Theses and Dissertations
This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students.
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- All Subjects: Glycemic index
- Creators: Johnston, Carol
Description
Background: Obesity is considered one of the most serious public health issues worldwide. Small, feasible lifestyle changes are necessary to obtain and maintain weight loss. Clinical evidence is inconclusive about whether meal preloading is an example of a small change that could potentially increase the likelihood of weight loss and weight maintenance. Objective: The aim of this study is to determine if consuming 23 grams of peanuts, as a meal preload, before a carbohydrate-rich meal will lower post prandial glycemia and insulinemia and increase satiety in the 2 hour period after a carbohydrate-rich meal. Design: 15 healthy, non-diabetic adults without any known peanut or tree nut allergies were recruited from a campus community. A randomized, 3x3 block crossover design was used. The day prior to testing participants refrained from vigorous activity and consumed a standard dinner meal followed by a 10 hour fast. Participants reported to the test site in the fasted state to complete one of three treatment meals: control (CON), peanut (NUT), or grain bar (BAR) followed one hour later by a carbohydrate-rich meal. Satiety, glucose and insulin were measured at different time points throughout the visit. Each participant had a one-week washout period between visits. Results: Glucose curves varied between treatments (p=.023). Blood glucose was significantly higher one hour after ingestion of the grain bar compared to the peanut and control treatments (p<.001). At 30 minutes after the meal, the control glucose was significantly higher than for the peanut or grain bar (p=.048). Insulin did vary significantly between treatments (p<.001). The insulin change one hour after grain bar consumption was significantly higher than after the peanut or control at the same time point (p<.001). The change in insulin one hour after peanut consumption was significantly higher than for the control treatment (p=.002). Overall satiety, expressed as the 180 minute AUC, differed significantly between treatments (p=.001). One hour after preload consumption, peanut and bar consumption was associated with greater satiety than the water control (p<.001). At 30 minutes post-meal, the grain bar was associated with greater satiety versus the water control (p=.049). The bar was also associated with greater satiety versus peanut and control at 60 and 90 minutes post-meal (p=.003 and .034, respectively). At 120 minutes post-meal, the final satiety measurement, the bar was still associated with greater satiety than the peanut preload (p=.023). Total energy intake, including test meal, on treatment days did not differ significantly between treatment (p=.233). Conclusions: Overall satiety, blood glucose and blood insulin levels differed at different time points depending on treatment. Both meal preloads increased overall satiety. However, grain bar ingestion resulted in sustained satiety, greater than the peanut preload. Grain bar ingestion resulted in an immediate glycemic and insulinemic response. However, the response was not sustained after the test meal was ingested. The results of this study suggest that a low-energy, carbohydrate-rich meal preload may have a positive impact on weight maintenance and weight loss by initiating a sustained increase in overall satiety. More research is needed to confirm these findings.
ContributorsFleming, Katie R (Author) / Johnston, Carol (Thesis advisor) / Wharton, Christopher (Christopher Mack), 1977- (Committee member) / Shepard, Christina (Committee member) / Arizona State University (Publisher)
Created2012
Description
ABSTRACT This randomized, controlled, double-blind crossover study examined the effects of a preprandial, 20g oral dose of apple cider vinegar (ACV) on colonic fermentation and glycemia in a normal population, with the ultimate intention of identifying the mechanisms by which vinegar has been shown to reduce postprandial glycemia and insulinemia. Fifteen male and female subjects were recruited, ages 20-60y, who had no prior history of gastrointestinal (GI) disease or resections impacting normal GI function, were non-smokers, were non-vegetarian/vegan, were not taking any medications known to alter (glucose) metabolism, and were free of chronic disease including diabetes. Subjects were instructed to avoid exercise, alcohol and smoking the day prior to their trials and to consume a standardized, high-carbohydrate dinner meal the eve prior. There was a one-week washout period per subject between appointments. Breath hydrogen, serum insulin and capillary glucose were assessed over 3 hours after a high-starch breakfast meal to evaluate the impact of preprandial supplementation with ACV or placebo (water). Findings confirmed the antiglycemic effects of ACV as documented in previous studies, with significantly lower mean blood glucose concentrations observed during ACV treatment compared to the placebo at 30 min (p=0.003) and 60 min (p=0.005), and significantly higher mean blood glucose concentrations at 180 min (p=0.045) postprandial. No significant differences in insulin concentrations between treatments. No significant differences were found between treatments (p>0.05) for breath hydrogen; however, a trend was observed between the treatments at 180 min postprandial where breath hydrogen concentration was visually perceived as being higher with ACV treatment compared to the placebo. Therefore, this study failed to support the hypothesis that preprandial ACV ingestion produces a higher rate of colonic fermentation within a 3 hour time period following a high-carbohydrate meal. Due to variations in experiment duration noted in other literature, an additional study of similar nature with an expanded specimen collections period, well beyond 3 hours, is warranted.
ContributorsMedved, Emily M (Author) / Johnston, Carol (Thesis advisor) / Sweazea, Karen (Committee member) / Shepard, Christina (Committee member) / Arizona State University (Publisher)
Created2012
Description
Background: Individuals in the general populations with a known gluten disorder is believed to be 6% and it is unclear why the gluten free diet (GFD) has risen sharply (28%) in recent years. However, science has revealed that gluten can cause colonic changes in those undiagnosed with a known gluten disorder. The ramifications of these changes are unknown. Three common ingredients found in gluten free products, such as pasta, are corn quinoa and rice. Evidence from the scientific literature has shown that corn and quinoa can produce more colonic hydrogen than refined wheat and rice, indicating that corn and quinoa have a reduced glycemic effect. Since rice and wheat have similar glycemic responses, corn and quinoa pastas would be expected to have a lower glycemic response than rice and wheat pasta
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Aim The aim of his study was to examine the glycemic response to three different types of pasta: wheat, rice and corn. Breath hydrogen, assessment of mood states, blood glucose and insulin were collected after ingestion of these pastas to determine the glycemic effects of these foods.
Methods: A double blinded crossover study design was utilized on a group of healthy individuals, and the test meals of wheat, rice and combinations of rice/corn, and corn/quinoa pastas were consumed one week apart in random order. Collections of fasting venous blood samples for insulin analysis, capillary blood from a finger stick for glucose analysis, breath hydrogen samples and satiety scales were used for glycemic response and mood states were collected prior to the meal (baseline) and then again after ingestion of the test meals. Attempts were made to explore the glycemic response of these test meals in relation to mood states.
Results: The glucose response showed no significant difference at baseline (p = .683) among all groups and no significant differences were seen post treatment at 30 minutes (p = .875). However, after 60 minutes all of the glucose concentrations began to decline except for the rice pasta which peaked at 90 minutes and the wheat pasta gave the most sustained decrease. The AUC glucose values showed no significant difference at both 120 (p=0.196) and 240 (p=0.734) minutes but with wheat pasta producing the lowest mean value. The POMS scores showed no significant differences between groups over time (p=.239) but the wheat group produced the highest score (worsening moods states).
Conclusion: These results indicate that the formulation and processing of gluten free pastas may affect the rate and absorption and the subsequent glycemic response after the consumption of these foods. Whether or not wheat contains an ingredient that slows absorption and/or negatively affects mood remains undetermined warrants future research in this area.
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Aim The aim of his study was to examine the glycemic response to three different types of pasta: wheat, rice and corn. Breath hydrogen, assessment of mood states, blood glucose and insulin were collected after ingestion of these pastas to determine the glycemic effects of these foods.
Methods: A double blinded crossover study design was utilized on a group of healthy individuals, and the test meals of wheat, rice and combinations of rice/corn, and corn/quinoa pastas were consumed one week apart in random order. Collections of fasting venous blood samples for insulin analysis, capillary blood from a finger stick for glucose analysis, breath hydrogen samples and satiety scales were used for glycemic response and mood states were collected prior to the meal (baseline) and then again after ingestion of the test meals. Attempts were made to explore the glycemic response of these test meals in relation to mood states.
Results: The glucose response showed no significant difference at baseline (p = .683) among all groups and no significant differences were seen post treatment at 30 minutes (p = .875). However, after 60 minutes all of the glucose concentrations began to decline except for the rice pasta which peaked at 90 minutes and the wheat pasta gave the most sustained decrease. The AUC glucose values showed no significant difference at both 120 (p=0.196) and 240 (p=0.734) minutes but with wheat pasta producing the lowest mean value. The POMS scores showed no significant differences between groups over time (p=.239) but the wheat group produced the highest score (worsening moods states).
Conclusion: These results indicate that the formulation and processing of gluten free pastas may affect the rate and absorption and the subsequent glycemic response after the consumption of these foods. Whether or not wheat contains an ingredient that slows absorption and/or negatively affects mood remains undetermined warrants future research in this area.
ContributorsSnyder, Darren (Author) / Johnston, Carol (Thesis advisor) / Ohri-Vachaspati, Punam (Committee member) / Lespron, Christy (Committee member) / Arizona State University (Publisher)
Created2015