Orange Phenolic Compound Consumption Increases Serum Antioxidant Capacity Independent of Orange Sugar and Ascorbic Acid

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Kfir Orgad and Dr. Tory Parker, Nutrition Department

Main Text

Recent scientific data has proposed that the oxidation of low density lipoproteins is the leading cause of cardiovascular disease, and thus premature death, in America. These studies have shown that people who consume more fruits and vegetables are less likely to develop cardiovascular disease as well as certain types of cancer (Lee et al., 1991; Hertog et al., 1993; van’t Veer et al., 2000). Because of this alarming statistic, fruits have been more closely scrutinized in recent research in order to understand the exact nutritional benefits that they offer. Primary emphasis has been placed on phenolic compounds found in fruits. These compounds have high antioxidant capacity in vitro, and this activity has shown great potential to protect essential physiological components like DNA, proteins, and lipids from oxidation (van’t Veer et al., 2000). The previous studies have proposed that there is a correlation between the antioxidant capacity of these compounds in vitro and the evidence provided for lowered occurrences of the conditions mentioned earlier.

We want to use the phenolic compounds in oranges that present in the highest concentrations in vitro and assess in vivo antioxidant capacity and phenolic content, thereby determining the actual level of effectiveness in the human body. These phenolic compounds are, ordered from highest concentration to lowest concentration in orange juice; hesperidin, luteolin, and naringenin. We will give our participants one of four samples; fresh squeezed orange juice, a combination of hesperidin, luteolin, and naringenin, hesperidin only, and a placebo. Our hypothesis is that the orange juice will show the highest levels of antioxidant capacity and phenolic content, the combination will show a lower antioxidant capacity and phenolic content than orange juice, hesperidin alone will show a lower antioxidant capacity and phenolic content than the combination, and the placebo will show the lowest antioxidant capacity and phenolic content.

The results obtained in the experiment show that the orange juice group had a significantly higher ORAC than the placebo group 1 hour post consumption. Additionally, the orange juice and placebo plus mixture groups were significantly higher than the placebo plus hesperidin group at hour 2. For the total phenolics assay we ran, the placebo, placebo plus hesperidin and placebo plus mixture groups were significantly higher than baseline at hour 2. For LO, there were significant decreases in area under the curve in the placebo group and the orange juice group (hours 2 and 3), and significant increases in lag time for the orange juice group (hours, 1, 2, 3) and the placebo plus mixture group (hour 2) compared to baseline. We were able to conlcude tht the placebo plus mixture group was most similar to orange juice, demonstrating that orange phenolic compounds play a role in the protective effects of orange juice against oxidation. The placebo plus mixture was also more effective than the placebo plus hesperidin, in agreement with previously published in vitro ORAC data on the same compound.

The main result of this experiment was proving that orange juice can have a very strong effect on fighting epidemics like cancer in terms of reducing oxidation. The findings are significant enough to show that in order to achieve a healthier lifestyle, antioxidants, like those present in orange juice need to be consumed daily due to its short term effects. This study is currently being submitted for publications in the Journal of Agricultural and Food Chemistry.

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