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Plant Polyphenols as Dietary Antioxidants in Human Health and Disease  [PDF]
Kanti Bhooshan Pandey,Syed Ibrahim Rizvi
Oxidative Medicine and Cellular Longevity , 2009, DOI: 10.4161/oxim.2.5.9498
Abstract: Polyphenols are secondary metabolites of plants and are generally involved in defense against ultraviolet radiation or aggression by pathogens. In the last decade, there has been much interest in the potential health benefits of dietary plant polyphenols as antioxidant. Epidemiological studies and associated meta-analyses strongly suggest that long term consumption of diets rich in plant polyphenols offer protection against development of cancers, cardiovascular diseases, diabetes, osteoporosis and neurodegenerative diseases. Here we present knowledge about the biological effects of plant polyphenols in the context of relevance to human health.
Pinto Beans (Phaseolus vulgaris L.) as a Functional Food: Implications on Human Health  [PDF]
Cristiane R. S. Camara,Carlos A. Urrea,Vicki Schlegel
Agriculture , 2013, DOI: 10.3390/agriculture3010090
Abstract: Most foods are considered functional in terms of providing nutrients and energy to sustain daily life, but dietary systems that are capable of preventing or remediating a stressed or diseased state are classified as functional foods. Dry beans ( Phaseolus vulgaris L.) contain high levels of chemically diverse components (phenols, resistance starch, vitamins, fructooligosaccharides) that have shown to protect against such conditions as oxidative stress, cardiovascular disease, diabetes, metabolic syndrome, and many types of cancer, thereby positioning this legume as an excellent functional food. Moreover, the United States has a rich dry bean history and is currently a top producer of dry beans in the world with pinto beans accounting for the vast majority. Despite these attributes, dry bean consumption in the US remains relatively low. Therefore, the objective of this manuscript is to review dry beans as an important US agricultural crop and as functional food for the present age with an emphasis on pinto beans.
Dietary Polyphenols and Their Biological Significance  [PDF]
Xiuzhen Han,Tao Shen,Hongxiang Lou
International Journal of Molecular Sciences , 2007, DOI: 10.3390/i8090950
Abstract: Dietary polyphenols represent a wide variety of compounds that occur in fruits,vegetables, wine, tea, extra virgin olive oil, chocolate and other cocoa products. They aremostly derivatives and/or isomers of flavones, isoflavones, flavonols, catechins andphenolic acids, and possess diverse biological properties such as antioxidant, antiapoptosis,anti-aging, anticarcinogen, anti-inflammation, anti-atherosclerosis, cardiovascularprotection, improvement of the endothelial function, as well as inhibition of angiogenesisand cell proliferation activity. Most of these biological actions have been attributed to theirintrinsic reducing capabilities. They may also offer indirect protection by activatingendogenous defense systems and by modulating cellular signaling processes such asnuclear factor-kappa B (NF-кB) activation, activator protein-1(AP-1) DNA binding,glutathione biosynthesis, phosphoinositide 3 (PI3)-kinase/protein kinase B (Akt) pathway,mitogen-activated protein kinase (MAPK) proteins [extracellular signal-regulated proteinkinase (ERK), c-jun N-terminal kinase (JNK) and P38 ] activation, and the translocationinto the nucleus of nuclear factor erythroid 2 related factor 2 (Nrf2). This paper covers themost recent literature on the subject, and describes the biological mechanisms of action andprotective effects of dietary polyphenols.
Protection of Dietary Polyphenols against Oral Cancer  [PDF]
Yijian Ding,Hua Yao,Yanan Yao,Leonard Yenwong Fai,Zhuo Zhang
Nutrients , 2013, DOI: 10.3390/nu5062173
Abstract: Oral cancer represents a health burden worldwide with approximate 275,000 new cases diagnosed annually. Its poor prognosis is due to local tumor invasion and frequent lymph node metastasis. Better understanding and development of novel treatments and chemo-preventive approaches for the preventive and therapeutic intervention of this type of cancer are necessary. Recent development of dietary polyphenols as cancer preventives and therapeutic agents is of great interest due to their antioxidant and anti-carcinogenic activities. Polyphenols may inhibit carcinogenesis in the stage of initiation, promotion, or progression. In particular, dietary polyphenols decrease incidence of carcinomas and exert protection against oral cancer by induction of cell death and inhibition of tumor growth, invasion, and metastasis. In this review, we discuss current progress of dietary polyphenols against oral cancers in vitro, in vivo, and at population levels.
Dietary Polyphenols as Antioxidants and Anticancer Agents: More Questions than Answers  [PDF]
Miao-Lin Hu
Chang Gung Medical Journal , 2011,
Abstract: High intake of fruit and vegetables is believed to be beneficial to human health. Fruit, vegetables and some beverages,such as tea and coffee, are particularly rich in dietary polyphenols. Various studies have suggested (but not proven) thatdietary polyphenols may protect against cardiovasucalar diseases, neurodegenerative diseases and some forms of cancer.Dietary polyphenols may exert their anticancer effects throughseveral possible mechanisms, such as removal of carcinogenicagents, modulation of cancer cell signaling and antioxidantenzymatic activities, and induction of apoptosis as well as cellcycle arrest. Some of these effects may be related, at least partly, to their antioxidant activities. In recent years, a new conceptof the antioxidant effects of dietary polyphenols has emerged,i.e., direct scavenging activity toward reactive species andindirect antioxidant activity; the latter activity is thought toarise primarily via the activation of nuclear factor-erythroid-2-related factor 2 which stimulates the activities of antioxidant enzymes such as glutathione peroxidase (GPx), glutathioneS-transferase, catalase, NAD(P)H: quinone oxidoreductase-1 (NQO1), and/or phase IIenzymes. The direct antioxidant activity of dietary polyphenols in vivo is probably limitedbecause of their low concentrations in vivo, except in the gastrointestinal tract where theyare present in high concentrations. Paradoxically, the pro-oxidant effect of dietary polyphenols may contribute to the activation of antioxidant enzymes and protective proteins in cultured cells and animal models because of the adaptation of cells and tissues to mild/moderate oxidative stress. Despite a plethora of in vitro studies on dietary polyphenols, manyquestions remain to be answered, such as: (1) How relevant are the direct and indirectantioxidant activities of dietary polyphenols in vivo? (2) How important are these activitiesin the anticancer effects of dietary polyphenols? (3) Do the pro-oxidant effects of dietarypolyphenols observed in vitro have any relevance in vivo, especially in the potential anticancer effect of dietary polyphenols? Apparently, more carefully-designed in vivo studiesare needed to answer these questions.
Polyphenols as dietary supplements: A double-edged sword  [cached]
Keith R Martin,Christy L Appel
Nutrition and Dietary Supplements , 2009,
Abstract: Keith R Martin, Christy L AppelNutrition Program, Healthy Lifestyles Research Center, College of Nursing and Health Innovation, Arizona State University, Mesa, AZ, USAAbstract: Increased consumption of fruits and vegetables is associated with a lower risk of chronic disease such as cardiovascular disease, some forms of cancer, and neurodegeneration. Pro-oxidant-induced oxidative stress contributes to the pathogenesis of numerous chronic diseases and, as such, dietary antioxidants can quench and/or retard such processes. Dietary polyphenols, ie, phenolic acids and flavonoids, are a primary source of antioxidants for humans and are derived from plants including fruits, vegetables, spices, and herbs. Based on compelling evidence regarding the health effects of polyphenol-rich foods, new dietary supplements and polyphenol-rich foods are being developed for public use. Consumption of such products can increase dietary polyphenol intake and subsequently plasma concentrations beyond expected levels associated with dietary consumption and potentially confer additional health benefits. Furthermore, bioavailability can be modified to further increase absorption and ultimately plasma concentrations of polyphenols. However, the upper limit for plasma concentrations of polyphenols before the elaboration of adverse effects is unknown for many polyphenols. Moreover, a considerable amount of evidence is accumulating which supports the hypothesis that high-dose polyphenols can mechanistically cause adverse effects through pro-oxidative action. Thus, polyphenol-rich dietary supplements can potentially confer additional benefits but high-doses may elicit toxicity thereby establishing a double-edge sword in supplement use.Keywords: antioxidant, bioavailability, flavonoids, polyphenols, supplement
Chemistry and Biochemistry of Dietary Polyphenols  [PDF]
Rong Tsao
Nutrients , 2010, DOI: 10.3390/nu2121231
Abstract: Polyphenols are the biggest group of phytochemicals, and many of them have been found in plant-based foods. Polyphenol-rich diets have been linked to many health benefits. This paper is intended to review the chemistry and biochemistry of polyphenols as related to classification, extraction, separation and analytical methods, their occurrence and biosynthesis in plants, and the biological activities and implications in human health. The discussions are focused on important and most recent advances in the above aspects, and challenges are identified for future research.
Impact of Dietary Polyphenols on Carbohydrate Metabolism  [PDF]
Kati Hanhineva,Riitta T?rr?nen,Isabel Bondia-Pons,Jenna Pekkinen,Marjukka Kolehmainen,Hannu Mykk?nen,Kaisa Poutanen
International Journal of Molecular Sciences , 2010, DOI: 10.3390/ijms11041365
Abstract: Polyphenols, including flavonoids, phenolic acids, proanthocyanidins and resveratrol, are a large and heterogeneous group of phytochemicals in plant-based foods, such as tea, coffee, wine, cocoa, cereal grains, soy, fruits and berries. Growing evidence indicates that various dietary polyphenols may influence carbohydrate metabolism at many levels. In animal models and a limited number of human studies carried out so far, polyphenols and foods or beverages rich in polyphenols have attenuated postprandial glycemic responses and fasting hyperglycemia, and improved acute insulin secretion and insulin sensitivity. The possible mechanisms include inhibition of carbohydrate digestion and glucose absorption in the intestine, stimulation of insulin secretion from the pancreatic b-cells, modulation of glucose release from the liver, activation of insulin receptors and glucose uptake in the insulin-sensitive tissues, and modulation of intracellular signalling pathways and gene expression. The positive effects of polyphenols on glucose homeostasis observed in a large number of in vitro and animal models are supported by epidemiological evidence on polyphenol-rich diets. To confirm the implications of polyphenol consumption for prevention of insulin resistance, metabolic syndrome and eventually type 2 diabetes, human trials with well-defined diets, controlled study designs and clinically relevant end-points together with holistic approaches e.g., systems biology profiling technologies are needed.
Dietary Polyphenols and Obesity  [PDF]
Mohsen Meydani,Syeda T. Hasan
Nutrients , 2010, DOI: 10.3390/nu2070737
Abstract: The prevalence of overweight and obesity and their associated metabolic disorders are considered a major threat to the public’s health. While several diet and exercise programs are available for weight loss and prevention of weight regain, progress is often slow and disappointing. Recently, natural bioactive phytochemicals present in foods have been discovered for their potential health benefit effects on the prevention of chronic disorders such as cancer, cardiovascular disease, inflammatory and metabolic diseases including obesity.Polyphenols are a class of naturally-occurring phytochemicals, of which some such as catechins, anthocynines, resveratrol and curcumin have been shown to modulate physiological and molecular pathways that are involved in energy metabolism, adiposity, and obesity. The potential in vivo, beneficial effects of these polyphenols on adiposity and obesity as complementary agents in the up-regulation of energy expenditure have emerged by investigating these compounds in cell cultures, animal models of obesity and in some human clinical and epidemiological studies. In this brief review, the efficacy of the above-named polyphenols and their potential efficacy to modulate obesity and some associated disorders are discussed.
Dietary Polyphenols in Prevention and Treatment of Prostate Cancer  [PDF]
Rahul K. Lall,Deeba N. Syed,Vaqar M. Adhami,Mohammad Imran Khan,Hasan Mukhtar
International Journal of Molecular Sciences , 2015, DOI: 10.3390/ijms16023350
Abstract: Prostate cancer is the most prevalent disease affecting males in many Western countries, with an estimated 29,480 deaths in 2014 in the US alone. Incidence rates for prostate cancer deaths have been decreasing since the early 1990s in men of all races/ethnicities, though they remain about 60% higher in African Americans than in any other group. The relationship between dietary polyphenols and the prevention of prostate cancer has been examined previously. Although results are sometimes inconsistent and variable, there is a general agreement that polyphenols hold great promise for the future management of prostate cancer. Various dietary components, including polyphenols, have been shown to possess anti-cancer properties. Generally considered as non-toxic, dietary polyphenols act as key modulators of signaling pathways and are therefore considered ideal chemopreventive agents. Besides possessing various anti-tumor properties, dietary polyphenols also contribute to epigenetic changes associated with the fate of cancer cells and have emerged as potential drugs for therapeutic intervention. Polyphenols have also been shown to affect post-translational modifications and microRNA expressions. This article provides a systematic review of the health benefits of selected dietary polyphenols in prostate cancer, especially focusing on the subclasses of polyphenols, which have a great effect on disease prevention and treatment.
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