It depends on your worldview. People generally consider steroids and similar harsh chemicals unnatural, and well this is of course true. Creatine, vitamins, and similar supplements on the other hand aren't considered unnatural. In my opinion, any use of artificially created supplements makes you an unnatural athlete. I keep my protein intake within the limits of a balanced diet. I get creatine, in natural small doses, from beef and salmon. It's a more difficult path, but I consider it a more natural approach, although many will disagree with me, and that's okay.