Nutritional factors affecting diet quality and endotoxin-induced inflammation
Creators: name: Ogilvie, Anna R.
Publisher: name: No Publisher Supplied
Year: 2024

description: Dietary needs change through the life cycle and into older adulthood the ability to absorb and utilize nutrients declines. With aging, there is also a propensity toward weight gain and increased risk of inflammatory conditions such as diabetes, cardiovascular disease, and osteoporosis. Therefore, it is essential to determine optimal dietary patterns that provide adequate intake of beneficial nutrients while preventing excess consumption of other dietary components augmenting risk of adverse health outcomes. For instance, consuming adequate dietary protein is frequently met with the difficulty of limiting dietary fat. Dietary protein is essential for maintaining lean body mass (LBM) and bone in older adults; however, dietary protein sources contribute the largest portion of total and saturated fat in the American diet. Consuming excess saturated fat increases risk for dyslipidemia, obesity, cardiovascular disease, and metabolic syndrome. The balance of these macronutrients in an omnivorous diet, where a significant portion of both fat and protein come from meat, poultry, and dairy, is crucial to understanding benefits and risks in the older adult population. Therefore, the objectives of this dissertation were to evaluate benefits of dietary protein on body composition and diet patterns during weight loss, and to determine risks associated with dietary fat intake related to inflammatory components that activate innate immunity (i.e. endotoxin via NF-kB pathway). The first study examined the influence of dietary protein on lean body mass and diet quality during weight loss in adults with overweight and obesity. This analysis included pooled data of multiple trials of 207 adults reporting food intake over 6 months of weight loss. The sample population was retrospectively divided by median protein intake (lower and higher protein). Our results showed that greater protein intake during calorie restriction attenuates loss of LBM and improves diet quality components by increasing intake of green vegetables and reducing intake of refined grains and added sugars. The food study addressed method development for detecting and quantifying lipopolysaccharide (LPS) in foods. Fifty foods were assessed using the recombinant Factor C assay (rFC) and further examined in experiments assessing the effect of freezing and filtering food samples. Grains which are known to contain LPS-producing gram-negative bacteria were further assessed with the human Toll-like receptor 4 (TLR4) cell reporter assay. It was observed that LPS can be detected in food samples using both the rFC and hTLR4 cell reporter assays after filtration. Furthermore, the rFC assay is beneficial for detecting very low levels of LPS, whereas the hTLR4 cell reporter assay detects more inflammatory structures of LPS. Both assays provide a method of characterizing presence of inflammatory pathogen-associated molecular patterns (PAMPs) within food systems.The last study in this dissertation is a trial using a randomized controlled crossover design examining how two levels of short-term dietary fat affected serum endotoxin and associated inflammatory markers in individuals with obesity compared to those with normal body weight. Thirty-two older adults were randomized to diet order of lower (20%) and higher (40%) fat diets. The group with obesity had a greater fasting serum LPS following HF diet compared to LF diet, whereas the group with normal body weight did not change. While HF diet increased serum LPS with obesity, the inflammatory markers increased in the entire sample. Our findings suggest that individuals with obesity are more susceptible to an elevation in serum LPS due to greater fat intake, but this does not consistently affect serum markers of inflammation.Overall, it can be concluded that diet quality is altered by protein intake, and that dietary endotoxin and fat could contribute to diet-induced inflammation. The findings from this dissertation elucidate the intricate physiological responses to diet patterns that contain a combination of macronutrients (moderately high fat or protein) and PAMPs that influence health outcomes in older adults.