The bittersweet story of aspartame

The serendipitous discovery of aspartame gave us a sugar substitute that is now used in foods and beverages. Despite being a popular artificial sweetener, aspartame continues to divide opinion. A.S.Ganesh explains aspartame’s discovery and the reasons behind why a cloud surrounds it constantly...

January 28, 2019 10:50 am | Updated November 10, 2021 12:18 pm IST

Image of sugar used for illustrative purposes only.

Image of sugar used for illustrative purposes only.

Have you seen elders in your house drop a small white tablet-like thing into their hot beverages in the morning? Found either this way as small tablets or in a sugar-like form in small sachets, these are artificial sweeteners that work as sugar substitutes in the piping hot cup of coffee or tea that the elders at the house drink to begin their day.

Not just hot drinks, artificial sweeteners have found their way into our lives through a myriad of food and beverages. Aspartame is one of the more popular ones these days, but it does come with its fair share of criticisms.

Search for anti-ulcer drug

The discovery of aspartame, a dipeptide protein containing two amino acids with the chemical formula C14H18N2O5, takes us back to 1965. James M. Schlatter, an American chemist and researcher working at a pharma company G. D. Searle, was tasked at that time with developing an anti-ulcer drug.

This involved synthesising tetrapeptide proteins, the likes of which are found in the stomach lining, to test the anti-ulcer drugs. During the synthesis, Schlatter inadvertently contaminated the tip of his index finger with a dipeptide that happened to be one of the intermediate steps.

Lucky lick

The story goes that Schlatter licked his finger later that day when he had to turn a page in a book that got stuck, or pick up a piece of paper that was lying around. Schlatter first wondered if the sweet taste was due to a donut he had had earlier in the day, but remembered that he had washed his hands after that.

Schlatter eventually deduced that the sweet taste belonged to the compound he had been working on. The dipeptide that had been produced during one of the intermediate steps of the synthesis turned out to be aspartame.

Sweeter than sugar

Confident that the dipeptide was safe, Schlatter and his lab partner tested some of the aspartame in their coffee and were quick to realise its potential as an artificial sweetener. Schlatter reported his discovery to his bosses and G.D. Searle sensed the commercial capability of the super sweet substance in their hands. They applied for their patent – Peptide sweetening agent – and received the same on January 27, 1970.

Aspartame is about 180 times sweeter than sugars such as sucrose at a fraction of the calorific equivalent. This might lead you to believe that the discovery would have been fast-tracked to a commercial product, but it wasn’t the case due to the time it took for regulatory approval from the U.S. Food and Drug Administration.

Is it safe?

Aspartame was investigated time and again through the 1970s to find out if it was safe to be consumed. It didn’t help that an individual study on rats revealed a possible link between aspartame and brain damage – a result that was later overturned when further investigation highlighted statistical flaws in this work. Even though several other tests stated that aspartame was safe, the damage had been done by then, providing enough fodder for the anti-aspartame camp and innumerable internet hoaxers.

Breaking down aspartame

Some in the anti-aspartame camp believed that the derivatives from aspartame could be harmful and pointed to it as a source of danger. Aspartame consists of two amino acids with an extra carbon atom stuck on one end and it breaks down completely into these components in the small intestine.

Aspartic acid and phenylalanine are the two amino acids that break-free from aspartame, and amino acids are generally perceived as the building blocks of life. The phenylalanine, however, could be dangerous to a small subset of the population having a rare genetic deficiency called phenylketonuria. For those with this disease, phenylalanine build-up can lead to brain damage and a warning label to this effect hence appears in substances containing aspartame.

The lone carbon atom, meanwhile, disengages from the amino acids and forms a single molecule of methanol. While methanol could prove toxic even if consumed in small amounts, the trace quantities that come from the breakdown of aspartame is comparable to that obtained from many natural foods.

All this meant that it was eventually only in the 1980s that aspartame received the nod to be sold to the public as an artificial sweetener. Even though it is now one of the most highly tested food additives of all time and is very popular as an artificial sweetener in foods and beverages, the debate surrounding the long-term safety of aspartame consumption continues to rage on.

Top News Today

Sign in to unlock member-only benefits!
  • Access 10 free stories every month
  • Save stories to read later
  • Access to comment on every story
  • Sign-up/manage your newsletter subscriptions with a single click
  • Get notified by email for early access to discounts & offers on our products
Sign in


Comments have to be in English, and in full sentences. They cannot be abusive or personal. Please abide by our community guidelines for posting your comments.

We have migrated to a new commenting platform. If you are already a registered user of The Hindu and logged in, you may continue to engage with our articles. If you do not have an account please register and login to post comments. Users can access their older comments by logging into their accounts on Vuukle.