Browsing by Subject "Fiber"
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Item Effects of fiber on satiety, food intake, glucose, insulin, and gut hormones in healthy human subjects.(2009-05) Willis, Holly JoEpidemiologic studies suggest that people who eat more fiber have a lower body weight than people who eat less fiber. Potential mechanisms for this relationship may include greater feelings of satiety, reductions in food intake, or changes in blood glucose, insulin, or gut hormone levels. The following work describes two unique intervention studies designed to help explain this relationship. In the first study we hypothesized that certain types of fiber would enhance satiety more than others when consumed in muffins for breakfast. Healthy men and women participated in this randomized double-blind, crossover study comparing satiety after subjects consumed four different fibers and a low-fiber control. Subjects used 100 mm visual analog scales (VAS) to rate satiety for 3 hours after muffin consumption. Satiety differed among treatments. Resistant starch and corn bran had the most impact on satiety, while polydextrose had little effect and behaved like the low-fiber treatment. In the second study we hypothesized that increasing doses of fiber would increase satiety and decrease food intake in a dose-dependent manner. We also hypothesized that glucose, insulin, ghrelin, GLP-1, and PYY3-36 would change in proportion to fiber dose. Healthy men and women participated in this randomized double-blind, crossover study. Subjects consumed muffins with 0, 4, 8, and 12 g of mixed fibers and proceeded to rate satiety with VAS over a three-hour period. Blood was drawn at regular intervals and ad libitum food intake was assessed at two different time points. The 12 g fiber muffin was consistently and significantly more satiating than the 0 g muffin; however, food intake did not differ among treatments. Glucose, insulin, ghrelin, and GLP-1 differed among treatment doses, but not in the manner we expected. Glucose and insulin did not correlate with each other or with appetite. Ghrelin was significantly higher after 12 g of fiber than after all other doses, and GLP-1 decreased consistently with fiber dose. PYY3- 36 did not differ among treatments. Results from these studies indicate that certain types and doses of fiber positively influence satiety. However, caution should be used when making blanket statements about fiber as a generic substance; this research suggests that some types and doses are not as effective as others. Furthermore, feelings of satiety may not be consistently linked to food intake or other commonly accepted physiologic measures for satiety.Item Finite element modeling of thin fiber reinforced concrete pavements(2023-07) Sharma, PranavThin concrete pavement is an economical option for low and moderate traffic roads, where thethickness of concrete slab varies from 4-inch to 6-inch. In conventional concrete pavement, dowel bars are used to increase load transfer efficiency (LTE) and mitigate transverse joint faulting. However, dowel bars cannot be accommodated in the thin concrete pavement due to insufficient clear cover. For such pavements, structural fibers are a good option for increasing joint performance or load transfer efficiency, as well as reducing faulting. However, only limited studies are available in understanding the contribution of structural fibers to the benefits of joint performance and the behavior of fibers during the transfer of loads across the joint. In this study, finite element analysis of the thin fiber reinforced concrete (FRC) pavement was performed. A six-slab model was developed with a granular aggregate layer, replicating the actual field conditions. The effect of concrete and base layer structure, material properties, traffic and environmental loads, and joint stiffness on the transverse joint performance and critical stresses were studied. It was found that around 40% of the wheel load is transferred through the pavement foundation and the rest through the aggregate interlocking and fibers’ lateral stiffness. Critical stresses for the fatigue cracks along the wheel path were also determined in this study. This study concluded the minimum required lateral stiffness of the structural fibers for a desired level of joint performance as a function of the pavement structure.Item Modulation Of Intestinal Cell Differentiation By Different Fiber Sources And Evaluation Of Using A Modified Three-Step Procedure To Predict Digestible And Metabolizable Energy Content In Growing Pigs(2017-03) Huang, ZhiminAccurate swine diet formulation is essential for optimizing caloric and nutritional efficiency of pork production. The large variability in energy and nutrient composition among high fiber ingredients from different sources requires the development and use of relatively rapid, inexpensive, and accurate methods to determine dynamic estimates of these ingredients. The overall goal of this thesis was to develop a better understanding of the potential value of using a 3-step in vitro digestibility system to obtain dynamic estimates of energy and nutrient digestibility, and determine the physiological effects of feeding high fiber ingredients to pigs. Specifically, the objectives were: 1) investigate the mechanisms of how high fiber ingredients affect nutrient utilization in swine by understanding how dietary fiber affects gastrointestinal physiology, specifically cell proliferation and differentiation of the small intestine, and 2) to develop and evaluate a modified three-step in vitro method for rapid estimation of the digestible and metabolizable energy content and fiber digestibility and fermentability among high fiber feed ingredients. To achieve these objectives, we conducted 4 studies. Chapter 2 describes the effects of different fiber source in the diet on modulation of intestinal cell differentiation in growing pigs. The results showed feeding diets containing what straw (WS) and corn distillers’ dried grains with solubles (DDGS) modulated intestinal differentiation by promoting goblet cells and altered expression of nutrient receptors and transporters in growing pigs, while feeding soybean hulls (SBH) had less effect. Chapter 3 describes differences of in vitro hydrolysis, fermentation, and estimated energy among and within high fiber ingredients using a modified three-step procedure in growing pigs. The results showed that this procedure was useful for detecting the variability of dry matter (DM) digestibility among and between WS, SBH, and corn DDGS sources. Chapter 4 involved evaluating the use of in vitro DM digestibility and gas production to predict apparent total tract digestibility (ATTD) of total dietary fiber (TDF) for growing pigs. Chapter 5 investigated prediction of digestible energy (DE) and metabolizable energy (ME) of DDGS for growing pigs from in vitro digestible nutrients. The results showed that in vivo digestible neutral detergent fiber (NDF), DM, and ether extract (EE) are the best predictors for DE and ME content of corn DDGS fed to growing pigs. Overall, the results from these 4 studies showed that WS, SBH, and corn DDGS 1) regulate intestinal cell differentiation differently, 2) have different fermentability, and 3) can be utilized by a modified three-step procedure and gas production technique to provide an accurate prediction of ATTD of TDF, and potentially, DE and ME content for growing pigs. However, further refinements are needed to improve the practical application of this procedure in evaluating high fiber ingredients.Item An observation about Aumann correlated equilibria points(University of Minnesota. Institute for Mathematics and Its Applications, 2014-06) Marchi, Ezio; Matons, MartínItem Role Of Dietary Factors On Nutrient Excretion And Manure Characteristics Of Growing Pigs(2016-02) Luo, ZhaohuiIn the U.S. pork industry, feed represents the largest proportion of the total production cost. Therefore, pork producers are continually trying to improve feed efficiency and reduce feed cost. This has become more important because the prices of conventional feed ingredients, including corn and soybean meal, has increased dramatically in recent years. As a result, the addition of increased amount of high fiber ingredients such as corn distillers dried grains with solubles (DDGS) and soybean hulls (SBH) to swine diets, and processing diets to achieve a smaller particle size have become common practices. However, manure foam accumulation on the surface of anaerobic deep pits on commercial swine farms has been a coincidental problem in recent years, and the potential cause has been associated with changes in diet composition. As a result, a better understanding of the connection between swine diet composition and nutrient excretion and manure foaming is critical for developing long-term mitigation strategies. Based on the theory of “froth flotation”, foam formation requires 3 contributing factors, including biogas production, surfactants, and stabilizers, which may come from undigested nutrients in the manure. Results from studies have suggested that specific undigested nutrients in the manure may serve as surfactants (lipids and long-chain fatty acids; LCFAs) and stabilizers (small particles) as well as substrates to produce biogas (fiber and protein) in foam formation. This evidence suggest that adding DDGS and SBH in swine diets may increase overall manure output due to higher levels of indigestible fiber, resulting in more dry matter (DM) and nutrients in manure. In addition, smaller particle size of diets may result in a greater concentration of stabilizers in the manure. As a result, methods to maximize feed digestibility and minimize nutrient excretion appear to be essential for reducing manure pit foaming. The research described in this thesis addressed the effects of feeding alternative feed ingredients (DDGS with variable oil content and SBH) with different particle size on nutrient excretion and manure characteristics of growing pigs. Results in Chapter 2 suggested that manure foaming capability (MFC) was impacted by diet particle size and fiber source. Greater MFC were only observed for pigs fed coarsely ground SBH diet. The relatively high concentration of soluble fiber in the soybean hulls diet compared with DDGS, which contains a high concentration of insoluble fiber, appears to have a greater effect on MFC. In addition, increased DM excretion and changes in manure pH resulting from diet composition were 2 significant factors that contributed to MFC. Results in Chapter 3 suggested that manure foaming does not occur when evaluating fresh manure samples, indicating that microbial fermentation is essential for manure foam formation. Further studies are encouraged to compare the microbial ecology between samples of foaming manure and non-foaming manure. In conclusion, when diets are coarsely ground, manure from pigs fed diets containing significant amounts of soluble fiber source tend to have greater MFC after fermentation. These results suggest that diet formulation strategies to maximize DM digestibility and reduce DM excretion by reducing diet particle size, along with minimizing the amount coarsely ground SBH in diets will decrease manure foaming incidence in anaerobic manure pits.Item Satiety, glycemic, and gastrointestinal effects of novel fibers(2012-06) Klosterbuer, Abby SusanEpidemiological studies have shown that dietary fiber consumption is inversely associated with body weight, and some research suggests that foods high in fiber increase satiety and reduce energy intake. The mechanism for this relationship is unknown, but may be related to changes in glucose, insulin, or gut hormone concentrations. Fiber may also benefit health by improving laxation, altering the gut microbiota, and increasing production of short chain fatty acids (SCFA). The following work describes two review articles, as well as an intervention study designed to help examine these effects. The first review focuses on the benefits of dietary fiber in clinical nutrition. This allowed for evaluation of the physiological effects of different types and combinations of fiber in subjects on a controlled diet. In general, blends of fibers with varying physicochemical properties provided greater benefits and were better tolerated than single fiber sources. Next, a systematic review of the effects of fiber intake on gut hormone concentrations examined the evidence for this relationship. Considerable variation was found in study design, population, fiber type and dose, which made comparisons difficult. Few studies reported a significant effect of fiber on gut hormone levels, and data suggest caloric load may have a more significant influence. Lastly, a randomized, double-blind, crossover study examined the effects of three novel fibers with varying physicochemical properties on satiety, stool characteristics, and the role of gut hormones, glucose, and insulin in appetite regulation. On Day 1 of the study, healthy men and women consumed either a low-fiber control breakfast or 1 of 4 iii breakfasts containing 25 g fiber from soluble corn fiber (SCF) or resistant starch (RS), alone or in combination with pullulan (SCF+P and RS+P). Subjects rated satiety using visual analog scales (VAS), and blood samples were collected at various time points for 3 hours following breakfast. The fiber treatments did not influence satiety or energy intake compared to control. The RS+P treatment significantly reduced glucose, insulin, and GLP-1 concentrations. To examine the effects of chronic fiber intake, subjects consumed the fiber treatments at home for 6 additional days, with a 3 week washout between periods. Stool samples were collected on Day 7 and tolerance was assessed following fiber intake on Day 1 and Day 6. Fiber did not alter stool weight or stool consistency. SCF reduced pH and increased total SCFA production compared to control, while RS+P increased the percentage of butyrate. Overall, fiber was well tolerated, although treatments containing pullulan tended to cause minor increases in symptoms. Both SCF treatments resulted in a significant shift in the microbial community. Results from these studies confirm that different fibers vary in their physiological effects, and consuming fiber from a variety of sources may be most beneficial. Although increased satiety and improved bowel function are commonly reported benefits of fiber intake, it is clear that not all fibers exert these effects. In addition, the relationship between fiber and potential biomarkers of satiety remains unclear. Thus, it is important to evaluate the effects of different fibers in human studies to better guide recommendations for their use.Item Wild Primate Gut Microbiota Protect Against Obesity(2017-04) Sidiropoulos, Dimitrios, N; Clayton, Jonathan; Al-Ghalith, Gabe; Shields-Cutler, Robin; Ward, Tonya; Blekhman, Ran; Kashyap, Purna; Knights, DanThe gastrointestinal tract hosts trillions of bacteria that play major roles in metabolism, immune system development, and pathogen resistance. Although there is increasing evidence that low dietary fiber in Westernized societies is associated with dramatic loss of natural human gut microbiome diversity, the role of this loss in obesity and inflammation is not well understood. Non-human primates (NHPs) can be used as model systems for studying the effects of diet and lifestyle disruption on the human gut microbiome. Captive primates are typically exposed to low-fiber diets and tend to have human-associated microbiota in place of their native microbiota. In order to explore interactions between the gut microbiota and dietary fiber, we transplanted captive and wild primate gut microbiota into germ-free mice and then exposed them to either a high- or low-fiber diet. We found that the group receiving low-fiber diet and captive primate microbiota became obese and had high levels of circulating inflammatory cytokines, while mice receiving high-fiber diet and wild primate microbiota remained healthy. Mice with the wild primate microbiota and low-fiber diet acquired intermediate levels of obesity, demonstrating an interaction between dietary fiber and the microbiota. These results show that the modern human gut microbiome interacts with low-fiber diets to cause inflammation and obesity, and suggest a possible clinical role for manipulation of the microbiota in the treatment of obesity.