Aspartame is a low-calorie sweetener which is used to sweeten a variety of foods and beverages, and as a tabletop sweetener. Since aspartame is about 200 times sweeter than sugar, very little is needed to adequately sweeten foods. Consequently, the calories in foods can be substantially reduced, and in many products be almost eliminated, by using aspartame in place of sugar

Aspartame is made by joining two protein components, aspartic acid and phenylalanine, and a small amount of methanol. Aspartic acid and phenylalanine are building blocks of protein and are found naturally in all protein-containing foods, including meats, grains and dairy products. Methanol is found naturally in the body and in many foods such as fruit and vegetable juices. Aspartame is digested just like any other protein. Upon digestion, aspartame breaks down into its basic components and is absorbed into the blood. Neither aspartame nor its components accumulate in the body over time. Aspartame is broken down in the body to the amino acids aspartic acid and phenylalanine as well as a small amount of methanol. These components are also found naturally in foods such as meats, milk, fruits and vegetables. The body uses these components in exactly the same way whether they come from aspartame or common foods. In fact, the foods you consume every day provide much greater amounts of these components than does aspartame.

Aspartame is marketed as table sweetener. It is also incorporated in a number of foodstuffs throughout the world, including drinks, desserts and sweets. It is a white, odourless powder, approximately 200 times sweeter than sugar, manufactured by combining phenylalanine and aspartic acid. Its main impurity is diketopiperazine that has no sweetening properties.

Aspartame is stable in the dry state and in frozen products. However, when stored in liquids at more than 30°C, it progressively converts into diketopiperazine, which is partially degraded into methanol, aspartic acid and phenylalanine. These transformations result in the loss of sweetness. Therefore, aspartame can not be used in cooked or sterilized foods.