From Nature:
If you’re in the market for an antioxidant to keep your body young and healthy, new research suggests you’d be much better off with oranges than vitamin C tablets. Although vitamin C is best known for its protection against scurvy and, possibly, the common cold, fruits rich in vitamin C are also powerful antioxidants that protect cellular DNA from being damaged by oxidation. But do vitamin C pills on their own have the same protective effect as fruit? Serena Guarnieri and a team of researchers in the Division of Human Nutrition at the University of Milan, Italy, designed a simple experiment to find out.
The team gave test subjects a single glass of blood-orange juice, vitamin-C-fortified water, or sugar water to drink. The blood-orange juice and the fortified water had 150 milligrams of vitamin C each, whereas the sugar water had none. Blood samples were taken from the test subjects 3 hours and 24 hours after their drink. Unsurprisingly, blood plasma vitamin C levels went up after drinking both the juice and the fortified water. The blood samples were then exposed to hydrogen peroxide, a substance known to cause DNA damage through oxidation. The damage was significantly less in the samples taken from volunteers who had ingested orange juice, in both the samples collected 3 hours after consumption and 24 hours after the drink. Unsurprisingly, the sugar water had no protective effect. But neither did the vitamin-C-fortified water. Vitamin C is provided in a matrix in fruits with many other beneficial substances and all of these may interact with each other.
More here.