A review of the metabolism of the aspartyl moiety of aspartame in experimental animals and man.

Aspartame (3-amino-N-(alpha-carboxyphenethyl) succinamic acid, methyl ester; the methyl ester of aspartylphenylalanine, SC-18862) is hydrolyzed in the gut to yield aspartic acid, phenylalanine, and methanol. This review of the literature describes the metabolic paths followed by aspartate in its conversion to CO2 or its incorporation into body constituents. About 70 percent of 14C from [asp-14C]-aspartame is converted in the monkey to 14CO2. Some of the aspartate is converted at the intestinal mucosal level to alanine by decarboxylation. This amino acid may be oxidized to CO2 by entering the tricarboxylic acid cycle via pyruvate and acetyl CoA. In addition, transamination of aspartate to oxaloacetate permits this product also to enter the tricarboxylic acid cycle. Aspartate may also be incorporated into body constitutents such as other amino acids, proteins, pyrimidines, asparagine, and N-acetylaspartic acid. It is concluded that the aspartate moiety of aspartame is metabolized in a manner similar to that of dietary aspartic acid.