I likely would have enjoyed In Defense of Food more had I not already read several other books denouncing the processed food industry, big agribusiness, and American overeating(Pandora's Lunchbox: How Processed Food Took Over the American Meal, Salt Sugar Fat: How the Food Giants Hooked Us, The Third Plate: Field Notes on the Future of Food, Fat Land) 
 Pollan does a great job of summarizing his argument in the beginning of the book: Eat food not ingredients. If you find that statement confusing or need more facts to back up the instruction, read the following chapters. However, I don't recommend the audiobook version. I just can't disassociate Scott Brick with his reading of Chicken Head in Blade Runner. *shudder*