Aspartame and its constituent amino acids: effects on prolactin, cortisol, growth hormone, insulin, and glucose in normal humans.

Because large doses of phenylalanine stimulate prolactin secretion in man, we studied the acute effects of oral doses of aspartame (0.534 g, equivalent to the amount of aspartame in approximately 1 L beverage), aspartic acid (0.242 g), and phenylalanine (0.3 and 1.0 g) on serum prolactin and other hormones in normal humans. Prolactin was not stimulated by any of the aspartame meals, aspartic acid, or 0.3 g phenylalanine; a small rise in serum prolactin, similar to that produced by a high-protein mixed meal, followed ingestion of 1.0 g phenylalanine. Serum growth hormone showed no statistically significant changes in response to any of the experimental meals whereas cortisol and insulin fell slightly and glucose rose slightly during each of the meals. We conclude that these doses of aspartame do not alter secretion of prolactin, cortisol, growth hormone, or insulin in normal individuals.