Per my friend Carol's suggestion, I picked up a copy of Michael Pollan's famous book, In Defense of Food. Unfortunately I couldn't get into it, I found it little too food-jargon heavy for me. But rather than give up I went for the book on CD and...success!
It's amazing how many processed foods we eat without knowledge - try flipping over a loaf of bread at the supermarket and you'll be surprised (like I was) to find that the list of ingredients goes way beyond yeast, flour, and water.
As a new subscriber to Pollan's wisdom I've been trying to reconcile my supermarket spending and stick to foods my great-grandmother would recognize as food. A.K.A. no frozen pizzas, pre-packaged veggies, etc. It's really eye opening! Now I'm onto his next book, The Omnivore's Dilemma...