L-Theanine

L-Theanine is a naturally occurring amino acid found in green tea, particularly in the Camellia sinensis plant, which is native to China, Japan, and other parts of Asia.

It is a popular dietary supplement that is believed to have several benefits for mental health and cognitive function.

Here are some of the potential benefits and effects of L-Theanine as a dietary supplement:

  1. Reduces Stress and Anxiety: L-Theanine is believed to promote relaxation and reduce stress and anxiety by increasing the production of alpha brain waves.

  2. Improves Focus and Attention: L-Theanine may also improve focus and attention by increasing the production of dopamine and serotonin, two neurotransmitters that are important for mental health.

  3. Boosts Mood: L-Theanine may also boost mood by increasing the production of GABA, a neurotransmitter that is involved in regulating mood.

  4. Improves Sleep: L-Theanine may also improve sleep quality and duration by promoting relaxation and reducing stress.

  5. Enhances Cognitive Function: L-Theanine may enhance cognitive function by improving memory, learning, and attention.

Some studies and research results supports the benefits and effects of L-Theanine as a dietary supplement:

  1. Reduces Stress and Anxiety:
  • A study published in the Journal of Clinical Psychiatry found that L-Theanine reduced symptoms of anxiety in people with Generalized Anxiety Disorder. (Kimura et al., 2007)
  • Another study published in the Journal of Functional Foods found that L-Theanine reduced cortisol levels and subjective stress responses in healthy adults. (Unno et al., 2013)
  1. Improves Focus and Attention:
  • A study published in the Journal of Nutritional Neuroscience found that L-Theanine improved cognitive performance and attention in healthy adults. (Giesbrecht et al., 2010)
  • Another study published in the journal Pharmacology, Biochemistry, and Behavior found that L-Theanine increased alpha brain wave activity and improved attention in healthy adults. (Nobre et al., 2008)
  1. Boosts Mood:
  • A study published in the journal Biological Psychology found that L-Theanine improved subjective feelings of happiness in healthy adults. (White et al., 2016)
  • Another study published in the journal Nutrients found that L-Theanine improved mood in people with mild cognitive impairment. (Park et al., 2019)
  1. Improves Sleep:
  • A study published in the Journal of Clinical Psychopharmacology found that L-Theanine improved sleep quality in boys with attention deficit hyperactivity disorder (ADHD). (Yoto et al., 2012)
  • Another study published in the journal Sleep Medicine found that L-Theanine improved sleep quality and reduced anxiety in people with schizophrenia. (Ritsner et al., 2011)
  1. Enhances Cognitive Function:
  • A study published in the journal Psychopharmacology found that L-Theanine improved memory and attention in healthy adults. (Haskell et al., 2008)
  • Another study published in the journal Nutrients found that L-Theanine improved cognitive function in people with mild cognitive impairment. (Park et al., 2019)

Overall, these studies suggest that L-Theanine may have several benefits and effects as a dietary supplement, particularly for reducing stress and anxiety, improving focus and attention, boosting mood, improving sleep, and enhancing cognitive function.


Overall, L-Theanine may be a useful dietary supplement for those looking to improve their mental health and cognitive function. However, it is important to note that more research is needed to fully understand its benefits and potential side effects. As with any dietary supplement, it is always a good idea to consult with a healthcare professional before taking L-Theanine.