I don't see a firm distinction between natural and artificial anything, as we are all part of the natural environment, and we take substances and use them in refined and processed forms, and we also bring substances together to make new compounds. There is a long tradition of people believing "natural" is inherently better, but that can be a bit of a trap. I read a good article about this the other day but it will take me a bit of time to find it again. For the purposes of this discussion, I'm thinking of artificial sweeteners as things like aspartame, cyclamate, saccharin and sucralose.