Date of Award

8-2009

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Food Science and Human Nutrition

Advisor

Mary Ellen Camire

Second Committee Member

Alfred A. Bushway

Third Committee Member

Richard A. Cook

Abstract

The prevalence of type 2 diabetes and obesity is increasing in the United States and other nations. Highly digestible carbohydrates may promote a high glycemic response, possibly contributing to obesity-related diseases. Anthocyanins have been found to exert in vitro a-glucosidase inhibitory effect, suggesting that foods containing anthocyanins may improve glycemic control. Wild Maine lowbush blueberries, Vaccinium angustifolium Ait., are a rich source of anthocyanins and contain 6 grams of dietary fiber and 45 kcal per 140 grams. The objective of this study was to evaluate the effect of wild blueberries and their juice on post-prandial serum glucose and satiety. A randomized cross-over blinded study was conducted using 11 overweight (body mass index (BMI) 25-29.9 kg/m2) and 10 normal weight (BMI 18.5-24.9 kg/m2) subjects who were 25-50 years old. Subjects were provided a base meal of cornflakes, milk and orange juice after an overnight fast. Four meal types were tested. One treatment included one cup (140g) of lowbush wild Maine blueberries; another had 112 mL of 100% wild blueberry juice. A placebo beverage mimicked the equivalent volume, acidity, and sugars to that of blueberry juice, was the third treatment, and lastly, a control meal with added glucose and fructose to match the amount in the berry meal. All meals as well as the control were adjusted to provide the same amount of carbohydrates, simple sugars, and calories. Fasting serum triglycerides and glucose were measured at baseline, and at 30, 60, 90, and 120 minutes. Serum insulin was measured at baseline, 30 and 60 minutes. Serum triglycerides and glucose was evaluated with the Beckman clinical analyzer, while serum insulin was determined with a FLUOstar Omega plate reader. Satiety was measured utilizing a visual analog scale (VAS) at baseline, 15, 30, 45, 60, 90, 120, and 180 minutes. After each intervention, participants kept food journals for the remainder of the day. Area under the curve was evaluated for overall changes in satiety responses. Results were analyzed using SYSTAT analytical software. A repeated measure General Linear Model was utilized for analysis of control and treatment groups. Test meals had no effect on serum glucose levels, insulin, triglycerides, or energy intake. Satiety responses differed among subjects with overweight and normal BMIs. Overweight subjects were more satisfied (P=0.05) and full (P=0.002) when compared to their lower BMI counterparts throughout all treatments. More human research is needed in order to evaluate the mechanisms by which anthocyanins may affect glycemic control, as well as to determine optimal dose efficacy.

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