Who is "they?" Because I can't find anything in the medical lit about that.

Of course, if not using them improves your feeling of well-being, hey. Don't use them. :-) I avoid sugars myself because of a family history of adult diabetes. And I avoid aspartame because it tastes like crap to me. If it weren't for the occasional Splenda soda used as a mixer ... well, if I have a few too many of those it's probably not the Splenda that's the problem.