One truly compelling case study that shows this all too well was done by a private citizen named Victoria Inness-Brown. She decided to perform her own aspartame experiment on 108 rats over a period of 2 years and 8 months.

Daily, she fed some of the rats the equivalent (for their body weight) of two-thirds the aspartame contained in 8-oz of diet soda. Thirty-seven percent of the females fed aspartame developed tumors, some of massive size.