Aspartame: the sweetener discovered by licking a finger

In December 1965, James Schlatter, a chemist at G.D. Searle & Company in Skokie, Illinois, was working on a synthetic compound intended as an intermediate step in making a tetrapeptide of the hormone gastrin — part of a research program to develop an anti-ulcer drug. He had synthesised the compound, L-aspartyl-L-phenylalanine methyl ester, and was handling the powder in his laboratory. When he licked his finger to pick up a piece of paper, he noticed an intensely sweet taste.

Schlatter had discovered aspartame, an artificial sweetener about 200 times sweeter than sugar. The discovery was entirely accidental — he was not looking for a sweetener, and the compound was never intended to be tasted. Searle quickly recognised the commercial potential and began developing aspartame as a sugar substitute.

The path to market was long and controversial. The FDA initially approved aspartame in 1974, but the approval was briefly revoked in 1975 after an FDA task force raised concerns about Searle's testing practices. A Public Board of Inquiry in 1980 recommended against approval due to unanswered questions about cancer in lab rats. The FDA re-approved aspartame in 1981, and it was approved for carbonated beverages in 1983, becoming a mainstream ingredient.

Aspartame was marketed under the brand names NutraSweet and Equal. Monsanto bought G.D. Searle in 1985 and spun off the aspartame business as a separate subsidiary. Ajinomoto became the world's largest manufacturer. By 2004, the global market was 14,000 metric tons per year. A chemist who licked his finger in a laboratory had launched a multi-billion dollar industry.