Ajinomoto Group AJINOMOTO GROUP Worldwide

Aspartame: neuropsychologic and neurophysiologic evaluation of acute and chronic effects

Paul A Spiers, LuAnn Sabounjjan, Allison Reiner, Diane K Myers, Judith Wurtman, and Donlad L Schomer


Background: Neurobehavioral symptoms have been reported anecdotally with aspartame.

Objective: This study sought to determine whether aspartame can disrupt cognitive, neuropsychologic, or behavioral functioning in normal individuals.

Design: Forty-eight healthy volunteers completed a randomized, double-blind, placebo-controlled, crossover study. The first month was aspartame free. Subjects then consumed sodas and capsules with placebo, aspartame, or sucrose for 20 d each. Order was randomized and subjects were assigned to either a high- (45 mg/kg body wt –1 d–1) or low- (15 mg/kg body wt –1 d–1) dose aspartame group. Neuropsychologic and laboratory testing was done on day 10 of each treatment period to determine possible acute effects and on day 20 for possible chronic effects.

Results: Plasma phenylalanine concentrations increased significantly during aspartame treatment. Neuropsychologic results; adverse experiences; amino acid, insulin, and glucose values; and electroencephalograms were compared by sex and by treatment. No significant differences were found for any dependent measure.

Conclusion: Large daily doses of aspartame had no effect on neuropsychologic, neurophysiologic, or behavioral functioning in healthy young adults.

Am J Clin Nutr 1998;68:531-7.