The Effect of Moderate Consumption of Non-Nutritive Sweeteners on Glucose Tolerance and Body Composition in Rats
Creators: name: Tovar, Ashley Power
Publisher: name: University of Nevada, Las Vegas
Year: 2016

description: The Effect of Moderate Consumption Of Non-Nutritive Sweeteners On Glucose Tolerance And Body Composition In Rats 
by Ashley Tovar 
John C. Young, Ph.D., Examination Committee Chair Professor, Kinesiology and Nutrition Sciences University of Nevada, Las Vegas 
Introduction: A comorbidity often seen with obesity is the development of impaired glucose tolerance. Abnormalities in the ability to metabolize glucose can lead to increased risk of developing pre-diabetes and if continued, diabetes mellitus type 2. To combat the effects of excess energy intake on obesity and glucose intolerance, low- energy and non-nutritive sweeteners have been introduced as a replacement for traditional sucrose and fructose sweeteners that contribute more energy density. Limited research has been done concerning the effects of moderate consumption of nonnutritive sweeteners on blood glucose tolerance and body composition. 
Purpose: The purpose of this study was to determine the effect of moderate consumption of NNS (aspartame and sucrose) on glucose tolerance and body composition in an animal model. 
Methods: Sprague-Dawley rats (N=30) were housed in pairs in a 12 hr light/dark cycle. Animals were randomized into one of three groups where they were each fed a standard chow diet, with the inclusion of a treatment. Treatments include the addition of aspartame (8.5 mg/kg/day) or sucralose (2.6 mg/kg/day) to water, or a control of unflavored water. All animals were given food ad libitum for 6 weeks prior to testing and sacrifice. The three treatment groups were as follows (n=10) aspartame (ASP), (n=10) sucralose (SUC), and (n=10) a control of water (CON). Assessments of lean mass and fat mass were determined from weighing of epididymal fat pads and the use of dual energy x-ray absorptiometry with small animal software prior to sacrifice at the completion of the 6 week treatment. After overnight fasting, an oral glucose tolerance test was administered. Blood glucose concentrations were measured with a tail prick sample, using a Bayer blood glucose monitor. Rats were then given an oral glucose load via oral gavage of 2 mg/kg, with samples then being taken every 15, 30, 60, and 120 minutes of load with blood glucose being examined immediately. Insulin was collected from a tail bleed, with samples being stored at -70° C for later analysis. Insulin assessment was completed with the use of a radioimmunoassay for insulin sensitive rats. 
Results: Following the 6 week intervention treatment of water with aspartame (ASP), water with sucralose (SUC), or control (CON), no significant differences were seen in the results of oral glucose tolerance testing. ASP (10,150 ± 595 mg/dL/120 min, p=0.282) and SUC (9,147 ± 231 mg/dL/120 min, p=0.870) areas under the glucose concentration curve (AUC) were not significantly different from the CON group AUC (9147.85 ± 465 mg/dL/120 min). The areas under the insulin concentration curve were not significantly different between the NNS groups and the control (ASP p= 0.120, SUC p=0.456). Changes in body mass from the beginning of treatment to final were not significantly different between each of the NNS groups and the control group (ASP p= 0.787, SUC p=0.587). Epididymal fat pad mass was significantly higher in the ASP group compared with the control group (5.50 ± 0.34 g, p=0.042). 
Conclusion: No significant effect was seen from the moderate consumption of aspartame or sucralose on glucose tolerance. No significant differences were seen in weight or overall body fat. However, while percent body fat was unaffected, aspartame consumption at low doses may alter body fat distribution. These results may be of importance in preventing increased abdominal obesity.