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The Many Roles of L-Theanine

The “treatment recommendations” section of neurotransmitter (NT) results interpretations almost universally includes L-theanine supplementation. Why is that? What is this important therapy and where does it come from?

While individualized treatment recommendations typically include specific amino acids targeted to demonstrated imbalances, L-theanine provides generalized support in most areas of NT imbalance. When discussing this concept, L-theanine is commonly considered, and often referred to as, the “adaptogen” of neurotransmitters – similar to the notion of herbs such as ashwaganda in adrenal dysfunction. While this concept works to briefly describe L-theanine’s vast actions on inhibitory and excitatory NT imbalances, some of the specific ways that L-theanine does this are:

  • By acting as a GABA agonist and through the additional ability to increase GABA levels.
    Because of this action, L-theanine is a treatment consideration when demonstrated neurotransmitter imbalances include low to low range GABA levels
  • Through promoting both neuroinhibitory and parasymptathetic responses.
    As a result, L-theanine is a main consideration when NT imbalances include upper range to elevated excitatory neurotransmitters including dopamine, norepinephrine and epinephrine.
  • By exhibiting antagonist effects on glutamate receptors.
    This modulation is why L-theanine is one of the main supplemental considerations when NT imbalances include elevated glutamate levels.
  • Through its ability to increase serotonin and dopamine levels.
    While targeted supplementation with precursor amino acids may be a more immediate consideration when demonstrated imbalances include low to low range serotonin and/or dopamine, L-theanine is beneficial in promoting release of these neurotransmitters, and, as such, may be part of a well-rounded treatment plan - particularly when additional NT imbalances are present.
  • By decreasing elevated serotonin levels.
    When serotonin is elevated, L-theanine has demonstrated the ability to reduce synthesis and increase degradation and, because of this action, is a primary treatment consideration when endogenous levels of serotonin are upper range to elevated.

An amino acid primarily found in green tea, L-theanine is commonly dosed 2-3 times daily to account for its relatively short half-life. Though L-theanine is often a go-to therapy for treatment of NT imbalances, it is generally used as a component in a more comprehensive supplementation program. Determining specific neurotransmitter imbalance(s) through Labrix’ urinary neurotransmitter testing is an easy and accurate means to identify excess or deficiency for targeted treatment. Join us at Labrix’ upcoming Core Training event in Portland, OR August 2, 2014 to review the essentials of both neurotransmitter and hormone imbalances and leave confident in these areas, ready to tackle your neuroendocrine cases Monday morning. Registration remains open and can be accessed online at


  • Cross DR, et al. A randomized targeted amino acid therapy with behaviourally at-risk adopted children. Child Care Health Dev. 2011;37:671-78
  • Hamilton LD, Meston CM. (2011). The role of salivary cortisol and DHEA-S in response to sexual, humorous, and anxiety-inducing stimuli. Hormonal Behavior, 59(5), 765-71.
  • Nathan PJ, Lu K, Gray M, Oliver C.The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent. J Herb Pharmacother. 2006;6(2):21-30.
  • Yamada T, Terashima T, Kawano S, et. al. Theanine, gamma-glutamylethylamide, a unique amino acid in tea leaves, modulates neurotransmitter concentrations in the brain striatum interstitium in conscious rats.Amino Acids. 2009 Jan;36(1):21-7. doi: 10.1007/s00726-007-0020-7. Epub 2008 Jan 15.
  • Yokogoshi H, Mochizuki M, Saitoh K. Theanine-induced reduction of brain serotonin concentration in rats. Biosci Biotechnol Biochem. 1998 Apr;62(4):816-7.
  • Yokogoshi H, Kobayashi M, Mochizuki M, Terashima T. Effect of theanine, r-glutamylethylamide, on brain monoamines and striatal dopamine release in conscious rats. Neurochem Res 1998;23:667-673


Labrix West Coast Core Training has been approved for 6 hours of general CE credit (Oregon) for Naturopathic Physicians.

Labrix Founder and Medical Director Dr. Jay Mead, CEO and Associate Medical Director Dr. Erin Lommen, and Staff Physicians Dr. Robyn Kutka, Dr. Lylen Ferris, and Dr. Sara Wood present the fundamentals of hormone balancing, broken down into simple core concepts and related in a single day of engaging presentations and discussions. This event is designed for the provider who is new to the field of hormone balancing or is looking to brush up on the basics.

Join us for this 8-hour training and leave with the tools and knowledge necessary to:

  • Identify patients who would benefit from hormone balancing
  • Understand the roles of major sex and adrenal hormones in men and women
  • Appreciate the relationships between the various hormones and the entire endocrine system
  • Recognize the role that sex and adrenal hormones play in several prominent disease processes
  • Treat hormone imbalances with nutritional supplements, botanical medicines and BHRT
  • Learn to incorporate neurotransmitter (NT) evaluation and treatment into your practice

This event will be held on Saturday, August 2nd, 2014 at the Hilton Portland & Executive Tower. If you are serious about adding this powerful tool into your practice, register to attend and secure your seat.

Registration is $150 and following successful completion of the course, you will receive a $100 credit on your testing account. Register anyone else in your practice (with a clinical degree) and you'll automatically receive $25 off their registration.

Sign Up Now For This Free, Live Webinar Event

Labrix' own Dr. Lylen Ferris is presenting a free, live webinar via Functional Medicine University, on Monday, August 25, at 5:00 pm PST. Dr. Ferris' webinar, "Moodiness, Madness, or Menopause?", will provide clinical answers for optimization of hormones, serotonin and other neurotransmitter imbalances.

Dr. Lylen Ferris, ND

Lylen Ferris is a licensed Naturopathic Physician living and practicing in Portland, OR. In addition to maintaining her private practice, Dr. Ferris works as a Staff Physician at Labrix Clinical Services where she has reviewed, interpreted and advised on tens of thousands of salivary hormone panels and neurotransmitter reports.

Prior to joining Labrix as a staff physician, she completed a residency in advanced women’s health and gynecology at the National College of Natural Medicine where she oversaw patient care and as well as taught gynecology and clinical education classes. Her extensive knowledge of women’s health and endocrinology coupled with her love of teaching have led her to develop curriculum and present at numerous integrative and alternative health conferences.

Click here to learn more about this webinar presentation.