Investigating the role of different dietary patterns on gut metabolites
File(s)
Author(s)
Brignardello, Jerusa
Type
Thesis
Abstract
This thesis investigates the interplay between dietary patterns and gut metabolites, focusing on short-chain fatty acids (SCFAs) and bile acids (BAs), key contributors to gut metabolism. It addresses the need to move beyond reductionist, nutrient-specific approaches by examining how whole dietary patterns shape metabolic outcomes. Using advanced analytical techniques, including novel Gas Chromatography-Mass Spectrometry (GC-MS) and Liquid Chromatography-Mass Spectrometry (LC-MS), this work evaluates gut-related metabolites across contrasting diets.
Two primary studies frame this research. The first examines SCFA and BA concentrations in free-living vegans and omnivores within a cross-sectional cohort. Significant metabolic differences emerged between these groups. Vegans showed elevated SCFA concentrations in biofluids, reflecting their high-fibre diets, whereas omnivores exhibited increased secondary bile acids in faecal samples, likely linked to higher fat intake. These results highlight the distinct effects of plant-based versus omnivorous dietary patterns on gut-derived metabolites and their potential implications for health.
The second study investigates the acute metabolic effects of contrasting dietary patterns in a randomised, controlled, crossover trial. By monitoring SCFA and BA concentrations following healthy and unhealthy diets, this study captures temporal fluctuations in metabolite profiles. SCFA levels varied with dietary intake and displayed notable inter- and intra-individual variability. For BAs, temporal variation appeared stronger than dietary effects. Integrating metabolomic and dietary data, this work emphasises the dynamic and personalised nature of gut metabolite responses among individuals consuming the same diet.
Overall, this thesis advances understanding of the complex interactions between diet, host metabolism, and the microbiota. Recognising the role of metabolite variability is essential for interpreting metabolic pathways and developing tailored dietary recommendations. By elucidating how dietary patterns shape gut metabolites under real-life and controlled conditions, this research contributes to future applications in precision nutrition and supports the development of metabolite-informed dietary strategies.
Two primary studies frame this research. The first examines SCFA and BA concentrations in free-living vegans and omnivores within a cross-sectional cohort. Significant metabolic differences emerged between these groups. Vegans showed elevated SCFA concentrations in biofluids, reflecting their high-fibre diets, whereas omnivores exhibited increased secondary bile acids in faecal samples, likely linked to higher fat intake. These results highlight the distinct effects of plant-based versus omnivorous dietary patterns on gut-derived metabolites and their potential implications for health.
The second study investigates the acute metabolic effects of contrasting dietary patterns in a randomised, controlled, crossover trial. By monitoring SCFA and BA concentrations following healthy and unhealthy diets, this study captures temporal fluctuations in metabolite profiles. SCFA levels varied with dietary intake and displayed notable inter- and intra-individual variability. For BAs, temporal variation appeared stronger than dietary effects. Integrating metabolomic and dietary data, this work emphasises the dynamic and personalised nature of gut metabolite responses among individuals consuming the same diet.
Overall, this thesis advances understanding of the complex interactions between diet, host metabolism, and the microbiota. Recognising the role of metabolite variability is essential for interpreting metabolic pathways and developing tailored dietary recommendations. By elucidating how dietary patterns shape gut metabolites under real-life and controlled conditions, this research contributes to future applications in precision nutrition and supports the development of metabolite-informed dietary strategies.
Version
Open Access
Date Issued
2025-01-12
Date Awarded
2026-01-01
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
License URL
Advisor
Dumas, Marc Emmanuel
Veselkov, Kirill
Publisher Department
Department of Metabolism, Digestion and Reproduction
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)