L-Theanine Supplementation for Mental Disorders: Systematic Review
Does L-theanine help mental health conditions?
Yes. L-theanine supplementation significantly reduces psychiatric symptoms in individuals with schizophrenia, anxiety disorders, and ADHD, with particularly strong evidence for depression and obsessive-compulsive disorder when used as an adjunct to standard medications. A systematic review of 11 randomized controlled trials published in BMC Psychiatry shows that this natural amino acid from tea leaves provides meaningful therapeutic benefits across multiple mental health conditions.
L-theanine works by increasing gamma-aminobutyric acid (GABA) production, which promotes relaxation and reduces stress, while also modulating serotonin and dopamine levels and enhancing alpha brain wave activity associated with calm alertness.