Environmental Influencers of Health: Investigating Interactions Between Psychological Stress and the Western Diet on Cardiometabolic Risk Factors

This thesis aimed to investigate the interaction of chronic dietary and psychological stress on health and disease, specifically, the impacts on the biological pathways implicated in altered cardiometabolic and mood states. As will be discussed in Chapter 1: Literature Review, numerous pathophysiological mechanisms and pathways associated with dietinduced obesity (DIO) can be modulated by chronic psychological stressors (CPS) to ultimately alter disease outcomes. However, our understanding of these interactions is incomplete due to the complex relationship between the stress-response and metabolic, immunological, behavioural, and microbial systems across the human lifespan. Furthermore, while being driven primarily by chronic overnutrition and obesity, the development of cardiometabolic disorders is multifactorial, with dysfunction of several tissues and homeostatic mechanisms contributing to disease outcomes. This complexity in the aetiology of these disease states requires a systems-based approach to properly understand the interactions between dietary and psychological stimuli across multiple organ systems and communication networks. This thesis aims to contribute to our understanding of the pathophysiology of metabolic and mood disorders by investigating the interactions that could occur between metabolic, cardiovascular, neuronal, and gastrointestinal systems to influence cardiometabolic risk, behaviour, and myocardial tolerance to injury. In this thesis, data from clinical research trials and data generated using animal models and ex vivo experiments were used to assess the impact of DIO and CPS on health and disease. The main research areas discussed within this thesis are cardiometabolic risk, colonic health, mood disorders, and myocardial ischaemic/reperfusion (I/R) injury. The contents of this thesis is organised into seven chapters and an appendix. Chapter 1 is a literature review that is broken down into four distinct sections. The first section focuses on the impact of dietary and stress-related ...