Once upon a time, organic food was available only at health food stores, marketed to "tree-hugging" consumers willing to pay extra for "natural," environmentally friendly foods. Today, organic foods are undeniably mainstream. Not only can they be found at most every neighborhood grocer, but even giants like Wal-Mart are getting into the act.

People who buy organic are seeking assurance that food production is gentle to the earth, and/or looking for safer, purer, more natural foods. But are organic foods really worth the added expense?