I don't think it's as much about avoiding as it is about emphasizing. You've heard it before: vegetables and fruit. Natural, unprocessed foods as much as possible. We recycle probably 1 can/week. Shop on the outside ring of the grocery store. Brown rice rather than white. Whole wheat bread rather than white. De-emphasize meat. Buy organic. Avoid alcohol. All that stuff. Some of that is avoiding things that are definitely bad for you, such as pesticides, and some of it is getting things that are good for you, like micronutrients. It makes a difference. Because of that, it's what the pros do.