A 13-week dietary toxicity and toxicokinetic study with l-theanine in rats

Food Chem Toxicol. 2006 Jul;44(7):1158-66. doi: 10.1016/j.fct.2006.03.014. Epub 2006 Apr 26.


This study was conducted to evaluate the safety of l-theanine (Suntheanine) when administered as a dietary admixture to male and female Crl:CD (SD)GS BR rats at concentrations providing doses of 0, 1500, 3000 or 4000 mg/kg bw/day for 13 weeks. The study design was consistent with OECD Guideline 408 and USFDA Redbook II (1993) and GLP. There were no consistent, statistically significant treatment-related adverse effects on behavior, morbidity, mortality, body weight, food consumption and efficiency, clinical chemistry, hematology, or urinalysis. There were no consistent treatment-related adverse effects in gross pathology, organ weights or ratios or histopathology. The increased incidence of renal tubular cell adenomas in high-dose females only were not consistent with the characteristics of a renal carcinogen (due to early onset and low number of animals affected) but were more consistent with a genetic predisposition than with direct organ toxicity. The no-observed-adverse-effect-level (NOAEL) was 4000 mg/kg bw/day, the highest dose tested.

MeSH terms

  • Animals
  • Area Under Curve
  • Behavior, Animal / drug effects
  • Blood Cell Count
  • Blood Chemical Analysis
  • Body Weight / drug effects
  • Diet
  • Eating / drug effects
  • Female
  • Glutamates / pharmacokinetics
  • Glutamates / toxicity*
  • Half-Life
  • Immune System / drug effects
  • Kidney / pathology
  • Male
  • Motor Activity / drug effects
  • Organ Size / drug effects
  • Rats
  • Sex Characteristics
  • Urinalysis


  • Glutamates
  • theanine