The new National Cancer Institute study significantly allays concerns raised by a recent Italian study that found that modest amounts of aspartame caused cancer in rats.

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.