It is not the aspertame that is harmful. Aspertame is made of 2 amino adids: aspartic acid, phenylalanine and a methyl group. Other than faking out your body metabolism, probably mostly harmless in moderation. But the new Pepsi contains sucralose and ACE K or acesulfame potassium which is "generally regarded as safe" without any significant study. The few studies out there on ACE K which is also added to Nutrasweet according to my neighbor who is a chemical engineer that worked for Nutrasweet, is that it can cause cancer in p53 haplodefficient mice. Also, Diet Pepsi contains the preservative Sodium Benozate which is a potent D-aminoacid oxidase inhibitor which interferes with sulfur metabolism which is behind the constilation of diabetes, dimentia, chronic and inflammatory diseases.