Acute and repeated dose oral toxicity of N-acetyl-l-aspartic acid in Sprague–Dawley rats

N-acetyl-l-aspartic acid (NAA) is a constituent of the mammalian central nervous system (CNS) that has been identified in a number of commonly consumed foods. The current study reports the outcome of acute and repeated dose oral toxicology studies conducted with NAA in Sprague–Dawley (SD) rats. No mortalities or evidence of adverse effects were observed in SD rats following acute oral administration of 2000 mg/kg NAA. In a separate study, NAA was added to the diets of SD rats (n = 10/sex group) at concentrations corresponding to daily doses of 10, 100, or 1000 mg/kg/day for 14 consecutive days and 100, 500, and 1000 mg/kg/day for another 14 days. All rats survived until scheduled sacrifice and no differences in body weights, feed consumption values, or clinical signs were observed in any of the treatment groups. No biologically significant differences were observed in functional observational battery (FOB), motor activity evaluations, ophthalmologic examinations, hematology, coagulation, clinical chemistry, or organ weights of any of the NAA treatment groups. Further, no test substance-related gross or microscopic changes were observed in NAA exposure groups. Based on these results, NAA was not considered acutely toxic following oral exposure to 2000 mg/kg and the no-observed-adverse-effect-level (NOAEL) for systemic toxicity from repeated dose dietary exposure to NAA is 1000 mg/kg/day.