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- Genre: Academic theses
- Creators: Johnston, Carol
- Status: Published
Description
Background: Vegan and vegetarian diets have gained in popularity in recent years. Stated reasons for this include some possible health benefits and concerns of animal welfare. Though considered to be nutritionally adequate, questions remain over whether current protein recommendations of 0.8 g/kg/d are sufficient to maintain body processes and growth. Protein is unique in that it is the only macronutrient that contains nitrogen. Its status can be determined through nitrogen balance analysis of the urine if protein content of the diet is known. Nitrogen balance is considered the gold standard for determining protein intake requirements. A negative balance indicates a catabolic state, whereas a positive nitrogen balance is seen during anabolism. In healthy people, nitrogen equilibrium is desired under normal circumstances. This equilibrium reflects the net synthesis and breakdown of proteins. While nitrogen balance techniques have been used for decades, currently, there are no known studies measuring nitrogen balance and protein intake in strict vegans. Methods: Twenty vegan, inactive, male participants were recruited and received a 5-day eucaloric diet with a known protein content held constant at 0.8 g/kg/d. On day five, 24-hour urine was collected by participants and aliquoted for future analysis. Nitrogen content of the urine was determined through photometric assay and compared to the known nitrogen content of the diet to calculate nitrogen balance status.
Results: Mean absolute nitrogen balance (-1.38 ± 1.22 g/d, effect size = -1.13) was significantly lower than zero (equilibrium) (p < .001). Mean relative nitrogen balance (-18.60 ± 16.96 mg/kg/d, effect size = -1.10) was significantly lower than zero (p < .001). There were no correlations seen between nitrogen balance and age, years as vegan, or fat- free mass.
Conclusion: Consuming 0.8 g/kg/d of protein is insufficient to produce nitrogen balance in long-term vegans.
ContributorsBartholomae, Eric (Author) / Johnston, Carol (Thesis advisor) / Sweazea, Karen (Committee member) / Wharton, Christopher (Committee member) / Lee, Chong (Committee member) / Kressler, Jochen (Committee member) / Arizona State University (Publisher)
Created2022
Description
Birds have the highest blood glucose concentrations of all vertebrates. Meanwhile, birds do not develop the same physiological complications (e.g., increased oxidative stress and glycation) that mammals do when blood glucose is elevated (i.e., diabetes). Therefore, birds may serve as a negative model animal for hyperglycemic complications. The physiological reason for high blood glucose in birds remains largely unknown although several unique characteristics of birds may contribute including a lack of the insulin responsive glucose transport protein, relatively high glucagon concentrations, as well as reliance on fatty acids to sustain the high energetic demands of flight. In breaking down triglycerides for energy, glycerol is liberated, which can be converted to glucose through a process called gluconeogenesis. In addition, the extent to which birds maintain homeostatic control over blood glucose in response to extreme dietary interventions remains unclear and few dietary studies have been conducted in wild-caught birds. Using Mourning Doves (Zenaida macroura) as a model organism, this dissertation tests four hypotheses: 1) Gluconeogenesis contributes to high circulating blood glucose concentration; 2-4) similar to mammals, a fully refined carbohydrate (i.e., white bread diet); a high saturated fat diet (60% kcal from fat); and an urban-type diet comprised of a 1:1 ratio of French fries and birds seed will increase blood glucose compared to a nutritionally-balanced diet after a four-week duration. Contrary to the hypothesis, 150 mg/kg Metformin (which inhibits glycerol gluconeogenesis) increased blood glucose, but 300 mg/kg resulted in no change. However, when 2.5 mg/kg of 1,4-dideoxy-1,4-imino-D-arabinitol (DAB; a glycogenolysis inhibitor) was given with 150 mg/kg of Metformin, blood glucose was not different from the control (50 ul water). This suggests that glycerol gluconeogenesis does not contribute to the naturally high blood glucose in birds and that a low dose of Metformin may increase the rate of glycogenolysis. In addition, all three experimental diets failed to alter blood glucose compared to control diets. Collectively, these results suggest that, in addition to a negative model for diabetes complications, birds can also serve a negative model for diet-induced hyperglycemia. Future research should further examine dietary manipulation in birds while controlling for and examining different variables (e.g., species, sex, duration, diet composition, urbanization).
ContributorsBasile, Anthony Joseph (Author) / Sweazea, Karen L (Thesis advisor) / Deviche, Pierre (Committee member) / Johnston, Carol (Committee member) / Trumble, Ben (Committee member) / Parrington, Diane J (Committee member) / Arizona State University (Publisher)
Created2022
Description
Food waste is gaining considerable attention from researchers in terms of its sources, its causes, and its potential effects on the environment, economy, and population health. To date, few instruments exist that allow researchers to measure food waste at the household level in reliable ways. This study aimed to assess the reliability of a newly developed self-assessment tool to measure household food waste, among participants living in Mexico. The survey tool consisted of 11 items which ask participants (N = 22) to estimate the amount of food per category that generally gets thrown away instead of eaten in the average week. Two tests of reliability were conducted, including Cronbach's Alpha for test-retest reliability, and Intra-class Correlation for internal reliability. Results varied across food categories evaluated by individual items. Items related to fresh fruit and bread products did not show reliability when testing for internal reliability or test-retest reliability. Fresh vegetables, meat and poultry products, meat alternative products, fish and seafood products, leftovers, and shelf stable foods were shown to be reliable when testing Cronbach's alpha and ICC. However, dairy products, eggs and frozen foods were inconclusive when testing for reliability. The study suggests future testing with larger sample sizes should be conducted to demonstrate reliability of the food waste self-assessment tool.
ContributorsLeone, Bryanna (Author) / Wharton, Christopher (Thesis advisor) / Shepard, Christina (Committee member) / Johnston, Carol (Committee member) / Arizona State University (Publisher)
Created2022
Description
Background. Research suggests that non-O blood types are at an increased risk of thrombosis and related health complications in cardiovascular disease (CVD). This is due in part to higher concentrations of von Willebrand factor (VWF), an important factor involved in blood clotting. Objective. The purpose of this study was to examine the effects of a vegetarian-like diet on blood coagulation and other health parameters in adults with type A blood compared to type O blood over a four week intervention. Given the lack of previous research on blood type and diet, it was hypothesized that no difference in blood coagulation would be observed. Design. This study was a randomized, parallel arm, dietary intervention using healthy, omnivorous adults with blood types A and O. A total of 39 subjects completed the study. Subjects were randomized into two groups: a vegetarian-like diet group made up of 12 type As and 12 type Os and an omnivorous control diet group made up of 11 type As and 12 type Os. At weeks 0 and 4, fasting blood was drawn and analyzed for prothrombin time (PT), activated partial thromboplastin time (APTT), von Willebrand factor (VWF), total cholesterol, LDL, HDL, triglycerides, and CRP. In addition, subjects were weighed and filled out a FFQ at weeks 0 and 4. Results. After adhering to a vegetarian-like diet for four weeks, type Os had a significant increase in PT (+0.24±0.32 sec/ p=0.050), whereas type As saw no significant change. There was a trend of weight loss for type Os in the vegetarian-like diet group (-1.8±2.6 lb/ p=0.092) and significant weight loss for type As (-0.9±2.1 lb/ p=0.037). Both blood types O and A experienced significant decreases in BMI (-0.3±0.4/ p=0.092 and -0.2±0.3/ p=0.037, respectively). No change was seen in APTT, VWF, total cholesterol, LDL, HDL, triglycerides, or CRP. Conclusion. Type Os saw an increase in PT, perhaps indicating a reduction in risk of thrombosis and its related health complications. Type As were less responsive to the dietary intervention and may require more rigid dietary guidelines or a longer time on such a diet to see the benefits.
ContributorsBrown, Jennifer (Author) / Johnston, Carol (Thesis advisor) / Martin, Keith (Committee member) / Shepard, Christina (Committee member) / Arizona State University (Publisher)
Created2013
Description
The medicinal use of vinegar dates to ancient times, and empirical evidence has mounted over the past several decades supporting health benefits from vinegar ingestion, including reductions in blood glucose, blood pressure, and blood cholesterol. Additionally, although clinical trial data are mixed, there are several reports demonstrating reductions in body mass and fat mass with daily vinegar ingestion. This blinded, randomized placebo-controlled trial examined the impact of daily vinegar ingestion on anthropometric measures in healthy young adults recruited from a campus population. Participants (n=28; aged 25.8±7.0 y; body mass index [BMI] > 23 kg/m2) were stratified by age, sex, and BMI and randomly assigned to the liquid [VIN] or pill [CON] groups. VIN participants diluted 2 tablespoons of red wine vinegar (750 mg acetic acid; Pompeian Inc.) in 8-12 ounces of water to drink with food at mealtime twice daily. CON participants consumed 1 vinegar pill daily (22.5 mg acetic acid; Spring Valley). All participants provided written consent for this IRB approved trial. The study lasted four weeks, and anthropometric measurements were conducted in a fasted state at weeks 0 and 4. Study adherence varied slightly (90±17% and 100±14% for VIN and CON respectively, p=0.029); hence, adherence was controlled for in all analyses. Changes in BMI (-0.1±0.5 and +0.1±0.3 kg/m2, p=0.127) and body weight (-0.3±1.4 and +0.1±1.1 kg, p=0.158) did not differ significantly between VIN and CON groups, respectively. However, both waist circumference and percent body fat were reduced significantly for VIN participants in comparison to CON participants (-0.5±1.3 vs. +0.6±2.4 cm [p=0.026]and -0.4±0.7 vs. +0.3±1.0% [p=0.045]. Although the observed differences between groups are modest, the study was short in duration and this protocol did not apply energy restriction or exercise interventions, suggesting a possible benefit of vinegar ingestion on adiposity.
ContributorsMeyer, Lexie Rae (Author) / Johnston, Carol (Thesis advisor) / Alexon, Christy (Committee member) / Grant, Shauna (Committee member) / Arizona State University (Publisher)
Created2024