Metabolism of aspartame in monkeys.

Aspartame (SC-18862, 3-amino-N-(a-carboxyphenethyl)succinarnic acid, methyl ester; the methyl ester of aspartyl-phenylalanine ) is a sweetening agent that organoleptically has about 180 times the sweetness of sugar. Because it so closely resembles naturally occurring dipeptides, it was believed that it would be digested in a similar manner. To show this, the metabolism of [14C]aspartame labeled separately in the methyl, aspartyl and phenylalanine moieties was compared with the metabolism of "C-labeled methanol, aspartic acid, and phenylalanine. The metabolism of each moiety of aspartame was found to be the same as its free counterpart. Parameters measured were: conversion to "COj, incorporation of 14C into plasma proteins, and urinary and fecal excretion of the label. It was concluded that aspartame was digested to its three constituents that were then absorbed as natural constituents of the diet. J. Nutr. 103: 1454-1459, 1973.