L-Theanine Supplementation Promising in Reducing Symptoms of Schizophrenia, Anxiety, and ADHD: Review

The findings, published in the journal BMC Psychiatry, indicate that L-theanine supplementation was more effective in reducing psychiatric symptoms compared to control interventions in individuals with schizophrenia, anxiety disorders, and attention-deficit hyperactivity disorder (ADHD). This implies its potential as a complementary treatment option alongside traditional therapies.

Amino acids like L-theanine (LT) have demonstrated potential as effective adjuncts to antidepressants, antipsychotics, and other psychopharmacological treatments, offering improvements in the symptomatic management of various mental disorders. However, despite this promising evidence, no comprehensive systematic reviews have been conducted to explore these associations thoroughly.

To address this gap, Reza Moshfeghinia, Substance Abuse Research Center, Shiraz University of Medical Sciences, Shiraz, Iran, and colleagues carried out a systematic review of randomized controlled trials to evaluate the effects of L-Theanine supplementation on mental health outcomes, focusing on its role as an adjunctive therapy for individuals with mental disorders.

For this purpose, the researchers conducted a comprehensive systematic review by searching six electronic databases—PubMed, Scopus, PsycINFO, Web of Science, CINAHL Complete, and Cochrane—from their inception until June 2023. The review focused on identifying randomized controlled trials that explored the effects of L-theanine supplementation on mental health outcomes in patients with mental health disorders. To ensure the quality and reliability of the findings, the Cochrane Risk of Bias Tool for Randomized Trials was utilized to assess the risk of bias in the included studies.

The following were the key findings:

• A total of 419 publications were identified during the initial search.

• After screening, 11 studies from six countries (Israel, Iran, USA, Japan, Australia, and Italy) were included in the final analysis.

• The included studies investigated a variety of mental health conditions, including:

• Schizophrenia

• Attention-Deficit/Hyperactivity Disorder (ADHD)

• Obsessive-Compulsive Disorder (OCD)

• Major Depressive Disorder (MDD)

• Sleep disorders

• Generalized Anxiety Disorder (GAD)

• Tourette syndrome

• Findings indicated that L-Theanine (LT) supplementation was more effective in reducing psychiatric symptoms compared to control conditions, specifically in individuals with:

• Schizophrenia

• Anxiety disorders

• ADHD

In conclusion, the systematic review represents the first comprehensive examination of L-Theanine’s effects across a range of mental disorders. The authors highlight LT's promising potential in reducing psychiatric symptoms, particularly in individuals with schizophrenia, anxiety disorders, and ADHD. Despite its strengths, the review acknowledges limitations, including the small number of studies, potential publication bias, and the lack of standardized dosages.

"These findings provide valuable insights into LT’s therapeutic promise while emphasizing the need for further well-designed research to confirm its efficacy, explore underlying mechanisms, and address existing gaps to optimize its use in mental health interventions," the researchers concluded.

Reference:

Moshfeghinia, R., Sanaei, E., Mostafavi, S. et al. The effects of L-theanine supplementation on the outcomes of patients with mental disorders: a systematic review. BMC Psychiatry 24, 886 (2024). https://doi.org/10.1186/s12888-024-06285-y