MSACL 2019 EU Abstract

Exploring the Interactions between Dietary Polyphenols, the Gut Microbiome and Human Health

Nicola Gray (1), Cíntia Rabelo e Paiva Caria (1), Wagner Vilegas (2), Christine Hinz (3), Christopher Titman (3), Glenn Gibson (1), Gunter Kuhnle (1)
(1) Department of Food and Nutritional Sciences, University of Reading, Reading, UK (2) Laboratory of Bioprospecting of Natural Products, Institute of Biosciences, Universidade Estadual Paulista (UNESP), São Vicente, Brazil (3) Shimadzu UK Ltd, Milton Keynes, UK

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Nicola Gray (Presenter) University of Reading, UK

Relevant Financial Disclosures (within past 24 months) Committee/Board/Advisory Board MSACL EU Early Career Scientist Committee Discussing Products? NO, presenter will NOT present educational content related to products/services of the ineligible company(ies) listed above. Conflict mitigation NOT REQUIRED.

Introduction:
Epidemiological and dietary intervention studies suggest that consumption of polyphenol-rich foods may have a number of health benefits, including reduced risk of cardiovascular disease. Increased intake of polyphenols, found at high levels in tea, fruit and vegetables, has been associated with health-promoting benefits including vascular and platelet function, blood pressure and improved plasma lipid profile. However, the mechanisms behind these benefits remain unclear, and the bioavailability of dietary polyphenols is highly variable between individuals. A significant fraction of dietary polyphenols can persist in the colon, where they are exposed to the gut microbiota. Since the study of the human gut microbiota is hindered by the complexity of this ecosystem and accessibility, in vitro gut models provide a powerful tool to build mechanistic knowledge around microbial polyphenol bioconversion.

Objectives:
The primary objective of this study was to understand the involvement of human microbiota in the metabolism of different plant polyphenol substrates using an in vitro. This approach enables investigation of broad metabolite perturbations and variations in microbial diversity to enhance mechanistic understanding of polyphenol bioactivity and nutritional influences to improve health through diet.

Methods:
Fermentation studies were performed using a three stage in vitro gut model with human stool from three donors, incubated in the presence of four different flavanol-containing substrates (Byrsonima intermedia, Rhizophora mangle, Serjania marginata and Theobroma cacao extracts). Samples were taken at ten time points over a 48-hour period (0, 1, 2, 3, 4, 5, 6, 8, 24 and 48 hrs).

Untargeted and targeted LC-MS metabolite profiling was applied to explore polyphenol metabolism and the influence on gut microbial activity.

Results:
Distinct metabolic differences were observed in the in vitro culture profiles in the presence of polyphenol substrates. Multivariate statistical analysis using principal components analysis (PCA) demonstrated variations in the metabolites produced by the different polyphenol extracts in a time dependent manner. Univariate analysis showed the magnitude of change between microbial metabolites and highlighted interindividual differences in metabolism, as well as changes in endogenous compounds in response to the polyphenol substrates. Targeted LC-MS/MS methods were also applied to profile phenolic, bile acid and short chain fatty acids to gain a deeper understanding into the potential mechanism of bioactivity of dietary polyphenols.

Conclusion:
The combination of untargeted and targeted LC-MS methods allowed for detailed exploration of gut microbial metabolism of plant polyphenols, providing an in-depth workflow to determine the bioconversion of dietary polyphenolic compounds.