|Abstract:||As rates of overweight and obesity, and their related comorbid conditions continue to rise, the need to understand the mechanisms of obesity and metabolic disease and recommend strategies for prevention and treatment has never been greater. Dietary strategies for weight loss and weight maintenance offer the greatest opportunity to provide low-cost, safe, and universally available treatments compared to pharmaceutical and surgical interventions. Some dietary patterns, like the Mediterranean diet pattern, are widely known for their promotion of metabolic and whole-body health. However, a complete understanding of the mechanisms by which foods associated with the Mediterranean diet pattern contribute to health is lacking. The Mediterranean diet pattern is characterized by a high intake of fruits, vegetables, whole grains, legumes, and nuts; moderate consumption of seafood and red wine; and low consumption of the red and processed meats and sugar-sweetened beverages common in the Western diet pattern. Dietary fiber, a nutrient far more abundant in a Mediterranean diet pattern than a Western pattern, decreases inflammation through a complex web of physiological interactions including the modulation of the gastrointestinal (GI) microbiota and bacterial fermentation end-products, GI barrier structure and function, and the enterohepatic circulation of bile acids.
One of the mechanisms by which consumption of dietary fibers may contribute to decreased whole-body inflammation is through the prevention of metabolic endotoxemia, defined as a 2- to 3- fold increase in the circulating concentrations of the pathogen associated molecular pattern lipopolysaccharide (LPS). As the largest reservoir of LPS in the body, the GI microbiota represents an under-investigated frontier of human metabolic health.
It was the aim of this thesis to investigate the effects of diet on the GI microbiota, metabolic endotoxemia, inflammation, and metabolic disease risk in adults of varying weight status.