evidence answer

Is L Theanine Reaction Time Randomized Trial safe?

Updated July 2026

Quick Answer

L Theanine Reaction Time Randomized Trial has evidence relevant to safety, limits, and clinician-discussion contexts, but conclusions should stay close to the cited sources. One representative finding is: Camellia sinensis Coffea arabica Camellia sinensis Paullinia cupana 1 2 3 3 3 4 3 5 l l Green tea () is an evergreen plant found mainly in the tropical and temperate regions of Asia, especially in China, Srí Lanka, Japan and India, and it has been consumed for centuries as food and for its beneficial effects on human health [,,].

Key Takeaways

  • 01Camellia sinensis Coffea arabica Camellia sinensis Paullinia cupana 1 2 3 3 3 4 3 5 l l Green tea () is an evergreen plant found mainly in the tropical and temperate regions of Asia, especially in China, Srí Lanka, Japan and India, and it has been consumed for centuries as food and for its beneficial effects on human health [,,]. [Mátyus Rebeka Olga (2025)]
  • 02Based on preclinical and clinical evidence, caffeine and-theanine are the two main constituents contributing to this effect []. [Mátyus Rebeka Olga (2025)]
  • 03Caffeine is a stimulant compound belonging to the group of methylxanthines and is found in several plants, including(coffee),and(guarana) [,]. [Mátyus Rebeka Olga (2025)]
  • 04The main constituents of the leaves are polyphenols, but other components such as methylxanthine derivatives (caffeine, theobromine, theophylline), organic acids, flavonoids, free amino acids (such as-theanine) and several flavor components are also present in fresh leaves []. [Mátyus Rebeka Olga (2025)]
The current Migaku evidence database contains 2 reusable source documents for L Theanine Reaction Time Randomized Trial. This answer focuses on safety, limits, and clinician-discussion contexts. - Camellia sinensis Coffea arabica Camellia sinensis Paullinia cupana 1 2 3 3 3 4 3 5 l l Green tea () is an evergreen plant found mainly in the tropical and temperate regions of Asia, especially in China, Srí Lanka, Japan and India, and it has been consumed for centuries as food and for its beneficial effects on human health [,,]. [Mátyus Rebeka Olga (2025); evidence level 1] - Based on preclinical and clinical evidence, caffeine and-theanine are the two main constituents contributing to this effect []. [Mátyus Rebeka Olga (2025); evidence level 1] - Caffeine is a stimulant compound belonging to the group of methylxanthines and is found in several plants, including(coffee),and(guarana) [,]. [Mátyus Rebeka Olga (2025); evidence level 1] - The main constituents of the leaves are polyphenols, but other components such as methylxanthine derivatives (caffeine, theobromine, theophylline), organic acids, flavonoids, free amino acids (such as-theanine) and several flavor components are also present in fresh leaves []. [Mátyus Rebeka Olga (2025); evidence level 1] - Evidence regarding the acute effects of caffeine (CAF), L-theanine (TEA), and their combination remains inconsistent, particularly with respect to their combined influence on physical and cognitive performance in athletic populations. [Tuncer SY (2026); evidence level 2] Evidence levels are sorting aids, not final clinical grades. Level 1 usually indicates systematic-review style evidence, level 2 indicates randomized trials or public-health guidance, and lower levels need more cautious wording. This page is educational. People with medical conditions, pregnancy, medication use, or unusual symptoms should ask a qualified clinician before changing supplements, medication, or treatment routines.

Learn next

Keep learning from this answer

SupplementL-TheanineA unique amino acid primarily found in green tea leaves that promotes relaxation, quietens menta...GuideL Theanine Reaction Time Randomized Trial: What the Evidence SaysL Theanine Reaction Time Randomized Trial has 2 source documents in the current Migaku evidence...GuideTheanine Reaction Time Randomized Trial: What the Evidence SaysTheanine Reaction Time Randomized Trial has 2 source documents in the current Migaku evidence da...GuideGinkgo Reaction Time Randomized Trial: What the Evidence SaysGinkgo Reaction Time Randomized Trial has 2 source documents in the current Migaku evidence data...GuideGreen Tea Reaction Time Randomized Trial: What the Evidence SaysGreen Tea Reaction Time Randomized Trial has 2 source documents in the current Migaku evidence d...DataL Theanine Reaction Time Randomized Trial Evidence TableStructured evidence table for L Theanine Reaction Time Randomized Trial, generated from 2 reusab...DataTheanine Reaction Time Randomized Trial Evidence TableStructured evidence table for Theanine Reaction Time Randomized Trial, generated from 2 reusable...DataGinkgo Reaction Time Randomized Trial Evidence TableStructured evidence table for Ginkgo Reaction Time Randomized Trial, generated from 2 reusable s...

Sources

  1. Promising, but Not Completely Conclusive—The Effect of l -Theanine on Cognitive Performance Based on the Systematic Review and Meta-Analysis of Randomized Placebo-Controlled Clinical Trials
  2. Acute effects of combined and isolated caffeine and theanine supplementation on physical and cognitive performance in competitive athletes: a randomized, double-blind, placebo-controlled crossover study.