Amino AcidsL-Theanine

GABA and L-theanine provide effective preoperative anxiolysis with minimal sedation and improved cognitive skills compared to alprazolam in surgical patients

In a randomized controlled trial of 168 preoperative surgical patients, both L-theanine and GABA produced effective anxiolysis with minimal sedation, while alprazolam caused significantly more sedation. Psychomotor and cognitive functions improved with L-theanine and GABA (P=0.0001) but decreased with alprazolam (P=0.0001).

Last updated: Aug 29, 2026•1 RCTs•📖 Read as article →

Evidence Score

Evidence Score42/100
Human RCT★★☆☆☆
Meta-analysis☆☆☆☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. Comparison of the effects of two amino acids, Gamma-aminobutyric acid (GABA) and L-theanine, on sedation, anxiety, and cognition in preoperative surgical patients - A randomized controlled study.

observational

Deshpande SS, Kurdi M, Baiju A, Athira AS, Sarasamma AG, Gangadharan AK · Journal of anaesthesiology, clinical pharmacology (2025)

Participants: N/A
Duration: 60 minutes (preoperative period)
Intervention: Oral L-theanine or oral GABA compared to oral alprazolam 0.25 mg as premedication
Outcome: Preoperative anxiety score, sedation score, psychomotor and cognitive performance scores measured 60 minutes before and after drug administration
Effect Size: N/A
Population: 168 patients aged 18-55 years, ASA physical status I and II, scheduled for major elective surgeries

Result:

PubMed: 40026748DOI: 10.4103/joacp.joacp_417_23

Mechanism Graph

L-theanine prevents stress and produces anxiolysis by modulating alpha brain wave activity
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GABA acts as the main inhibitory neurotransmitter in the mammalian brain, regulating anxiety and stress
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Both amino acids reduce anxiety without excessive sedation
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Result: Effective preoperative anxiolysis with minimal sedation and improved cognitive performance

Limitations

  • ⚠Exact doses of L-theanine and GABA not reported in the abstract
  • ⚠Only short-term effects (60 minutes) were measured, not long-term outcomes
  • ⚠Study population limited to ASA I and II patients, may not generalize to higher-risk patients

Frequently Asked Questions

What are the benefits of L-theanine and GABA over alprazolam for preoperative anxiety?▼

L-theanine and GABA provide effective anxiety reduction with minimal sedation and improved cognitive function, whereas alprazolam causes more sedation and impairs psychomotor and cognitive performance.

How do L-theanine and GABA affect cognitive function in surgical patients?▼

Both L-theanine and GABA improved psychomotor and cognitive performance scores significantly (P=0.0001), while alprazolam decreased these scores.

Are L-theanine and GABA safe alternatives to benzodiazepines for premedication?▼

The study suggests they are safer alternatives due to minimal sedation and cognitive improvement, but exact doses and adverse reactions were not fully detailed in the abstract.

What was the sample size and design of this study?▼

This was a randomized controlled trial with 168 patients divided into three groups receiving either L-theanine, GABA, or alprazolam 0.25 mg.

Products

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References

  1. 1.Deshpande SS, Kurdi M, Baiju A, Athira AS, Sarasamma AG, Gangadharan AK. "Comparison of the effects of two amino acids, Gamma-aminobutyric acid (GABA) and L-theanine, on sedation, anxiety, and cognition in preoperative surgical patients - A randomized controlled study.." Journal of anaesthesiology, clinical pharmacology, 2025. PMID: 40026748 DOI: 10.4103/joacp.joacp_417_23
Disclaimer: This content is for educational purposes only and is not medical advice. Evidence scores reflect the quality and quantity of available research, not clinical recommendations. Always consult a healthcare professional before starting any supplement or intervention.