A tea-derived amino acid studied alone and alongside caffeine. Small attention studies offer useful signals, with important limits.
L-theanine is often discussed as a partner to caffeine. Evidence for a particular combination should stay attached to that combination, task and population. Human absorption has been studied, but a tidy claim that it reliably cancels caffeine's adverse effects goes beyond the sources included here.
Selected small human studies are included. Combination findings do not establish theanine-alone benefit.
Assessment belongs to each claim and outcome. An article’s editorial status is not a grade of a substance’s safety or efficacy.The kinetic study detected theanine and its metabolites in people. It does not establish which molecule explains a cognitive effect. [2]
Descriptions of experience in their reported context. Direction does not imply benefit, and these observations do not define a universal intensity score.
Not assessed. No sourced subjective observations have been curated for this article.
What the research measured, for whom, and under which exposure. Findings remain attached to the study’s task or clinical endpoint.
Some task performance improved with the caffeine combination. The result does not isolate a standalone theanine benefit. [1]
Published exposure records, distinguished by source category. These describe study or reference context and are not personal dosing recommendations.
100 mg [1]
Studied with 50 mg caffeine. Research context, not a recommended stack.
Absorption, metabolism and elimination depend on the analyte, route, formulation, physiology and other exposures.
Uptake was measured, but no elimination estimate has been curated for this article. [2]
Measured analyte: L-theanine. Route: Oral. Formulation: Capsules and green tea. Population: 12 healthy participants in the crossover study.
Uptake was measured, but no elimination estimate has been curated for this article.
Read the source context ↗Not establishedNo numeric estimate [2]
Uptake was measured, but no elimination estimate has been curated for this article.
Tea and capsules gave similar kinetic results in the cited small crossover study; this does not validate every commercial product. [2]
Related observationAdverse effects, interactions, tolerance and withdrawal in the cited contexts. This section is not an exhaustive interaction checker.
This small, acute study cannot establish long-term benefit or show that theanine removes caffeine-related sleep disruption. [1]
The source, the finding and its limitations. Funding information is reported where curated; an unassessed disclosure does not mean a study had no commercial funding.
Caffeine with L-theanine improved some attention-task outcomes in 27 healthy volunteers.
Limitations Small, short-term study; selected laboratory tasks do not establish everyday productivity or long-term benefit. Authors were affiliated with Unilever.
Funding / disclosures Funding not assessed; author affiliations include Unilever.
Measured uptake and metabolites after tea or capsule ingestion in 12 healthy participants.
Limitations Small study focused on exposure, not clinical benefit or long-term safety.
Funding / disclosures Not assessed; consult the original disclosure.
Source for molecular identity, formula, molecular weight and the structure diagram.
Limitations A compound record does not establish a product's purity, identity or clinical benefit.
Funding / disclosures Public database maintained by NCBI.
Each relationship retains its participants, roles and context. Shared membership does not imply that substances should be combined.
27 healthy volunteers; acute crossover comparison with placebo.
Limitation This does not isolate theanine-alone benefit.
Evidence strength: not formally assessed.
Healthy volunteers in a small crossover study.
Limitation Uptake does not establish a cognitive mechanism or equivalent exposure from every product.
Evidence strength: not formally assessed.
Not assessed. Absence of a legal record is not a statement of legal status.
This article is a sourced draft. Editorial review has not been recorded. Content date: Sep 29, 2026.