INGREDIENTS & RESEARCH

L-Theanine

BACKGROUND

Ingredient Type: Amino acid 

Also Known As: Gamma-ethylamino-L-glutamic acid, γ-L-Glutamylethylamide

L-Theanine is a non-essential amino acid found primarily in tea leaves (specifically Green Tea), but it has also been isolated in mushrooms.  It was discovered in green tea in Japan in 1949 and has since become a popular additive to foods.  It is believed to calm stress, boost mood, and improve cognitive performance.

L-Theanine has a chemical structure very similar to glutamate, an amino acid that occurs naturally in the body and helps transmit nerve impulses in the brain.

 

TRADITIONAL USES 

L-Theanine is used in health supplements today to promote relaxation and focused concentration.  

 

WHAT DOES SCIENCE TELL US?

Cognitive Performance: Preliminary clinical research shows that taking theanine 100 mg prior to cognitive testing reduces the rate of errors compared with placebo in healthy adults.

Stress: One clinical study shows that taking L-theanine (Taiyo Kagaku) 200 mg prior to a psychological exam reduced tension-anxiety and prevented blood pressure increases caused by psychological stress.  Other preliminary clinical research shows that pharmacy students taking theanine 200 mg twice daily for one week prior to and for the first 10 days of a pharmacy practice period had decreased subjective stress scores compared to placebo. 

 

SAFETY

Theanine is possibly safe when used orally, short-term.  Theanine has been used safely once per week for 3 weeks.  It is not known if use for longer periods of time is safe.  Theanine is sold in the United States as a dietary supplement and has been granted GRAS (generally recognized as safe) status for food by the Food and Drug Administration.  Few adverse reactions have been reported.  Adverse reactions recorded in human studies using tea extracts include a headache, dizziness, and mild GI symptoms.

 

REFERENCES

  1. L-theanine. Review of Natural Products. Facts &Comparisons Online. April 2010. Accessed April 20, 2010.
  2. Graham HN. Green tea composition, consumption, and polyphenol chemistry. Prev Med 1992;21:334-50.
  3. Scheid L, et al. Kinetics of L-theanine uptake and metabolism in healthy participants are comparable after ingestion of L-theanine via capsules and green tea. J Nutr. 2012;142(12):2091-2096.
  4. Dodd FL, Kennedy DO, Riby LM, Haskell-Ramsay CF. A double-blind, placebo-controlled study evaluating the effects of caffeine and L-theanine both alone and in combination on cerebral blood flow, cognition and mood. Psychopharmacology. 2015;232(14):2563-2576
  5. Lu K, Gray MA, Oliver C, et al. The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans. Hum Psychopharmacol 2004;19:457-65.
  6. Unno K, et al. Anti-stress effect of theanine on students during pharmacy practice: positive correlation among salivary a-amylase activity, trait anxiety and subjective stress. Pharmacol Biochem Behav. 2013;111:128-135
  7. Sakato Y. The chemical constituents of tea: III. A new amide theanine. Nippon Nogei Kagakukaishi 1949;23:262-267.
  8. Yoto A, Motoki M, Murao S, Yokogoshi H. Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses. J Physiol Anthropol. 2012;31:28.
  9. Lu K, Gray MA, Oliver C, et al. The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans. Hum Psychopharmacol 2004;19:457-65
  10. Haskell, C. F., Kennedy, D. O., Milne, A. L., Wesnes, K. A., and Scholey, A. B. The effects of L-theanine, caffeine and their combination on cognition and mood. Biol.Psychol. 2008;77(2):113-122
  11. Matsumoto, K., Yamada, H., Takuma, N., Niino, H., and Sagesaka, Y. M. Effects of green tea catechins and theanine on preventing influenza infection among healthcare workers: a randomized controlled trial. BMC.Complement Altern.Med. 2011;11:15
  12. Giesbrecht, T., Rycroft, J. A., Rowson, M. J., and De Bruin, E. A. The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutr Neurosci. 2010;13(6):283-290.
  13. Camfield DA, Stough C, Farrimond J, Scholey AB. Acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis. Nutr Rev. 2014;72(8):507-522
  14. http://www.wellnessresources.com/health/articles/l-theanine_as_a_remedy_for_wound_up_nerves/

See the AminoAcidStudies.org entry for theanine, the Examine.com entry for theanine, the RXList entry for theanine, or the WebMD entry for theanine for more information.