Dietary polyphenol intake in Europe: the European Prospective Investigation into Cancer and Nutrition (EPIC) study

Bioavailability and In Vivo Antioxidant Activity of a Standardized Polyphenol Mixture Extracted from Brown Propolis

Several lines of evidence demonstrate the antioxidant, anti-inflammatory and antimicrobial activities of propolis, mostly ascribed to its polyphenol content. However, little is known regarding the bioavailability of propolis in acute and prolonged settings of oral administration. In this study, we first determined the content of the main polyphenols in a brown propolis extract obtained using a patented extraction method (Multi Dinamic Extraction—M.E.D.) by RP-HPLC-UV-PDA-MSn analysis, followed by the bioavailability of galangin and chrysin, the most abundant polyphenols in the mixture (7.8% and 7.5% respectively), following acute (single bolus of 500 mg/kg containing about 3.65 mg of the polyphenol mixture) and prolonged (100, 250 and 500 mg/kg body for 30 days) oral administration in 30 male 8 weeks old C57BL/6 wild-type mice. In the acute setting, blood was taken at 30 s and 5, 10, 15, 20, 25, 30, 45, 60 and 120 min following the oral bolus. In the prolonged setting, blood samples were obtained after 10, 20 or 30 days of administration. At the end of treatment, expression of antioxidant enzymes (superoxyde dismutase, SOD-1; catalase, CAT; glutathione peroxidase, GSS) was evaluated in liver tissue. Following both acute and prolonged administration, neither galangin nor chrysin were detectable in the plasma of mice, whereas the glucuronide metabolite of galangine was detectable 5 min after acute administration. At the end of the prolonged treatment SOD-1 was found to have increased significantly, unlike CAT and GSS. Overall, these data suggest that oral administration of whole brown propolis extract is followed by rapid absorption and metabolization of galangin followed by adaptations of the antioxidant first line defense system.

Flavonoid Mixture Inhibits Mycobacterium tuberculosis Survival and Infectivity

BACKGROUND

Flavonoids have been shown to exert anti-pathogenic potential, but few studies have investigated their effects on Mycobacterium tuberculosis (Mtb) infectivity. We hypothesized that a flavonoid mixture would have a favorable influence on cell death and the resolution of Mtb infection in THP-1 macrophages and in granulomas derived from both healthy participants and those with type 2 diabetes mellitus (T2DM).

METHODS

THP-1 macrophages, and in vitro granulomas from healthy participants (N = 8) and individuals with T2DM (N = 5) were infected with Mtb. A mixed flavonoid supplement (MFS) at a concentration of 0.69 mg per ml was added as treatment to Mtb infected THP-1 macrophages and granulomas for 8 to 15 days.

RESULTS

MFS treatment significantly reduced the intracellular Mtb survival, increased cell density, aggregation, and granuloma formation, and increased glutathione (GSH) levels. IL-12 and IFN-γ levels tended to be higher and IL-10 lower when Mtb infected THP-1 macrophages and granulomas obtained from healthy subjects were treated with MFS compared to control.

CONCLUSIONS

MFS treatment exerted a strong influence against Mtb infectivity in THP-1 macrophages and in granulomas including antimycobacterial effects, GSH enrichment, cytokine regulation, and augmented granuloma formation. Our data support the strategy of increased flavonoid intake for managing tuberculosis.

Green Coffee Extract Improves Cardiometabolic Parameters and Modulates Gut Microbiota in High-Fat-Diet-Fed ApoE-/- Mice

Chlorogenic acids (CGA) are the most abundant phenolic compounds in green coffee beans and in the human diet and have been suggested to mitigate several cardiometabolic risk factors. Here, we aimed to evaluate the effect of a water-based standardized green coffee extract (GCE) on cardiometabolic parameters in ApoE-/- mice and to explore the potential underlying mechanisms. Mice were fed an atherogenic diet without (vehicle) or with GCE by gavage (equivalent to 220 mg/kg of CGA) for 14 weeks. We assessed several metabolic, pathological, and inflammatory parameters and inferred gut microbiota composition, diversity, and functional potential. Although GCE did not reduce atherosclerotic lesion progression or plasma lipid levels, it induced important favorable changes. Specifically, improved metabolic parameters, including fasting glucose, insulin resistance, serum leptin, urinary catecholamines, and liver triglycerides, were observed. These changes were accompanied by reduced weight gain, decreased adiposity, lower inflammatory infiltrate in adipose tissue, and protection against liver damage. Interestingly, GCE also modulated hepatic IL-6 and total serum IgM and induced shifts in gut microbiota. Altogether, our results reveal the cooccurrence of these beneficial cardiometabolic effects in response to GCE in the same experimental model and suggest potential mediators and pathways involved.

Total polyphenol intake and breast cancer risk in the Seguimiento Universidad de Navarra (SUN) cohort

Polyphenols are a wide family of phytochemicals present in diverse foods. They might play a role in cancer development and progression.In vivoandin vitrostudies have suggested beneficial properties and potential mechanisms. We aimed to evaluate the association between total and main classes of polyphenol intake and breast cancer (BC) risk in the Seguimiento Universidad de Navarra project – a prospective Mediterranean cohort study. We included 10 713 middle-aged, Spanish female university graduates. Polyphenol intake was derived from a semi-quantitative FFQ and matching food consumption data from the Phenol-Explorer database. Women with self-reported BC were asked to return a copy of their medical report for confirmation purposes; death certificates were used for fatal cases. Cox models were fitted to estimate multivariable-adjusted hazard ratios (HR) and 95 % CI for the association between tertiles (T) of polyphenol intake and BC. After 10·3 years of median follow-up, 168 probable incident BC cases were identified, out of which 100 were confirmed. We found no association between polyphenol intake and the overall BC risk. Nevertheless, we observed a significant inverse association between total polyphenol intake and BC risk for postmenopausal women, either for probable or only for confirmed cases (HRT3v.T10·31 (95 % CI 0·13, 0·77;Ptrend=0·010)). Also, phenolic acid intake was inversely associated with postmenopausal BC. In summary, we observed no significant association between total polyphenol intake and BC risk. Despite a low number of incident BC cases in our cohort, higher total polyphenol intake was associated with a lower risk of postmenopausal BC.

Anthocyanin Consumption and Risk of Colorectal Cancer: A Meta-Analysis of Observational Studies

This meta-analysis aimed to summarize the association between anthocyanin consumption and the risk of colorectal cancer. All relative articles were located on online databases, including PubMed, Embase, and the Cochrane Library as of June 11, 2018. Risk ratios (RRs) or odds ratio and their 95% confidence intervals (CIs) were calculated through the STATA 12.0 software package. A total of seven studies were included in the meta-analysis. A significant inverse association was found between total anthocyanin consumption and colorectal cancer risk (RR = 0.78; 95% CI, 0.64-0.95). Likewise, there was significant evidence of a relationship between anthocyanin intake and colorectal cancer in the colon site (RR = 0.81; 95% CI, 0.71-0.92); men (RR = 0.88; 95% CI, 0.81-0.95), and case-control studies (RR = 0.69; 95% CI, 0.60-0.78). A dose-response relationship was not found in this meta-analysis. The Grades of Recommendations Assessment, Development, and Evaluation quality in our study was very low. This meta-analysis indicates that anthocyanin consumption is inversely associated with the risk of colorectal cancer. Anthocyanins may play an active role in the prevention of colorectal cancer. Key teaching points: Some epidemiological studies found an inverse correlation between the high consumption of anthocyanins and low risk of colorectal cancer. Because of this structure, anthocyanins/anthocyanidins have a powerful capability of donating electrons, which can be characterized as antioxidant properties. Anthocyanins can also inhibit colon cancer by interfering in the cell cycle and inducing the effect of anti-proliferation and apoptosis. The formation of cytoplasmic vacuoles in cells also indicates that anthocyanins may induce autophagy. From the findings of nonrandomized controlled trials, anthocyanins may play an active role in the prevention of colorectal cancer.

Niacin, alkaloids and (poly)phenolic compounds in the most widespread Italian capsule-brewed coffees

Coffee is one of the most popular beverages worldwide and, nowadays, one of the most practical way for its preparation is by prepacked capsules. The aim of this study was comparing the content in caffeine, trigonelline, N-methylpyridinium (NMP), niacin, and chlorogenic acids of 65 different capsule-brewed coffees, commercialised by 5 of the most representative brands in Italy. Coffees were prepared from capsules following manufacturer’s instructions and analysed with an optimized UHPLC-MS/MS method able to assess all these phytochemicals in one single run. Inter-lot and capsule variability were also studied for a subset of coffee capsules. Except for decaffeinated coffees, caffeine amount accounted between 54 and 208 mg/serving. Regular espresso coffees showed higher trigonelline, NMP, and niacin concentrations than large (lungo) and decaffeinated samples, with average serving amounts of 17.96, 1.78, and 0.66 mg, respectively. Regarding chlorogenic acids, caffeoylquinic acids were the most relevant ones (20–117 mg/serving). Feruloylquinic acids were quantified between 8 and 50 mg/serving. Coumaroylquinic acids, hydroxycinnamate dimers, caffeoylshikimic acids, and caffeoylquinic lactones were also present at lower concentrations. Multivariate analysis provided comprehensive information on the phytochemical profile of the different types of coffee, showing a great variability among coffees with some brand-related insights. This study supports the need for accurately characterizing espresso coffees while investigating the beneficial effects of coffee on human health.

Insights about urinary hippuric and citric acid as biomarkers of fruit and vegetable intake in patients with kidney stones: The role of age and sex

OBJECTIVES

Urinary hippuric acid (HA) and citrate can represent useful biomarkers of fruit and vegetable (FAV) intake in nephrolithiasis. However, their clinical significance across the life span has been poorly investigated. The aim of this study was to investigate the association between the two biomarkers with FAV intake across different age groups and sexes in a large group of stone formers (SFs).

METHODS

SFs undergoing baseline 24-h urinary collection for metabolic profile of lithogenic risk at our institution were consecutively enrolled for a 6-y time span (N = 1185; 625 men). HA and citrate excretions were determined by ion chromatography and ultraviolet method, respectively. SFs completed a food frequency questionnaire on the intake of FAV. Stepwise logistic regression was applied to investigate factors associated with very low FAV (≤1 servings/d) and analysis of covariance to compare citrate and HA excretion across age groups and sexes.

RESULTS

Very low FAV intake prevalence declined with age (P_trend < 0.001), and was inversely associated with HA and citrate excretion (P < 0.001) in a stepwise logistic regression model. A significant increasing trend was verified for both biomarkers across age groups until the age of 65 for HA (P < 0.001) and 55 for citrate (P < 0.001). Citrate excretion significantly declined after the age of 65, and was higher in women than men in adult age groups, regardless of FAV intake.

CONCLUSIONS

Both urinary citrate and HA were positively associated with FAV intake in SFs. However, unlike HA, citrate excretion was significantly influenced by the female sex and by older age.

Dietary intake of (poly)phenols in children and adults: cross-sectional analysis of UK National Diet and Nutrition Survey Rolling Programme (2008-2014)

PURPOSE

Current evidence accounts for the role of (poly)phenolic compounds in the prevention of non-communicable diseases. Detailed information on population-level intakes is required to translate these findings into recommendations. This work aimed to estimate (poly)phenol intake in the UK population using data from a nationally representative survey.

METHODS

Data from 9374 participants (4636 children aged 1.5-18 years and 4738 adults aged 19 years and over) from the National Diet and Nutrition Survey Rolling Programme (NDNS RP) 2008-2014 was used. (Poly)phenol content of foods consumed in the NDNS RP was identified using Phenol-Explorer and through literature searches. Data on flavonoids, phenolic acids, and stilbenes were collected. Total (poly)phenol content was also assessed.

RESULTS

Mean total (poly)phenol intake ranged from 266.6 ± 166.1 mg/day in children aged 1.5-3 years to 1035.1 ± 544.3 mg/day in adults aged 65 years and over, with flavan-3-ols and hydroxycinnamic acids being the most consumed (poly)phenols across all age groups. (Poly)phenol intake was higher in males in all age groups except for adults aged 19-34 and 50-64 years, where intakes were marginally higher in females. Energy-adjusted intakes accounted for the pattern of increasing (poly)phenol intakes with age and a higher intake was observed in females across all age groups, with the exception of children aged 1.5-3 years. The main food sources were non-alcoholic beverages and fruits, being the main compounds flavan-3-ols and caffeoylquinic acids.

CONCLUSIONS

This analysis provides estimates of (poly)phenol intake from a representative sample of the UK general population, which can help inform the health implications of (poly)phenol intake.

Dietary intake of total polyphenol and polyphenol classes and the risk of colorectal cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort

Polyphenols may play a chemopreventive role in colorectal cancer (CRC); however, epidemiological evidence supporting a role for intake of individual polyphenol classes, other than flavonoids is insufficient. We evaluated the association between dietary intakes of total and individual classes and subclasses of polyphenols and CRC risk and its main subsites, colon and rectum, within the European Prospective Investigation into Cancer and Nutrition (EPIC) study. The cohort included 476,160 men and women from 10 European countries. During a mean follow-up of 14 years, there were 5991 incident CRC cases, of which 3897 were in the colon and 2094 were in the rectum. Polyphenol intake was estimated using validated centre/country specific dietary questionnaires and the Phenol-Explorer database. In multivariable-adjusted Cox regression models, a doubling in total dietary polyphenol intake was not associated with CRC risk in women (HRlog2 = 1.06, 95% CI 0.99-1.14) or in men (HRlog2 = 0.97, 95% CI 0.90-1.05), respectively. Phenolic acid intake, highly correlated with coffee consumption, was inversely associated with colon cancer in men (HRlog2 = 0.91, 95% CI 0.85-0.97) and positively associated with rectal cancer in women (HRlog2 = 1.10, 95% CI 1.02-1.19); although associations did not exceed the Bonferroni threshold for significance. Intake of other polyphenol classes was not related to colorectal, colon or rectal cancer risks. Our study suggests a possible inverse association between phenolic acid intake and colon cancer risk in men and positive with rectal cancer risk in women.

Prospective Association between Total and Specific Dietary Polyphenol Intakes and Cardiovascular Disease Risk in the Nutrinet-Santé French Cohort

BACKGROUND

Epidemiological and experimental evidence support a protective effect of dietary polyphenols on chronic diseases, but high quality longitudinal data are needed, including details on categories of polyphenols. Our objective was to investigate the prospective association between total and individual classes and subclasses of dietary polyphenols and the risk of major cardiovascular disease in the NutriNet-Santé cohort.

METHODS

A total of 84,158 participants, who completed at least three 24 h dietary records, were included between May 2009 and June 2017. Individual polyphenols intakes were obtained by matching food consumption data from the 24 h dietary records with the Phenol-Explorer polyphenol composition database. Multivariable Cox proportional hazards models were used to characterize the associations between dietary polyphenols and the incidence of cardiovascular diseases, comparing tertile T3 vs. T1 of classes and subclasses of polyphenols.

RESULTS

Over a median of 4.9 years of follow-up, 602 major cardiovascular events were diagnosed. Intakes of anthocyanins, catechins, and flavonols were strongly inversely associated with cardiovascular disease risk (anthocyanins: Hazard Ratio (HR)for a 1-point increment of 10 mg/day = 0.98 (0.96⁻0.99, p = 0.03, HRT3vs.T1 = 0.66 (0.52⁻0.83), ptrend = 0.0003; catechins: HRfor a 1-point increment of 10 mg/day = 0.98 (0.96⁻0.99), p = 0.02, HRT3vs.T1 = 0.74 (0.60⁻0.91), ptrend = 0.004; flavonols: HRfor a 1-point increment of 10 mg/day = 0.94 (0.90⁻0.99), p = 0.02, HRT3vs.T1 = 0.75 (0.61⁻0.94), ptrend = 0.006). Intakes of dihydrochalcones, proanthocyaninidins, dihydroflavonols, hydroxybenzoic acids, and stilbenes were also associated with a decrease (13%, 19%, 24%, 24%, and 27%, respectively) in cardiovascular disease risk, when comparing tertile T3 to T1.

CONCLUSIONS

Higher intakes of polyphenols, especially of anthocyanins, catechins, and flavonols, were associated with a statistically significant decreased cardiovascular disease risk.

Relationship between Mediterranean Dietary Polyphenol Intake and Obesity

Obesity is a multifactorial and complex disease defined by excess of adipose mass and constitutes a serious health problem. Adipose tissue acts as an endocrine organ secreting a wide range of inflammatory adipocytokines, which leads to systemic inflammation, insulin resistance, and metabolic disorders. The traditional Mediterranean diet is characterized by a high phenolic-rich foods intake, including extra-virgin olive oil, nuts, red wine, vegetables, fruits, legumes, and whole-grain cereals. Evidence for polyphenols’ effect on obesity and weight control in humans is inconsistent and the health effects of polyphenols depend on the amount consumed and their bioavailability. The mechanisms involved in weight loss in which polyphenols may have a role are: activating β-oxidation; a prebiotic effect for gut microbiota; inducing satiety; stimulating energy expenditure by inducing thermogenesis in brown adipose tissue; modulating adipose tissue inhibiting adipocyte differentiation; promoting adipocyte apoptosis and increasing lipolysis. Even though the intake of some specific polyphenols has been associated with body weight changes, there is still no evidence for the effects of total polyphenols or some polyphenol subclasses in humans on adiposity.

Impact of a (poly)phenol-rich extract from the brown algae Ascophyllum nodosum on DNA damage and antioxidant activity in an overweight or obese population: a randomized controlled trial

Background

Epidemiologic evidence suggests that a diet rich in (poly)phenols has beneficial effects on many chronic diseases. Brown seaweed is a rich source of (poly)phenols.

Objective

The aim of this study was to investigate the bioavailability and effect of a brown seaweed (Ascophyllum nodosum) (poly)phenol extract on DNA damage, oxidative stress, and inflammation in vivo.

Design

A randomized, double-blind, placebo-controlled crossover trial was conducted in 80 participants aged 30-65 y with a body mass index (in kg/m2) ≥25. The participants consumed either a 400-mg capsule containing 100 mg seaweed (poly)phenol and 300 mg maltodextrin or a 400-mg maltodextrin placebo control capsule daily for an 8-wk period. Bioactivity was assessed with a panel of blood-based markers including lymphocyte DNA damage, plasma oxidant capacity, C-reactive protein (CRP), and inflammatory cytokines. To explore the bioavailability of seaweed phenolics, an untargeted metabolomics analysis of urine and plasma samples after seaweed consumption was determined by ultra-high-performance liquid chromatography-high-resolution mass spectrometry.

Results

Consumption of the seaweed (poly)phenols resulted in a modest decrease in DNA damage but only in a subset of the total population who were obese. There were no significant changes in CRP, antioxidant status, or inflammatory cytokines. We identified phlorotannin metabolites that are considered potential biomarkers of seaweed consumption including pyrogallol/phloroglucinol-sulfate, hydroxytrifurahol A-glucuronide, dioxinodehydroeckol-glucuronide, diphlorethol sulfates, C-O-C dimer of phloroglucinol sulfate, and C-O-C dimer of phloroglucinol.

Conclusions

To the best of our knowledge, this work represents the first comprehensive study investigating the bioactivity and bioavailability of seaweed (poly)phenolics in human participants. We identified several potential biomarkers of seaweed consumption. Intriguingly, the modest improvements in DNA damage were observed only in the obese subset of the total population. The subgroup analysis should be considered exploratory because it was not preplanned; therefore, it was not powered adequately. Elucidation of the biology underpinning this observation will require participant stratification according to weight in future studies. This trial was registered at clinicaltrials.gov as NCT02295878.

Review of polyphenol-rich products as potential protective and therapeutic factors against cadmium hepatotoxicity

Recently, the growing attention of the scientific community has been focused on the threat to health created by environmental pollutants, including toxic metals such as cadmium (Cd), and on the need of finding effective ways to prevent and treat the unfavorable health effects of exposure to them. Particularly promising for Cd, and thus arousing the greatest interest, is the possibility of using various ingredients present in plants, including mainly polyphenolic compounds. As the liver is one of the target organs for this toxic metal and disturbances in the proper functioning of this organ have serious consequences for health, the aim of the present review was to discuss the possibility of using polyphenol-rich food products (e.g., chokeberry, black and green tea, blueberry, olive oil, rosemary and ginger) as the strategy in protection from this xenobiotic hepatotoxicity and treatment of this heavy metal-induced liver damage. Owing to the ability of polyphenols to bind ions of Cd and the strong antioxidative potential of these compounds, as well as their abundance in dietary products, it seems to be of high importance to consider the possibility of using polyphenols as potential preventive and therapeutic agents against Cd hepatotoxicity, determined by its strong pro-oxidative properties. Although most of the data on the effectiveness of polyphenols comes from studies in animals, the fact that some of them are derived from experimental models that reflect human exposure to this metal allows us to assume that some polyphenol-rich food products may be promising protective agents against Cd hepatotoxicity in humans.

A new food-composition database for 437 polyphenols in 19,899 raw and prepared foods used to estimate polyphenol intakes in adults from 10 European countries

BACKGROUND

Accurate assessment of polyphenol intakes is needed in epidemiologic research in order to study their health effects, and this can be particularly challenging in international study settings.

OBJECTIVE

The purpose of this work is to describe the procedures to prepare a comprehensive polyphenol food-composition database that was used to calculate standardized polyphenol intakes from 24-h diet recalls (24HDRs) and dietary questionnaires (DQs) in the European Prospective Investigation into Cancer and Nutrition (EPIC).

Design

With the use of the comparable food classification and facet-descriptor system of the computerized 24HDR program EPIC-Soft (renamed GloboDiet), foods reported in the 24HDR (n = 74,626) were first aggregated following a stepwise process. Multi-ingredient and generic foods were broken down into ingredients or more-specific foods with consideration of regional consumption habits before matching to foods in the Phenol-Explorer database. Food-composition data were adjusted by using selected retention factors curated in Phenol-Explorer. DQ foods (n = 13,946) were matched to a generated EPIC 24HDR polyphenol-composition database before calculation of daily intakes from the 24HDR and DQ.

RESULTS

Food matching yielded 2.0% and 2.7% of foods with missing polyphenol content in the 24HDR and DQ food data sets, respectively. Process-specific retention factors for 42 different polyphenol compounds were applied to adjust the polyphenol content in 35 prioritized Phenol-Explorer foods, thereby adjusting the polyphenol content in 70% of all of the prepared 24 food occurrences. A detailed food-composition database was finally generated for 437 polyphenols in 19,899 aggregated raw and prepared foods reported by 10 EPIC countries in the 24HDR.

Conclusions

An efficient procedure was developed to build the most-comprehensive food-composition database for polyphenols, thereby standardizing the calculations of dietary polyphenol intakes obtained from different dietary assessment methods and European populations. The whole database is accessible online. This procedure could equally be used for other food constituents and in other cohorts.

Intestinal phase-II metabolism of quercetin in HT29 cells, 3D human intestinal tissues and in healthy volunteers: a qualitative comparison using LC-IMS-MS and LC-HRMS

Flavonoids are a large class of dietary molecules, among which quercetin is the most ubiquitous, which undergo an extensive intestinal phase-II metabolism. We compared the in vivo metabolism of quercetin in healthy volunteers with two in vitro models, HT29 cells and 3 D human intestinal tissues. Supernatants of the in vitro experiments and the human intestinal fluids (HIF) were analyzed by LC-IMS-MS and LC-HRMS in a qualitative way. Quercetin glucuronides, sulfates and their methyl conjugates were detected in all three systems. The metabolic profiles were found to be different, both in terms of the metabolites produced and their relative proportions. In particular, quercetin sulfates were almost absent in supernatants from HT29 cells incubations while they were a major metabolite in HIF and also found in 3 D intestinal tissues incubations. IMS provided structural information as well as a third dimension of characterization, while HRMS brought increased sensitivity and MS/MS confirmation. HT29 cells are a useful tool to generate phase-II metabolites but do not represent the in vivo situation. 3 D intestinal tissues appear as a more relevant tool to study the intestinal phase-II metabolism of flavonoids.

Polyphenols, food and pharma. Current knowledge and directions for future research

Polyphenols are a large family of phytochemicals with great chemical diversity, known to be bioactive compounds of foods, species, medicinal plants and nutraceuticals. These compounds are ingested through the diet in significant amounts, around 1 g per day, an amount that be may be increased through supplements. The in vitro action of many representative polyphenols has been reported. However, their beneficial effects and their role in modulating the risk of high-prevalence diseases are difficult to demonstrate due to the wide variability of polyphenol structures and bioactive actions; the complexity of estimating the polyphenol content of food as a result of their variability in foods and cooked dishes; the potential modulation of the effects of polyphenols by food matrices; the addition of polyphenols and their synergistic interactions with each other and with other dietary bioactive components; the modulation of polyphenol bioavailability as a consequence of food composition and culinary techniques; their metabolism by the human body and the polyphenol gut microbiota metabolism in each metabotypes. Computational strategies, including virtual screening, shape-similarity-screening and molecular docking, were recently used to identify potential targets of polyphenols and thus gain a better understanding of the therapeutic effects exerted of polyphenols and modify natural polyphenol structures to potentiate specific activities. Here, we present the most relevant current knowledge and propose directions for future research in these fields, from the culinary world to the clinical setting. We hope this commentary will prompt scientists and clinicians to consider the therapeutic value of bioactive polyphenols and help shed some light on how much scientific truth lies in Hippocrates' famous quote: "Let your food be your medicine".

Dietary polyphenol intake and their major food sources in the Mexican Teachers' Cohort

Several descriptive studies on the intake of polyphenols, mostly flavonoids, have been published, especially in Europe and the USA, but insufficient data are still available in Latin-American countries, where different types of foods are consumed and different dietary habits are observed. The goal of this cross-sectional study was to estimate dietary intakes of polyphenols, including grand total, total per classes and subclasses and individual compounds, and to identify their main food sources in Mexican women. The Mexican Teachers' Cohort includes 115 315 female teachers, 25 years and older, from twelve states of Mexico, including urban and rural areas. Dietary data were collected in the period 2008-2011 using a validated FFQ, and individual polyphenol intake was estimated using food composition data from the Phenol-Explorer database. Median total polyphenol intake was the highest in Baja California (750 mg/d) and the lowest in Yucatan (536 mg/d). The main polyphenols consumed were phenolic acids (56·3-68·5 % total polyphenols), followed by flavonoids (28·8-40·9 %). Intake of other polyphenol subclasses (stilbenes, lignans and others) was insignificant. Coffee and fruits were the most important food sources of phenolic acids and flavonoids, respectively. Intake of a total of 287 different individual polyphenols could be estimated, of which forty-two were consumed in an amount ≥1 mg/d. The most largely consumed polyphenols were several caffeoylquinic acids (ranging from 20 and 460 mg/d), ferulic acid, hesperidin and proanthocyanidins. This study shows a large heterogeneity in intakes of individual polyphenols among Mexican women, but a moderate heterogeneity across Mexican states. Main food sources were also similar in the different states.

Triphala: current applications and new perspectives on the treatment of functional gastrointestinal disorders

Background

Ayurvedic medicine is based on natural healing methods that use herbal medicine to cleanse the body of toxins and to attain physical and mental regeneration. Triphala (TLP) is one of the most important ayurvedic supplements and is believed to have a beneficial effect on the entire gastrointestinal (GI) tract.

Purpose

We aim to summarize available literature focused on the components of TLP (Terminalia chebula, Terminalia bellerica and Phyllanthus emblica) and discusse their effectiveness and therapeutic value for improving lower GI symptoms in functional GI disorders, particularly irritable bowel syndrome (IBS).

Methods

This study is based on pertinent papers that were retrieved by a selective search using relevant keywords in PubMed and ScienceDirect databases.

Results

The components of TLP are believed to cause restoration of the epithelium lining of the digestive tract, and by exhibiting mild laxative properties facilitate passage of stool in the colon. TLP is rich in polyphenols, vitamin C and flavonoids, which provide antioxidant and anti-inflammatory effects. It also contains various types of acids, such as gallic, chebulagic and chebulinic, which additionally possess cytoprotective and antifungal properties.

Conclusion

Triphala holds potential in improving lower GI symptoms and may be a valuable and effective addition to standard treatment of IBS. Supplementation of TLP herbal formulations alone or along with other probiotics can be recommended in ongoing clinical studies.

Antimicrobial and antioxidant activities of phenolic metabolites from flavonoid-producing yeast: Potential as natural food preservatives

We analysed the antimicrobial and antioxidant activities of phenolic metabolites secreted from a naringenin-producing Saccharomyces cerevisiae strain (a GRAS organism), against the pure flavonoid naringenin and its prenylated derivatives, to assess their potential as natural food preservatives. Agar disc diffusion assay was used to analyse the antimicrobial activity against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213, while DMPD chemiluminescence assay was used to analyse antioxidant activity, based on DMPD⁺-scavenging activity. Our results showed that the engineered yeast metabolites exhibited both strong antimicrobial and DMPD⁺-scavenging activity, particularly the metabolite phenylacetaldehyde. Pure naringenin had poor antimicrobial and DMPD⁺-scavenging effects. Prenylated varieties, 6-prenylnaringenin and 8-prenylnaringenin, inhibited only S. aureus, while only 8-prenylnaringenin exhibited moderate DMPD⁺-scavenging activity. Our results suggested that phenolic metabolites secreted from naringenin-producing yeast would be a sustainable source of natural food preservatives.

Chlorogenic Acid Prevents AMPA-Mediated Excitotoxicity in Optic Nerve Oligodendrocytes Through a PKC and Caspase-Dependent Pathways

In the CNS, including the optic nerve, oligodendrocytes play a critical role in the myelination of axons. Oligodendrocytes are exceptionally sensitive to insults to the CNS, such as injury, ischemia, or inflammation, which result in the loss of oligodendrocytes and myelin and eventually secondary axon degeneration. Oligodendrocytes are sensitive to excitotoxic insults mediated by overactivation of their AMPA ionotropic glutamate receptors. Phenolic compounds, which are widely distributed in fruits and vegetables, received the great attention of scientists due to their antioxidant activities and free radical scavenging abilities. Chlorogenic acid (CGA) has been demonstrated to possess potent neuroprotective activities against oxidative stress in various cellular models and pathological conditions. Hence, CGA protect against oxidative stress and excitotoxic insults mediated by AMPA receptors and that the protective mechanisms involve free radical scavenging, Ca²⁺ handling in the cytosol, and modulating antioxidant enzyme system. CGA was associated with the protein kinase A (PKC) signaling pathways transduction. Caspases and calpains have been studied as apoptotic mediators and cell death in this model of AMPA toxicity. Inhibitors of caspases initiators, caspases 1, 8, and 9, the upstream of caspase 3 effectors, have totally abrogated the protective activity of CGA. Inhibitors of calpains also totally abrogated the protective activity of CGA. In addition, a potential role for the CGA in inhibiting Bax in oligodendrocyte cell model undergoing AMPA is inducing excitotoxic death. Our results indicate that CGA exhibits a protective potential via antioxidant and apoptosis caspases and calpains dependent against AMPA-mediated excitotoxicity, and these finding indicate that CGA is able to be a good candidate for preventive approach for neurodegenerative disorders associated with loss and damage in oligodendrocytes and AMPA-mediated excitotoxicity.

Polyphenol exposure and risk of type 2 diabetes: dose-response meta-analyses and systematic review of prospective cohort studies

Background

Type 2 diabetes is characterized by impaired glucose metabolism. Bioactive compounds in fruits and vegetables such as polyphenols have been suggested to influence glucose metabolism.

Objective

The aim of the current study was to systematically review the literature and conduct dose-response meta-analyses to summarize evidence of polyphenol exposure in association with incident type 2 diabetes.

Design

Prospective epidemiologic studies published before January 2018 were searched through 2 databases. Log-transformed multivariable adjusted hazard and odds ratios were combined in a random-effects model. Meta-analyses comparing extreme quantiles of polyphenol exposure were further explored with the use of linear and nonlinear dose-response meta-analyses.

Results

Eighteen studies investigated the association between polyphenols (51 different compounds in total) and type 2 diabetes. A comparison of extreme quantiles revealed inverse associations for intakes of polyphenols (HR: 0.56; 95% CI: 0.34, 0.93), flavonoids (HR: 0.88; 95% CI: 0.81, 0.96), flavonols (HR: 0.92; 95% CI: 0.85, 0.98), flavan-3-ols (HR: 0.89; 95% CI: 0.81, 0.99), catechins (HR: 0.86; 95% CI: 0.75, 0.97), anthocyanidins (HR: 0.86; 95% CI: 0.81, 0.91), isoflavones (HR: 0.92; 0.86, 0.97), daidzein (HR: 0.89; 95% CI: 0.83, 0.95), genistein (HR: 0.92; 95% CI: 0.86, 0.99), and stilbenes (HR: 0.44; 95% CI: 0.26, 0.72), and biomarkers of daidzein (HR: 0.81; 95% CI: 0.66, 0.99) and genistein (HR: 0.79; 95% CI: 0.62, 0.99). In the dose-response meta-analysis, nonlinear associations were observed for intakes of polyphenols, flavonoids, flavanones, anthocyanidins, anthocyanins, and biomarkers of genistein. A linear dose-response association was observed for phenolic acids.

Conclusions

This study adds to the evidence showing that diets rich in polyphenols, and particularly flavonoids, play a role in the prevention of type 2 diabetes. For most associations evidence for nonlinearity was found, suggesting a recommendable amount of intake associated with the lowest risk of type 2 diabetes. Therefore, future studies are warranted in which nonlinear associations are further explored.

The potential effects of Ocimum basilicum on health: a review of pharmacological and toxicological studies

INTRODUCTION

Basil (Ocimum basilicum L., OB) is a plant world widely used as a spice and a typical ingredient of the healthy Mediterranean diet. In traditional medicine, OB is indicated for many maladies and conditions; OB-containing nutritional supplements are increasingly sold. Conversely, safety concerns have been raised about the promutagens and procarcinogens alkenylbenzenes contained in OB. Areas covered: A critical review of the current status of OB as a nutraceutical, the pharmacology of its bioactive components, the rationale for its indications, and its safety. Expert opinion: Due to the polyphenolic and flavonoidic content, OB can be considered as an important ingredient in healthy diets; OB preparations may be effective as chemopreventive agents or adjunctive therapy in the treatment of different clinical conditions. From a toxicological perspective, since the tumorigenic potential of alkenylbenzenes is counteracted by other OB constituents such as nevadensin, it can be concluded that OB consumption in food and preparations is safe. The only concern relates to OB essential oils: in this case, a concentration limit for alkenylbenzenes should be precautionary defined, and the use of plant chemotypes with no or low levels of these alkylbenzenes for the preparation of essential oils should be made compulsory.

Coffee Consumption and Cardiovascular Disease: A Condensed Review of Epidemiological Evidence and Mechanisms

Coffee is one of the most widely consumed beverages, and some studies have suggested it may be related to cardiovascular disease (CVD), the leading cause of poor health in the world. This review evaluates the evidence on the effect of habitual coffee consumption on CVD incidence and mortality. The review is based mostly on observational studies and meta-analyses of the literature. In healthy people, in comparison to not consuming coffee, habitual consumption of 3-5 cups of coffee per day is associated with a 15% reduction in the risk of CVD, and higher consumption has not been linked to elevated CVD risk. Moreover, in comparison to no coffee intake, usual consumption of 1-5 cups/day is associated with a lower risk of death. In people who have already suffered a CVD event, habitual consumption does not increase the risk of a recurrent CVD or death. However, hypertensive patients with uncontrolled blood pressure should avoid consuming large doses of caffeine. In persons with well-controlled blood pressure, coffee consumption is probably safe, but this hypothesis should be confirmed by further investigations.

Intestinal disposition of quercetin and its phase-II metabolites after oral administration in healthy volunteers

OBJECTIVES

Quercetin is one of the main dietary flavonoids and undergoes a substantial intestinal phase-II metabolism. Quercetin conjugates have been detected in plasma and in urine, but their presence in the small intestine has not been assessed. This study aimed to investigate the intestinal metabolism and metabolite excretion of quercetin by the human small intestinal wall after oral dosing.

METHODS

Six healthy volunteers were given a capsule of 500 mg of quercetin with 240 ml of water. Duodenal fluids were collected using the intraluminal sampling technique for 4 h and analysed by LC-MS/MS.

KEY FINDINGS

Phase-II metabolites of quercetin were detected and quantified in aspirated intestinal fluids. Metabolites appeared almost immediately after administration, indicating an intestinal metabolism and apical excretion into the lumen. Quercetin-3'-O-glucuronide was found to be the main intestinal metabolite. Our results could not conclude on the enterohepatic recycling of quercetin or its metabolites, although several individual profiles showed distinctive peaks.

CONCLUSIONS

This study highlights the intestinal metabolism and excretion of quercetin and its conjugates in humans and gives insights into the relevant concentrations which should be used to investigate potential food-drug interactions in vitro.

Ingestion of coffee polyphenols suppresses deterioration of skin barrier function after barrier disruption, concomitant with the modulation of autonomic nervous system activity in healthy subjects

The aim of this study was to evaluate the effect of consumption of coffee polyphenols (CPPs) on the autonomic nervous system activity and decreased skin barrier function caused by sodium dodecyl sulfate (SDS) treatment. In this single-blind, placebo-controlled study, ten healthy male subjects consumed either a beverage containing CPPs or a placebo beverage for four weeks. CPPs significantly suppressed the deterioration in skin barrier function and skin moisture content induced by SDS treatment after the third week. Furthermore, in the heart rate variability analysis, CPPs significantly produced an increase in parasympathetic nervous activity, and a decrease in sympathetic nervous activity after the four weeks of beverage consumption. These results suggest that CPPs might influence the regulation of the autonomic nervous system and contribute to the suppressive effect on deterioration of skin barrier function.

Targeted proteomic analysis of habitual coffee consumption

BACKGROUND

Coffee drinking has been implicated in mortality and a variety of diseases but potential mechanisms underlying these associations are unclear. Large-scale systems epidemiological approaches may offer novel insights to mechanisms underlying associations of coffee with health.

OBJECTIVE

We performed an analysis of known and novel protein markers linked to cardiovascular disease and their association with habitual coffee intake in the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS, n = 816) and followed up top proteins in the Uppsala Longitudinal Study of Adult Men (ULSAM, n = 635) and EpiHealth (n = 2418).

METHODS

In PIVUS and ULSAM, coffee intake was measured by 7-day dietary records whilst a computer-based food frequency questionnaire was used in EpiHealth. Levels of up to 80 proteins were assessed in plasma by a proximity extension assay.

RESULTS

Four protein-coffee associations adjusted for age, sex, smoking and BMI, met statistical significance in PIVUS (FDR < 5%, P < 2.31 × 10^-3 ): leptin (LEP), chitinase-3-like protein 1 (CHI3L), tumour necrosis factor (TNF) receptor 6 and TNF-related apoptosis-inducing ligand. The inverse association between coffee intake and LEP replicated in ULSAM (β, -0.042 SD per cup of coffee, P = 0.028) and EpiHealth (β, -0.025 SD per time of coffee, P = 0.004). The negative coffee-CHI3L association replicated in EpiHealth (β, -0.07, P = 1.15 × 10^-7 ), but not in ULSAM (β, -0.034, P = 0.16).

CONCLUSIONS

The current study supports an inverse association between coffee intake and plasma LEP and CHI3L1 levels. The coffee-CHI3L1 association is novel and warrants further investigation given links between CHI3L1 and health conditions that are also potentially influenced by coffee.

Effects of dietary almond- and olive oil-based docosahexaenoic acid- and vitamin E-enriched beverage supplementation on athletic performance and oxidative stress markers

Functional beverages based on almonds and olive oil and enriched with α-tocopherol and docosahexaenoic acid (DHA) could be useful in modulating oxidative stress and enhancing physical performance in sportsmen. The aim of this work was to evaluate the effects of supplementation with functional beverages on physical performance, plasma and erythrocyte fatty acids' and polyphenol handling, oxidative and nitrative damage, and antioxidant and mitochondrial gene expression in young and senior athletes. Athletes performed maximal exercise tests before and after one month of dietary supplementation and blood samples were taken immediately before and one hour after each test. The beverages did not alter performance parameters during maximal exercise. Supplementation increased polyunsaturated and reduced saturated plasma fatty acids while increasing the DHA erythrocyte content; it maintained basal plasma and blood polyphenol levels, but increased the blood cell polyphenol concentration in senior athletes. Supplementation protects against oxidative damage although it enhances nitrative damage in young athletes. The beverages enhance the gene expression of antioxidant enzymes in peripheral blood mononuclear cells after exercise in young athletes.

Influence of 2-Weeks Ingestion of High Chlorogenic Acid Coffee on Mood State, Performance, and Postexercise Inflammation and Oxidative Stress: A Randomized, Placebo-Controlled Trial

This study measured the influence of 2-weeks ingestion of high chlorogenic acid (CQA) coffee on postexercise inflammation and oxidative stress, with secondary outcomes including performance and mood state. Cyclists (N = 15) were randomized to CQA coffee or placebo (300 ml/day) for 2 weeks, participated in a 50-km cycling time trial, and then crossed over to the opposite condition with a 2-week washout period. Blood samples were collected pre- and postsupplementation, and immediately postexercise. CQA coffee was prepared using the Turkish method with 30 g lightly roasted, highly ground Hambela coffee beans in 300 ml boiling water, and provided 1,066 mg CQA and 474 mg caffeine versus 187 mg CQA and 33 mg caffeine for placebo. Plasma caffeine was higher with CQA coffee versus placebo after 2-weeks (3.3-fold) and postexercise (21.0-fold) (interaction effect, p < .001). Higher ferric reducing ability of plasma (FRAP) levels were measured after exercise with CQA coffee versus placebo (p = .01). No differences between CQA coffee and placebo were found for postexercise increases in plasma IL-6 (p = .74) and hydroxyoctadecadienoic acids (9 + 13 HODEs) (p = .99). Total mood disturbance (TMD) scores were lower with CQA coffee versus placebo (p = .04). 50-km cycling time performance and power did not differ between trials, with heart rate and ventilation higher with CQA coffee, especially after 30 min. In summary, despite more favorable TMD scores with CQA coffee, these data do not support the chronic use of coffee highly concentrated with chlorogenic acids and caffeine in mitigating postexercise inflammation or oxidative stress or improving 50-km cycling performance.

Polyphenols and Their Interactions With Other Dietary Compounds: Implications for Human Health

Regular and optimal intake of polyphenols associates with numerous health-promoting effects. Bioavailability and activity of polyphenols depend on foods' structure and interactions with other food constituents, especially proteins, lipids, and carbohydrates. Polyphenols-proteins interactions can result in various biological effects, such as sense of astringency. So far, polyphenols interactions with food lipids have not been of special importance, except in case of plant oils. Polyphenols-carbohydrates interactions can influence the organoleptic properties, while interactions with dietary fibers are particularly significant. Polyphenols can decrease the synthesis of fats and fatty acids in the liver, or delay their absorption in intestines. Also, polyphenols can slow down digestion of carbohydrates, through the inhibition of digestive enzymes or modulation of glucose uptake. Both animal and plant proteins have low impact on the bioavailability of polyphenols, but some in vitro studies reported that milk proteins could enhance intestinal absorption of polyphenols from tea. Dietary fats may alter the passage of polyphenols through gastrointestinal tract and impact absorption of more hydrophobic polyphenols in particular. While some studies reported that associations with carbohydrates could decrease bioavailability of polyphenols, the others showed the opposite effects. Macronutrients can be used for encapsulation of polyphenols, which can increase their bioavailability and ensure controlled and targeted release. Polyphenols' interactions in the body include their incorporation in cell membranes which causes changes in fatty acid profile and impacts membrane-bound transporters and enzymes. Finally, gut microbiota plays essential role in metabolism of both polyphenols and macronutrients and thus can have great impact on their interactions.

Excretion of Avenanthramides, Phenolic Acids and their Major Metabolites Following Intake of Oat Bran

SCOPE

Wholegrain has been associated with reduced chronic disease mortality, with oat intake particularly notable for lowering blood cholesterol and glycemia. To better understand the complex nutrient profile of oats, we studied urinary excretion of phenolic acids and avenanthramides after ingestion of oat bran in humans.

METHODS AND RESULTS

After a 2-d (poly)phenol-low diet, seven healthy men provided urine 12 h before and 48 h after consuming 60 g oat bran (7.8 μmol avenanthramides, 139.2 μmol phenolic acids) or a phenolic-low (traces of phenolics) control in a crossover design. Analysis by ultra-high performance liquid chromatography (UPLC)-MS/MS showed that oat bran intake resulted in an elevation in urinary excretion of 30 phenolics relative to the control, suggesting that they are oat bran-derived. Mean excretion levels were elevated between 0-2 and 4-8 h, following oat bran intake, and amounted to a total of 33.7 ± 7.3 μmol total excretion (mean recovery: 22.9 ± 5.0%), relative to control. The predominant metabolites included: vanillic acid, 4- and 3-hydroxyhippuric acids, and sulfate-conjugates of benzoic and ferulic acids, which accounted collectively for two thirds of total excretion.

CONCLUSION

Oat bran phenolics follow a relatively rapid urinary excretion, with 30 metabolites excreted within 8 h of intake. These levels of excretion suggest that bound phenolics are, in part, rapidly released by the microbiota.

Cinnamon, a promising prospect towards Alzheimer's disease

Over the last decades, an exponential increase of efforts concerning the treatment of Alzheimer's disease (AD) has been practiced. Phytochemicals preparations have a millenary background to combat various pathological conditions. Various cinnamon species and their biologically active ingredients have renewed the interest towards the treatment of patients with mild-to-moderate AD through the inhibition of tau protein aggregation and prevention of the formation and accumulation of amyloid-β peptides into the neurotoxic oligomeric inclusions, both of which are considered to be the AD trademarks. In this review, we presented comprehensive data on the interactions of a number of cinnamon polyphenols (PPs) with oxidative stress and pro-inflammatory signaling pathways in the brain. In addition, we discussed the potential association between AD and diabetes mellitus (DM), vis-à-vis the effluence of cinnamon PPs. Further, an upcoming prospect of AD epigenetic pathophysiological conditions and cinnamon has been sighted. Data was retrieved from the scientific databases such as PubMed database of the National Library of Medicine, Scopus and Google Scholar without any time limitation. The extract of cinnamon efficiently inhibits tau accumulations, Aβ aggregation and toxicity in vivo and in vitro models. Indeed, cinnamon possesses neuroprotective effects interfering multiple oxidative stress and pro-inflammatory pathways. Besides, cinnamon modulates endothelial functions and attenuates the vascular cell adhesion molecules. Cinnamon PPs may induce AD epigenetic modifications. Cinnamon and in particular, cinnamaldehyde seem to be effective and safe approaches for treatment and prevention of AD onset and/or progression. However, further molecular and translational research studies as well as prolonged clinical trials are required to establish the therapeutic safety and efficacy in different cinnamon spp.

Dietary Polyphenols in the Aetiology of Crohn's Disease and Ulcerative Colitis-A Multicenter European Prospective Cohort Study (EPIC)

BACKGROUND

Oxidative stress may be involved in the aetiology of inflammatory bowel disease and whether dietary polyphenols, which possess antioxidants properties, prevent its development is unknown.

METHODS

A total of 401,326 men and women aged 20 to 80 years from 8 countries were recruited between 1991 and 1998 and at baseline completed validated food frequency questionnaires. Dietary polyphenol intake was measured using Phenol-Explorer, a database with information on the content of 502 polyphenols. Incident cases of Crohn's diseases (CD) and ulcerative colitis (UC) were identified during the follow-up period of up to December 2010. A nested case-control study using conditional logistic regression estimated the odds ratios (ORs), and 95% confidence intervals, for polyphenol intake (categories based on quartiles) and developing CD or UC.

RESULTS

In total, 110 CD (73% women) and 244 UC (57% women) cases were identified and matched to 440 and 976 controls, respectively. Total polyphenol intake was not associated with CD (P trend = 0.17) or UC (P trend = 0.16). For flavones and CD, there were reduced odds for all quartiles, which were statistically significant for the third (OR3rd versus 1st quartile = 0.33; 95% confidence interval, 0.15-0.69) and there was an inverse trend across quartiles (P = 0.03). Similarly, for resveratrol, there was an inverse association with CD (OR4th versus 1st quartile = 0.40; 95% confidence interval, 0.20-0.82) with an inverse trend across quartiles (P = 0.02). No significant associations between subtypes of polyphenols and UC were found. Effect modification by smoking in CD was documented with borderline statistical significance.

CONCLUSIONS

The data supports a potential role of flavones and resveratrol in the risk of developing CD; future aetiological studies should investigate these dietary components and further examine the potential for residual confounding.

WNT Inhibitory Activity of Malus Pumila miller cv Annurca and Malus domestica cv Limoncella Apple Extracts on Human Colon-Rectal Cells Carrying Familial Adenomatous Polyposis Mutations

Inhibitors of the Wingless-related Integration site (WNT)/β-catenin pathway have recently been under consideration as potential chemopreventive agents against Familial Adenomatous Polyposis (FAP). This autosomal-dominant syndrome is caused by germline mutations in the gene coding for the protein APC and leads to hyperactivation of the WNT/β-catenin signaling pathway, uncontrolled intestinal cell proliferation and formation of adenocarcinomas. The aim of the present work was to: (i) test, on in vitro cultures of cells carrying FAP mutations and on ex vivo biopsies of FAP patients, the WNT inhibitory activity of extracts from two common southern Italian apples, Malus pumila Miller cv. 'Annurca' and Malus domestica cv 'Limoncella'; (ii) identify the mechanisms underpinning their activities and; (iii) evaluate their potency upon gastrointestinal digestion. We here show that both Annurca and Limoncella apple extracts act as WNT inhibitors, mostly thanks to their polyphenolic contents. They inhibit the pathway in colon cells carrying FAP mutations with active dilutions falling in ranges close to consumer-relevant concentrations. Food-grade manufacturing of apple extracts increases their WNT inhibitory activity as result of the conversion of quercetin glycosides into the aglycone quercetin, a potent WNT inhibitor absent in the fresh fruit extract. However, in vitro simulated gastrointestinal digestion severely affected WNT inhibitory activity of apple extracts, as result of a loss of polyphenols. In conclusion, our results show that apple extracts inhibit the WNT pathway in colon cells carrying FAP mutations and represent a potential nutraceutical alternative for the treatment of this pathology. Enteric coating is advisable to preserve the activity of the extracts in the colon-rectal section of the digestive tract.

Polyphenols and health: Interactions between fibre, plant polyphenols and the gut microbiota

A high‐fibre diet and one rich in fruit and vegetables have long been associated with lower risk of chronic disease. There are several possible mechanisms underpinning these associations, but one likely important factor is the production of bioactive molecules from plant‐based foods by the bacteria in the colon. This links to our growing understanding of the role of the gut microbiome in promoting health. Polyphenolic‐rich plant foods have been associated with potential health effects in many studies, but the bioavailability of polyphenol compounds, as eaten, is often very low. Most of the ingested molecules enter the large intestine where they are catabolised to smaller phenolic acids that may be the key bioactive effectors. Dietary fibres, present in plant foods, are also fermented by the bacteria to short‐chain fatty acids, compounds associated with several beneficial effects on cell turnover, metabolism and eating behaviour. Polyphenols and fibre are often eaten together, but there is a lack of research investigating the interaction between these two groups of key substrates for the colonic bacteria. In a project funded by the Biotechnology and Biological Sciences Research Council Diet and Health Research Industry Club, we are investigating whether combining different fibres and polyphenol sources can enhance the production of bioactive phenolic acids to promote health. This could lead to improved dietary recommendations and to new products with enhanced potential health‐promoting actions.

Cardiovascular and Antiobesity Effects of Resveratrol Mediated through the Gut Microbiota

Encouraging scientific research into the health effects of dietary bioactive resveratrol has been confounded by its rapid first-pass metabolism, which leads to low in vivo bioavailability. Preliminary studies have shown that resveratrol can modulate gut microbiota composition, undergo biotransformation to active metabolites via the intestinal microbiota, or affect gut barrier function. In rodents, resveratrol can modify the relative Bacteroidetes:Firmicutes ratio and reverse the gut microbial dysbiosis caused by a high-fat diet. By upregulating the expression of genes involved in maintaining tight junctions between intestinal cells, resveratrol contributes to gut barrier integrity. The composition of the gut microbiome and rapid metabolism of resveratrol determines the production of resveratrol metabolites, which are found at greater concentrations in humans after ingestion than their parent molecule and can have similar biological effects. Resveratrol may affect cardiovascular risk factors such as elevated blood cholesterol or trimethylamine N-oxide concentrations. Modulating the composition of the gut microbiota by resveratrol may affect central energy metabolism and modify concentrations of satiety hormones to produce antiobesity effects. Encouraging research from animal models could be tested in humans.

Polyphenols: dietary assessment and role in the prevention of cancers

PURPOSE OF REVIEW

Polyphenols are a large and diverse family of phytochemicals widely consumed by humans. Here we summarize the latest epidemiological evidence for associations between cancer risk and polyphenol intake, taking into account difficulties in the accurate estimation of exposure.

RECENT FINDINGS

Flavonoids are the most studied subgroup of polyphenols with regard to cancer risk. In recent epidemiological studies, total flavonoid intake has rarely been associated with a reduction in cancer risk. However, isoflavones, whose main dietary source is soy foods, plausibly reduce the risk of colorectal, breast, and prostate cancers, especially in Asian countries. Findings depend heavily upon the assessment of polyphenol intake, which is usually measured by food frequency questionnaires coupled to databases of food polyphenol composition. To a lesser extent, nutritional biomarkers have been used whenever estimating associations of polyphenol intake with cancer.

SUMMARY

Polyphenol intake may mitigate cancer risk but this depends on cancer site, the subgroup of compounds under study, and accurate assessment of dietary exposure. Further work must better characterize the effects of intake of different flavonoid subclasses and begin to investigate the role of phenolic acids and other minor polyphenol classes.

Intake of Individual Flavonoids and Risk of Carcinogenesis: Overview of Epidemiological Evidence

Several epidemiological findings have demonstrated that specific flavonoids can be responsible for reduction of the risk of certain cancer types. However, these results are still rather limited, inconclusive and controversial. Therefore, in this comprehensive review article the findings reported to date about the associations between dietary intake of individual flavonoid compounds and cancer incidence are compiled and analyzed. Also, the possible reasons for inconsistencies are brought forth and discussed. As diet is a potentially modifiable factor in our behavioral choices, further large-scale prospective studies with longer follow-up times, different populations, various doses and exposure timing as well as diverse well-controlled confounders are highly needed to confirm or disprove the current epidemiological knowledge about the role of flavonoids on cancer risk. Regarding the promising data to date, more research on bioavailability, metabolism and biological action mechanisms of these plant secondary metabolites is also encouraged.

Serum gamma-glutamyltransferase is inversely associated with dietary total and coffee-derived polyphenol intakes in apparently healthy Japanese men

PURPOSE

Serum γ-glutamyltransferase (GGT) has been proposed as a marker of oxidative stress. Here, we examined the association between serum GGT and the dietary intake of polyphenols, which have antioxidant properties.

METHODS

A cross-sectional survey including 7960 apparently healthy Japanese men (aged 22-86 years) who participated in health checkups was conducted in Shizuoka, Japan. We analyzed these subjects' clinical serum parameters and lifestyle factors, including dietary polyphenol intake, which was evaluated by a self-administered questionnaire and by matching the subjects' food consumption data with our original polyphenol content database.

RESULTS

The average intake of polyphenols was 1157 ± 471 mg/day, and green tea was the largest source of polyphenols at 40%, followed by coffee at 36%. Dividing the population according to quintiles of total polyphenol intake, the difference in polyphenol intake from coffee between the groups was much greater than the difference in polyphenol intake from green tea. The analysis of the association between polyphenol intake and biological parameters showed a significant negative association between polyphenol intake and the levels of systolic and diastolic blood pressure (SBP and DBP), GGT, and alanine aminotransferase (ALT) after adjusting for age, smoking habit, energy intake and alcohol intake. The GGT levels were inversely associated with the polyphenol intake from coffee, but not with that from green tea. Multivariable linear regression analyses demonstrated that the subjects' GGT levels were negatively and independently associated with their polyphenol intake.

CONCLUSIONS

The intake of total polyphenol including coffee as a major contributor is inversely associated with the serum GGT concentration in Japanese males.

Signatures of anthocyanin metabolites identified in humans inhibit biomarkers of vascular inflammation in human endothelial cells

SCOPE

The physiological relevance of contemporary cell culture studies is often perplexing, given the use of unmetabolized phytochemicals at supraphysiological concentrations. We investigated the activity of physiologically relevant anthocyanin metabolite signatures, derived from a previous pharmacokinetics study of 500 mg 13 C5 -cyanidin-3-glucoside in eight healthy participants, on soluble vascular adhesion molecule-1 (VCAM-1) and interleukin-6 (IL-6) in human endothelial cells.

METHODS AND RESULTS

Signatures of peak metabolites (previously identified at 1, 6, and 24 h post-bolus) were reproduced using pure standards and effects were investigated across concentrations ten-fold lower and higher than observed mean (<5 μM) serum levels. Tumor necrosis factor-α (TNF-α)-stimulated VCAM-1 was reduced in response to all treatments, with maximal effects observed for the 6 and 24 h profiles. Profiles tested at ten-fold below mean serum concentrations (0.19-0.44 μM) remained active. IL-6 was reduced in response to 1, 6, and 24 h profiles, with maximal effects observed for 6 h and 24 h profiles at concentrations above 2 μM. Protein responses were reflected by reductions in VCAM-1 and IL-6 mRNA, however there was no effect on phosphorylated NFκB-p65 expression.

CONCLUSION

Signatures of anthocyanin metabolites following dietary consumption reduce VCAM-1 and IL-6 production, providing evidence of physiologically relevant biological activity.

Polyphenols: Physicochemical and Biological Properties and Perspectives of Their Use in a Zero-Waste Society

The 28th International Conference on Polyphenols, held in Vienna (Austria) in July 2016, offered a venue for global exchanges on the active research on polyphenols and for the presentation and discussion of the latest advances. The multidisciplinary event attracted 280 scientists from four continents working in different fields, from analytical and biosynthetic chemistry through genetic and metabolic engineering, plant physiology, and ecology to food nutrition and health sciences as well as industrial applications. This special issue presents a selection of papers from oral presentations and poster contributions shown within the framework of sessions focusing on research in the fields of (1) chemistry and physicochemistry, (2) food, nutrition, and health, and (3) applied polyphenolics. This introductory paper also briefly summarizes general properties of this versatile and largest group of secondary metabolites and their use in bioeconomical approaches.

Identification of Urinary Polyphenol Metabolite Patterns Associated with Polyphenol-Rich Food Intake in Adults from Four European Countries

We identified urinary polyphenol metabolite patterns by a novel algorithm that combines dimension reduction and variable selection methods to explain polyphenol-rich food intake, and compared their respective performance with that of single biomarkers in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. The study included 475 adults from four European countries (Germany, France, Italy, and Greece). Dietary intakes were assessed with 24-h dietary recalls (24-HDR) and dietary questionnaires (DQ). Thirty-four polyphenols were measured by ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS-MS) in 24-h urine. Reduced rank regression-based variable importance in projection (RRR-VIP) and least absolute shrinkage and selection operator (LASSO) methods were used to select polyphenol metabolites. Reduced rank regression (RRR) was then used to identify patterns in these metabolites, maximizing the explained variability in intake of pre-selected polyphenol-rich foods. The performance of RRR models was evaluated using internal cross-validation to control for over-optimistic findings from over-fitting. High performance was observed for explaining recent intake (24-HDR) of red wine (r = 0.65; AUC = 89.1%), coffee (r = 0.51; AUC = 89.1%), and olives (r = 0.35; AUC = 82.2%). These metabolite patterns performed better or equally well compared to single polyphenol biomarkers. Neither metabolite patterns nor single biomarkers performed well in explaining habitual intake (as reported in the DQ) of polyphenol-rich foods. This proposed strategy of biomarker pattern identification has the potential of expanding the currently still limited list of available dietary intake biomarkers.

Unfolding Novel Mechanisms of Polyphenol Flavonoids for Better Glycaemic Control: Targeting Pancreatic Islet Amyloid Polypeptide (IAPP)

Type 2 diabetes (T2D) is characterised by hyperglycaemia resulting from defective insulin secretion, insulin resistance, or both. The impact of over-nutrition and reduced physical activity, evidenced by the exponential rise in obesity and the prevalence of T2D, strongly supports the implementation of lifestyle modification programs. Accordingly, an increased consumption of fruits and plant-derived foods has been advocated, as their intake is inversely correlated with T2D prevalence; this has been attributed, in part, to their contained polyphenolic compounds. Over the last decade, a body of work has focussed on establishing the mechanisms by which polyphenolic compounds exert beneficial effects to limit carbohydrate digestion, enhance insulin-mediated glucose uptake, down-regulate hepatic gluconeogenesis and decrease oxidative stress; the latter anti-oxidative property being the most documented. Novel effects on the inhibition of glucocorticoid action and the suppression of amylin misfolding and aggregation have been identified more recently. Amyloid fibrils form from spontaneously misfolded amylin, depositing in islet cells to elicit apoptosis, beta cell degeneration and decrease insulin secretion, with amyloidosis affecting up to 80% of pancreatic islet cells in T2D. Therefore, intervening with polyphenolic compounds offers a novel approach to suppressing risk or progression to T2D. This review gives an update on the emerging mechanisms related to dietary polyphenol intake for the maintenance of glycaemic control and the prevention of T2D.