Effects Of Dietary Polyphenols Research Articles

Effect of dietary polyphenols on chronobiology in mammalian cells in vitro

Circadian clocks play a key role in metabolic homeostasis, and disruption of circadian rhythms is inextricably intertwined with metabolic disorders [1]. Emerging evidence in the literature suggests that polyphenols possess the potential to modulate metabolic processes associated with circadian rhythms. This review aims to evaluate the effects of polyphenols on metabolic homeostasis via circadian rhythms and their potential mechanism(s) of action on circadian rhythmicity of clock components and linked metabolic processes, by critically assessing the literature on mammalian cells in vitro. To ensure that all relevant studies in this area were included, a systematic search protocol was developed by defining the inclusion and exclusion criteria based on the population, intervention, comparator and outcome framework, along with limiting the source of evidence to original research written in English. Three databases (Ovid Medline, Web of Science, and Scopus) were searched with no time constraints. The search identified 5842 studies and, after duplicate removal and initial screening, 48 studies were reviewed in full. Of those, 38 were eligible for inclusion. The included studies were published between 2008-2023, with a notable surge in publications after 2016, which is indicative of the growing attention towards polyphenols and circadian biology. 33 polyphenols were examined for their effects on circadian cellular processes (n = 16 papers), expression of clock genes and/or proteins (n = 26), or circadian rhythm features of clock genes (n = 10). A handful of studies examined the role of polyphenols in regulating disrupted glucose and lipid metabolism through clock components. The findings suggested that the underlying mechanisms were BMAL1-dependent. It must be noted that the effects of the reported polyphenols were elucidated at concentrations exceeding the normal range found in human plasma and target tissues (˃ 10 μM). However, a single study revealed that (−)-epigallocatechin-3-gallate (EGCG) at a physiologically-relevant concentration (10 μM), improved hepatic glucose metabolism [2]. Further, the polyphenols reported in this review exhibited the potential to influence numerous clock components, mainly BMAL1, PER2 and RORα/γ, at mRNA and/or protein levels when administered at physiologically-relevant concentrations. These polyphenols include nobiletin, tangeretin, curcumin, bavachalcone, cinnamic acid, (−)-epigallocatechin-3-gallate, resveratrol and Urolithin A. Polyphenols have the potential to regulate circadian oscillators and associated metabolic processes in various types of cells. However, there is significant methodological heterogeneity among the studies, which makes it difficult to compare outcomes. Thus, this review will help future research in the field of circadian impacts of polyphenols to integrate standardised approaches, in aspects such as utilisation of a synchronisation method and physiologically-relevant concentrations of polyphenols (≤ 10 μM) in cultured cells. This is critical for understanding how polyphenols might modulate circadian-metabolic health in humans.

Polyphenol intake beneficially associates with inflammation and cognitive performance, and is mediated by MRI‐derived features

AbstractBackgroundEarly changes to cognitive performance and neurophysiological biomarkers offer insights into one’s future risk of developing Alzheimer’s disease or other dementias. Evidence suggests a link between polyphenol intake and reduced incidence of age‐associated cognitive decline and neurodegeneration. These relationships may be driven by the effect of dietary polyphenols on inflammation and degeneration of critical neurological structures and systems. These relationships are challenging to assess, as few cohorts allow cohesive assessment of polyphenol intake, systemic inflammation, neurophysiological measures and cognition.MethodPolyphenol intake was assessed in two UK cohorts: The Airwave Health Monitoring Study and UK Biobank (UKB). Diet diary and questionnaire data were integrated with polyphenol composition data from Phenol‐Explorer to allow for testing of associations between polyphenol intake, blood biomarkers of inflammation, and cognitive performance. 9008 Airwave participants and 209,163 UKB participants were included in a cross‐sectional analysis. C‐reactive protein (CRP) and fibrinogen were used as blood biomarkers of inflammation, and cognitive assessments included reaction time (milliseconds) and fluid intelligence (score /13). Neuroimaging assessments included grey matter volumes and white matter integrity, and were considered individually and using PCA.ResultLinear regressions showed inverse associations between total polyphenol intake and CRP: ß ‐0.00702 (Airwave) and ß = ‐0.00672 (UKB), both P <0.001, as well as fibrinogen: ß ‐0.00221; P = 0.038 (Airwave only), in addition to biomarker associations with polyphenols at the compound group level. Regarding cognition, linear regressions revealed beneficial associations between total intake and performance in fluid intelligence tests: ß 0.00657; P = 0.009 (Airwave) and ß 0.00715, P <0.001 (UKB), and reaction time ß ‐0.0000977; P = 0.020 (UKB). Mediations of the polyphenol‐fluid intelligence relationship were detected for IDPs including grey matter volumes of hippocampal‐associated regions, and white matter integrity measured using ISOVF.ConclusionWe described polyphenol intake in two large, contemporary UK cohorts, and discovered associations between higher intake and improved inflammatory markers and cognitive performance, as well as mediations of the polyphenol‐cognition relationship by physical neurological markers. This contributes to evidence supporting the health benefits of dietary polyphenols, clarifies the physiological pathways through which they may act, and highlights their relevance when considering preventative interventions for neurodegeneration.

Polyphenol intake beneficially associates with inflammation and cognitive performance, and is mediated by MRI‐derived features

AbstractBackgroundEarly changes to cognitive performance and neurophysiological biomarkers offer insights into one’s future risk of developing Alzheimer’s disease or other dementias. Evidence suggests a link between polyphenol intake and reduced incidence of age‐associated cognitive decline and neurodegeneration. These relationships may be driven by the effect of dietary polyphenols on inflammation and degeneration of critical neurological structures and systems. These relationships are challenging to assess, as few cohorts allow cohesive assessment of polyphenol intake, systemic inflammation, neurophysiological measures and cognition.MethodPolyphenol intake was assessed in two UK cohorts: The Airwave Health Monitoring Study and UK Biobank (UKB). Diet diary and questionnaire data were integrated with polyphenol composition data from Phenol‐Explorer to allow for testing of associations between polyphenol intake, blood biomarkers of inflammation, and cognitive performance. 9008 Airwave participants and 209,163 UKB participants were included in a cross‐sectional analysis. C‐reactive protein (CRP) and fibrinogen were used as blood biomarkers of inflammation, and cognitive assessments included reaction time (milliseconds) and fluid intelligence (score /13). Neuroimaging assessments included grey matter volumes and white matter integrity, and were considered individually and using PCA.ResultLinear regressions showed inverse associations between total polyphenol intake and CRP: β ‐0.00702 (Airwave) and β = ‐0.00672 (UKB), both P <0.001, as well as fibrinogen: β ‐0.00221; P = 0.038 (Airwave only), in addition to biomarker associations with polyphenols at the compound group level. Regarding cognition, linear regressions revealed beneficial associations between total intake and performance in fluid intelligence tests: β 0.00657; P = 0.009 (Airwave) and β 0.00715, P <0.001 (UKB), and reaction time β ‐0.0000977; P = 0.020 (UKB). Mediations of the polyphenol‐fluid intelligence relationship were detected for IDPs including grey matter volumes of hippocampal‐associated regions, and white matter integrity measured using ISOVF.ConclusionWe described polyphenol intake in two large, contemporary UK cohorts, and discovered associations between higher intake and improved inflammatory markers and cognitive performance, as well as mediations of the polyphenol‐cognition relationship by physical neurological markers. This contributes to evidence supporting the health benefits of dietary polyphenols, clarifies the physiological pathways through which they may act, and highlights their relevance when considering preventative interventions for neurodegeneration.

Dietary polyphenols maintain homeostasis via regulating bile acid metabolism: a review of possible mechanisms.

The synthesis and metabolism of bile acids (BAs) have been implicated in various metabolic diseases, including obesity and diabetes. Dietary polyphenols, as natural antioxidants, play a vital role in synthesizing and metabolizing bile acids. This paper reviews the mechanism of dietary polyphenols involved in bile acid (BA) synthesis and metabolism. The impact of different gut microorganisms on BA profiles is discussed in detail. The regulation of BA metabolism by dietary polyphenols can be divided into two modes: (1) dietary polyphenols directly activate/inhibit farnesol X receptor (FXR) and Takeda G protein-coupled receptor (TGR5); (2) dietary polyphenols regulate BA synthesis and metabolism through changes in intestinal microorganisms. Research on direct activation/inhibition of FXR and TGR5 by polyphenols should be ramped up. In addition, the effect of dietary polyphenols on intestinal microorganisms has been paid more and more attention and has become a target that cannot be ignored.

Effects of dietary polyphenols on maternal and fetal outcomes in maternal diabetes.

The incidences of short-term or long-term adverse maternal and fetal outcomes caused by maternal diabetes are increasing. Due to toxicity or side effects, economic pressures, and other problems associated with injections or oral hypoglycemic drugs, many researchers have investigated natural treatment methods. Polyphenols can protect against chronic pathologies by regulating numerous physiological processes and provide many health benefits. Moreover, polyphenols have anti-diabetic properties and can be used to treat diabetic complications. Diets rich in polyphenols are beneficial to pregnant women with diabetes. Here, we review the epidemiological and experimental evidence on the impact of dietary polyphenols on maternal and fetal outcomes in pregnant women with diabetes, and the effects of polyphenols on biological changes and possible mechanisms. Previous data (mainly from in vitro and animal experiments) showed that polyphenols can alleviate gestational diabetes mellitus and diabetic embryopathy by reducing maternal hyperglycemia and insulin resistance, alleviating inflammation and oxidative stress, and regulating related signaling pathways. Although polyphenols have shown many health benefits, further research is needed to better understand the complex interactions between polyphenols and maternal diabetes.

Pomegranate (Punica granatum L.) Attenuates Neuroinflammation Involved in Neurodegenerative Diseases.

Food scientists have studied the many health benefits of polyphenols against pernicious human diseases. Evidence from scientific studies has shown that earlier healthy lifestyle changes, particularly in nutrition patterns, can reduce the burden of age-related diseases. In this context, a large number of plant-derived components belonging to the class of polyphenols have been reported to possess neuroprotective benefits. In this review, we examined studies on the effect of dietary polyphenols, notably from Punica granatum L., on neurodegenerative disease, including Alzheimer’s disease, which is symptomatically characterized by impairment of cognitive functions. Clinical trials are in favor of the role of some polyphenols in maintaining neuronal homeostasis and attenuating clinical presentations of the disease. However, discrepancies in study design often bring inconsistent findings on the same component and display differences in their effectiveness due to interindividual variability, bioavailability in the body after administration, molecular structures, cross-blood-brain barrier, and signaling pathways such as nuclear factor kappa B (NF-κB). Based on preclinical and clinical trials, it appears that pomegranate may prove valuable in treating neurodegenerative disorders, including Alzheimer’s disease (AD) and Parkinson’s disease (PD). Therefore, due to the lack of information on human clinical trials, future in-depth studies, focusing on human beings, of several bioactive components of pomegranate’s polyphenols and their synergic effects should be carried out to evaluate their curative treatment.

Effect of Dietary Polyphenols on Osteoarthritis-Molecular Mechanisms.

Osteoarthritis is a common crippling and degenerative disease resulting in irreversible functional changes due to damage of the cartilage and other tissues of the joint. With limited safe and effective pharmaceutical treatments, the demand and use for alternative therapeutic approaches with symptomatic relief for OA patients have increased. Clinical, pre-clinical, and in vitro studies have demonstrated that polyphenols can exert pain-relieving symptoms coupled with increased functional capacity in OA models. This review will highlight studies carried out in the last five years to define the efficacies and underlying mechanisms in polyphenols such as quercetin, resveratrol, curcumin, epigallocatechin-3-gallate, rosmarinic acid, genistein, ginger, berries, silver fir, pine bark, and Boswellia. Most of these studies indicate that polyphenols exhibit their beneficial roles through regulating changes at the biochemical and molecular levels, inducing or inhibiting various signaling pathways related to inflammation and oxidative stress. Polyphenols have also been implicated in modulating microRNA at the posttranscriptional level to counteract OA pathogenesis.

The Effect of Dietary Polyphenols on Vascular Health and Hypertension: Current Evidence and Mechanisms of Action.

The aim of this review was to explore existing evidence from studies conducted on humans and summarize the mechanisms of action of dietary polyphenols on vascular health, blood pressure and hypertension. There is evidence that some polyphenol-rich foods, including berry fruits rich in anthocyanins, cocoa and green tea rich in flavan-3-ols, almonds and pistachios rich in hydroxycinnamic acids, and soy products rich in isoflavones, are able to improve blood pressure levels. A variety of mechanisms can elucidate the observed effects. Some limitations of the evidence, including variability of polyphenol content in plant-derived foods and human absorption, difficulty disentangling the effects of polyphenols from other dietary compounds, and discrepancy of doses between animal and human studies should be taken into account. While no single food counteracts hypertension, adopting a plant-based dietary pattern including a variety of polyphenol-rich foods is an advisable practice to improve blood pressure.

Heat Stress in Broiler Chickens and the Effect of Dietary Polyphenols, with Special Reference to Willow (Salix spp.) Bark Supplements-A Review.

Over the last decade, there has been a growing interest in the use of a wide range of phytoadditives to counteract the harmful effects of heat stress in poultry. Willow (Salix spp.) is a tree with a long history. Among various forms, willow bark is an important natural source of salicin, β-O-glucoside of saligenin, but also of polyphenols (flavonoids and condensed tannins) with antioxidant, antimicrobial, and anti-inflammatory activity. In light of this, the current review presents some literature data aiming to: (1) describe the relationship between heat stress and oxidative stress in broilers, (2) present or summarize literature data on the chemical composition of Salix species, (3) summarize the mechanisms of action of willow bark in heat-stressed broilers, and (4) present different biological effects of the extract of Salix species in different experimental models.

Cancer Chemoprevention by Flavonoids, Dietary Polyphenols and Terpenoids

The world population is aging, and cancer is always considered to be one of the major causes of death all over the globe. The advent of recent drug-targeted therapies undoubtedly is going to reduce the incidence of cancer over the coming years. However, the frequency of occurrence of such chronic diseases like cancer would continue to increase. Therefore, the search for a safer and cost-effective treatment is urgently needed. Phytochemicals found in plants, foods, vegetables, tea, etc. have emerged as proven therapeutic compounds modulating signaling pathways involved in cancer. We carried out a structured search of bibliographic databases for peer-reviewed research literature using the keywords: cancer chemoprevention, flavonoids, dietary polyphenols, terpenoids, bioactive, microbiota. Quality of the retrieved papers and characteristic outcomes of the articles included in the study was assessed by employing standard tools and deductive qualitative content analysis methodology. The development of personalized supplements comprising particular phytochemicals has been the key, especially dealing with chronic inflammatory disorders like cancer. Better understanding at the molecular level explains the influence of phytochemicals on human health, which has been extensively covered through this review. Moreover, the wide collection of dietary polyphenols that has significant properties in reference to human health has been highlighted. Furthermore, the etiology of end products of such phytochemicals, especially on the modulation of gut microbiota and the host-microbial interactions thereof, need to be properly understood. The present study summarizes the chemoprevention and treatment of cancer using the bioactive components, including flavonoids, dietary polyphenols, and terpenoids. Likewise, the effect of dietary polyphenols on the human gut microbiota has been realized more recently. However, more research is needed in this field, especially focused on the communications, interlinks between the gut microbiota and polyphenols with the precise mechanism of action.

Effects of dietary polyphenols on mucosal and humoral immune responses, antioxidant defense and growth gene expression in beluga sturgeon (Huso huso)

Tannins are a class of polyphenols, well known for their potent natural antioxidant properties, which have a beneficial effect on the digestive tract and contribute to improving the welfare of terrestrial farmed animals. This study reports the effect of tannins on haematological and non-specific immune parameters, serum enzyme activity and expression of growth genes of juvenile beluga sturgeon (Huso huso). Tannins were extracted from chestnut wood by SILVATEAM and provided in form of powder, under the commercial name of Silvafeed®ATX. Triplicate groups of 35 Beluga juveniles each (39.20 ± 0.63 g) were placed in 9 oval tanks (350 L) and fed with the basal control diet (0% tannins) and the tannin supplemented basal diet (at 0.05 or 0.1%). The trial lasted 6 weeks. The dietary supplementation of 0.1% tannins significantly improved weight parameters and food conversion ratio (FCR) with respect to the control group (P < .05). Dietary tannins had no significant effect on body composition and haematological parameters. Skin and mucus lysozyme and oxidative stress related enzymes activity (CAT, PPO and SOD) significantly increased in the groups fed tannins enriched diets (P < .05). The enzymatic activity of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase did not change between control and tannin fed groups. Finally, the expression of two growths related genes: gh and igf-i was upregulated in the tannin fed groups. Such outcomes indicate that tannins improve growth performance and the general health status of juvenile beluga sturgeon. Thus, our results suggest that tannins administered to juvenile beluga sturgeon may act as growth promoters.

Effects of dietary polyphenols from agricultural by-products on mucosal and humoral immune and antioxidant responses of convict cichlid (Amatitlania nigrofasciata)

In the present study, the effects of dietary supplementation with polyphenols extracted from agricultural by-products were investigated on serum and/or skin mucus antioxidant and immune responses, and hematological parameters of the convict cichlid (Amatitlania nigrofasciata). Polyphenols extracted from chestnut wood (CW) and olive mill waste water (OMWW) were provided as a mixture (PMIX) (9:1, CW:OMWW). PMIX concentrations of 0.5, 1.0 and 2.0 g/kg of diet were employed. Fish were stocked in 12 tanks and fed with the enriched diets for 8 weeks. After the 8-week period, serum total protein, lysozyme, total immunoglobulins (Ig), catalase (CAT) and radical scavengering activity (RS), skin mucus total protein, total Ig and peroxidase activity, and blood hematological parameters were determined. The results showed that, regardless of inclusion level, skin mucus total Ig and lysozyme activity were significantly increased in the PMIX-treated fish compared to control. The most pronounced changes were related to the supplementation with 2.0 g/kg of PMIX. Similar results were noticed in cases of serum total protein and total Ig. Serum RS and peroxidase activity the fish receiving the 2.0 g/kg PMIX treatment were significantly higher than the other treatments. However, there were no significant differences in the activities among the other treated groups. Serum CAT activity of the fish in the 2.0 g/kg PMIX treatment was significantly higher than the other treatments. Serum CAT activity of the fish in 1.0 g/kg PMIX was significantly higher than the control group, but there were no significant differences in the serum CAT activity between the control and 0.5 g/kg PMIX treatments. There were no significant difference in blood RBC, hematocrit and MCV values among the treatments. In conclusion, PMIX at 2.0 g/kg markedly improves humoral and mucosal immune responses and serum antioxidant responses of the convict cichlid, effects that are probably related to the antioxidant and health-promoting nature of PMIX. Therefore, 2.0 g/kg PMIX is recommended as dietary inclusion levels to increase the overall health of convict cichlid.

The Effects of Dietary Polyphenols on Circulating Cardiovascular Disease Biomarkers and Iron Status: A Systematic Review.

The prevalence of cardiovascular disease (CVD) is rising worldwide, remaining the major cause of death in developed countries. Polyphenols have been shown to have cardioprotective properties; however, their impact on iron bioavailability and potential impact on other aspects of health is unclear. A systematic review was undertaken to evaluate the current status of the relationship between habitual polyphenol consumption, iron status, and circulating biomarkers of CVD. Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2009 guidelines, searches were performed across 5 electronic databases (PubMed, Cochrane Library, Scopus, Web of Science, and CINAHL) to identify randomized controlled trials which investigated the effects of polyphenol consumption on inflammatory markers, serum lipid profile, and iron absorption and bioavailability. In total, 1174 records were identified, with only 7 studies meeting the inclusion criteria. The selected studies involved 133 participants and used a variety of foods and supplements, including olive oil and cherries, rich in polyphenols including hydroxytyrosol, quercetin, and resveratrol, as well as catechin enriched drinks. The duration of the studies ranged from between 56 and 145 days, with total polyphenolic content of the food items and supplements ranging from 45 to 1015 mg (per 100 g). Polyphenols did not appear to interfere with iron status, and most studies reported improvements in inflammatory markers and lipid profile. While these results are promising, the limited number of studies and considerable heterogeneity across the interventions support the need for more extensive trials assessing the relationship between polyphenol intake, iron bioavailability, and CVD risk.

Effect of dietary polyphenols on the in vitro starch digestibility of pigmented maize varieties under cooking conditions

Interest in using polyphenols as modulators of the activity of starch digestive enzymes is increasing. The main purpose of this study was to investigate the role of phenolic compounds characterising pigmented maize flours in the modulation of in vitro starch digestibility. Flours from three different pigmented maize varieties were evaluated under cooking conditions and compared to common yellow maize (YM). The untargeted metabolomics-based approach comprehensively annotated around 300 phenolic compounds, with a high distribution of anthocyanins and phenolic acids (in free and bound fractions of maize samples) and significant differences across genotypes. Following in vitro starch digestion, the cooked pigmented maize flours showed higher resistant starch content (from 5.1 to 6.9 g /100 g dry matter), as well as lower starch hydrolysis index (HI) when compared to YM flour, with the “Rostrato Rosso” maize having the lowest HI (i.e., 61). Coherently, multivariate statistics following metabolomics showed the discrimination potential of anthocyanins' profile after cooking, characterising the “Rostrato Rosso” during in vitro digestion. These findings might be related to the modulation of enzyme activity by phenolic compounds during in vitro digestion. Therefore, the use of pigmented maize flours might help in the formulation of gluten-free foods with slowly digestible starches by exploiting the wide phenolic composition of these matrices.

The antioxidant potential of the Mediterranean diet in patients at high cardiovascular risk: an in-depth review of the PREDIMED

Cardiovascular disease (CVD) is the leading global cause of death. Diet is known to be important in the prevention of CVD. The PREDIMED trial tested a relatively low-fat diet versus a high-fat Mediterranean diet (MedDiet) for the primary prevention of CVD. The resulting reduction of the CV composite outcome resulted in a paradigm shift in CV nutrition. Though many dietary factors likely contributed to this effect, this review focuses on the influence of the MedDiet on endogenous antioxidant systems and the effect of dietary polyphenols. Subgroup analysis of the PREDIMED trial revealed increased endogenous antioxidant and decreased pro-oxidant activity in the MedDiet groups. Moreover, higher polyphenol intake was associated with lower incidence of the primary outcome, overall mortality, blood pressure, inflammatory biomarkers, onset of new-onset type 2 diabetes mellitus (T2DM), and obesity. This suggests that polyphenols likely contributed to the lower incidence of the primary event in the MedDiet groups. In this article, we summarize the potential benefits of polyphenols found in the MedDiet, specifically the PREDIMED cohort. We also discuss the need for further research to confirm and expand the findings of the PREDIMED in a non-Mediterranean population and to determine the exact mechanisms of action of polyphenols.

A5354 - Effect of dietary polyphenols on fructose uptake by human intestinal epithelial cells (Caco-2)

A5354 - Effect of dietary polyphenols on fructose uptake by human intestinal epithelial cells (Caco-2)

I7 Interaction of polyphenols with gut microbiota; understanding the health effects of polyphenols

(Poly) Phenols constitute a large family of phytochemicals with high chemical diversity that are known to be active principles of plant-derived nutraceuticals and herbal medicinal products. Their pharmacological activity, however, is difficult to demonstrate due to their mild physiological effects, and to the large inter-individual variability observed. Many polyphenols have little bioavailability and reach the colon almost unaltered. There they encounter the gut microbes resulting in a two-way interaction in which polyphenols modulate the gut microbiota composition, and the intestinal microbes catabolize the ingested phenolic compounds to release metabolites that are often more active and better absorbed than the native phenolic compounds. The type and quantity of the polyphenol metabolites produced in humans depend on the gut microbiota composition and function, and different metabotypes have been identified. However, not all the metabolites have the same biological activity, and therefore the final health effects of dietary polyphenols depend on the gut microbiota composition. Stratification in clinical trials according to individuals’ metabotypes is necessary to fully understand the health effects of phenolic compounds. Here we present and discuss the most significant and updated knowledge regarding the reciprocal interrelation of the gut microbiota with dietary polyphenols as a key factor that modulates the health effects of these compounds. The review will focus in those polyphenols that are known to be metabolized by gut microbiota resulting in bioactive metabolites.

Effect of dietary polyphenols on fructose uptake by human intestinal epithelial (Caco-2) cells

Intake of high-fructose products is associated with metabolic syndrome development. We investigated if dietary polyphenols can interfere with fructose absorption by the human intestinal epithelial Caco-2 cell line.Acutely, several polyphenols induced a significant decrease (15–20%) in 14C-fructose uptake. Chronically, 14C-fructose uptake was also affected by polyphenols; quercetin, chrysin and apigenin (100µM) were the most effective (±25% decrease). These compounds (100µM) appear to interfere with both GLUT2 and GLUT5 activity; accordingly, they caused a very marked decrease in the mRNA expression levels of GLUT2 (≅90%) and GLUT5 (≅75%). The effect of these compounds on 14C-fructose uptake does not involve interference with PKC, PKA, PI3K and p38 MAPK intracellular signaling pathways.Quercetin, apigenin and chrysin might decrease the intestinal absorption of fructose. Further studies are needed to test for their beneficial effects on metabolic syndrome.

Impact of the Consumption of Tea Polyphenols on Early Atherosclerotic Lesion Formation and Intestinal Bifidobacteria in High-Fat-Fed ApoE-/- Mice.

There is an increasing interest in the effect of dietary polyphenols on the intestinal microbiota and the possible associations between this effect and the development of some cardiovascular diseases, such as atherosclerosis (AS). However, limited information is available on how these polyphenols affect the gut microbiota and AS development. This study was designed to evaluate the modulation of dietary tea polyphenols (TPs) on intestinal Bifidobacteria (IB) and its correlation with AS development in apolipoprotein E-deficient (ApoE−/−) mice. Fifty C57BL/6 ApoE−/− mice were randomized into one of the five treatment groups (n = 10/group): control group fed normal diet (CK); a group fed a high-fat diet (HFD); and the other three groups fed the same HFD supplemented with TPs in drinking water for 16 weeks. The total cholesterol and low-density lipoprotein cholesterol (LDL-C) were decreased significantly (P < 0.05) after TP interference. In addition, the TP diet also decreased the plaque area/lumen area (PA/LA) ratios (P < 0.01) in the TP diet group. Interestingly, copies of IB in the gut of ApoE−/− mice were notably increased with TP interference. This increase was dose dependent (P < 0.01) and negatively correlated with the PA/LA ratio (P < 0.05). We conclude that TPs could promote the proliferation of the IB, which is partially responsible for the reduction of AS plaque induced by HFD.

Effects of dietary polyphenols on metabolic syndrome features in humans: a systematic review

Dietary polyphenols constitute a large family of bioactive substances potential beneficial effect on metabolic syndrome (MetS). This review summarizes the results of clinical studies on patients with MetS involving the chronic supplementation of a polyphenol-rich diet, foods, extracts or with single phenolics on the features of MetS (obesity, dyslipidemia, blood pressure and glycaemia) and associated complications (oxidative stress and inflammation). Polyphenols were shown to be efficient, especially at higher doses, and there were no specific foods or extracts able to alleviate all the features of MetS. Green tea, however, significantly reduced body mass index and waist circumference and improved lipid metabolism. Cocoa supplementation reduced blood pressure and blood glucose. Soy isoflavones, citrus products, hesperidin and quercetin improved lipid metabolism, whereas cinnamon reduced blood glucose. In numerous clinical studies, antioxidative and anti-inflammatory effects were not significant after polyphenol supplementation in patients with MetS. However, some trials pointed towards an improvement of endothelial function in patients supplemented with cocoa, anthocyanin-rich berries, hesperidin or resveratrol. Therefore, diets rich in polyphenols, such as the Mediterranean diet, which promote the consumption of diverse polyphenol-rich products could be an effective nutritional strategy to improve the health of patients with MetS. © 2016 The Authors. Obesity Reviews published by John Wiley & Sons Ltd on behalf of World Obesity.