruit products. This practice unfortunately leads to false claims of effectiveness and to their acceptance by consumers as fact when actually the research is too premature to warrant conclusions about health benefits. 

Red raspberries contain dense contents of ellagic acid, ellagitannins, and several other polyphenols under active research for potential health benefits as anti-inflammatory factors. These phenolic compounds have importance in research on diseases that start first with inflammation, such as cancer, chronic arthritis, Alzheimer s disease, diabetes, and obesity. In research done at Cornell University, scientists studying four cul-tivars of red raspberry identified differences in polyphenol content that were directly related to the color intensity of the respective juices. The color of the juice correlated well to the anthocyanin contents of each raspberry cultivar. In the same studies, proliferation of human liver cancer cells—as part of a laboratory test of potential anticancer activity— was significantly suppressed by the raspberry polyphenols. 

Second, plant compounds called phytochemicals are nonnutrient components of plant foods that may impart health benefits, similar to the pigment antioxidant polyphenols, on the basis of which nearly all superfruit juices are promoted with eye-catching advertisements. Because these phytochemicals await final scientific proof of what they really do in the human body, they are regarded neither as nutrients nor as essential to health. 

Organic production methods lead to increases in nutrients, particularly organic acids and polyphenolic compounds, many of which are considered to have potential human health benefits as antioxidants. The impact... 

Research into food safety, both microbial and chemical food safety, has been accompanied by a parallel effort to identify, test, and optimize healthy constituents of foods. The interest in chemicals in foods extends beyond traditional areas - vitamins, essential minerals, etc. - to secondary chemicals sometimes termed phytonutrients or neutraceuticals which have positive health benefits including prevention or alleviation of diabetes, heart disease, Alzheimer s disease, cancer, arthritis, and many other diseases. Food producers use this information as a marketing tool. Compounds of interest include phenols/polyphenols, flavonoids, carotenoids, anthocyanins, and several other classes that function as antioxidants,... 

Wine phenols are commonly referred to as polyphenols , due as may be seen in Figure 2, to the presence of multiple phenolic groups in their structures, which confer on these compounds various properties linked to health benefits, specifically the antioxidant properties attributed to the consumption of moderate amounts of red wine. Much has been published on this subject and the area and references to reviews may be found in Further reading section. 

Polyphenols are the most important phytochemicals found in a variety of fruits, vegetables, and plant-based foods. Currently there is an increasing interest for the separation, characterization, and valorification of these compounds due to their bioactive properties, health benefits, and potential use as natural antioxidants in foods, pharmaceuticals, and cosmetics. 

Over the last two decades, the scientific community has become aware of the potential health-related benefits of antioxidants and the properties of polyphenols-rich dark chocolate and cocoa. More than 200 studies were reported on bioactive compounds, chemical compositions, and health benefits of cocoa and cocoa products. Many of the proposed health-protective activities associated with the crmsumption of cocoa and chocolate have been attributed to flavan-3-ols, including monomers. Reported pharmacological activities of procyanidins include antioxidative and anticancer effects, protection against cardiovascular disease, risk reduction of blood clotting, protection against urinary tract infectirms, decrease of LDL-c, decrease of blood pressure, and improvement of endothelium vasodilatation. Moreover, there is some scientific evidence about an increase in blood flow and perfusion of the brain by... 

Three major classes of secondary metabolites are involved in these phytochemicals, which are alkaloids, terpenes, and phenoUcs [16]. There are many phytochemicals recognized with health benefits such as sulfur-containing compounds of garlic family, various terpenoids, and polyphenols (anthocyanins, flavones, flavanols, isoflavones, stilbenes, ellagic acid, etc.). 

Details about structure, biosynthesis, and classification of phenolics are described in the other chapters in this handbook. Plant phenolics have a distinctive ability to form non-covalent, intermolecular complexes with each other and with both large and small molecules. Recognition of the antioxidant activities of many polyphenols has established correlation with the health benefits by such compounds [34]. This leads to the development of commercial products containing free-radical-scavenging phytochemical mixtures, for example, Pycnogenol (procyanidin extracted from Pinus maritima). Table 82.2 represents a list of polyphenolic compounds used in nutraceuticals and their biologic effects on human health. 

The potential health benefits of plant polyphenols, such as the flavonoids, have been addressed over the years in the framework of the oxidative stress concept. Oxidative stress, as initially formulated by Sies (1985), refers to an imbalance in the dynamic equilibrium between oxidants and antioxidants that favors the formers, potentially leading to damage. As several diseases are supposed to mechanistically involve oxidative stress, such as atherosclerosis, ischemia-reperfusion injury, cancer, and neurodegenerative disorders (Halliwell Gutteridge, 1999), an impressive number of studies on the in vitro antioxidant activity of polyphenols have spotted these compounds as putatively useful to counteract the deleterious oxidant imbalance associated with disease. However, as will be discussed later, because of limited bioavailability and recent updated concept of oxidative stress, the putative activity of polyphenols as global antioxidants is a limited and simplistic view of polyphenol activity in vivo that can be scarcely supported by experimental data. 

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