Aspartame: neuropsychologic and neurophysiologic evaluation of acute and chronic effects

Am J Clin Nutr. 1998 Sep;68(3):531-7. doi: 10.1093/ajcn/68.3.531.


Background: Neurobehavioral symptoms have been reported anecdotally with aspartame.

Objective: This study sought to determine whether aspartame can disrupt cognitive, neurophysiologic, 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 x kg body wt(-1) x d(-1)) or low- (15 mg x kg body wt(-1) x 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.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aspartame / administration & dosage
  • Aspartame / adverse effects*
  • Behavior / drug effects*
  • Blood Glucose / drug effects
  • Cognition / drug effects*
  • Cross-Over Studies
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Electroencephalography / drug effects
  • Humans
  • Male
  • Nervous System / drug effects*
  • Phenylalanine / blood
  • Psychological Tests


  • Blood Glucose
  • Phenylalanine
  • Aspartame