The FDA recommends ingesting no more than 50 milligrams of aspartame per kilogram of body weight every day. That amounts to 22 cans of diet soda for a 175-pound man, and 15 cans for a 120-pound woman. If you're putting two packets of artificial sugar into coffee, that would be about 116 cups of coffee for the man in this example, and 79 cups for the woman.

"I really think that if you are consuming five or six cans a day, you may have more problems from consuming too much caffeine or acid than from the sweeteners," Walters said.

*Eric Walters -- Ph.D. in Medicinal Chemistry
Professor of Pharmaceutical Sciences
Professor of Biochemistry and Molecular Biology