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Colon cancer, a leading cause of cancer-related deaths worldwide, is largely preventable through lifestyle modifications including diet. While epidemiologic evidence associates foods rich in phytochemicals and dietary fiber with a reduced risk of cancer, the chemopreventive efficacy of specific dietary interventions to reduce colon cancer risk is still uncertain. In four studies, this thesis aims to explore the effects of three dietary interventions (red wheat, apiaceous and cruciferous vegetables, and prebiotic dietary fiber) on colon cancer risk in rodents and to characterize the effectiveness of the Total Western diet as a rodent background diet for colon cancer and inflammatory disease models. The first study used a mouse model to explore the effects of different wheat classes and milling fractions on colon cancer prevention. However, the results were inconclusive. Ultimately this mouse model was unsuitable due to challenges with the carcinogen dosage and toxicity, tissue incompatibility with a major biomarker assay, and the limited volume of tissue available for study due to a mouse’s small size. The second study continued this work using a rat model and added the variable of a comparison of background diets: a standard, optimized rodent diet (AIN-93G) or a newer diet based on the typical Western diet (Total Western Diet; TWD). We found some evidence that whole red wheat may reduce CC risk, but only with the TWD background diet, indicating that TWD may be a better background diet for CC rodent models. The third study examined the effects of apiaceous and cruciferous vegetables on colonic inflammation and compared TWD with the Diet Induced Obesity (DIO) model, which uses the same micronutrient concentrations as the AIN-93G diet. Vegetables decreased colon inflammation, but only with the TWD background diet, further supporting its use in modeling lifestyle diseases. The final study examined the effects of prebiotic dietary fibers, including the novel prebiotic fiber polylactose, on CC risk. We found no evidence that polylactose decreases CC risk, but limited evidence that polydextrose decreases CC risk indicates the need for further research in this area. Taken together, these studies expand our understanding of the effect of diet on CC risk by highlighting the detrimental role of mild micronutrient deficiency modeled by the TWD and providing modest support for consuming nutrient rich foods such as whole red wheat, apiaceous and cruciferous vegetables, and prebiotic fibers to reduce CC risk.

Fundamento y objetivos: La microbiota intestinal influye en la salud de los individuos. Los alimentos son una variable crucial que modulan la composición de la misma por lo que diferentes patrones dietéticos, afectan de diferente forma. Se ha comprobado que la fibra genera cambios beneficiosos. El objetivo del presente estudio era valorar el impacto de un nutracéutico en forma de batido, rico en proteína vegetal, en la microbiota intestinal en participantes con sobrepeso. Métodos: 40 hombres y mujeres se asignaron de forma aleatoria y paralela a 2 grupos en una intervención durante 3 semanas. Ambos grupos consumieron un batido con base de proteína vegetal. El batido del grupo intervención tenía incluidos, además, beta-glucanos, almidón resistente e inulina. Se solicitaron Cuestionarios de Frecuencia de Consumo de Alimentos (CFCA) y Síntomas Gastrointestinales (SGI), muestras de sangre y heces, y medidas antropométricas, al inicio y al final del estudio. Las diferencias en las medidas antropométricas y bioquímicas se calcularon empleando t-test o Mann-Whitney. Las diferencias en patrones microbianos se analizaron mediante Mann-Whitney. Se aplicó el test de correlación de Spearman para analizar la asociación entre frecuencias de consumo de alimentos y microbiota. Resultados: Se encontraron diferencias en las abundancias de taxones bacterianos tras la intervención. Dichas diferencias se asocian en su totalidad a la toma del nutracéutico, ya que se comprobó que no había correlación entre un posible cambio el consumo de alimentos durante la intervención y los cambios en microbiota. Sin embargo, el efecto añadido de los beta-glucanos, inulina y almidón resistente no resultó en un beneficio adicional. Además, no se encontraron diferencias de interés ni en la bioquímica ni en las medidas antropométricas. Conclusiones: Los resultados sugieren que, efectivamente, el batido rico en proteína vegetal modula favorablemente la microbiota. Sin embargo, la literatura actual carece de información sobre ciertos taxones bacterianos que resultan de interés.

Hemp (Cannabis sativa L.) is used in the United States as a source of CBD oil, fiber, and grain. While hempseeds are consumed whole or as dehulled hemp hearts, hempseed oil is also a desirable seed oil in human nutrition. The process of collecting hempseed oil leaves behind hempseed cakes that are abundant in protein and fiber. Feeding of hempseed cakes to animals, including ruminants, has only initially been explored. Extraction of CBD from hemp inflorescences generates organic waste that may find a second purpose as a fiber feed for cattle. Little is known about the exact fiber composition of hempseed or hemp inflorescences. Certain polymers are expected in the cell wall of dicotyledonous plants like hemp such as cellulose, xyloglucans, xylans, mannans, pectins, and lignin. Structural variation in the exact degree of branching and substitution types exist between plant species and tissue types, and these differences have impacts on interactions within the wall. To characterize the cell wall polysaccharides of hempseeds, water-insoluble and water-soluble cell wall material was isolated from the ground and defatted, whole hempseeds (2SO4) hydrolysis and methanolysis, were employed to release monosaccharides which were separated and detected with HPAEC-PAD. Linkage types in the polysaccharides were determined by the generation and analysis of partially methylated alditol acetates (PMAAs) with GC-MS and GC-FID. Targeted enzymatic screenings were conducted to release xyloglucan oligosaccharides and pectic arabinans and galactans which were consequently analyzed with HPAEC-PAD/MS and HPAEC-PAD, respectively. Acetyl bromide soluble lignin was determined spectrophotometrically. Then, insoluble cell wall material was used as substrate in an experiment using the ANKOM DaisyII system to evaluate in vitro true digestibility (IVTD) with rumen inoculum. Intact and CBD-extracted inflorescences from two hemp cultivars were analyzed for their monosaccharide composition with Saeman hydrolysis and methanolysis, and their linkage types were assessed via the generation and analysis of PMAAs. The analyses revealed an abundance of cellulose and xylans in the hempseed cell wall. Mannans, pectins, and xyloglucans were also identified. Xyloglucans in the hempseed cell wall were less substituted in the insoluble material than in the water-soluble material. Arabinans from hempseeds were both branched and linear, and the ABSL content of the hempseeds was 17.0 ± 1.0%. Fermentation of the insoluble hempseed cell wall material yielded an IVTD of 36.02 ± 2.91% after 48 hours. Analysis of hemp inflorescences revealed the same polysaccharide components, but a much smaller proportion of xylans and a larger proportion of arabinans. While co-extraction with supercritical CO2 and ethanol may have removed some pectins, it seems that cultivar has a greater impact on the polysaccharide profile of hemp inflorescences than the CBD extraction process. While resistant to microbial digestion, hempseed is fiber-rich and warrants further research in vivo to investigate its integration into ruminant diets and an exploration of the fiber impact on the human gut microbiome.

The host-microbiome interaction and the functions of microbial-derived metabolites, including butyrate, are important in colon health. Butyrate is the preferred energy source in colonocytes and has multiple physiological functions in the colon. A metabolic shift in colonocytes toward increased glucose utilization from butyrate oxidation is followed by several critical genetic modifications in cancerous colonocytes. Moreover, it has been suggested that the gut-microbiota composition is influenced by environmental factors, such as diets and the host's physiological status. Therefore, an understanding of the role of colonocyte metabolism toward impacting the host-microbiota commensal relationship would be an important step in understanding the functional importance of how diet, microbiome, and the host interact in colonic physiology. This dissertation demonstrates that (1) colorectal cancer cells exhibit a metabolic shift from butyrate oxidation toward glycolysis; (2) the key factor in the metabolic shift is decreased pyruvate kinase M1 (PKM1), rather than increased pyruvate kinase M2 (PKM2); (3) an increase in HIF1⍺ through pyruvate metabolites reduction by a decrease in PKM1 is a critical mechanism to repress butyrate oxidation in colorectal cancer cells. Also, this dissertation explains that (1) a diminishment of short-chain acyl dehydrogenase (SCAD) in the non-disease mice model reduces butyrate oxidation in colonocytes and instead uses energy from glycolysis as a compensation mechanism; (2) the reduction of butyrate oxidation in SCAD-deficient mice causes a large diminishment in the butyrate-producing bacteria population; (3) these SCAD-deficient mice fail to respond in a prebiotic manner to dietary fiber. These findings begin to characterize the different roles of the PKM isoforms in the cancerous colonocytes and show how these proteins change metabolism in a disease model. Also, the results allude to how colonocyte metabolism affects the population of gut microbiota in the gastrointestinal (GI) tract, which defines a significant relationship between butyrate metabolism in colonocyte and colonic gut microbiota homeostasis.

Members of the mammalian gut microbiota metabolize dietary carbohydrates that are not digested by the host. While the enzymes and transporters that each strain uses to establish a nutrient niche in the gut are often exquisitely specific, the relationship between carbohydrate structure and microbial ecology is imperfectly understood. The present study takes advantage of recent advances in complex carbohydrate structure determination to test the effects of fiber monosaccharide composition on microbial fermentation. Catabolism of human milk oligosaccharides (HMOs) by the genus Bifidobacterium is reviewed to illustrate gut microbial metabolism of specific dietary fiber structures and the resulting production of acidic microbial metabolites (AMMs), such as acetic acid. In the present study, 55 fibers with varied monosaccharide composition are fermented by a pooled feline fecal inoculum in a modified MiniBioReactor array (MBRA) system over a period of 72 hours. The content of the monosaccharides glucose and xylose and the concentration of the AMMs acetic acid, propionic acid, glyceric acid, and indole-3-acetic acid are significantly associated with the reduction of pH during fermentation. Microbiome diversity and composition are also significantly associated with monosaccharide content and AMM concentration, suggesting that monosaccharide composition offers a generalizable method to compare any dietary fiber of interest and uncover unexplored links between diet, the gut microbiota, and metabolite production.

Diet is known to be a strong determinant of gut microbiome composition and function, and it is also known that gut microbiome dysbiosis is strongly linked to the risk of chronic disease. However, it is not clear how to intervene through diet or supplementation to beneficially alter the gut microbiome in individuals who have dysbiosis or who are at risk for chronic diseases such as cardiovascular disease and Alzheimer’s disease (AD). Hypothesis driven studies to determine how dietary changes affect the diet-gut microbiome-host interrelationship are critical for the discovery of solutions to improve health and mitigate disease risk. In this dissertation, three chapters are included to discuss important aspects of study design and prebiotic selection, and the outcomes of a study investigating the effects of a prebiotic supplement.In the first chapter, critical factors in successful study design for diet-microbiome research are discussed. For example, the importance of detailed dietary data collection and analysis, tight control of background diet, and stabilizing diet in the days prior to sample collection is critical for reducing noise and amplifying the signal that can be detected of the effects of the intervention diet. Specific recommendations such as including multiple consecutive sampling per study timepoint and collection of multiple consecutive days of diet records, particularly the days prior to sample collection, are discussed. High interindividual variability in gut microbiome composition is a well-established phenomenon that has been known since the early results from the Human Microbiome Project. Because of this high interindividual variability, some study designs are not well suited to discovering the effects of a dietary intervention. Instead, we discuss the double-blinded, randomized order, placebocontrolled, cross-over study design is the optimal study design for gut microbiome research, enabling the detection of the effects of even a subtle diet intervention. We also discuss the importance of precision nutrition approaches for nutritional recommendations. As an example, we discuss nutritional recommendations for egg intake, taking into account the link between egg-derived components (i.e., choline and cholesterol) and their interaction with the gut microbiome and subsequent health outcome measures important in cardiovascular disease.The second chapter emphasizes why we care about changes in gut microbiome in human health and how we can better utilize certain dietary interventions such as prebiotics to modulate human health and diseases focusing particularly on AD. Prebiotics are oligosaccharide and polysaccharide structures isolated from plants or synthesized from sugars that are shown to modulate the microbiome and are associated with health benefits. We summarized the importance of dietary fiber intake for maintaining a healthy gut microbiota, with a focus on short chain fatty acid production, mucus secretion, and protection from pathogens. The specific links between healthy gut physiology, gut immune function and the brain are also discussed. The importance of anti-inflammatory metabolites produced by gut microbes consuming specific substrates in modulating critical signaling pathways in the brain is discussed in the context of AD prevention. We conclude by discussing which specific bacterial genera are increased and decreased in AD patients and highlight the potential of increasing bifidobacteria abundance through the intake of specific prebiotic substrates as a promising approach for beneficially modulating the gut microbiome and improving health outcomes in AD patients.The final chapter summarizes the findings from our human clinical trial in healthy subjects consuming a low fiber diet (< 15 g/day) to determine whether a low-dose, easy to use bifidogenic prebiotic supplement formulation increases bifidobacteria and produces measurable metabolomic and metagenomic changes over the course of 4 weeks. We used the double-blinded, placebo-controlled, randomized order crossover study design highlighted as the optimal study design for diet-microbiome studies in chapter 1, to study the effects of the prebiotic supplements in 20 otherwise healthy young individuals consuming diets low in fiber, typical of the average American diet. As hypothesized, the relative abundance of bifidobacteria significantly increased after the prebiotic supplement, as did the gene counts of genes associated with prebiotic utilization, acetate production, and choline oxidation. Importantly, these changes in gut microbiome composition and function were reflected by changes in the concentrations of microbially-derived metabolites in the plasma, and point to novel pathways by which increasing the abundance of bifidobacteria may confer beneficial health effects on the host.

Hibiscus calyces have anti-inflammatory effects, reduce metabolic risk factors, and act as a prebiotic in the human gut. Bioactive compounds in hibiscus include dietary fiber, polyphenols and vitamins and hibiscus calyces have a well appreciated flavor. Preparation of juice from hibiscus is done using hot or cold aqueous maceration procedures. When hibiscus beverages are made, the remaining biomass, the spent calyces, is discarded. Little information is available on the composition of the spent calyces. To determine whether the spent calyces have potential value, it is important to evaluate the composition of major bioactive elements and other potentially valuable components like aromas. The overall goal of this work was to determine if hibiscus spent calyces have components that would be of nutritional value, and to investigate consumer interest in hibiscus consumption in the U.S. The first objective was to measure the contents of sugar, fiber, anthocyanins, other phenolics, vitamin C, and organic acids (hibiscus/garcinic, citric, succinic, fumaric acid) in spent calyces. The second objective was to identify and quantify flavor compounds in the spent calyces. The third objective was to assess American consumers knowledge and perception of hibiscus products. Cold and hot aqueous extractions were carried out on whole calyces of red and white hibiscus using a calyces:water ratio of 1:15. The spent calyces were freeze-dried and analyzed for sugar, fiber, anthocyanins, total phenolics, vitamin C, organic acids and flavor compounds and compared to whole calyces. Soluble and insoluble dietary fiber were measured using sequential enzymatic digestion and gravimetric filtration according to the AOAC method. HPLC was used to determine sugars, anthocyanins and vitamin C, acids. UPLC to identify polyphenols and GCMS with SPME to identify and quantify aroma compounds. Results of the survey show that most of the American consumers who participated in this study have consumed hibiscus products before and were aware of the health attributes of hibiscus products. The most liked products were tea and juices. Main reason for hibiscus consumption was in order: taste, health, flavor, and trend. The health statement provided to the participants of the survey did not affect their willingness-to-pay (WTP) for hibiscus beverages. Spent calyces contained significant amounts of sugars, anthocyanins, total phenolic, organic acids, vitamin C, dietary fiber, and aroma compounds. More fiber was found in the spent calyces than in the raw ones; volatiles profile and phenolics profile were similar to those of the raw calyces. These important nutritional compounds make hibiscus spent calyces useful as a functional ingredient in food products or for producing nutraceutical products. Use of spent calyces will increase value of hibiscus products benefit to both consumers and industrials and help reduce economic and environmental issues related to food waste management.

BACKGROUND: Metabolic syndrome, elevated blood pressure (BP), elevated cholesterol and type 2 diabetes mellitus are health conditions that increase cardiometabolic risk (CMR). Sleep, physical activity, diet, are modifiable risk factors for the prevention of cardiometabolic disorders. Dietary fiber which is associated with higher fruit and vegetable intakes is known to lower the effects of obesity-related health issues. Further, these foods have an abundance of beneficial vitamins and minerals as well as low energy density. There is controversial, however, regarding the effect of fruit juice intake on CMR, particularly due to its lower fiber content. The objectives of this research were to estimate the effect of intakes of whole fruit and fruit juice on CMR, including effects on Body Mass Index (BMI), overweight/obesity, hypertension/prehypertension, lipid, and blood glucose levels. METHODS: The National Heart, Lung, and Blood Institute’s National Growth and Health Study (NGHS) cohort of white and black girls ages 9-10 years at baseline participated in a 10-year longitudinal study. Cardiometabolic outcomes included repeated measures of adiposity (e.g., body mass index (BMI)), and blood pressure, as well as laboratory measures such as fasting glucose and lipid levels. Linear regression and logistic regression were used to assess the association of fruit intake and fruit juice intake on CMR, while adjusting for age, race, tv/video, total vegetables, lean meat, and % calories from fat. Statistical Analysis Software (SAS Institute 15.2) analysis of data was performed. Results were considered statistically significant when p-value was

Lactose, a low value dairy product, was polymerized to a soluble dietary fiber called polylactose using twin-screw extrusion. Non- enzymatic browning reactions occurring during extrusion produce colored compounds and hydroxymethylfurfural. Thisresearch focuses on development and optimization of a purification method for polylactose using activated carbon and resins. Polylactose was ground, solubilized in water at three different concentrations (50 mg/mL, 100 mg/mL and 150 mg/mL). Forty mL of polylactose solution was flowed through the filtration system utilizing gravity. The filtration system was rinsed with 20 mL double distilled water. The rinse water plus the filtrate collected were freeze dried to achieve a powder form suitable for different analysis. 42.4% Purolite A874 resin followed by 42.4% Activated carbon and 3% diatomaceous earth was proven to have the best purification results increasing dietary fiber content from 54.48% to 92.24% while reducing the hydroxymethylfurfural content by 90.91% to a level that was lower than the maximum level determined by the Joint FAO/WHO Expert Committee on Food Additives HMF limit in polydextrose (0.1%). Furthermore, the effect of polylactose solution concentration for filtering 40 mL polylactose solution was determined. Using 50 mg/mL concentration achieved the highest dietary fiber content. This could be since less polylactose had to interact with the same amount of filtration material resulting in removing more impurities and caramelization products. However, the hydroxymethylfurfural content reduction was the same for 50 mg/mL and 100 mg/mL concentrations.

Yellow peas are a rich source of protein and phytochemicals. Peas are compatible with many diets restricted by sensitivities, allergies, or personal choice. As a result, peas are gaining popularity in food markets, despite the challenges they present. The biggest challenges for pea proteins in food markets are high content of fiber, starch, and saponins. These components cause processing challenges and create undesirable textures and bitter flavors. Pea proteins are typically extracted with alkaline extraction or air classification methods which result in 80% and 50% protein products respectively. With low protein purity, these products are not competitive with other, more established, plant-based proteins like soy. The objectives of this study are to (1) Determine the effect of fungal fermentation on the protein, saponin, phenolic, and dietary fiber content of dry processed proteins (DPP), (2) Describe the effects fungal fermentation has on the saponin, protein, starch, and phenolic composition of dehulled peas (DHP), (3) Understand how fermentation, drying method, and antimicrobial techniques affect alkaline extraction and isoelectric precipitation from DPP and DHP. In DPP and DHP, fermentation has potential to improve composition. Fermentation increased protein, total saponins, and total phenolic content for both substrates. During fermentation, total dietary fiber decreased in DPP, and starch content decreased in DHP. With high fiber- and starch- contamination in DPP and DHP respectively, these results indicate that fermentation may reduce these unwanted components. In addition, increased phenolic- and saponin content may provide increased antioxidant activity and health benefits. Extraction of both DPP and DHP indicate that chemical antimicrobials are superior to autoclaving in terms of protein yield, extraction yield and protein content of isolates. Drying method does not significantly impact protein extraction. Fermentation increased solubility but resulted in unrecoverable protein during isoelectric precipitation. Methods such as ultrafiltration may be a superior method for protein recovery. These results demonstrate that fungal fermentation has potential to broaden the application of pea proteins in food markets. Fungal fermentation improves composition of DPP and DHP in regard to protein and starch as well as non-nutritive components like saponins, phenolics and fiber. Fermentation also may produce a more soluble protein isolate.

Abstract: Obesity and associated comorbidities have reached epidemic proportions worldwide. Observational studies provide consistent evidence that plant-based diets rich in dietary fibers (DFs) reduce chronic disease risk. Mechanistic studies have established processes by which DFs improve health, with one emerging mechanism being the modulation of gut microbiota composition and its functions. However, results from human interventions with purified DFs remain inconsistent with extensive between-study heterogeneity. Therefore, questions remain as to whether DFs can exert reliable health effects when a reductionist approach is used with purified DFs, what the efficacious doses are, and if such doses are tolerable. The overall goal of this dissertation was to explore the potential of purified DFs to improve human health through more targeted approaches. This was achieved by the following objectives. The first objective of this dissertation was to summarize the effects of purified DFs on immunometabolic disease markers in humans and consider the role of DF dose, physicochemical properties, intervention duration, and the placebo. Systematic review of 77 publications revealed that purified DFs reduced markers of insulin resistance and cholesterol in 36-49% of interventions, while 50%), and longer durations for CRP and glucose (50%). Although additional research is needed, a more targeted application of purified DF with specific physicochemical properties at higher doses and for longer durations shows promise for improved clinical efficacy. As both the dose and physicochemical properties of DF were relevant to health, the second objective was to characterize the effects of high doses of soluble, fermentable arabinoxylan (AX) on fecal microbiota composition and short-chain fatty acids (SCFA), as compared to insoluble, non-fermentable microcrystalline cellulose (MCC), and integrate findings using an ecological framework. Using a randomized controlled design, we showed that AX exerted global shifts to bacterial community composition (AX-vs-MCC: baseline p=0.17, week 6 p=0.019, PERMANOVA), promoted Bifidobacterium longum and Prevotella copri (q

Worldwide, breast cancer is the most commonly diagnosed malignancy in women with over 2 million cases diagnosed each year. Breast cancer is a heterogeneous disease that could be classified into subtypes based on the molecular features, for example, by hormone receptor status. The majority of breast cancer cases are estrogen receptor (ER) positive, and less than 20% are ER- negative. These subtypes have different etiologies, clinical characteristics, and survival rates. The effects of risk factors may also differ by hormone receptor status. For Chapter 1 through 3, I examined potential dietary factors in three pooled analyses of diet and risk of breast cancer in an international consortium of more than 20 prospective cohorts. Over 1 million women were included in the analyses, among whom around 40,000 incidence breast cancer cases were documented. In each chapter, a 2-stage approach was used for data analysis. In stage 1, Cox proportional hazard regression was used to get study-specific hazard ratios for breast cancer overall and the subtypes defined by ER status. In stage 2, the study-specific multivariable HRs were pooled using random-effects model. Chapter 1 focused on dietary fiber as an example of nutrient. We found that dietary fiber intake was inversely associated with breast cancer risk. The association could mainly be attributed to fiber from fruits and vegetables, but not grains, and was modified by fat intake, where the association became weaker and nonsignificant among people with higher fat intake. In subtype analysis, the association was stronger for ER- tumors than that for ER+, although difference by ER status reached statistical significance only for fiber from vegetables. In Chapter 2, dairy products were examined as examples of food items. Individual dairy products showed null or very weak inverse associations with risk of overall breast cancer. Differences by ER status were suggested for yogurt and cottage/ricotta cheese where associations were observed for ER-negative tumors only. Dietary calcium intake was only weakly associated with breast cancer risk, and the effect estimates did not differ by ER status. In Chapter 3, the focus was on red meat and other major protein sources, to explore the substitution effects of different food groups on risk of breast cancer. Total red meat, processed meat, and unprocessed meat intakes were not significantly associated with risk of breast cancer when holding other protein sources constant. However, inverse associations were observed when substituting red meat with an energy-equivalent amount of mature beans or dairy products. There were no significant substitution effect replacing total or unprocessed red meat with poultry, seafood, eggs, or nuts. The results were similar for ER-positive and ER-negative breast cancer. To quantify the theoretical impact of interventions, population attributable risk (PAR%) helps set priority and guide personal decision. Wide range of PAR% of cancer incidence by modifiable risk factors has been reported, yet there is no consensus on what contributed to the variation. Chapter 4 investigated the PAR% of breast cancer by a group of modifiable risk factors and examined its variation by choices of exposures and methods. Fruits and vegetable intake, physical activity, adult weight gain, and alcohol consumption were the exposures of interest in the analysis. Partial PAR% was calculated from three models: baseline only, simple updates of repeated measures, or cumulative averages of repeated measures. For each model, two methods were applied - one based on the four factors individually, and the other based on comparison between an overall high- versus low-risk group. The models based on repeated measures yielded greater estimated PAR%. PAR% estimates by the low-risk method were higher than that based on each factor individually, but in similar pattern. Therefore, PAR% by modifiable risk factors in current literatures likely underestimated the preventable fraction, if relied on studies with baseline data only. In conclusion, the first three chapters found modest inverse associations with risk of breast cancer for dietary fiber, especially that from fruits and vegetables; for yogurt and cottage cheese consumption and ER- tumors; and when substituting red meat by beans or dairy. The last chapter emphasized the importance of high-quality repeated measure data in PAR% calculation and called for cautious interpretation of PAR% in the current literature.

According to the American Heart Association, cardiovascular disease (CVD) is the leading cause of death in the U.S., representing about 20-30% of all deaths every year in the U.S. Major risk factors for developing CVD include high blood lipid and LDL-cholesterol levels. A large number of heart attacks and strokes could be prevented by controlling these factors through lifestyle modifications and diet interventions. Epidemiological evidence shows that consumption of dry or common beans (Phaseolus vulgaris L.) has positive effects on reducing blood LDL-cholesterol and lipid levels. These health benefits are mainly attributed to the high content of dietary fiber (DF) of beans, including soluble and insoluble DF (SDF and IDF). Some proposed mechanisms to explain the cholesterol and lipid-lowering effects of DF are related to the physico-chemical properties (e.g. viscosity) of DF, and involve binding to bile salts (BS) in the small intestinal to prevent BS re-absorption which further promote cholesterol catabolism and delay lipid digestion. Nevertheless, the precise mechanisms are not fully understood yet. In addition, cooking and processing operations, and in particular high-hydrostatic pressure (HHP) processing, can modify the composition, structure and functional properties of foods; however, whether HHP affects the ability of beans to interfere with different aspects of lipid digestion remains unknown. The overall goal of this research is to understand how common beans and HHP processing impact the ability of beans to bind BS and influence lipid digestion in vitro. The specific objectives are 1) to evaluate the effect of HHP treatments (and compared it with conventional cooking (HT)) on the thermo-rheological and functional properties of dry beans; 2) to identify the impact of major bean components on the in vitro BS-binding ability of beans, the role played by the bean matrix and how this is affected by HHP processing; 3) to investigate how bean (micro)structure and fiber fractions, as well as HHP processing of dry beans, influence lipid digestion in vitro. Results showed that HT caused complete starch gelatinization and protein denaturation of beans, while HHP treatments induced partial or no starch gelatinization and a lower degree of protein denaturation, which resulted in enhanced protein solubility and emulsifying activity/stability. It was observed that, while HT treatment reduced the capacity of bean flours to retain BS because of severe disruption of the bean cell wall integrity, protein matrices, and starch granules, HHP treatments maintained or enhanced BS retention, possibly by promoting the formation of starch/protein/fiber networks able to entrap BS. Furthermore, by using an in vitro dialysis-based digestion model combined with viscosity measurements and thermal analysis, it was shown that the interaction between bean tissue materials and primary BS was not only related to viscosity but also involved hydrophobic linkages. The contribution of IDF and proteins (other than SDF) to retain BS was also significant. There was a different binding preference of beans to four primary BS with sodium glycochenodeoxycholate, the more hydrophobic BS, showing the largest retention levels while sodium taurocholate being the least effectively retained BS by beans. Diverse sequences of the same processing operations showed distinct impacts on BS-retention by dry beans. By means of an in vitro digestion model simulating conditions in the upper gastrointestinal tract, bean flours delayed the digestion of extrinsic lipids to a higher extent, compared to isolated IDF and SDF. Furthermore, HHP treatment and less severe mechanical disintegration maintained the ability of beans to modulate lipid digestion, which suggests the importance of bean structural integrity in reducing the lipolysis rate and extent by beans. Overall, this research work shows that HHP processing is a promising minimal processing technology to produce bean flours with improved functionality. It also highlights the importance of considering the structure of foods, and not just their nutrient content, when evaluating potential health impacts. This knowledge could be applied to develop a range of bean-based ingredients and formulations with desirable health benefits. This work can be extended to research the influence of beans on the gut microbiota and profile of secondary BS and short-chain fatty acids, which are also closely related to cholesterol and lipid metabolism.

The worldwide Greek yogurt market is a growing multi-billion dollar industry in need of a solution for its environmentally problematic acid whey (GAW) byproduct. Utilization of supercritical fluid extrusion (SCFX) technology presents the opportunity to convert GAW into value-added and high-protein sweet and savory snack foods that will resonate with today’s market. Additionally, hydrolysis of the lactose in GAW prior to extrusion has the potential to polymerize into galactooligosaccharides (GOS) under the high temperature, pressure, and shear conditions, transforming lactose into a source of dietary fiber. This study evaluated the effects of concentrated 12 ˚Bx Greek acid whey substituted in lieu of water during the extrusion of milk protein concentrate-based snacks. Water, unhydrolyzed GAW, and hydrolyzed GAW were used as the three liquid sources during extrusion and physicochemical, textural, and sensory properties of the extrudates were evaluated. Addition of GAW significantly (P < 0.05) increased extrudate radial expansion ratio and porosity and decreased piece density. GAW generally improved textural characteristics of hardness, crispness, and crunchiness or produced extrudates comparable to commercial products. A consumer sensory acceptance test showed that GAW significantly improved hedonic and JAR scores in all four attribute categories. GOS content was analyzed and found to be 2.5% tetrasaccharides and 0.9% trisaccharides in the sweet formulation with hydrolyzed GAW. The results indicate GAW’s potential to replace water during extrusion, simultaneously utilizing an environmentally undesirable byproduct while improving extruded snack foods.

Camelina sativa, a sustainable short-season cover crop, is an oilseed (35% oil) gaining interest due to the increasing global demand for sustainably sourced ingredients. Camelina provides numerous agricultural benefits—low production cost, low nitrogen requirements, drought resistance, cold weather tolerance, and short growing season—in addition to being high in protein (20%) and dietary fiber (30%), which are two of the fastest growing segments of the food ingredient market. In order to create functional, market-viable ingredients from camelina, the following need to be explored: efficient means of protein extraction, evaluation of protein functional properties, and chemical characterization of the dietary fiber constituents. The objectives of this study were as follows: (1) determine the impact of oil pressing conditions and protein extraction protocol on protein yield and content; (2) characterize structural differences in proteins extracted following salt precipitation and pH solubilization; (3) determine the impact of structure and enzymatic modification on the functionality of the different protein extracts; (4) isolate, quantify, and characterize the insoluble and soluble dietary fiber fractions of defatted camelina meal (DCM) prepared by two different oil pressing conditions. Protein extraction by pH solubilization and salt precipitation was tested and optimized. Camelina meal obtained from hot and cold press was further defatted by hexane and analyzed for protein content. Protein from DCM was extracted following degumming and pH solubilization at pH 12, separating non-protein material by centrifugation, acidifying the supernatant to pH 5 to precipitate out the protein, neutralizing and desalting. Protein from DCM was also extracted following salt precipitation, first by solubilizing the protein using 0.05 M phosphate buffer (pH 8, 1 M NaCl), followed by precipitation using 85% saturated ammonium sulfate solution, and desalting. To produce protein hydrolysates, extracted proteins were subjected to hydrolysis with Aspergillus oryzae protease by pH-stat methodology to a degree of hydrolysis less than 8%. Protein purity of the extracts was analyzed, and mass balances were tracked in order to evaluate extraction yields. The denaturation state, protein profile, and surface hydrophobicity of the protein extracts were determined using DSC, SDS-PAGE, and a fluorometric assay, respectively. Functionality was evaluated by determining protein solubility as well as emulsification, foaming, and gelation properties. Total dietary fiber (TDF) from DCM was determined following the AOAC method 2011.25, and three fractions —insoluble dietary fiber (IDF), soluble dietary fiber that precipitates in 78% ethanol (SDFP), and soluble dietary fiber that is soluble in 78% ethanol (SDFS) — were isolated preparatively. IDF and SDFP were analyzed spectrophotometrically for pectin content. The monomers of IDF and SDFP fractions were determined by alditol acetate formation and measured by GC-FID. Degree of pectin methylation (DM) of SDFP was determined by 1H NMR. The degree of polymerization (DP) of saccharides in the SDFS fraction (DP 2 – DP 7) was determined by liquid chromatography-ESI-mass spectrometry (LC-MS) using a ligand-exchange stationary phase and quantified by high performance anion exchange chromatography coupled with a pulsed amperometric detector (HPAEC-PAD). Disaccharides in DCM were differentiated and quantified spectrophotometrically following standard enzymatic assays. Compared to camelina protein concentrates (CPC) produced by alkaline pH extraction, CPC produced by salt extraction were less denatured and more functional. The functionality of the salt extracted CPC was comparable and sometimes better than that of soy protein isolate (SPI). Specifically, the solubility of the salt extracted CPC at pH 3.4 was significantly (P < 0.05) higher than that of SPI. Additionally, salt extracted CPC had significantly higher emulsification capacity and foaming capacity than SPI. On the other hand, the gelation property of CPC was inferior to that SPI, an observation attributed to the molecular size of camelina protein compared to SPI. Upon hydrolysis of CPC with Aspergillus oryzae protease, a limited benefit to solubility was noted at pH 7 post thermal treatment. TDF of DCM averaged 51.2% (45.3 – 49.1% IDF, 2.00 – 5.98% SDFP, 1.1 – 1.2% SDFS). The SDFS fraction was comprised mainly of stachyose and raffinose, which is in line with other Brassicaceae crops. The chief disaccharide present in DCM was verified to be sucrose (2.43 – 3.36%). Free glucose and fructose were also present in the SDFS fraction. Of the pectic polysaccharides measured in SDFP, low methoxyl pectin represented the major constituent, with a DM of 12.5 – 14.5%. Based on alditol acetate analysis, glucose was the main monomer in the IDF fraction. Other monosaccharides detected in the IDF fraction were xylose, arabinose, mannose, and galactose. The monosaccharide composition indicated the presence of cellulose, xyloglucans, galactomannans, and arabinoxylans in the IDF fraction. In SDFP, the monosaccharides rhamnose, arabinose, galactose, and mannose were evenly distributed. Monomer composition of the SDFP fraction indicated the presence of pectin and galactomannans. Results show that camelina meal contains a significant amount of protein and dietary fiber that can be isolated into functional ingredients. This is the first study to provide a comprehensive evaluation of protein and dietary fiber from camelina as potential alternatives to traditional ingredients. Further work is needed to understand how isolated camelina ingredients interact in various food matrices.

In order to reduce feed costs, the use of high-fiber ingredients such as corn dried distiller’s grains with solubles and wheat middlings has become a common practice among swine farmers. However, caloric efficiency and growth of pigs fed high-fiber feed ingredients is usually less than pigs fed corn-soybean meal diets. Supplementation of pigs fed high-fiber diets with fiber-degrading enzymes is an approach to increase energy and amino acid digestibility that may result in a more cost-effective production method. Different components of fiber will modify the intestinal microbiome and epithelial parameters such as mucin expression, likely leading to changes in the intestinal immune response. Therefore, the focus of this thesis is to identify the cytokine profile in the swine intestine caused by fiber sources and fiber-degrading enzymes, and to define whether fiber actions on the intestinal epithelium are mediated through the activation of a localized immune response.

Cereal fibers that can be metabolized by gut microbiota have been shown to promote the growth of beneficial bacteria in the gut. Increased consumption of cereal fibers may improve host / gut microbiota interactions in obesity and other metabolic diseases by normalizing gut dysbiosis. The present dissertation describes four research projects to assess the impact of cereal dietary fibers on gut microbiota and host metabolism. In the first study, we determined the treatment temperatures for production of soluble, non-digestible, feruloylated oligo- and polysaccharides (FOPS) from maize bran and wheat bran, and determined the fermentation properties of partially purified FOPS from maize bran and wheat bran. In vitro fermentation revealed that wheat FOPS were more bifidogenic than maize FOPS. However, maize FOPS led to continual production of short-chain fatty acids (SCFA), resulting in the highest SCFA and butyrate production at the end of the fermentation. In addition, maize FOPS showed significantly higher antioxidant activity than wheat FOPS. The study showed FOPS from maize bran may exhibit enhanced benefits on gut health compared to those of wheat bran. In the second study, we further determined whether the colonic fermentation of FOPS could counteract the deleterious metabolic effects of a high-fat (HF) diet through modulating the gut microbiota using a mouse model. Our results suggest that colonic fermentation of FOPS plays an important role in preventing metabolic disorders in HF-fed mice, and that these metabolic improvements depend on specific alterations of the gut microbiota through FOPS fermentation. Blautia and Akkermansia might be considered potential therapeutic targets for improving body and adipose tissue weights, while SCFA production seems linked to improvements in glucose metabolism. In the third study, by obtaining long-term dietary records from fecal donors, we aimed to determine the correlations between dietary intake variables and dietary fiber degradation and short-/branched-chain fatty acid (BCFA) and ammonia production during in vitro fecal fermentation. We found that butyrate production was correlated with fecal donor intake of many nutrients, of which principal component analysis revealed were mostly contributed by grain-, nut-, and vegetable-based foods. Negative correlations were found for propionate with intake of total carbohydrate, added sugar, and sucrose and for ammonia and BCFA production with intake of unsaturated fats. These results suggest that diets high in plant-based foods and high in unsaturated fats are associated with microbial metabolism that is consistent with host health. In the fourth study, we determined the impacts of long-term dietary pattern on gut microbiota composition and the change in composition of the gut microbiota during fermentation of predigested whole wheat flour. Butyrate production was significantly correlated with the abundance of Butyricicoccus, Coprococcus, Dorea, Faecalibacterium, and Lachnospiracea incertae sedis. BCFA and ammonia production displayed negative correlations with the abundance of Roseburia and Parasutterella. Bifidobacterium and Butyricicoccus were enhanced by pre-digested whole wheat flour. Taken together, these results provide new evidence for modulating the gut microbiota through dietary treatment and indicate its contribution to host metabolism. Advisor: Devin J Rose

Abstract: Rice bran (RB) is an underutilized byproduct of rice milling industry. RB is rich in insoluble dietary fiber (IDF) but poor in soluble dietary fiber (SDF). Recently, SDF derived from RB has been proven for its superior antioxidant and prebiotic activities which confer human health benefits (digestive, cardiovascular, nerve health, etc.). Moreover, SDF can improve sensory and physicochemical properties (texture, color, uniformity, water binding capacity, hydration, etc.) of SDF-enriched foods. Therefore, conversion of RB-IDF to RB-SDF would be to utilize this affordable byproduct to add value to the rice bran processing industry as a common functional food ingredient. The aim of this study was to maximize soluble pentosan content (a major SDF component) in RB, by investigating the effect of physical (extrusion) and enzymatic (xylanase) technologies in individual and combined ways on water-washed rice bran and its soluble compositions. A water washing procedure was necessary to remove water solubles as a strategy to increase the proportion of total dietary fiber (IDF + SDF) that could be converted to SDF after treatment. Even though water washing wasted native SDF along with starch and other solubles, preparing the sample this way was practical due to the large subsequent increase in IDF. The sequentially combined process of extrusion and enzyme treatments, compared to the individual and simultaneously combined treatments, significantly increased total solubility and soluble pentosan content of the final RB product. The warm-water-soluble pentosan content of treated RB was 6.5% by the sequentially combined process, 4% by either parallel combined process or extrusion alone or xylanase treatment alone. The hot-water-soluble pentosan of treated RB achieved a higher level of 10.5% by the sequentially combined process, 4.8% by extrusion alone, and 6.5% by xylanase treatment alone. A maximum total hot water solubility of 25% was achieved, of which 10.5% was pentosan, when water-washed rice bran was treated with extrusion and enzyme in sequence, representing an approximately four fold increase compared to untreated RB. Overall, washing rice bran with water was shown to be an efficient method to remove non-dietary fiber components. This study will likely represent the first published example for rice bran demonstrating an alternative to enzymatic methods used conventionally (e.g. amylase, protease, lipase) to hydrolyze non-dietary fiber compounds for further fiber processing.

Objective: To examine the relationship between diet and inflammation, and adiposity in minority youth. Design and Methods: A cross-sectional analysis of 142 overweight (≥85th BMI percentile) Hispanic and African American adolescents (14-18 y) with the following measures: anthropometrics, adiposity via magnetic resonance imagine (MRI), dietary intake via 24-hour dietary recalls, and inflammation markers from fasting blood draws utilizing a multiplex panel. Partial correlations were estimated and ANCOVA models fit to examine the relationship between dietary variables, inflammation markers, and adiposity measures with the following a priori covariates: Tanner stage, ethnicity, sex, total energy intake, total body fat, and total lean mass. Results: Inference based on ANCOVA models showed that the highest tertile of fiber intake (mean intake of 21.3 ± 6.1 g/d) versus the lowest tertile of fiber intake (mean intake of 7.4 ± 1.8 g/d) was associated with 36% lower plasminogen activator inhibitor-1 (PAI-1) (P = 0.02) and 43% lower resistin (P = 0.02), independent of covariates. Similar results were seen for insoluble fiber. No other dietary variables included in this study were associated with inflammation markers. Conclusions: These results suggest that increases in dietary fiber could play an important role in lowering inflammation and therefore metabolic disease risk in high-risk minority youth.

Low value dairy products such as lactose and acid whey, pose a huge opportunity to be converted into value-added products. This research evaluated the effect of formula and processing conditions on the polymerization of lactose by reactive extrusion into indigestible oligomers. Three citric acid concentrations (2%, 4% and 6%) and two feed rates (15 kg/hr and 30 kg/hr) were evaluated for their effect on the polymerization of lactose. Samples extruded at 15 kg/hr resulted in a higher yield of indigestible oligomers (46.7-56.4%) than at 30 kg/hr (33.7-43.5%). A successful cleanup procedure for Greek yogurt acid whey was developed so that it could be concentrated and drum dried. Heat treating the acid whey resulted in a reduction of protein, fat, and moisture. Washing the condensed whey resulted in a reduction of lactic acid, protein, and a lighter colored drum dried product.

The aim of this thesis project was to obtain corn bran AX of varying structure by using different extraction conditions, oxidatively cross-link them, and determine the microbial fermentability of both the non-cross-linked and cross-linked samples. To reach this goal the following objectives were defined: *Determine the influence of NaOH concentration used for AX extraction on structural characteristics of extracted AX. *Determine the influence of a post extraction procedure, ball milling, on the structural characteristics of extracted AX. *Cross-link differently extracted AX by using laccase and oxygen. *Determine the effects of ferulate cross-linking on fermentability in an in vitro fermentation experiment and analyze fermentation end products (pH, gas volume, and SCFAs). *Determine the release/formation of phenolic metabolites by gut microorganisms as well as the percentage of original FA being metabolized by gut microbiota.

The incidence of obesity continues to be a major public health problem in the United States and comorbidities such as type 2 diabetes, cardiovascular disease and fatty liver that accompany obesity have dramatically increased over the last several decades. The health costs associated with the diagnosis and treatment of obesity-related disorders, particularly type 2 diabetes, are extraordinary and will be an enormous financial burden on the economy. Due to these dire circumstances, there is great interest in identifying foods that reduce the accumulation of adipose tissue and decrease the progression of insulin resistance. The consumption of dietary fibers that decrease the postprandial glucose curve is associated with decreased adiposity and a reduced incidence of type 2 diabetes, but it is controversial as to which property of dietary fiber is responsible for these effects. The objective of this research was to investigate the effect of increasing the small intestinal contents viscosity on the progression of obesity and type 2 diabetes. In the first study, non-fermentable hydroxypropyl methylcellulose (HPMC) was used to increase the small intestinal contents viscosity in a model of obesity with type 2 diabetes, the Zucker Diabetic Fatty rat. Rats fed HPMC showed improvements in insulin resistance and fatty liver but only a modest effect on reducing obesity. There was also a decrease in diabetic wasting as there was a greater food efficiency ratio and less urinary glucose excretion. In the second study, it was shown that adding barley flour containing a high concentration of viscous fermentable β-glucans had similar outcomes to those observed in the first study, including decreased insulin resistance and fatty liver, and a greater concentration of plasma adiponectin. In the third study, a model of diet-induced obesity was used to determine differences in fuel utilization when consuming viscous dietary fibers. Adding non-fermentable HPMC and fermentable guar gum to a high fat diet significantly decreased adiposity and fatty liver, yet there was no difference in insulin resistance. Consumption of both HPMC and guar gum increased the postprandial respiratory quotient compared to cellulose and also increased metabolic flexibility. There was no added effect of fermentability on any measure of adiposity, glucose control or fatty liver disease, indicating that SCFAs produced from fermentation had little or no effect on metabolic disease. In summary, the consumption of soluble dietary fibers that increase the viscosity of the small intestinal contents reduces the progression of obesity, insulin resistance and fatty liver, while the property of fermentation appears to have little discernable effect.

Abstract: Aim of this study was to assess effects of non-digestible carbohydrates on the pathobiology of mucosal injury after chemotherapy. Rats bearing colon tumor (n=6/diet) were fed diets including 8% (w/w) as either cellulose, inulin, fructo-oligosaccharide (OligoF), 50:50 (w/w) inulin and oligoF (Synergy®), isomalto-oligosaccharide (IMO), type IV resistant starch (RS4) or cornstarch. Animals were treated with 2 cycles of CPT-11/5-fluorouracil. Animals fed RS4 or Synergy® were least ill with the least weight loss and anorexia, highest levels of gut associated lymphoid tissue (GALT) CD3+ and CD3CD8+ cells, least acute phase responses (haptoglobin, α-1-acid glycoprotein), least GALT OX6+ cells, CD152+ and CD71+ expression on CD8+ cells. Animals fed IMO or cornstarch were the most ill by these same criteria (p

Abstract: Viscosity and fermentability are considered important properties of dietary fiber. Viscosity increases digesta viscosity and reduces digesta passage rate, nutrient digestion and absorption whereas fermentability increases fermentation into short chain fatty acids (SCFA). The objectives were to enhance the understanding of these properties of dietary fiber and their effects on digestive physiology using surgical models in pigs. In study 1, three catheterized pigs fed 3 diets containing 0, 3, or 6% oat β-glucan concentrate (BG0, BG3, and BG6) in a repeated 3 × 3 Latin square. Pigs fed BG6 had a lower net glucose flux. Pigs fed BG6 tended to have lower portal C-peptide without lowered insulin. Pigs fed BG6 had lower portal glucose dependent insulinotropic peptide (GIP) and glucagon like peptide-1 (GLP-1), which in turn were correlated (R2 = 0.81 and 0.88, respectively) with portal glucose. Pigs fed BG3 and BG6 had a higher net SCFA flux, indicating increased fermentation. In study 2 and 3, ileal cannulated grower pigs were fed semi-purified diets supplemented with 5% purified non-starch polysaccharides (NSP) in a 2 (low and high viscous) × 2 (low, and high fermentable) factorial arrangement using cellulose (CEL), carboxymethylcellulose (CMC), and low and high viscous oat β-glucan (LBG and HBG, respectively). The CMC, LBG and HBG induced high ileal digesta viscosity coinciding with high nutrient digestibility; in contrast, CEL had lowest viscosity and nutrient digestibility. The CEL, LBG and HBG increased fecal SCFA. Linear discriminate analysis of NSP and TRFLP profiles and 16S rRNA gene copy numbers of bacterial groups revealed that CMC resulted in distinctive bacterial communities. The gene copy number of butyryl-CoA CoA transferase was higher than for butyrate kinase, indicating that this pathway is dominant for butyrate production in pigs. In study 4, similar dietary treatments were fed to catheterized pigs. High viscous and fermentable HBG increased net butyrate flux and insulin and GLP-1 production but did not affect net glucose flux. Thus, the viscosity and fermentability are important functional properties of dietary fiber that better explained the physiological effects on kinetics of digestion, absorption, hormones responses, fermentation and thus nutrient flow and intestinal health.

Instant, dietary fiber-supplemented beverage mixes were developed from the dietary fiber extract of papaya fruit (Carica papaya Linn.). Pectin was extracted, precipitated, semi-purified, dried and used for beverage mixes. Besides pectin from papaya, the five beverage formulations also consisted of a synthetic flavoring agent (watermelon flavor), sweetening agents (sucrose/fructose/aspartame/ combinations), sodium chloride and citric acid. The reconstituted beverages, reddish orange in color, contained 2.2% w/v of papaya pectin; the total dietary fiber content was 3.64 g per serving (1 glass = 250 ml), 3.44 g of which was soluble dietary fiber. Sensory evaluation was carried out, using 9-point Hedonic Scale method among 50 panelists. Analysis of Variance (ANOVA) was used for interpretations of the acceptance of the reconstituted beverage. The mean hedonic scores for all 5-formulae were not significantly different (P>0.01).

In a number of mammalian species, susceptibility to enteric coronavirus infection has been shown to be age-related. This is thought to be associated with enterocyte maturation and receptor protein expression. One of the factors that can influence differentiation and maturation of enterocytes is the availability of short-chain fatty acids (SCFA) in the intestinal lumen. These compounds are by-products of the bacterial fermentation of dietary fiber and serve as the primary energy source for enterocyte metabolism. The overall objective of this dissertation was to evaluate the effects of dietary fiber and short-chain fatty acids on enterocyte differentiation, maturation, and susceptibility to coronavirus infection in turkeys. Initial work involved the development of an indirect immunoperoxidase assay (IPA) for the identification and localization of turkey coronavirus (TCV) in paraffin-embedded, acid-ethanol fixed tissue. IPA was found to be superior to indirect immunofluorescent antibody test (IFA) for this and other diagnostic purposes. To evaluate cellular differentiation and maturation, an SDS-PAGE/immunoblot technique was developed to determine relative levels of villin expression in turkey embryos. Villin is an actin-bound cytoskeletal protein known to be expressed in increasing quantities at the apical surfaces of maturing enterocytes. Villin expression level was found to increase linearly as a function of embryo age. Villin localization was performed by IPA on paraffin-embedded, acid-alcohol fixed tissue. As enterocytes (embryos) matured, villin was found to concentrate at the apical surfaces and eventually at the basolateral membranes. Experiments were also conducted to see what effect in ovo butyrate administration would have on developing embryonic enterocytes. Butyrate has been shown to enhance differentiation of non-neoplastic and neoplastic cells in culture as well as promote healing of damaged intestinal epithelium in human. Villin expression was significantly enhanced in embryos receiving 0.2 and 0.3 M butyrate 36 hours post-administration. Butyrate appeared to enhance villin expression and therefore enterocyte maturation in a dose-dependent manner. Susceptibility of turkey embryos to TCV infection as a function of age and butyrate treatment was investigated as well as epithelial localization of TCV infection in poults. The level of TCV infection of epithelium was found to increase with embryo age between 17 and 23 days. Poults showed higher levels of infection on the distal 2/3 of villi and no evidence of infection in the intestinal crypts. Butyrate administration in 21-day-old embryos followed by TCV inoculation caused a significant increase of the number of infected cells per villus. This data suggested that butyrate might be used as a means to manipulate enterocyte susceptibility to TCV infection. In the final set of experiments, the effects of fiber-fortified poult diets containing 5% cellulose or 5% guar gum on luminal SCFA levels, enterocyte maturation, and TCV infection were investigated. SCFA levels in cecal contents were determined by gas chromatography. Enterocyte maturation was assessed by the determination of villin expression on immunoblot and the severity of TCV infection was determined by IPA and lesion score. Fiber-fortified diets enhanced SCFA production and villin expression, but contrary to embryo studies, TCV infection appeared to be reduced. In general, poults performed better on the diet containing cellulose. Mechanisms regarding the roles of dietary fiber and SCFA in enterocyte differentiation, maturation, and TCV susceptibility are proposed as well as future directions for research. The in ovo and poults system used in this research may serve as models for further investigation of the influences of host and dietary factors on enteric viral infection and recovery.

The objective of this study is to determine if fat as an energy source, and fiber in a pasture supplement will be beneficial when compared to a concentrate high in sugar and starch. In the first experiment, 12 pregnant and lactating mares were used in three different glycemic response tests to determine the effect of feeds on pregnant mares. The mares were fed a pelleted concentrate (PC) three months before foaling; after foaling they were divided into two groups and fed a feed high in sugar and starch (SS), or a feed high in fat and fiber (FF). The second experiment, used the same 12 mares (R mares) and 10 barren mares (B mares) in three different tests to determine the effects of the feeds, season and reproductive stage. A series of blood samples was collected via a jugular catheter from 0 to 390 min after consuming a meal. Glucose and insulin baseline and peak values, increments and areas under curves (AUC) were compared by ANOVA. For the first experiment, responses to PC did not differ between the two groups. Peak plasma glucose and insulin concentrations were higher in SS group than in FF during both early and late lactation. Glucose and insulin AUCs were higher in SS than in FF during both early and late lactation. In the second experiment, peak glucose increments had differences for the main effects feed, pregnancy and season, and interactions feed by pregnancy and feed by season. The glucose AUC values showed similar differences for the main effects and the interaction feed by pregnancy. Peak insulin increments had a difference for feed and pregnancy, but not the interactions. Insulin AUCs also revealed a difference between feed and pregnancy, and also for season, and the interaction feed by pregnancy. These results indicate that metabolic fluctuations are moderated by the replacement of sugar and starch with fat and fiber. This replacement may reduce the risk of certain digestive and metabolic disorders.

จากข้อมูลการสำรวจภาวะสุขภาพของคนไทยพบว่า ปัจจุบันคนไทยบริโภคผักผลไม้น้อย เป็นสาเหตุหลักทำให้เกิดปัญหาท้องผูกและเพิ่มความเสี่ยงของการเกิดโรคมะเร็งลำไส้ใหญ่ การบริโภคใยอาหารในปริมาณ 25-30 กรัมต่อวัน จะช่วยป้องกันและรักษาอาการท้องผูกได้ การศึกษานี้มีวัตถุประสงค์เพื่อศึกษาผลของการบริโภคน้ำผักผลไม้ผสมใยอาหารต่อการขับถ่ายอุจจาระในผู้ที่มีอาการท้องผูก รูปแบบการวิจัยเป็นเชิงทดลองแบบสุ่มชนิดปกปิดสองด้านมีกลุ่มควบคุม (Randomized, Double-blind, Controlled Trial) กลุ่มตัวอย่างถูกแบ่งเป็น 2 กลุ่ม กลุ่มละ 30 คน กลุ่มแรกบริโภคน้ำผักผลไม้ผสมใยอาหาร (ใยอาหารปริมาณ 10 กรัม) วันละ 300 มล.กลุ่มที่สอง บริโภคน้ำผักผลไม้ (ใยอาหารปริมาณ 2 กรัม) วันละ 300 มล. เป็นเวลา 4 สัปดาห์ ประเมินการขับถ่ายอุจจาระทุกวันเป็นระยะเวลา 7 สัปดาห์ รวมทั้งวัดสัดส่วนของร่างกายในสัปดาห์ที่ 0 และ 4 ผลการศึกษาพบว่า การบริโภคน้ำผักผลไม้ทั้ง 2 กลุ่ม ช่วยเพิ่มความถี่ในการขับถ่ายอุจจาระ เพิ่มปริมาณอุจจาระ รูปร่างอุจจาระอ่อนนุ่มมากขึ้น สีอุจจาระดีขึ้น ความรุนแรงของกลิ่นอุจจาระลดลงเมื่อเปรียบเทียบกับก่อนการทดลอง โดยเห็นผลในสัปดาห์แรกหลังการบริโภคน้ำผักผลไม้ (p