Home > RESEARCH > Vitamins & Antioxidants > Fruit protects against oxidative damage; vitamin C alone shows no effect

Fruit protects against oxidative damage; vitamin C alone shows no effect   In this featured study, a team of researchers at the University of Milan turned their attention to the broadly studied benefits of oranges and their food compound derivatives. The study's objective was to determine whether or not whole foods increase cellular resistance to DNA damage as compared to single compounds, such as vitamin C alone.   In the first phase of the experimental design, blood plasma concentrations of vitamin C were measured following consumption of three beverages: blood orange juice (providing 150 mg of bioavailable vitamin C), water supplemented with vitamin C alone (150 mg) and a water/sugar solution. Vitamin C concentrations were measured at baseline, then again at one hour intervals thereafter. Blood plasma concentrations reached a similar peak at 2-3 hours, in both beverages containing vitamin C. No statistical difference in absorption between the blood orange juice (BOJ) and fortified water was noted throughout the experiment; the results suggest the human physiology readily absorbs whole foods and single compounds equally. However, Guarnieri et al noted a measurable difference in utilization.   In order to measure the potential difference in cellular capacity to utilize the two sources of vitamin C - BOJ and fortified water - zero hour, 3h and 24h samples of blood plasma were exposed to hydrogen peroxide, a substance known to cause DNA damage in mononuclear blood cells (MNBC). A statistically significant increase in resistance to oxidative damage was measured in MNBC samples of test subjects who ingested the BOJ. The vitamin C fortified drink was no more effective than the sugar water solution: both had no protective effect.   Ruling out absorption as a critical factor, researchers turned to the source of the vitamin C to discuss the outcomes of their research. Because all test subjects who consumed the BOJ demonstrated benefit, the investigators speculate that food compounds, such as flavanones and carotenoids, may account for the protective effects observed. Vitamin C in fruits is delivered in a matrix of food compounds; thus, the authors propose that such compounds may act synergistically with vitamin C to confer the protective benefit. In another in vitro test, Guarnieri et al also demonstrated superior efficacy of a kiwi fruit extract over a solution of vitamin C alone.   Study: Guarnieri S., Riso P. & Porrini M. Brit. J. Nutr., 97. 639-643 (2007)

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