However, it's important to note that the people observed in the new study were only 50 to 69 years old. In contrast, the Italian researchers allowed the rats to die a natural death, equivalent to people living into their 80s, 90s, or older. If aspartame only causes cancer in truly elderly people, the new study wouldn't detect a problem. Also, the new study's means of measuring aspartame consumption -- food-frequency questionnaires -- is imprecise. That approach is not capable of detecting small increases in cancer rates.