The link: Calorie watchers scored a win when diet sodas were introduced in the early 1950s. Then lab studies suggested that the sweetener cyclamate caused bladder cancer in rats, and the U.S. Food and Drug Administration banned its use. Then saccharin, the replacement of choice, was also shown to cause tumors in rats. Although saccharin was never banned, all products containing the sweetener were required to carry a cancer warning on their packaging.
The reality: No evidence has since emerged that either cyclamate, which is used in other countries, or saccharin causes cancer in humans, according to the National Cancer Institute. Although cyclamate is still banned, saccharin was taken off the government's list of possible carcinogens in 2000, the same year in which saccharin products shed the warning label. The sweetener aspartame has come under suspicion, but scientists have found no increased risk of cancer in humans.