Aspartame is a sugar substitute frequently used in products like diet soda. Unlike sugar, aspartame is a non-carbohydrate based product, so it contains virtually no calories. It is also used in very small amounts because aspartame is approximately 180 times sweeter than sugar. The product is the result of an accidental discovery in 1965 by James Schlatter, who was working on a drug to prevent ulcers. When he made aspartame from aspartic acid and phenylalanine, he noticed its sweet taste.

Unlike sugar, aspartame tends to break down when it is heated, so it does not make a good sugar substitute in baked products. At room temperature, little packets of the product used for sweetening coffee or tea have a shelf life slightly under a year. Aspartame also breaks down under high pH values in foods or liquids. In sodas, the pH is low enough to allow aspartame to stabilize for up to a month. This is one reason soda companies now frequently put an expiration date on their sodas.

Many find the taste of aspartame not equal to that of sugar. It tends to last longer in the mouth, and is sometimes called a “long sweetener.” Others enjoy the taste as evidenced by the number of diet sodas, and dietetic foods containing aspartame that are purchased by the public. Since aspartame is so sweet, only a small amount is required in recipes, which means adjusting recipes according. This is why diet drinks may have a different flavor spectrum from a non-diet drink. In addition to the substitution of aspartame, other aspects of the recipe must be adjusted to make up for the amount of sugar used.

Since the FDA approved aspartame in the 1980s, it has been controversial. Many suggest that aspartame may be indicated in increasing the risk the development of several cancers, citing studies on rats in the 1970s. However, the medical communities of Europe and America have dismissed these studies, and as recently as 2005, testing supports the safety of aspartame.

Aspartame is dangerous, however, for anyone with phenylketonuria (PKU), a disease that makes the body produce too much tyrosine when phenylalanines are ingested. Those with PKU should avoid any products that contain the sugar substitute, as they pose a significant health threat. As well, too much aspartame may cause mild stomach upset and diarrhea, so although it is almost calorie free, one should still not consume a great deal of it, since greater amounts tend to cause stomach upset.