From the L.A. Times:

Organic produce is more expensive than the conventional variety, and there are many reasons why consumers fork over that extra money. But if one of those reasons is a belief that organic fruits and veggies are healthier, Danish researchers have some bad news.

A detailed scientific assessment of carrots, potatoes and onions – some grown conventionally and some grown organically – found that all of the veggies had essentially the same levels of flavonoids and phenolic acids, two types of nutrients that are thought to be helpful in preventing ailments such as heart disease, cancer and dementia.

Organic vegetables don't have extra nutrients, researchers say