This is an older study but it was interesting information nonetheless.
The research conducted suggests that organic foods are naturally higher in anti-oxidants than non-organic foods. Tests on different vegetables and fruits showed higher anti-oxidant compounds compared to the same non-organic fruit or vegetable. This is in addition to finding lower levels of toxic metals and pesticides in organic foods versus non-organic foods. The increase in anti-oxidants is equal to about 1 or 2 more servings of fruit or vegetables. Amazing!
However, there is still no clear reason as to why this is true. Some believe that pesticides cause plants to produce less anti-oxidants, which are a natural defense against pest attacks. Others believe that the lack of artificial fertilizers cause organic plants to be "tougher" through natural selection.
Overall, a person's health is more about his or her nutritional intake and not just about organic foods. You can eat a ton of organic foods but lack the overall nutrition you need for a healthy diet. Sorry, but a bowl of organic chocolate covered blueberries is still not as healthy as a bowl of organic broccoli. Organic nuts are obviously great for you too!
Here's the article if you'd like to read more: