Bagged salad greens: healthy or not?

Those pre-packaged salads on produce shelves provide an easy way to get your daily serving of leafy greens. But does the convenience of bag-to-bite come at a price?

To find out how the processing of produce may affect its nutrient content, CNN consulted Mario G. Ferruzzi, a professor in the Department of Food, Bioprocessing and Nutrition Sciences at North Carolina State University.

Bagged greens are often pre-washed. But washing, which is intended to clean produce, can also damage plant tissues and expose them to oxygen dissolved in the washing water. This can cause a loss of vitamins that are water-soluble and sensitive to oxygen, such as vitamin C and the B vitamin folate.

Still, Ferruzzi said that companies are "doing it in a way to maximize quality, and this can minimize losses" and that there is still a lot of nutrition left in the leaves after they are washed.

Interestingly, chopping may actually increase the amount of beneficial compounds known as polyphenols: plant chemicals with antioxidant properties that may help protect against the development of cancers, cardiovascular diseases, diabetes, osteoporosis and neurodegenerative diseases. "When damaged, plant tissues have the ability to release more polyphenols as a stress response," Ferruzzi said.

Read more at CNN (Lisa Drayer)