The effect of fermentable carbohydrates on diabetes & obesity
File(s)
Author(s)
Fountana, Sofia
Type
Thesis
Abstract
Fermentable carbohydrates have been shown to exert beneficial effects on dysregulated metabolic conditions such as obesity and diabetes by improving insulin sensitivity and glucose homeostasis, independent of weight loss. Short-chain fatty acids produced by the fermentation of these carbohydrates are considered the primary mediators of these beneficial effects. This thesis aims to evaluate the effect of fermentable carbohydrates on metabolic profiles of pre-diabetic individuals at high risk of developing diabetes and the effect of colonic propionate on glucose and lipid homeostasis in obese individuals.
The work presented in this thesis comprises of two axes. The first one is centered on the development and validation of an analytical approach of quantifying SCFAs in human plasma, serum and urine. The applicability of the assay in nutritional studies is also assessed in the second aim.
The second part explores the metabolic profiles of pre-diabetic and obese individuals with the employment of 1H nuclear magnetic spectroscopy and mass spectrometry analysis. Concentrations of SCFAs and alteration of the lipid profile were also assessed. The responses to dietary interventions were compared using multivariate statistics.
The fermentable carbohydrate inulin increased the production of postprandial SCFAs in pre-diabetic individuals but did not exhibit a significant effect on the overall metabolic profile. Colonic propionate improved the postprandial lipaemia in obese individuals and exerted higher microbial derived metabolites suggesting a role for propionate in the lipid homeostasis in obesity. Propionate levels in the circulation were not affected but systemic acetate significantly increased during the meal test. Finally, the controlled intervention with the non-fermentable carbohydrate cellulose improved lipid profiles in pre-diabetic and obese individuals.
The work presented in this thesis comprises of two axes. The first one is centered on the development and validation of an analytical approach of quantifying SCFAs in human plasma, serum and urine. The applicability of the assay in nutritional studies is also assessed in the second aim.
The second part explores the metabolic profiles of pre-diabetic and obese individuals with the employment of 1H nuclear magnetic spectroscopy and mass spectrometry analysis. Concentrations of SCFAs and alteration of the lipid profile were also assessed. The responses to dietary interventions were compared using multivariate statistics.
The fermentable carbohydrate inulin increased the production of postprandial SCFAs in pre-diabetic individuals but did not exhibit a significant effect on the overall metabolic profile. Colonic propionate improved the postprandial lipaemia in obese individuals and exerted higher microbial derived metabolites suggesting a role for propionate in the lipid homeostasis in obesity. Propionate levels in the circulation were not affected but systemic acetate significantly increased during the meal test. Finally, the controlled intervention with the non-fermentable carbohydrate cellulose improved lipid profiles in pre-diabetic and obese individuals.
Version
Open Access
Date Issued
2017-12
Date Awarded
2018-08
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Nicholson, Jeremy
Frost, Gary
Publisher Department
Department of Surgery & Cancer
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)