They are often used in soft drinks such as cola and food labelled as "diet".
Due to health reasons, primarily to lose weight, some people have to control their caloric intake by substituting sugar with other sweetener with little or no calories. Others such as diabetics must limit their consumption of sugar.
Some sweeteners, such as sorbitol, are used instead of sugar, not because they lack calories, but because they don't promote tooth decay or because they have advantages for people with diabetes in that they are metabolized more slowly than sugar and hence cause blood sugar levels to remain more stable.
People using sweeteners instead of sugar take the risk of replacing one health problem with a different one. For example, saccharin is shown to be a carcinogen to lab animals when taken in high quantities, while aspartame is an alleged neurotoxin in high quantities. The U.S. Food and Drug Administration determined in 1981 that aspartame is safe to use in foods. It has also ruled that all products containing aspartame must include a warning to phenylketonurics that the sweetener contains phenylalanine, and continues to review complaints alleging adverse reactions to products that contain aspartame.