DEAR DOCTOR K: Most nutrition advice starts with "avoid processed foods." What exactly are processed foods? Are they all bad for you?
DEAR READER: A processed food is any food that has been changed in some way from its original state. Processing includes canning, cooking, freezing, dehydration or milling. As you say, nutrition gurus often urge us to spurn processed foods. I spoke with Stacey Nelson, a registered dietitian and manager of clinical nutrition at Harvard-affiliated Massachusetts General Hospital. She noted that most food needs to go through some degree of processing in order to make it edible and digestible.