Aspartame is composed of two naturally occurring amino acids (the building blocks of protein) - phenylalanine and aspartate. Aspartame has a flavor similar to sucrose, and also functions as a taste intensifier and enhancer. Aspartame is 200 times sweeter than sucrose and has no aftertaste. A packet of this sweetener is equivalent in sweetness to two teaspoons of sugar (32 calories), for just four calories.
Products that contain aspartame must carry a warning to people with phenylketonuria, a rare genetic disorder that prevents proper metabolism of phenylalanine.
Unlike the alternate sweeteners saccharin, cyclamate acesulfame K, neotame and sucralose, which have no nutritional value, aspartame contributes calories. This is due to the fact that it can be used by the body just as any other protein, but the amounts are so small that its caloric value is insignificant. Aspartame does not contribute to tooth decay.