Browsing by Subject "Diet"

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Building assets and resilience : the role of the local food system in reducing health and economic disparities
(2011-05) Muraida, Laura Cristina; Wilson, Patricia Ann
In recent years, studies have linked various structural and environmental factors to disproportionately increased rates of morbidity, mortality, and adverse health outcomes in low-income racial and ethnic minority neighborhoods. Among the adverse health outcomes, is the constraint on the ability to access and afford a healthy diet. While local food systems play a significant role in influencing urban health and well-being outcomes, they also present an opportunity to develop community-based assets and resilience. By identifying limitations and successes in current food system literature and practice, this report examines how a more comprehensive approach to equitable community health and wellness can be achieved and sustained. Effective disparity reduction relies on cross-sectoral partnerships that not only promote food equity, but also provide participatory social, economic, and educational opportunities to marginalized communities.
Comparisons of physical activity and dietary components in an overweight/obese population and their normal weight controls matched for gender, age and height
(2004) Davis, Jaimie Nicole; Gillham, Martha B.
The objectives of this study were: 1) to assess differences in voluntary physical activity and dietary components between an overweight/obese population and normal weight matched controls; 2) to assess the accuracy of commonly used activity factors, i.e., indices that represent physical activity in predictive equations for energy, established by the World Health Organization (WHO) and the Institute of Medicine (IOM) in the Dietary Reference Intakes (DRIs). Adults, aged 19-69 years, 53 overweight/obese and 53 normal weight subjects matched for gender, age (± 1 year) and height (±1 inch) were recruited from the local area and university community. Diets were assessed by the Block 60-item food frequency questionnaire, physical activity by the Yale Physical Activity Survey, and body composition by the dual energy X-ray absorptiometry. Resting energy expenditure was obtained by indirect calorimetry and later multiplied by a conversion factor to yield basal energy expenditure. A sub-sample of 62 adults, 31 in each group, wore an accelerometer, an instrument that detects body movement, for seven consecutive days. Accelerometer data showed that overweight/obese adults were less physically active, expended fewer kilocalories per kilogram of body weight, recorded fewer accelerometer counts throughout the week, and spent less time in moderate or greater intensity activity than their normal weight controls. Overweight/obese subjects consumed more total fat, saturated fat and cholesterol and less carbohydrate, complex carbohydrate and dietary fiber than controls. Reported intakes of dietary fiber and carbohydrate were inversely related to percent body fat with and without controlling for potential confounding factors, i.e., age, gender, physical activity-related energy expenditure and other macronutrients. Activity factors derived from accelerometers were significantly lower than those determined by the WHO and DRI methodology for normal but not overweight/obese subjects, suggesting that energy needs for many adults may be overestimated by using these prediction equations. In summary, limited physical activity-related energy expenditure, especially time spent in moderate intensity or greater activity, diet composition, especially low dietary fiber, and overestimation of energy needs by current prediction methodology are implicated in the etiology of obesity. These findings indicate areas of interest for future research and program development aimed at weight management and obesity prevention.
Cost Benefit Analysis of Popular Diets
(2023-05) Steele, Quincy
The increase in obesity in recent years has led to the creation of numerous diets claiming to induce weight loss and improve overall health. While all diets claim to be the best, it is difficult to determine which diet provides the most utility given the costs of participation. These diets have varying scientific evidence to support the claims made and participants have mental, temporal, and financial costs associated with each. This thesis examines each diet and the costs and benefits associated with each. The benefits of the diet were researched, and scientific evidence was recorded. The mental and temporal costs were determined by a one-week personal trial. The financial costs were calculated using the HEB website and meal plans provided by the text. The scientific evidence, personal data, and financial data were compared for each diet to determine which diet provides the most utility for the lowest cost. The Volumetrics diet was found to have the most scientific evidence to support the benefits, the lowest mental and temporal costs, and the lowest cost to participate in long-term.
Diet and related behaviors of low-income, overweight women in early postpartum
(2009-05) Shah, Bijal Sanghani; Freeland-Graves, Jeanne H.
The purpose of this study was to determine the influence of diet and physical activity behaviors on weight status and lipid profiles in low-income women in early postpartum. In addition, the relationship of nutrition knowledge with dietary intakes was evaluated. A convenience sample of low-income mothers was recruited from public health clinics, community centers, and doctor's offices. Inclusion criteria was Hispanic, African American, or Caucasian ethnicity; body mass index (BMI) [greater-than or equal to] 25 kg/m², low-income (annual household income <185% federal poverty line); parity<3 and ability to speak and write English. Demographic, dietary (24-hr recalls and 2 day food intake recalls), psychosocial, anthropometric, serum lipids (LDL, HDL and total cholesterol and triglycerides) and physical activity (pedometer steps) data were collected. For study 1, the Healthy Eating Index-2005 (HEI-2005) scores were computed as a measure of diet quality in a sample of 125 women. Analysis of Covariance and linear regression was performed to determine the relationship between HEI-2005 and serum lipids. The mean total index score of the sample was 51.4 and was associated inversely with BMI ([beta]=-0.117), LDL ([beta]=-.659) and total ([beta]=-.690) and positively with HDL ([beta]=.216) (P<0.05). Less than 20% of the sample failed to meet the recommendations for fruits, total vegetables, whole grains and oil and 60% had overconsumption of solid fats, alcohol and added sugars. In study 2, snacking frequency and choices of 134 postpartum women were evaluated. Influence of snacking frequency on HEI-2005 scores and disparities in snack choices by BMI categories was assessed by performing ANCOVA. A majority of the sample (82%) consumed snacks and the most favored snack group was sweets and desserts. Increase in snacking frequency was associated with higher mean total HEI-2005 scores, and total fruit, dark green vegetables and legumes, total grains, and saturated fat (P<0.05) component scores when adjusted for energy intakes. Snacking frequency was also associated with higher intakes of protein, vitamins A and C, and calcium (P<0.05). In study 3, 66 new mothers participated and completed an 8-week weight loss intervention promoting exercise by using pedometers. Paired t test revealed improvement in physical activity after intervention. Linear regression analysis determined the ability of pedometer steps to predict weight loss ([beta]=0.465), % body fat ([beta]=-0.316), triglycerides ([beta]=-0.549), LDL ([beta]=-0.391) and total cholesterol ([beta]=-0.418). In study 4, a nutrition knowledge scale was developed and validated in new mothers. Knowledge was associated with greater consumption of grains, low fat meats and dairy (P<0.01), fiber (p<0.01), calcium (p<0.001), and iron (p<0.05). Participants appeared to be more cognizant of information about vitamins and minerals and weight management and less of energy nutrients and calorie counting. Hierarchical regression model identified age, education, ethnicity and income as determinants of knowledge.
Dietary behavior in low income postpartum women : psychosocial and body weight correlates
(2004-05) George, Goldy Chacko, 1973-; Freeland-Graves, Jeanne H.
The purpose of this research was to examine psychosocial and body weight correlates of dietary behavior in low-income tri-ethnic women. In Study 1, a semi-quantitative food frequency questionnaire (FFQ) was developed and validated against diet records in 95 college women and 50 low-income postpartum women. Pearson's correlations were 0.42 among college women and 0.45 among low-income women. Cross-classification of participants into quartiles resulted in 76% of college women and 79% of low-income women being classified correctly. These results suggested that the FFQ was valid for dietary assessment among young women in the southwestern United States. In Study 2, approximately 160 mothers were recruited in the hospital 0-1 days following childbirth, and prepregnancy weight and demographic information were obtained. Weight was measured at 6 months and 1 year postpartum; psychosocial factors were assessed at 1 year. Diet during pregnancy and postpartum was assessed via food frequency questionnaires administered at 1.5 months, and at 6 and 12 months postpartum, respectively. From pregnancy to postpartum, % calories from fat (delta = +1.1%, p<0.05) and added sugar (delta = +2.0%, p<0.05) increased. A greater percentage of lactating than non-lactating women (64% vs. 38%, p<0.05) met recommendations for fruits during pregnancy. Mean intakes of calcium, vitamin A and dairy foods were higher in women who had retained <10% of their prepregnancy weight at 1 year postpartum than in those who had gained [greater-than or equal to] 10%. During late postpartum, women in the highest tertile of compliance with dietary recommendations had a more positive body image (p<0.041) than those in the lowest tertile, and less neglect of self-care (p<0.001), weight-related distress (p<0.006), stress (p<0.009), depressive symptoms (p<0.020), and perceived barriers to weight loss (p<0.039). These findings suggest that the transition from pregnancy to postpartum is associated with a negative impact on dietary behavior in low-income women. Intakes of calcium, vitamin A and dairy foods may be associated with lower weight retention in postpartum. Furthermore, psychosocial variables may influence adherence to dietary guidelines during this time.
Dough for Dough: How Socioeconomic Status Affects Gluten-Free Eating
(2020-05) Tai, Jennie
With the growing number of gluten-related conditions around the world, it is important to identify the circumstances of people in low socioeconomic communities that influence and potentially deter healthy eating patterns and broader health inequalities. Conducting my own research, I interviewed 84 low-income, gluten-free eaters and surveyed 552 gluten-free individuals across all income levels to understand the drivers of attitudes and behaviors towards diets that are best understood through qualitative research. I found that gluten-free substitutes were about twice as expensive per ounce than their non-gluten-free counterparts. About 60% of respondents from both income groups stated no healthcare professional ever taught them about gluten or how to eat gluten-free. This led to a knowledge gap and certain deficiencies in their diets, all of which can be detrimental to people’s health. The interviews also showed that low-income, gluten-free eaters do not make the same dietary choices as other low-income, non-gluten-free eaters might, which meant that the gluten-free diet acts as a forcing factor for healthy eating. Finally, I discovered a correlation between people who have been gluten-free for a longer period of time and having the skills to purchase and prepare gluten-free foods easily and more economically. Much of the conclusions in this paper are data-driven from the surveys and rely on the interview results. This thesis focuses on the social implications of the gluten-free diet and understanding how socioeconomic status affects people’s coping mechanisms with their gluten-related conditions.
Effects of a time-restricted high- or low-fat diet on lipid absorption
(2021-12-07) Balderrama, Jesse, Jr.; Bray, Molly S.
Background: Chronic high-fat diets and time-restricted feeding have been shown to impact multiple cardiometabolic parameters. The purpose of this work was to investigate the effects of timed macronutrient intake on lipid absorption. Methods: Adult male FVB/N mice were randomly assigned to one of 6 feeding groups (n=45, 7-8 animals/group) and kept on a strict 12h light: 12h dark feeding schedule (lights on at 10pm (Zeitgeber Time - ZT0) and lights off at 10am (ZT12)). Food was made available continuously to mice in the control ad libitum low-fat (CALF) and control ad libitum high-fat (CAHF) feeding groups. Mice in the control low-fat (CLF) and control high-fat (CHF) groups received low fat or high fat food, respectively, exclusively during ZT 12-16 and ZT 20-24. Mice in the early high-fat (EHF) group received access to high-fat food during ZT 12-16 and low-fat food during ZT 20-24. Mice in the early low-fat (ELF) group received access to the low-fat food during ZT 12-16, and high-fat food during ZT 20-24. EHF and ELF groups did not have access to food during ZT 16-20. Rodent diet foods were 45% kcal from fat or 10% kcal from fat in high-fat groups and low-fat groups, respectively. After 12 weeks of study protocol, fecal samples were collected over a 24h period. Lipid extractions were performed to quantify fecal lipid content. Plasma samples were collected during mice sacrifice and triglyceride concentration was quantified. Results: There was a significant effect of feeding group (p=0.0016) as well as a significant effect of time on fecal lipid content (p=<0.05). Cosinor analysis revealed that feeding groups CALF, CLF, EHF, ELF showed significant rhythmicity for fecal lipid content, with no rhythmicity in fecal lipid content for either group exclusively eating a high fat diet (CAHF and CHF). There was a significant difference in plasma triglycerides between feeding groups (F (5,24) = 13.14, p = <0.05). A Scheffe post hoc test revealed that fasting plasma triglycerides showed a trend toward higher concentrations in groups fed low-fat food. Conclusion: Chronic high-fat diets resulted in greater fecal lipid content and lower fasting plasma triglycerides compared to low-fat diets
The effects of acute exercise on postprandial metabolism
(2012-05) Trombold, Justin Ross; Coyle, Edward F., 1952-; Tanaka, Hirofumi; Brothers, Robert M.; Nunez, Nomeli; Hursting, Stephen
These studies determined the role of carbohydrate deficit from acute exercise on postprandial triglyceride elevation (PPTG). In Study 1, when energy expenditure was held constant in the exercise trials, both acute moderate (~50% VO₂ peak; MIE) and high intensity endurance exercise (90% VO₂ peak intervals; HIE) were effective to lower PPTG compared to a non-exercise control [CON; 54.9 (13.5) % and 75.2 (15.5) %, respectively, relative to CON, p<0.05], with HIE significantly lower than MIE (p=0.03). Total postprandial fat oxidation was increased in both MIE [83.3 (10.6) %] and HIE [89.1 (9.8) %] compared to CON [69.0 (16.1) %, p<0.05), with HIE significantly greater then MIE (p=0.012). These effects occurred in the absence of any change in glucose tolerance. In Study 2, when an isoenergetic meal was provided immediately after an acute exercise session (80 min; 60 min at ~65% VO₂peak and 10, 2 min intervals) consisting of either low carbohydrate (EX+LCHO) or high carbohydrate content (EX+HCHO), PPTG was siginificantly higher in EX+HCHO compared to EX+LCHO [449 (118) mg/dL/4h and 325 (63) mg/dL/4h, respectively, p=0.03], despite similar energy balance. Furthermore, postprandial fat oxidation was higher in EX+LCHO compared to EX+HCHO [256.7 (57.6) kcal/4h and 209.4 (56) kcal/4h, respectively, p=0.002]. PPTG was significantly related to fat oxidation (r=-0.61), fasting plasma [beta]-hydroxybutyrate (r=-0.62) and carbohydrate deficit (r=0.51), but not energy deficit (r=0.25). In summary, these data suggest that post-exercise carbohydrate balance from both increasing carbohydrate oxidation during exercise (i.e., exercise intensity) or by reducing post-exercise carbohydrate intake, is an important determinant of PPTG-lowering effects of exercise and that this may result from changes in fat oxidation.
Effects of prolonged sitting and walking for two days on postprandial triglycerides in men : interaction with energy intake
(2011-05) Park, Sanghee; Coyle, E. F. (Edward F.), 1952-; Brothers, Robert M.
Postprandial hypertriglyceridemia (PPHT), an independent risk factor for atherosclerosis (Smyth and Heron 2006; Nordestgaard, Benn et al. 2007), is strongly associated with metabolic syndrome and cardiovascular diseases (CVD) (Kolovou, Anagnostopoulou et al. 2005). It has been proposed that elevated triglycerides after a high-fat meal may be a postprandial phenomenon (Zilversmit 1979). PPHT are commonly concurrent with sedentary behaviors, such as extended sitting, which amplify PPHT (Levine, Vander Weg et al. 2006). The purpose of this study was to examine the effects of prolonged sitting with or without a balanced caloric diet and walking with a balanced diet on postprandial triglycerides (PPTG). Seven healthy, young men (age, 25.6 ± 3.7 y; height, 174 ± 5 cm; weight, 71.4 ± 6.2kg; VO2max, 49.3 ± 7.7 ml/kg/min) were recruited from a college and from within the Austin community. After 2 days of food and activity control (D1and D2), subjects performed one of three trials in a randomized, cross-over design for 2 days (D3 and D4); (1) active walking with a balanced diet (WB), (2) prolonged sitting with a hyper-caloric diet (SH), and (3) prolonged sitting with a balanced diet (SB). High fat tolerance tests (HFTT) were conducted on the following day, (D5), after 13 hour over-night fasting. Blood samples were obtained in the fasting state and every hour for 6 hours after subjects had eaten a high fat test meal consisting of 1.2 g fat, 1.1 g CHO, 0.2 g protein/kg body mass. All food was provided during the 5-day duration of the study. Body postures, heart rate, and daily steps were monitored. In both sit trials (SH and SB), subjects sat ~320 minutes longer and took 10 times fewer steps than WB. In WB, the total area under the curves for plasma triglycerides (AUC[subscript T] TG) was lower, compared to SH by 21.3% (p<0.001) and to SB by 19.7% (N.S.; p = 0.055), respectively. In WB, the incremental AUC TG (AUC[subscript I] TG), an index of postprandial response, was lower than both SH by 17.4% (p <0.005) and SB by 20.1% (p <0.05), respectively. Postprandial plasma insulin concentration was lower in WB, compared to SH by 19.4% (p <0.005) in AUC[scubscript T] and 18.8 % (p < 0.05) in AUC[subscript I]. No differences were shown in the metabolic responses between SB and SH despite the diet modifications. These findings indicate that two days of prolonged sitting significantly amplifies PPTG and suppresses insulin action.
Gene-diet interaction effects on brain function in middle age
(2019-09-20) Oleson, Stephanie Marie; Haley, Andreana P.; Davis, Jaimie N; Holahan, Charles J; Smits, Jasper A J
Cognitive decline in older age is a significant public health concern in the face of a globally expanding population and lack of effective therapies for dementia. Thus, identifying modifiable risk factors that affect brain integrity is imperative for preserving cognitive function throughout the lifespan. Accumulating evidence suggests dietary factors plan an important role in cognitive health. Epidemiological data suggests that high sugar and saturated fat (SFA) intake is associated with poorer cognitive outcomes, while research points toward a protective role of polyunsaturated fat (PUFA) intake against dementia. In particular, greater omega-3 (ω-3) PUFA consumption is seen as especially beneficial for brain health. However, effect sizes in intervention-based supplementation studies have been small, highlighting the need for further research to elucidate the underlying mechanisms and contributing factors to dietary effects on the brain. Therefore, the major aim of Study 1 was to conduct a novel investigation of the association between major macronutrient intake (PUFA, SFA, carbohydrates, and protein) and cerebral metabolism in middle-aged adults. The study utilized proton magnetic resonance spectroscopy to quantify cerebral metabolites of neurobiological significance. In Study 2, the role of Apolipoprotein E (APOE) genotype was explored as a potential moderator of the relationship between dietary PUFA and cerebral metabolism. APOE is of special interest due to its critical role in lipid transport as well as its established status as a genetic risk factors for Alzheimer’s disease. Finally, Study 3 expanded the investigation of gene-diet interaction effects on brain function by examining the relationship between dietary PUFA and functional brain activity during a cognitive task, as well as the potential role of APOE genotype as a moderator of this relationship. In sum, the proposed studies examined novel relationships between dietary nutrients and indices of brain function, and also explore the role of APOE genotype as a moderator of these associations. Identifying biomarkers associated with dietary effects in middle age is critical given that prevention is currently the most promising opportunity of intervention for dementia. Additionally, major implications of this work include potential for developing and augmenting dietary interventions that can be personalized according to genetic risk for AD.
Lingual fungiform papillae and teh evolution of the primate gustatory system
(2009-05) Alport, Laura Jean; Kirk, E. Christopher, 1974-
Among humans, the density of lingual fungiform papillae (DFP) is correlated with taste sensitivity. The purpose of this dissertation was to investigate the evolution of the primate gustatory system through a comparative analysis of DFP. This investigation was conducted in three separate studies. The first study took a broad perspective incorporating data from 37 primate species to assess the relationships among DFP, body mass, taste sensitivity, and diet. Among the major findings of this first study: (1) Sucrose sensitivity was negatively correlated with DFP and positively correlated with papilla area. (2) Sucrose sensitivity was not correlated with the percent of leaves or fruit in the diet. (3) DFP and papilla area were correlated with diet. (4) The relationships between fungiform papillae and diet differed among different taxonomic groups. The second study of DFP investigated whether there are sex differences in the DFP of non-human primates, as there are in humans. In all five primate species investigated, females had higher mean DFPs than males. These sex differences were significant in Pan troglodytes and Cebus apella, and not significant in Alouatta palliata, Cercopithecus aethiops, or Varecia variegata. Pan, Cebus, and Homo share large relative brain sizes with associated life history parameters making each offspring very costly. Accordingly it was suggested that sex differences in DFP may be due to the particularly high risk of lacking nutrients or ingesting toxins for females of these three species. The third study was a comparison of phenylthiocarbamide (PTC) taste ability and DFP in humans and chimpanzees. The major questions addressed in this study were (1) Is DFP correlated with PTC phenotype in chimpanzees as it is in humans? (2) Are there sex differences in PTC genotype and phenotype as there are in DFP? Although females had greater DFPs than males, and significantly more females had the genotype for higher PTC taste sensitivity, there was no correlation between DFP and PTC phenotype. Several explanations for the differences between human and chimpanzee results were offered, including small sample sizes for chimpanzees and greater accuracy in determining PTC sensitivity among humans.
Nutrition knowledge, attitudes, and diet associated with postpartum weight retention in low-income and minority women
(2006-05) Nuss, Henry Joseph; Freeland-Graves, Jeanne H.
The purpose of this research was to discern associations of nutrition knowledge, attitudes, and diet with postpartum weight retention 1 year following childbirth. Subjects for this research were low-income, Hispanic, non-Hispanic black, and non-Hispanic white women recruited in a hospital 0 -- 1 day postpartum. In study 1, a nutrition attitudes scale was developed and validated in 134 low-income women at 1.5 months post-delivery. The final scale was administered to a second group of 206 women at 1.5, 6 and 12 months postpartum. Attitudes at each time were compared to demographics and weight status. Obese women at 1 year had higher barriers to healthful eating subscale averages than normal and overweight subjects at 1.5 and 6 months, and overweight participants at 12 months. Obese individuals also had greater emotional eating subscale scores than both normal and overweight subjects at 12 months. In study 2, a test of general nutrition knowledge was developed and validated in a sample of 151 women at 1 day post-delivery. The validated instrument was then administered to a test sample of 140 women at 0 and 12 months postpartum. Body weights were measured at 1.5, 6, and 12 months and height 1.5 months. Women with < 5% weight retention at 1 year had greater knowledge at 0 (53% vs.49%, p<0.05) and 12 months (55% vs. 51%, p <0.05) than those with >̲5%. Women who lactated >̲ 6 months had more knowledge than those who lactated < 6 months. In study 3, 182 women visited the research site at 1.5, 3, 6, and 12 months postpartum where dietary data were collected via one 24-hour recall and 2 days of diet records. Weight status was measured during each clinic visit; height was measured at 1.5 months. At 1 year postpartum, obese women had a greater percentage of energy from carbohydrates than their normal weight counterparts (52.5 % vs. 49.6%, p<0.05). Less than half of the population met the recommendations for folate, calcium, magnesium, and vitamins B6, D, E and C at all time points, regardless of ethnicity, BMI and lactation status.
Preference and performance in a population of checkerspot butterflies with known diet history
(2010-12) Hasanah, Nur; Singer, Michael C.; Parmesan, Camille
This thesis describes a relationship between maternal preference and offspring performance in a population of the butterfly Euphydryas editha that used two host plants, Pedicularis semibarbata and Collinsia torreyi from 1979 to 2001, but now no longer uses Collinsia. In the light of the known history of diet change in this butterfly population, it is not surprising that maternal oviposition preference was variable. Although the diet of the butterflies that evolved rapidly in the 1980’s is no longer changing, I still discovered some females with a chemical preference for Collinsia. This seems to be a legacy of recent anthropogenic diet evolution. The evolution of host preference of females in Rabbit Meadow has not finished yet. Variation of offspring weight and survival were measured and showed a complex relationship with adult preference. Although quite a few adults strongly rejected Collinsia, their offspring grew well on this host, and there was no significant trend for the offspring of strongly Pedicularis-preferring butterflies to perform more poorly on Collinsia.
The associations between nutrient intake and eating patterns with adiposity, metabolic risk factors, and the gut microbiome in Hispanic college freshmen
(2017-08) Pilles, Kiona Natasha; Davis, Jaimie Nicole; Freeland-Graves, Jeanne; Bray, Molly; Powers, Dan; Morrow, Casey
Hispanics are at an increased risk of obesity and metabolic disease in the United States. Some studies have shown 70% of college students gain weight during their freshman year and is a critical transition period contributing to the rise in obesity rates. Research indicates that obesity is associated with an altered gut microbiome, a dynamic community of microbes that encode for proteins that perform diverse metabolic roles, are associated with disease states and may be affected by dietary intake. The objective of this study was to examine the relationship between the gut microbiome and dietary intake, eating patterns, adiposity, and metabolic measures in a population of college Hispanic freshmen. This cross-sectional study and secondary analysis was performed at The University of Texas at Austin and involved Hispanic college freshmen (18-19 years of age). The first aim was to examine the relationship between dietary intake, adiposity, and metabolic markers. Fiber intake was negatively associated with hepatic fat (HF), glucose, insulin, and leptin. Saturated fat intake was positively associated with HF, subcutaneous adipose tissue (SAT), total body fat, cholesterol, insulin, insulin resistance, leptin, and C-reactive protein (CRP). Saturated fat intake was also associated with increased odds of non-alcoholic fatty liver disease (NAFLD). The second aim was to examine the relationship between the gut microbiome and the diet. Subjects who met saturated fat recommendations compared to those who exceeded recommendations had a more diverse microbiome. The third aim was to evaluate the relationship between the gut microbiome, adiposity, and metabolic measures. Subjects who had a low percent body fat, low insulin values, and high LDL values had a more diverse microbiome compared to subjects with a high percent body fat, high insulin values, and low LDL values. Collectively, these data suggest that an intake of saturated fat is associated with unfavorable health outcomes and the microbiome may be a possible mechanism and/or target for treatment and prevention.
The ecology of amphibian-associated bacterial communities
(2020-03-03) Correa Filho, Decio Tadeu; Matz, Mikhail V.; Leibold, Mathew A.; Bolnick, Daniel; Rodriguez, David; Ryan, Michael; Mueller, Ulrich
Multicellular organisms are habitat for a diverse bacterial community (microbiome) that can often be associated with host health and well-being. To better understand that relationship I explored several ecological aspects of the host-associated microbiomes using pre- and post-metamorphic amphibians. First, I investigated the relative roles of local selection (due to host species identity) and regional effects (due to water body identity) on the community structure of the gut microbiome of tadpoles. I found that each water body represents a relatively distinct species pool of bacteria available for community assembly, making the water body more important in shaping the microbiome of tadpoles than their species identity. I then showed that the gut microbiome of tadpoles is not homogeneous throughout its gut length as there are changes in composition, abundance, richness, and diversity from the anterior to the posterior parts of the gut. Moreover, the gut microbiome of the anterior portion is unstable, i.e., it is highly influenced by exposition to external bacteria, while the microbiome of the posterior gut has higher stability. The posterior part harbors the functional microbiome that helps tadpoles with digestion. In fact, I found that most of the essential amino acids in the tadpole tissue are derived from bacteria. I then manipulated their gut microbiome and diet and found that the composition of the microbiome can have profound impacts on the performance and fitness of the tadpole, as distinct microbiomes affect growth, development, and mortality of the host. Finally, as tadpoles metamorphose and leave the water, their microbiome is reshaped due to changes in conditions related to both the environment and the host. I tested and showed that closely related species of adult amphibians have a tendency to harbor similar skin microbiome, but the same signal was not found for their gut microbiome. In summary, I found that the gut of tadpoles harbor several distinct but connected microbiomes that vary in composition, diversity, and stability and that can profoundly affect the fitness of the host. Its composition is ultimately determined by the environmental bacteria tadpoles were exposed to. For adult amphibians, closely related species have more similar skin but not gut microbiome.
Tracing organic matter pathways in marine food webs using fatty acids and compound specific stable isotope analysis
(2015-08) Smith, Stephanie Denise; McClelland, James W.; Dunton, Kenneth H; Walther, Benjamin D
Organic matter inputs to the marine environment vary over seasonal and spatial scales, altering the type and availability of food sources for marine consumers. It is important to identify diet in order to understand basic ecology, characterize trophic interactions, and predict consequences of biotic and abiotic change within a community. Methods of direct observation of diet and feeding can be difficult, so indirect methods have been developed such as analysis of gut contents and fecal pellets. However, these methods only represent a snapshot of the last meal, and provide information about what was ingested, but not what was actually incorporated into consumer tissues. Therefore, biogeochemical approaches such as fatty acid (FA) and stable isotope analyses have been developed, which provide a time-integrated measure of diet. Further, stable isotope measurements of specific FA markers can be used to identify carbon sources, and can be applied to a variety of food web studies (Iverson et al., 2004). The purpose of this research is to examine the linkages between organic carbon sources and trophic transfer by consumers. To achieve this, we use FA biomarkers and compound specific stable isotope analysis (CSIA) to trace carbon cycling. This study has two main components: environmental sampling and experimental research. Chapter 1 demonstrates the use of these tools for elucidating seasonal trophic linkages in invertebrates collected from the Alaskan Arctic coast. Overall, invertebrate diets were characterized by terrestrial, detrital, and carnivorous sources in winter and spring, with a shift toward autochthonous diatom-based diets in summer. Our results demonstrate the importance of terrestrial organic carbon as a subsistence food source in winter, whereas in situ production in summer was critical for accumulating FA stores rich in essential FAs. Chapter 2 is an experimental feeding study designed to quantify the incorporation rates of 18:2n-6 from diet to tissue in Atlantic croaker. Liver tissues accumulated FAs more quickly than muscle tissues, but both tissues reached equilibrium at 5 to 7 weeks. From these experiments, quantitative assessments of diet sources can be made with confidence when using FAs to understand trophic interactions of Atlantic croaker and other similar species.