"Organic farming methods have increased antioxidant levels in some cases by over 300 percent. On average, across 7 studies that reported direct comparisons of the levels of antioxidants in conventional and organic foods, levels in organic food averaged about 1/3 higher.", Dr Charles Benbrook for the U.S. Organic Center , January 2005
"Organically grown plants display higher levels of antioxidants because they are grown without the added protection of synthetic pesticides and therefore suffer more stress.
Organic culture works to feed the soil, which gives plants the necessary nutrients with which to "heal" themselves when presented with this added stress. Emphasis is placed on soil nutrition rather than simply using a pesticide to remedy problems.
The Journal of Agriculture and Food Chemistry (2003), February agrees "that good soil nutrition appears to increase levels of natural compounds that have anti-cancer, immune boosting and anti-aging properties." Brightly colored fruits and vegetables, such as tomatoes, blueberries, red cabbage, strawberries, plums, broccoli, watercress, red grapes, kale and spinach tend to accumulate the highest levels of antioxidants. It also happens to be where many systemic pesticides tend to build up. Peeling the skin on conventionally grown produce may perhaps reduce your risk of chemical exposure somewhat, however it also reduces the amount of disease fighting antioxidants you consume."
Source: Economii.com, Yahoo