Submitted to: Journal of American College of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2006
Publication Date: 4/15/2007
Citation: Prior, R.L., Wu, X., Gu, L., Jacob, R.A., Cao, G., Cook, R.A. 2007. Plasma antioxidant capacity changes following a meal as a measure of the ability of a food to alter in vivo antioxidant status. Journal of American College of Nutrition. 26(2):170-171.
Interpretive Summary: Fruits may provide more health benefits that just the vitamins and other nutrients they contain. This is because there are other "dietary factors", called phytochemicals that may positively affect cell function. One aspect of these phytochemicals is prevention of damaging oxidative processes which is a important component in the initiation of cardiovascular disease, some cancers and other chronic degenerative diseases. Compounds that prevent oxidation are antioxidants. These studies were undertaken to better understand how diet might increase in vivo antioxidant status and thereby prevent some of these oxidative processes. Berries and some other fruits (blueberry, dried plum, dried plum juice, grape, cherry, kiwi and strawberry) have been shown to increase the potential to prevent oxidation. It is important to know which foods can increase the antioxidant levels in people. We measured changes in antioxidants in the blood and found that a meal from dried plums or dried plum juice did not alter blood level of antioxidants; whereas, consumption of high doses of blueberries or grapes increased the antioxidants in blood. These results indicate a potential for increasing antioxidants by eating fruits, however it remains to be seen if this translates into a decreased risk of chronic degenerative disease.
Technical Abstract: The change in antioxidant capacity in plasma following consumption of various berries and fruits (blueberry, dried plum, dried plum juice, grape, cherry, kiwi and strawberry) following a single meal was studied in 5 different clinical trials. The area under the curve (AUC) of the change from baseline in hydrophilic or lipophilic antioxidant capacity (Oxygen Radical Absorbance Capacity: ORACFL) was calculated for each subject. In two studies, the control meal contained additional macronutrients (carbohydrate, fat, protein), and the same level of macronutrients was calculated for the particular berry or fruit treatment. Intake of 6.7 or 10.8 mmoles TE of antioxidant capacity (AOC) measured as ORACFL from dried plums or dried plum juice did not alter the hydrophilic or lipophilic AOC AUC. Intake of 12.5 or 39.9 mmoles TE of AOC from blueberry in 2 different studies increased the hydrophilic AOC AUC. Lipophilic AOC following the meal of 12.5 mmole TE AOC from blueberry also increased. Consumption of a meal of grape powder (8.6 mmole TE AOC) increased hydrophilic AOC AUC. The control group in the 2 studies in which additional micronutrients (carbohydrate, fat and protein) were provided decreased from the baseline measurement. Consumption of 280 g of cherries caused an increase in plasma lipophilic AOC but a decrease in hydrophilic AOC compared to the baseline value before the meal. An increased plasma antioxidant capacity in the postprandial state was observed with a high dose of blueberries, grapes, cherry and kiwi indicating a potential for increasing in vivo antioxidant capacity, however it remains to be seen if this translates into a decreased risk of chronic degenerative disease.