Most do not contain any calories. Even though some sweeteners, such as aspartame, contain calories, they are used in such small amounts that they add essentially no calories to foods and beverages. As a result, these sweeteners practically eliminate or substantially reduce calories in some foods and beverages such as carbonated soft drinks, light yogurt and sugar-free pudding. Aspartame tastes very similar to sucrose but is 200-times sweeter. In fact, a glass of tomato juice provides six times as much methanol as a similar amount of diet soda.
Many prepared foods contain aspartame which is also available as a tabletop sweetener.
Aspartame underwent extensive safety testing for more than a decade before the FDA concluded in 1981 that aspartame is safe for use by consumers and thus approved its use. Products made with aspartame, however, must carry a statement on the label that they contain phenylalanine. The statement is important for people with phenylketonuria, a rare hereditary disease, because they cannot properly metabolize phenylalanine. It also is 200-times sweeter than sucrose. Over 90 studies were conducted to test its safety before the FDA approved its use in 1988.