Date of Award

12-2011

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

Rodney Bushway

Third Committee Member

Armand Cardello

Abstract

The aim of this study was to determine the ability of cranberry phenolics to influence postprandial glycemia and satiety in overweight humans. Anthocyanins and tannins have been shown to inhibit the digestive enzymes responsible for carbohydrate digestion. This inhibition may improve postprandial glycemia, as well as prolong satiety. A randomized cross-over double-blinded study was performed using 24 overweight participants (body mass index 25-29.9 kg/m2) between the ages of 25 and 50 years. Participants were provided a standard meal of cornflakes, milk, toast, butter and a banana after an overnight fast. Cranberry juice treatments included two concentrations of cranberry juice, 27% and 54%. Each treatment had a placebo specifically designed to match its physical and chemical properties with the exception of phenolic compounds; all drinks were of equivalent in volume and calories. Blood samples were collected from subjects at 0,15, 30, 45, 60, 90, 120,150, and 180 minutes. Serum samples were analyzed for glucose, insulin, leptin ghrelin and ORAC values. After 4 hours, subjects were provided with lunch and additional servings could be requested. Satiety was measured using a 200 mm SLIM scale at 0, 15, 30, 45, 60, 90, 120, 150,180, 210, 240 and 270 minutes. Meal acceptability was rated on a 9 point hedonic scale in SIMS 2000. Area under the curve values were calculated for all serum and satiety measurements. Results were analyzed using SYSTAT analytical software; General Linear Modeling was used to detect differences at each measurement among beverage treatments. Participants were secondarily grouped into two groups based on their fasting glucose levels: low and high (100, respectively). The results of this study showed that cranberry juice was able to significantly reduce postprandial glycemia in both groups. No significant differences were shown in serum insulin between treatments. The 27% CJ was able to significantly increase serum leptin at several time points. No significant differences were observed in satiety between treatments and placebos. Meal acceptability revealed significant differences during the lunch meal, but not during the breakfast meal. This study was subject to large standard deviations, despite efforts to account for differences among sub-groups. It is apparent that the BMI classification "overweight" represents a metabolically diverse group; this variability in metabolic response increased standard deviations. Additional human research is necessary to evaluate peak dose efficiency and the practical implications of this inhibition.

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