The Impact of Dietary Fibers and Environmental Xenobiotics on Metabolic Homeostasis Via the Gut Microbiota

Abstract

The global rise in obesity and type 2 diabetes (T2D) is strongly linked to diet and environmental exposures that influence host metabolism and the gut microbiota. Dietary fibers, including beta-glucan, pectin, wheat dextrin, and resistant starch, are fermented by gut microbes into short-chain fatty acids that regulate energy balance and glucose homeostasis. However, fibers are heterogeneous in structure and function, and their independent effects on metabolism and the gut microbiota remain unclear. In parallel, environmental xenobiotics such as glyphosate, the most widely used herbicide, and chlorination agents used in drinking water, can disrupt microbial composition and promote inflammation, yet their long-term, sex-specific, and diet-dependent impacts on metabolic health are poorly defined.This dissertation examines how environmental factors shape host-microbiota interactions and contribute to metabolic disease. Chapter 1 reviews the role of the gut microbiota in regulating metabolic homeostasis. Chapter 2 investigates how distinct dietary fibers influence host metabolism through microbiota-mediated mechanisms. Chapter 3 explores the effects of glyphosate exposure on the gut microbiota and metabolic outcomes. Chapter 4 focuses on the impact of chlorinated drinking water on metabolic homeostasis through changes in the gut microbiota. Together, these studies provide new insight into how diet and environmental exposures modulate host-microbe interactions and impact metabolic health.