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- Genre: Doctoral Dissertation
- Member of: Theses and Dissertations
- Status: Published
Description
The winter holiday period has been highlighted as a major risk period for weight gain due to excess caloric intake in the form of fat and sugar. Furthermore, diets high in fat and sugar have been implicated in the pathogenesis of diabetes and cardiovascular disease. Exercise aids in the prevention of weight/fat gain, and prevents deleterious changes in cardiometabolic function. The objective of this study was to examine the effects of a fat-sugar supplemented diet, with and without two different exercise training protocols, on body composition, glycemic control and other markers of cardiovascular disease in an at-risk population of overweight and obese males. Twenty-seven, healthy overweight/obese (BMI >25 kg/m2) males were fed 2 donuts per day, 6 days/week, for four weeks, while maintaining their current diet. In addition, all subjects were randomized to one of the following conditions: sedentary control, 1,000 kcal/week moderate-intensity continuous training (MICT) (50% of peak oxygen consumption), or 1,000 kcal/week high-intensity interval training (HIIT) (90-95% of peak heart rate). Supervised exercise training was performed 4 days/week on a cycle ergometer. Changes in body weight and composition, endothelial function, arterial stiffness, glycemic control, blood lipids and cardiorespiratory fitness (CRF) were assessed before and after the intervention. Body weight, lean mass and visceral fat increased significantly in HIIT (p<0.05) and were unchanged in MICT. There was a trend for a significant increase in body weight (p=0.07) and lean mass (p=0.11) in control. Glycemic control during the 2-h OGTT improved significantly in MICT and control, with no change in HIIT. Hepatic insulin resistance index (IRI) and 30-min insulin during the OGTT improved significantly after MICT and worsened following control (p=0.03), while HIIT was unchanged. CRF increased significantly in both HIIT and MICT, with no change in control (p<0.001). There were no significant changes in other markers of cardiovascular disease. The addition of a fat-sugar supplement (~14,500 kcal) over a 4-week period was not sufficient to induce deleterious changes in body composition and cardiometabolic health in overweight/obese young males. Exercise training did not afford overweight/obese males additional health benefits, with the exception of improvements in fitness and hepatic IRI.
ContributorsTucker, Wesley Jack (Author) / Gaesser, Glenn A (Thesis advisor) / Angadi, Siddhartha S (Committee member) / Whisner, Corrie M (Committee member) / Buman, Matthew P (Committee member) / Shaibi, Gabriel (Committee member) / Arizona State University (Publisher)
Created2016
Description
Mobile healthy food retailers are a novel alleviation technique to address disparities in access to urban produce stores in food desert communities. Such retailers, which tend to exclusively stock produce items, have become significantly more popular in the past decade, but many are unable to achieve economic sustainability. Therefore, when local and federal grants and scholarships are no longer available for a mobile food retailer, they must stop operating which poses serious health risks to consumers who rely on their services.
To address these issues, a framework was established in this dissertation to aid mobile food retailers with reaching economic sustainability by addressing two key operational decisions. The first decision was the stocked product mix of the mobile retailer. In this problem, it was assumed that mobile retailers want to balance the health, consumer cost, and retailer profitability of their product mix. The second investigated decision was the scheduling and routing plan of the mobile retailer. In this problem, it was assumed that mobile retailers operate similarly to traditional distribution vehicles with the exception that their customers are willing to travel between service locations so long as they are in close proximity.
For each of these problems, multiple formulations were developed which address many of the nuances for most existing mobile food retailers. For each problem, a combination of exact and heuristic solution procedures were developed with many utilizing software independent methodologies as it was assumed that mobile retailers would not have access to advanced computational software. Extensive computational tests were performed on these algorithm with the findings demonstrating the advantages of the developed procedures over other algorithms and commercial software.
The applicability of these techniques to mobile food retailers was demonstrated through a case study on a local Phoenix, AZ mobile retailer. Both the product mix and routing of the retailer were evaluated using the developed tools under a variety of conditions and assumptions. The results from this study clearly demonstrate that improved decision making can result in improved profits and longitudinal sustainability for the Phoenix mobile food retailer and similar entities.
To address these issues, a framework was established in this dissertation to aid mobile food retailers with reaching economic sustainability by addressing two key operational decisions. The first decision was the stocked product mix of the mobile retailer. In this problem, it was assumed that mobile retailers want to balance the health, consumer cost, and retailer profitability of their product mix. The second investigated decision was the scheduling and routing plan of the mobile retailer. In this problem, it was assumed that mobile retailers operate similarly to traditional distribution vehicles with the exception that their customers are willing to travel between service locations so long as they are in close proximity.
For each of these problems, multiple formulations were developed which address many of the nuances for most existing mobile food retailers. For each problem, a combination of exact and heuristic solution procedures were developed with many utilizing software independent methodologies as it was assumed that mobile retailers would not have access to advanced computational software. Extensive computational tests were performed on these algorithm with the findings demonstrating the advantages of the developed procedures over other algorithms and commercial software.
The applicability of these techniques to mobile food retailers was demonstrated through a case study on a local Phoenix, AZ mobile retailer. Both the product mix and routing of the retailer were evaluated using the developed tools under a variety of conditions and assumptions. The results from this study clearly demonstrate that improved decision making can result in improved profits and longitudinal sustainability for the Phoenix mobile food retailer and similar entities.
ContributorsWishon, Christopher John (Author) / Villalobos, Rene (Thesis advisor) / Fowler, John (Committee member) / Mirchandani, Pitu (Committee member) / Wharton, Christopher (Christopher Mack), 1977- (Committee member) / Arizona State University (Publisher)
Created2016
Description
Abstract
Healthy eating promotes the optimal growth and development of children and can help reduce the risk of developing many health-related problems such as obesity and diabetes in both children and adults. Low-income, minority children disproportionately suffer from several chronic diseases when compared to middle to upper class non-Hispanic whites. The school is an environment in which children can learn about the importance of healthy eating by observing foods served, observing role models and interacting with a curriculum that emphasizes health and good nutrition. Parent involvement has been shown to play a role in improving health habits of children. Therefore, promoting nutrition education in the school by effectively improving parent involvement among minority parents is a promising approach.
The purpose of this action research was to examine the process of developing and evaluating a culturally sensitive, family-based nutrition newsletter for Latino parents of preschool children. The study aimed to: 1) identify challenges and explore education outreach and food-related issues facing preschool Latino families and 2) develop and evaluate a culturally sensitive, family-based nutrition education newsletter that promotes family engagement and healthy eating. The four phases of this research included: 1) a formative stage; 2) a development stage;3) an evaluation stage and 4) a sustainability stage. Descriptive statistics and thematic coding was used to analyze the data. Findings from parent and staff surveys indicated that newsletters and healthy recipes were the preferred methods of receiving food and nutrition-related information and the priority health issues for participants were diabetes and obesity. Based on the preferences of parents and staff, a family based nutrition newsletter was developed that was designed to encourage parents and children to work together while engaging with newsletter material. The newsletter was evaluated by parents and staff for content, format and effectiveness.
Overall, the newsletters were well received by parents and staff. The newsletter increased interest in nutrition, but participants wanted more information and wanted more fun activities for the children. The findings of this study indicated that the tailored approach to designing newsletters is not only feasible, but acceptable regarding the audience’s specific needs and preferences in this specific context and is a viable delivery method for nutrition education and sustainable nutrition education outreach for this Center. The development of culturally sensitive nutrition education materials that meet the needs of the specific intended audiences is discussed.
Healthy eating promotes the optimal growth and development of children and can help reduce the risk of developing many health-related problems such as obesity and diabetes in both children and adults. Low-income, minority children disproportionately suffer from several chronic diseases when compared to middle to upper class non-Hispanic whites. The school is an environment in which children can learn about the importance of healthy eating by observing foods served, observing role models and interacting with a curriculum that emphasizes health and good nutrition. Parent involvement has been shown to play a role in improving health habits of children. Therefore, promoting nutrition education in the school by effectively improving parent involvement among minority parents is a promising approach.
The purpose of this action research was to examine the process of developing and evaluating a culturally sensitive, family-based nutrition newsletter for Latino parents of preschool children. The study aimed to: 1) identify challenges and explore education outreach and food-related issues facing preschool Latino families and 2) develop and evaluate a culturally sensitive, family-based nutrition education newsletter that promotes family engagement and healthy eating. The four phases of this research included: 1) a formative stage; 2) a development stage;3) an evaluation stage and 4) a sustainability stage. Descriptive statistics and thematic coding was used to analyze the data. Findings from parent and staff surveys indicated that newsletters and healthy recipes were the preferred methods of receiving food and nutrition-related information and the priority health issues for participants were diabetes and obesity. Based on the preferences of parents and staff, a family based nutrition newsletter was developed that was designed to encourage parents and children to work together while engaging with newsletter material. The newsletter was evaluated by parents and staff for content, format and effectiveness.
Overall, the newsletters were well received by parents and staff. The newsletter increased interest in nutrition, but participants wanted more information and wanted more fun activities for the children. The findings of this study indicated that the tailored approach to designing newsletters is not only feasible, but acceptable regarding the audience’s specific needs and preferences in this specific context and is a viable delivery method for nutrition education and sustainable nutrition education outreach for this Center. The development of culturally sensitive nutrition education materials that meet the needs of the specific intended audiences is discussed.
ContributorsPazzaglia, Gina (Author) / Margolis, Eric (Thesis advisor) / Appleton, Nicholas (Committee member) / Paredes, Maria (Committee member) / Arizona State University (Publisher)
Created2016
Description
Currently, there has been limited research on evaluating the social media use and
competency level of registered dietitian
utritionists (RD/N). With health information increasingly sought on social media, it is imperative to understand the social media competency of health professionals. The social media use, reach, and competency level of a nationwide RD/N sample was assessed utilizing an online survey. The sample (n=500) while mostly female (97%) was representative of RD/Ns compared to the nationwide statistics from the Commission on Dietetic Registration. The sample included RD/Ns from forty-six states with California (n=44), New York (n=42), and Texas (n=34) having the largest proportion of respondents. The majority of RD/Ns engage in social media for personal use (92.4%) and 39.2% engage for professional use. One hundred and twenty-five RD/Ns reported 777 ± 1063 (mean ± SD) social media followers. As compared to non-millennial RD/Ns, millennial RD/Ns engaged significantly more in social media for personal and professional use (+10% and +13.5% respectively, p<0.001) and scored significantly higher for social media competency (p<0.001). Additionally, food and nutrition management and consultant/private practice/industry RD/Ns had significantly higher competency scores than clinical RD/Ns (p=0.015 and p=0.046, respectively). RD/Ns who use social media personally and professionally had a significantly higher competency score than RD/Ns who did not (p<0.001). There were significant associations of Facebook, Twitter, total followers and total average followers with the social media competency score (r=0.265, 0.404, 0.338, & 0.320, respectively) in RD/Ns. Specifically, the social media competency score, was found to explain 16% of the variation in the number of Twitter followers and 10% of the variation in the average number of followers by platform. These data suggest an opportunity to increase RD/Ns’ social media reach (i.e. following) by improving competency level.
competency level of registered dietitian
utritionists (RD/N). With health information increasingly sought on social media, it is imperative to understand the social media competency of health professionals. The social media use, reach, and competency level of a nationwide RD/N sample was assessed utilizing an online survey. The sample (n=500) while mostly female (97%) was representative of RD/Ns compared to the nationwide statistics from the Commission on Dietetic Registration. The sample included RD/Ns from forty-six states with California (n=44), New York (n=42), and Texas (n=34) having the largest proportion of respondents. The majority of RD/Ns engage in social media for personal use (92.4%) and 39.2% engage for professional use. One hundred and twenty-five RD/Ns reported 777 ± 1063 (mean ± SD) social media followers. As compared to non-millennial RD/Ns, millennial RD/Ns engaged significantly more in social media for personal and professional use (+10% and +13.5% respectively, p<0.001) and scored significantly higher for social media competency (p<0.001). Additionally, food and nutrition management and consultant/private practice/industry RD/Ns had significantly higher competency scores than clinical RD/Ns (p=0.015 and p=0.046, respectively). RD/Ns who use social media personally and professionally had a significantly higher competency score than RD/Ns who did not (p<0.001). There were significant associations of Facebook, Twitter, total followers and total average followers with the social media competency score (r=0.265, 0.404, 0.338, & 0.320, respectively) in RD/Ns. Specifically, the social media competency score, was found to explain 16% of the variation in the number of Twitter followers and 10% of the variation in the average number of followers by platform. These data suggest an opportunity to increase RD/Ns’ social media reach (i.e. following) by improving competency level.
ContributorsThompson-Felty, Claudia (Author) / Johnston, Carol (Thesis advisor) / Swan, Pamela (Committee member) / Lespron, Christy (Committee member) / Thornton, Leslie-Jean (Committee member) / Lee, Chong (Committee member) / Arizona State University (Publisher)
Created2017
Description
Sustainability, as it relates to nutrition, affects all aspects of food from systems-level production to consumption. Viability of local food systems in the southwest of the United States has been largely understudied. In order to address this gap in the literature, semi-structured interviews were conducted with 20 farmers in Arizona and New Mexico to determine best practices, challenges and barriers to farming. Interviews were recorded, transcribed, and coded for themes. Many trends were consistent with those reported elsewhere in the US, but the importance of water emerged, a unique need not explicitly noted in other regional studies.
Vegetarian diets are typically more sustainable than omnivorous ones due to using less environmental resources in the production of food. An important consideration with plant protein and vegetarian diets, however, is whether this would affect athletic performance. To examine this, 70 male and female endurance athletes were compared for maximal oxygen uptake (VO2 max), peak torque when doing leg extensions, and body composition. Vegetarians had higher VO2 max, but peak torque was not significantly different by diet. Omnivores had higher total body mass, lean body mass, and there was a trend for peak torque to be higher.
To investigate whether plant-protein can comparably support development of lean body mass and strength development in conjunction with strength training, 61 healthy young males and females began a 12-week training and protein supplementation study. While previous training studies have shown no differences for lean body mass or strength development when consuming either soy (plant) or whey (animal) protein supplements in very large amounts (>48 grams), when consuming around 15-20 grams, whey has contributed to greater lean body mass accrual, although strength increases remain similar. The present study matched supplements by leucine content instead of by total protein amount since leucine has been shown to be a key stimulator of muscle protein synthesis and is more concentrated in animal protein. There were no significant differences between the whey or soy group for lean body mass or strength development, as assessed using isokinetic dynamometry doing leg extensions and flexions.
Vegetarian diets are typically more sustainable than omnivorous ones due to using less environmental resources in the production of food. An important consideration with plant protein and vegetarian diets, however, is whether this would affect athletic performance. To examine this, 70 male and female endurance athletes were compared for maximal oxygen uptake (VO2 max), peak torque when doing leg extensions, and body composition. Vegetarians had higher VO2 max, but peak torque was not significantly different by diet. Omnivores had higher total body mass, lean body mass, and there was a trend for peak torque to be higher.
To investigate whether plant-protein can comparably support development of lean body mass and strength development in conjunction with strength training, 61 healthy young males and females began a 12-week training and protein supplementation study. While previous training studies have shown no differences for lean body mass or strength development when consuming either soy (plant) or whey (animal) protein supplements in very large amounts (>48 grams), when consuming around 15-20 grams, whey has contributed to greater lean body mass accrual, although strength increases remain similar. The present study matched supplements by leucine content instead of by total protein amount since leucine has been shown to be a key stimulator of muscle protein synthesis and is more concentrated in animal protein. There were no significant differences between the whey or soy group for lean body mass or strength development, as assessed using isokinetic dynamometry doing leg extensions and flexions.
ContributorsLynch, Heidi (Author) / Wharton, Christopher M (Thesis advisor) / Johnston, Carol (Committee member) / Dickinson, Jared (Committee member) / Buman, Matthew (Committee member) / Swan, Pamela (Committee member) / Ransdell, Lynda (Committee member) / Arizona State University (Publisher)
Created2017
Description
Chronic diseases are the leading causes of death in the United States. Dietary behaviors influence the risk of developing multiple chronic diseases. The U.S. population consumes too few fruits and vegetables and too much sugar sweetened beverages (SSB) and fast food. The Social Ecological Model (SEM) was created as a framework for health promotion interventions. The SEM organizes factors that can influence health into five layers: intrapersonal factors, interpersonal processes, institutional/organizational factors, community factors, and public policy. Each layer can influence dietary behaviors and other layers.
This work aims to understand how the community layer, represented by the food environment, moderates the association of two other layers and dietary behaviors: the interpersonal layer, represented by receiving health care provider’s (HCP) advice to lose weight, and the policy layer, represented by participation in the Supplemental Nutrition Assistance Program (SNAP), and a policy change within the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC).
Participant data were obtained from a household telephone survey of 2,211 adults in four cities in New Jersey from two cross-sectional panels in 2009-10 and 2014. Community food data were purchased and classified according to previously established protocol. Interaction and stratified analyses determined the differences in the association between HCP advice, SNAP participation, and time (for WIC participants) and eating behaviors by the food environment.
Interaction and stratified analyses revealed that HCP advice was associated with a decrease in SSB consumption when participants lived near a small grocery store, or far from a supermarket, limited service restaurant (LSR), or convenience store. SNAP participation was associated with a higher SSB consumption when respondents lived close to a small grocery store, supermarket, and LSR. There were no differences in fruit and vegetable consumption between two time points among WIC participants, or by food outlet.
The food environment, part of the community layer of SEM, moderated the relationship between the interpersonal layer and dietary behaviors and the policy layer and dietary behaviors. The association between HCP advice and dietary behaviors and SNAP participation and dietary behaviors were both influenced by the food environment in which participants lived.
This work aims to understand how the community layer, represented by the food environment, moderates the association of two other layers and dietary behaviors: the interpersonal layer, represented by receiving health care provider’s (HCP) advice to lose weight, and the policy layer, represented by participation in the Supplemental Nutrition Assistance Program (SNAP), and a policy change within the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC).
Participant data were obtained from a household telephone survey of 2,211 adults in four cities in New Jersey from two cross-sectional panels in 2009-10 and 2014. Community food data were purchased and classified according to previously established protocol. Interaction and stratified analyses determined the differences in the association between HCP advice, SNAP participation, and time (for WIC participants) and eating behaviors by the food environment.
Interaction and stratified analyses revealed that HCP advice was associated with a decrease in SSB consumption when participants lived near a small grocery store, or far from a supermarket, limited service restaurant (LSR), or convenience store. SNAP participation was associated with a higher SSB consumption when respondents lived close to a small grocery store, supermarket, and LSR. There were no differences in fruit and vegetable consumption between two time points among WIC participants, or by food outlet.
The food environment, part of the community layer of SEM, moderated the relationship between the interpersonal layer and dietary behaviors and the policy layer and dietary behaviors. The association between HCP advice and dietary behaviors and SNAP participation and dietary behaviors were both influenced by the food environment in which participants lived.
ContributorsLorts, Cori Elizabeth (Author) / Ohri-Vachaspati, Punam (Thesis advisor) / Adams, Marc (Committee member) / Hooker, Steven (Committee member) / Roberto, Anthony (Committee member) / Tasevska, Natasha (Committee member) / Arizona State University (Publisher)
Created2017
Description
It is widely documented and accepted that athletes have difficulty maintaining adequate hydration status and that dehydration is a key risk factor for the heat-related illnesses commonly observed among athletes. Research has also suggested that hydration status can influence cognitive performance. Educational interventions focused on rehydration strategies have had minimal success reducing dehydration rates; hence, alternative interventions promoting adequate hydration status in athletes should be explored. This trial examined the efficacy of a commercial hydration mobile application (app) for reducing dehydration rates in campus athletes. Fifty-eight college students aged 18-40 y, who participated in club-level collegiate athletics were recruited from a large Southwestern university and randomized by team to one of two study arms, the Standard of Care – Education (EDU) or the hydration mobile app (APP), to determine if app technology improved hydration status as compared to traditional education messaging. Twenty-three (79%) in the EDU group and twenty (69%) in the APP group were mildly-dehydrated at baseline based on the three-day averages of hydration assessment (USG 1.010). Moreover, 31% (n=9) and 28% (n=8) of the EDU and APP groups, respectively, were dehydrated (USG 1.020). No significant differences were found between the EDU and APP groups following the intervention. Three-day average post-intervention USG testing showed 76% (n=22) and 72% (n=21) of the EDU and APP groups respectively were at best mildly-dehydrated. Additionally, 28% (n=8) and 17% (n=5) were considered dehydrated. Neither intervention improved hydration status after four weeks of treatment. Further analyses of cognitive measures were conducted by hydration assessment groups at baseline and post-intervention: hydrated (HYD) (USG < 1.020) or dehydrated (DEH) (USG 1.020). No significant differences between hydration status were found between intervention groups. Additionally, no significant improvements were seen for either group, which indicates there is still a need for a novel way to improve hydration status in this population. Multi-dimensional interventions and individualized interventions to improve hydration status in this at-risk population may be more effective. Additional research should be conducted to determine if there is any cognitive performance enhancement associated with dehydration or mild-dehydration by reassessing previous data and conducting future trials.
ContributorsZemek, Kate A (Author) / Johnston, Carol (Thesis advisor) / Hekler, Eric (Committee member) / Mayol-Kreiser, Sandra (Committee member) / Ransdell, Lynda (Committee member) / Swan, Pamela (Committee member) / Arizona State University (Publisher)
Created2017
Description
Exclusivity and duration of breastfeeding and the provision of human milk in the United States is suboptimal. In the absence of adequate banked donor human milk for distribution to all infants in need, many families choose to engage in the practice of Private Arrangement Milk Sharing (PAMS), partially facilitated through social media, to procure human milk for their infants. Evidence regarding the participant and infant characteristics and risk abatement practices is incomplete. This dissertation describes and explores the characteristics of recipient participants and infants, family constellation, donor screening practices, and related risk abatement strategies. Data was collected via on-line survey as a sub-group of a larger data set including donor participants and international participants. Binary logistic regression modeling of factors that contribute to consistent screening and risk abatement practices and important antecedents to engaging in PAMS was conducted. Results are contextualized within a tailored socioecological framework of factors affecting infant feeding practices. Tailoring was accomplished via qualitative descriptive analysis of participant responses applied to an existing breastfeeding framework. Participants in this sample were predominantly white, married, with a mean age of 32.9 years, with at least some college education and above median income. Risk abatement and screening practices were influenced by support of a healthcare provider during decision-making, college education, infant age and health status, having lactation support, birth type and birth attendant, and the duration and sources sought for learning about milk sharing.
ContributorsBond, Angela Bowen (Author) / Reifsnider, Elizabeth G. (Thesis advisor) / Keller, Colleen (Committee member) / Todd, Michael (Committee member) / Arizona State University (Publisher)
Created2016
Description
Background Hemodialysis (HD) patients elicit an oxidant-antioxidant imbalance in addition to a selenium deficiency, possibly contributing to cardiovascular disease (CVD) mortality. Objective To evaluate the effect of selenium supplementation on CVD outcomes and antioxidant status in HD patients. Design A randomized controlled intervention trial conducted from October 2012 to January 2013. Participants/setting The study included 27 maintenance HD patients (61.1+17.5y, 14M, 13F) receiving HD in the greater Phoenix, AZ area. Intervention Patients received one of three treatments daily: 2 Brazil nuts, (5g, 181µg/day of selenium as selenomethionine [predicted]), 1 tablet of selenium (200µg/day of selenium as selenomethionine), or control (3 gummy bears). Main outcome measures Antioxidant status outcome measures included total antioxidant capacity, vitamin C, and RBC and plasma glutathione peroxidase (GSH-Px). CVD outcomes measures included brain natriuretic peptide; plasma cholesterol, high density lipoprotein, low density lipoprotein, triglycerides; blood pressure, and thoracic cavity fluid accumulation. Statistical analyses performed Repeated measures ANOVA analyzed changes over time and between groups at months 0 and 2 and months 0 and 3. Results Independent analysis showed the Brazil nuts provided 11µg of selenium/day and the pill provided 266µg of selenium/day. Consequently, the Brazil nut group was combined with the placebo group. 21 patients completed 2 months of the study and 17 patients completed the study in its entirety. Data was analyzed for months 0, 1 and 2. No significant differences were noted for antioxidant status outcome measures with the exception of plasma GSH-Px. Patients receiving the selenium pill had a significant increase in plasma GSH-Px compared to the placebo group (6.0+11 and -4.0+7.6, respectively, p=0.023 for change between month 0 and month 2). No significant differences were seen in total antioxidant capacity or for CVD outcome measures over time or between groups. Conclusions These data indicate that selenium supplementation increased plasma GSH-Px concentration in HD patients; however, oxidative stress was not altered by selenium supplementation. The low vitamin C status of HD patients warrants further research, specifically in conjunction with selenium supplementation.
ContributorsSussman, Elizabeth Jessica (Author) / Johnston, Carol S (Thesis advisor) / Boren, Kenneth (Committee member) / Mayol-Kreiser, Sandra (Committee member) / Sweazea, Karen (Committee member) / Vaughan, Linda (Committee member) / Arizona State University (Publisher)
Created2013
Description
High fiber diets have been associated with improved cardiometabolic health with specific efforts to lower circulating levels of low-density lipoprotein (LDL cholesterol). Whole grain and grain-based foods are major contributors of dietary fiber in the American diet, of which wheat has been extensively studied. Corn, however, has not been well studied for its cholesterol-lowering properties. Further, the mechanisms by which grains improve cardiometabolic health require further exploration with regard to the human microbiome. The objective of this single-blind randomized controlled, crossover trial was to assess the impact of three different corn flours (whole grain, refined, and bran-enhanced refined flour mixture) on serum LDL cholesterol and the gut microbiota diversity and composition. Twenty-three participants were recruited, between the ages of 18-70 with hypercholesterolemia (Male = 10, Female = 13, LDL >120 mg/dL) who were not taking any cholesterol-lowering medications. Participants consumed each flour mixture for 4 weeks prepared as muffins and pita breads. At the beginning and end of each 4-week period serum for cholesterol assessment, anthropometrics, and stool samples were obtained. Serum cholesterol was assessed using a clinical analyzer. Stool samples were processed, and microbial DNA extracted and sequenced based on the 16S rRNA gene. A generalized linear model demonstrated a significant treatment effect (p=0.016) on LDL cholesterol and explained a majority of the variance (R-squared= 0.89). Post hoc tests revealed bran-enhanced refined flour had a significant effect on cholesterol in comparison to whole grain flour (p=0.001). No statistically significant differences were observed for gut microbial community composition (Jaccard and weighted Unifrac) after corn consumption. However, relative abundance analysis (LEfSE) identified Mycobacterium celatum (p=0.048 FDR=0.975) as a potential marker of post-corn consumption with this microbe being differentially less abundant following bran-enhanced flour treatment. These data suggest that corn flour consumption may be beneficial for individuals with hypercholesterolemia but the role of gut microbiota in this relationship requires further exploration, especially given the small sample size. Further research and analysis of a fully powered cohort is needed to more accurately describe the associations and potential mechanisms of corn-derived dietary fiber on circulating LDL cholesterol and the gut microbiota.
ContributorsWilson, Shannon L (Author) / Whisner, Corrie M (Thesis advisor) / Sears, Dorothy (Committee member) / Buman, Matthew (Committee member) / Dickinson, Jared (Committee member) / Zhu, Qiyun (Committee member) / Arizona State University (Publisher)
Created2022