Date of Award

5-2003

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Food Science and Human Nutrition

Advisor

Richard A. Cook

Second Committee Member

Alfred A. Bushway

Third Committee Member

Rodney J. Bushway

Abstract

Increased fruit and vegetable consumption is the single most protective characteristic of a diet against disease. While the exact mechanism by which this protection is offered remains unclear, the leading theory is centered on the antioxidant content of fruits and vegetables. Recent studies have shown that certain fruits and vegetables have significantly higher antioxidant contents than others. Wild North American blueberries (Vaccinium angustifolium) have one of the highest antioxidant contents of all h i t s and vegetables tested. This thesis investigates the relationship between the consumption of blueberries and blood antioxidant levels in 24 elderly women. In addition, fruits and vegetables with similar Oxygen Radical Absorbance Capacity (ORAC) were grouped together in the development of an ORAC-based food frequency questionnaire. Twenty-four, independently living women, over the age of 60, were recruited from a fitness center. These women were randomly assigned to either a control group (n=12) or a blueberry-consuming group (n=12). Dietary data was collected via an interviewer assisted Tufts Food Frequency Questionnaire. Baseline blood antioxidant tests were collected on the morning before the blueberry-consuming group was given their 30 day supply of frozen wild North American blueberries. Blood antioxidant tests included total lymphocyte antioxidant content (Spectrox®), plasma ORAC with protein, non-protein plasma ORAC (ORAC ac), and Ferric-Reducing Ability of Plasma (FRAP). In addition, bilirubin and uric acid analyses were performed as methods of identifying contributing antioxidant characteristics. Immediately following the consumption of one cup of blueberries each day for 30 days, all blood tests were repeated. Those women assigned to the blueberry consuming group experienced both a significant increase in overall FRAP scores (+28 uM Trolox equivalentdml, @.036) as well as a significant increase in non-protein plasma ORAC scores (+234.5 uM Trolox equivalentsImL, @.048), with no significant changes observed in the control group. Additionally, women assigned to the control group experienced a significant decline in plasma ORAC scores (-1 153 uM Trolox equivalent/ml, p=0.038), with no concomitant changes in the blueberry consuming group. Absence of increases in plasma uric acid and bilirubin levels among both groups showed no antioxidant interference from this parameter, as further validation that the increases were due to the antioxidants coming from the blueberries.

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