Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Diet-induced alterations to postprandial metabolism and the gut microbiota(Montana State University - Bozeman, The Graduate School, 2022) Wilson, Stephanie Michelle-Gandia; Chairperson, Graduate Committee: Mary P. Miles; This is a manuscript style paper that includes co-authored chapters.Obesity is a key component of a cluster of metabolic risk factors for chronic disease which include dyslipidemia, hyperglycemia, and hypertension. Stark changes in diet and lifestyle contribute to growing metabolic disorder prevalence. Many Americans regularly consume foods low in fiber and rich in fat and sugar, which can negatively influence glucose and lipid metabolism over time. A nutritionally poor diet exerts deleterious effects on the gastrointestinal microbial community which has larger host health implications. As a modifiable risk factor, diet can be part of the solution to counter the rise of chronic disease. However, dietary responses as it pertains to glucose and lipid metabolism display high interindividual variability. This interindividual variability with diet can also be observed at the microbial level in our gastrointestinal system. In metabolically at-risk adults, we examined postprandial responses and the efficacy of a long-term lentil dietary intervention in improving postprandial glycemic responses. We further assessed the effect of an antioxidant-rich juice from the Aronia melanocarpa berry and its anti-inflammatory potential against a high fat diet in a gnotobiotic mouse model to evaluate how specific gut microbial communities transferred from metabolically at-risk adults with different inflammatory profiles may impact dietary responses. Postprandial triglyceride responses in adults with overweight and obesity can be partially explained by central adiposity, insulin resistance, and the ability to switch between glucose and fat metabolism to a metabolic stress. A long-term dietary intervention with lentils, a fiber-rich pulse crop, worked in a dose-dependent manner to reduce insulin resistance in adults with increased central adiposity without an increase in gastrointestinal symptoms, a common deterrent to incorporating fiber-foods in the diet. Our gnotobiotic mouse experiments revealed donor- dependent changes in dietary responses. We observed protective effects of Aronia juice in mice, particularly in mice from the low inflammation stool donor. Metabolomic changes in phospholipids such as phosphatidylcholine and sphingomyelin were further detected, with changes respectively unique to Aronia juice and high-fat diet. Taken together, this dissertation provides an improved understanding of our metabolic responses and microbial alterations to the foods we consume, and how these responses influence the progression of metabolic diseases.Item Post-prandial serum concentrations of Trimethylamine-N-oxide in overweight and obese adults with low and high systemic inflammation(Montana State University - Bozeman, College of Education, Health & Human Development, 2018) Wilson, Stephanie Michelle; Chairperson, Graduate Committee: Mary P. MilesPurpose: Elevated trimethylamine-N-oxide (TMAO) levels have been implicated in the development of atherosclerosis. The impact of a high-fat meal on the post-prandial TMAO response in healthy overweight and obese adults was explored, accounting for additional variables that may affect the rate of TMAO conversion. Methods: Forty overweight and obese men and women participated in a high-fat meal challenge containing 50 g fat. Blood samples were collected at fasting and hourly in the 4 hours after meal ingestion and tested for concentrations of TMAO, liver enzymes, lipids, creatinine, insulin, and inflammatory markers. An initial mixed-effects model was constructed to analyze TMAO changes in participants who classified as having low or high levels of systemic inflammation accounting for factors that may influence TMAO concentrations. Backward refinement of the initial model was performed based off p-values. Results: Model refinement found that the log TMAO response was best explained by inclusion of estimated glomerular filtration rate (eGFR), insulin over time, a linear interaction between time and inflammation phenotype, and random effects on subject. Log TMAO after the meal was not different between inflammation phenotypes (p = 0.33). Estimated GFR was the most important determinant in the log TMAO response (p = 0.03), with lower log TMAO observed with higher eGFR values. In conclusion, serum TMAO concentrations during a high fat-meal challenge were strongly determined by eGFR, but not by fasting inflammation status.Item Diet and performance in high school athletics(Montana State University - Bozeman, 1956) Hart, Neil W.Item Distribution, characterization, and dietary risk assessment of indigenous salts in Mongolia's Darhad Valley(Montana State University - Bozeman, College of Agriculture, 2008) Barber, Loren Mickelle; Chairperson, Graduate Committee: Cliff Montagne.Natural salt deposits around the world are used as human and livestock dietary mineral sources. The nomadic herders of the Darhad Valley, in northern Mongolia, harvest the precipitate that forms around saline lakes throughout their valley. The precipitate is termed hujir, and the main harvest location is Tukh. Darhad people are concerned about the declining amount of a hujir in the Tukh precipitate area and are curious about possible health effects related to hujir consumption. These studies focus on formulating the best management practices for sustainable hujir harvest by evaluating factors influencing the formation of hujir, and by establishing the mineralogy and ionic concentrations in Tukh soil, water, and hujir through chemical and spatial analyses. A dietary risk assessment was also accomplished by obtaining consumption rates through interviews, and determining exposure values from the consumption rates and ionic concentrations. Exposures were compared to chronic oral endpoints to relate potential health risks. A map of Tukh was created using Global Positioning System and Geographic Information System technologies and acts as baseline spatial data on the area. Minerals present include trona, halite, calcite, and other evaporites. According to pH and EC results, the area used for human harvesting at Tukh is more saline than the remainder of the lake. The soil profile within the precipitate area showed a TDS of 49 mg/L and pH of 7.2 in the surface horizon relative to an EC of 0.4 mg/L and a pH of 6.4 lower in the profile. This indicates a presence of capillary rise from groundwater, resulting in evaporation and salt precipitate at the soil surface. High exposure of arsenic, antimony, and lead compared to U.S. Environmental Protection Agency and World Health Organization endpoint values resulted in risk quotients of 33, 1.7, and 14, respectively, which create concern in the population's hujir consumption. Further epidemiological and biomonitoring research would provide insight in the health relationships to hujir consumption. Future research could benefit from the resulting spatial and chemical data completed in these studies.