Omnivore's Dilemma. although a book about food and nutrition and the sourcing of food was highly entertaining and a fun read.  I ran across this quote from the book today and I remember when I read it in the book.  It caused me to think about how different our food is  these days.  Even innocent fruits and veggies come in a bag with added preservatives to help them stay fresh longer.    My best advice which I'm sure you have heard is to shop the perimeter of the grocery store which is where the fresh food is located and buy minimally from the central isles which is where the processed food is.   Eat fresh and whole foods.