Mark, I'll let Bruce address your issue and don't worry, there is plenty of info here.
I did want to write on this aspertame issue. Be very, very careful how you interpret so called studies on these products. Quickly, I don't think any artificial product is going to be terribly good for you if you pile it down your gullet in vast quantities. As for causing AN's - well, who knows because at present, the jury is out on about 20 different possible causes including analog mobile phones to a faulty gene.
Anyway, back to the aspertame, you will find that there has never been any study published in any renowned medical journal about this stuff and its effects. The studies have been conducted by "interest groups" sort of like the cigarrette studies and the effects on lung cancer were all funded by tobacco companies - no wonder they manipulated the results acordingly for so long.
One question to ALWAYS ask with any study like the one posted by Samantha is - for all those conditions and percentages, what are the results of the same quantity of randomly selected people. This way, you have a benchmark.
I'm not saying that study was wrong, just be careful what you read and how you interpret information. There is so much out there, you just have to decipher the useful from the useless without accepting everything on face value.
cheers Laz