The FDA does not regulate "All Natural" but if you are a large company and lie your name will be smeared and you'll end up changing it with a possible lawsuit. Naked Juice anyone?
Xanthan is natural, sodium benzoate is synthetic. Yes if you wiki it, it says it comes from some berry, but that was 100 years ago, nowadays it is synthesized in a lab, same as potassium sorbate, and a bunch of others.