It is 160 times sweeter than sugar (sucrose), and is marketed under a number of trademarked names, such as "NutraSweet" and "Canderel". It is a common sweetener in foods, particularly soft drinks. Because phenylalanine is part of its composition, and is deleterious to sufferers of the genetic disorder phenylketonuria, products containing aspartame usually have a warning label that they contain phenylalanine.
One of the (many) hypotheses about the causes of Gulf War Syndrome is that the soldiers, drinking huge quantities of fluids in the extreme heat, accumulated toxic doses of methanol from the breakdown of aspartame into its component molecules. However, the symptoms do not greatly resemble those of classic methanol poisoning, and the body, in its normal metabolism, produces methanol quantities comparable or greater than would be ingested via aspartame, so this theory does not have wide support.