Inter-individual variability in the production of flavan-3-ol colonic metabolites: preliminary elucidation of urinary metabotypes

Host-Microbe Interplay in the Cardiometabolic Benefits of Dietary Polyphenols

Polyphenols are nonessential phytonutrients abundantly found in fruits and vegetables. A wealth of data from preclinical models and clinical trials consistently supports cardiometabolic benefits associated with dietary polyphenols in murine models and humans. Furthermore, a growing number of studies have shown that specific classes of polyphenols, such as proanthocyanidins (PACs) and ellagitannins, as well as the stilbenoid resveratrol, can alleviate several features of the metabolic syndrome. Moreover, mounting evidence points to the gut microbiota as a key mediator of the health benefits of polyphenols. In this review we summarize recent findings supporting the beneficial potential of polyphenols against cardiometabolic diseases, with a focus on the role of host-microbe interactions.

Bioavailability and metabolism of selected cocoa bioactive compounds: A comprehensive review

Cocoa beans and their co-products are a rich source of beneficial compounds for health promotion, including polyphenols and methylxanthines. Knowledge of bioavailability and in vivo bioactivity of these phytochemicals is crucial to understand their role and function in human health. Therefore, many studies concerning bioavailability and bioactivity of cocoa bioactive compound have been done in both in vivo animal models and in humans. This critical review comprehensively summarizes the existing knowledge about the bioavailability and the major metabolic pathways of selected cocoa bioactive compounds (i.e. monomeric flavan-3-ols, procyanidins, anthocyanins, flavonols, phenolic acids, N-phenylpropenoyl-L-amino acids, stilbenes, and methylxanthines). The compiled results indicated that many of these compounds undergo extensive metabolism prior to absorption. Different factors have been suggested to influence the bioavailability of polyphenols and methylxanthines among them the role of gut microbiota, structure of these compounds, food matrix and occurrence of other substances were the most often considered. Aforementioned factors decided about the site where these bioactive compounds are digested and absorbed from the alimentary tract, as well as the pathway by which they are metabolized. These factors also determine of the type of transport through the intestine barrier (passive, involving specific enzymes or mediated by specific transporters) and their metabolic path and profile.

Procyanidin-Cell Wall Interactions within Apple Matrices Decrease the Metabolization of Procyanidins by the Human Gut Microbiota and the Anti-Inflammatory Effect of the Resulting Microbial Metabolome In Vitro

B-type oligomeric procyanidins in apples constitute an important source of polyphenols in the human diet. Their role in health is not known, although it is suggested that they generate beneficial bioactive compounds upon metabolization by the gut microbiota. During apple processing, procyanidins interact with cell-wall polysaccharides and form stable complexes. These interactions need to be taken into consideration in order to better assess the biological effects of fruit constituents. Our objectives were to evaluate the impact of these interactions on the microbial metabolization of cell walls and procyanidins, and to investigate the potential anti-inflammatory activity of the resulting metabolome, in addition to analyzing the taxonomical changes which the microbiota undergo. In vitro fermentation of three model apple matrices with microbiota from 4 healthy donors showed that the binding of procyanidins to cell-wall polysaccharides, whether covalently or non-covalently, substantially reduced procyanidin degradation. Although cell wall-unbound procyanidins negatively affected carbohydrate fermentation, they generated more hydroxyphenylvaleric acid than bound procyanidins, and increased the abundance of Adlercreutzia and Gordonibacter genera. The best results in terms of production of anti-inflammatory bioactive metabolites were observed from the apple matrix with no bonds between procyanidins and cell wall polysaccharides, although the matrix with non-covalent bonds was not far behind.

Some New Findings Regarding the Antiadhesive Activity of Cranberry Phenolic Compounds and Their Microbial-Derived Metabolites against Uropathogenic Bacteria

Findings concerning the antiadhesive activity of cranberry phenolic compounds and their microbial-derived metabolites against Gram-negative ( Escherichia coli ATCC 53503 and DSM 10791) and Gram-positive ( Enterococcus faecalis 04-1) bacteria in T24 cells are reported. A-Type procyanidins (A2 and cinnamtannin B-1) exhibited antiadhesive activity (at concentrations ≥250 μM), a feature that was not observed for B-type procyanidins (B2). The metabolites hippuric acid and α-hydroxyhippuric acid also showed effective results at concentrations ≥250 μM. With regard to conjugated metabolites, sulfation seemed to increase the antiadhesive activity of cranberry-derived metabolites as 3-(3,4-dihydroxyphenyl)propionic acid 3- O-sulfate presented active results, unlike its corresponding nonsulfated form. In contrast, methylation decreased antiadhesive activity as 3,4-dihydroxyphenylacetic acid was found to be active but not its corresponding methylated form (4-hydroxy-3-methoxyphenylacetic acid). As a whole, this work sustains the antiadhesive activity of cranberry-derived metabolites as one of the mechanisms involved in the beneficial effects of cranberries against urinary tract infections.

Impact of Fermentable Fibres on the Colonic Microbiota Metabolism of Dietary Polyphenols Rutin and Quercetin

Dietary fibre and polyphenols are both metabolised to short-chain fatty acids (SCFAs) and phenolic acids (PA) by the colonic microbiota. These may alter microbiota growth/diversity, but their interaction is not understood. Interactions between rutin and raftiline, ispaghula or pectin were investigated in human faecal batch cultures (healthy participants; 19⁻33 years, 4 males, 6 females, BMI 18.4⁻27.4) after a low (poly)phenol diet three days prior to study. Phenolic acids were measured by gas chromatography-mass spectrometry and SCFAs by gas chromatography-flame ionisation after 2, 4, 6, and 24 h. Rutin fermentation produced Phenyl acetic acid (PAA), 4-Hydroxy benzoic acid (4-OHBA), 3-Hydroxy phenyl acetic acid (3-OHPAA), 4-Hydroxy phenyl acetic acid (4-OHPAA), 3,4-Dihydroxy phenyl acetic acid (3,4-diOHPAA), 3-Hydroxy phenyl propionic acid (3-OHPPA), and 4-Hydroxy phenyl propionic acid (4-OHPPA). 3,4-DiOHPAA and 3-OHPAA were predominant at 6 h (1.9 ± 1.8 µg/mL, 2.9 ± 2.5 µg/mL, and 0.05 ± 0.0 µg/mL, respectively) and 24 h (5.5 ± 3.3 µg/mL, 3.1 ± 4.2 µg/mL, and 1.2 ± 1.6 µg/mL). Production of all PA except 3-OHPPA and 4-OHPPA was reduced by at least one fibre. Inhibition of PA was highest for rutin (8-fold, p < 0.01), then pectin (5-fold, p < 0.01), and ispaghula (2-fold, p = 0.03). Neither rutin nor quercetin had a detectable impact on SCFA production. These interactions should be considered when assessing dietary polyphenols and potential health benefits.

Wine-Derived Phenolic Metabolites in the Digestive and Brain Function

Wine, and specifically red wine, is a beverage with a great chemical complexity comprising a particular combination of phenolic compounds which are directly associated with its health-promoting properties. Wine polyphenols could induce changes in the composition of intestinal microbiota that would affect the production of physiologically active phenolic metabolites modifying the content and phenolic profile at the systemic level. In addition, in the human population, it seems that different “metabotypes”, or patterns of metabolizing wine polyphenols, exist, which would be reflected in the different biological fluids (i.e., plasma, urine and feces) and tissues of the human body. Moreover, wine polyphenols might change the composition of oral microbiota by an antimicrobial action and/or by inhibition of the adhesion of pathogens to oral cells, thus contributing to the maintenance of oral health. In turn, polyphenols and/or its metabolites could have a direct action on brain function, by positively affecting signaling routes involved in stress-induced neuronal response, as well as by preventing neuroticism-like disorders (i.e., anxiety and depression) through anti-inflammatory and epigenetic mechanisms. All of this would condition the positive effects on health derived from moderate wine consumption. This paper reviews all these topics, which are directly related with the effects of wine polyphenols at both digestive and brain level. Further progresses expected in the coming years in these fields are also discussed.

Effect of Food Structure and Processing on (Poly)phenol-Gut Microbiota Interactions and the Effects on Human Health

The two-way interaction of food (poly)phenols with the human gut microbiota has been studied throughout the past ten years. Research has shown that this interaction can be relevant to explain the health effects of these phytochemicals. The effect of the food matrix and food processing on this interaction has only been partially studied. In this article, the studies within this field have been critically reviewed, with a special focus on the following groups of phenolic metabolites: citrus flavanones, pomegranate ellagitannins, and cocoa proanthocyanidins. The available research shows that both the food matrix and food processing can be relevant factors for gut microbiota reshaping to reach a healthier microbial ecology and for the conversion of polyphenols to bioactive and bioavailable metabolites. There are, however, some research gaps that indicate a more comprehensive research approach is needed to reach valid conclusions regarding the gut microbiota-mediated effects of polyphenols on human health.

Breakthroughs in the Health Effects of Plant Food Bioactives: A Perspective on Microbiomics, Nutri(epi)genomics, and Metabolomics

Plant bioactive compounds consumed as part of our diet are able to influence human health. They include secondary metabolites like (poly)phenols, carotenoids, glucosinolates, alkaloids, and terpenes. Although much knowledge has been gained, there is still need for studies unravelling the effects of plant bioactives on cardiometabolic health at the individual level, using cutting-edge high-resolution and data-rich holistic approaches. The aim of this Perspective is to review the prospects of microbiomics, nutrigenomics and nutriepigenomics, and metabolomics to assess the response to plant bioactive consumption while considering interindividual variability. Insights for future research in the field toward personalized nutrition are discussed.