"Natural"...sounds innocent enough, right?
Here's what the US Code of Federal Regulations says about "natural flavors":
the essential oil, oleoresin, essence or extractive, protein hydrolysate, distillate, or any product of roasting, heating or enzymolysis, which contains the flavoring constituents derived from a spice, fruit or fruit juice, vegetable or vegetable juice, edible yeast, herb, bark, bud, root, leaf or any other edible portions of a plant, meat, seafood, poultry, eggs, dairy products, or fermentation products thereof, whose primary function in food is flavoring rather than nutritional.
In English: Start with something only nominally edible (like bark), do pretty much whatever you want to it, and call it a "natural flavor".
I would claim that there's nothing natural about hydrolyzed soy protein, for instance. And I don't want it in my food.
Calling these things "natural flavors" is a deliberately misleading move on the part of food processing companies. It allows them to sell us cheap food, synthesized in a factory, not grown on a farm.
It's not always easy to make your own food from scratch, but it's always worth it.