Key Evidence #1
observationalPublic scholarly dataCitation signal: 131
It is suggested that L-theanine has the potential to promote mental health in the general population with stress-related ailments and cognitive impairments.
Tier-BPublic-ready6/13/2026
L-Theanine
Stress Response and Sleep Changes is the main area connected here, and any felt benefit should be read together with the human evidence base.
Representative tier calculated from paper evidence that passed the collection audit.
Papers analyzed
20
Caution signal
Low
Representative score
67.4
Stress Response and Sleep ChangesCognition, memory, and focusNutrient status markers
Main benefit evidence
The representative ingredient tier is calculated from these target-level evidence groups.
Stress and mood4 studiesTier-BStress Response and Sleep ChangesFairly consistent positive signal in studiesFelt benefit focusSupplement contextThese findings come from stress response, cortisol, anxiety, or sleep outcomes. They may mix felt benefits with physiological markers.Open metrics>
Stress and mood
4 studiesTier-B
Stress Response and Sleep Changes
Fairly consistent positive signal in studiesFelt benefit focusSupplement context
These findings come from stress response, cortisol, anxiety, or sleep outcomes. They may mix felt benefits with physiological markers.
Open metrics
>Stress and mood balanceSleep quality
No direct rate reported. Read direction and evidence strength together.
Evidence score
66.0
Score reflects signal strength. Tier also considers paper count, repetition, and study context.
Cognition and focus2 studiesTier-CCognition, memory, and focusFairly consistent positive signal in studiesFelt benefit focusSupplement contextPotential benefit studied in Cognition and focus.Open metrics>
Cognition and focus
2 studiesTier-C
Cognition, memory, and focus
Fairly consistent positive signal in studiesFelt benefit focusSupplement context
Potential benefit studied in Cognition and focus.
Open metrics
>Cognition, memory, and focus
No direct rate reported. Read direction and evidence strength together.
Evidence score
46.6
Score reflects signal strength. Tier also considers paper count, repetition, and study context.
Nutrient status1 studiesTier-CNutrient status markersSome positive signal observedResearch marker focusSupplement contextThis card is closer to a measured biomarker or lab outcome than a directly felt user benefit.Closer to a research marker than a directly felt benefit.Open metrics>
Nutrient status
1 studiesTier-C
Nutrient status markers
Some positive signal observedResearch marker focusSupplement context
This card is closer to a measured biomarker or lab outcome than a directly felt user benefit.
Closer to a research marker than a directly felt benefit.
Open metrics
>Nutrient status and deficiency markers
No direct rate reported. Read direction and evidence strength together.
Evidence score
37.2
Score reflects signal strength. Tier also considers paper count, repetition, and study context.
Exercise performance and recovery1 studiesTier-CExercise performance and recoverySome positive signal observedFelt benefit focusSupplement contextPotential benefit studied in Exercise performance and recovery.Open metrics>
Exercise performance and recovery
1 studiesTier-C
Exercise performance and recovery
Some positive signal observedFelt benefit focusSupplement context
Potential benefit studied in Exercise performance and recovery.
Open metrics
>Exercise performance and recovery
No direct rate reported. Read direction and evidence strength together.
Evidence score
27.5
Score reflects signal strength. Tier also considers paper count, repetition, and study context.
Animal or cell research1 studiesTier-CAnimal or Cell-Study ClueSome positive signal observedResearch marker focusSupplement contextThis is an early research clue, not direct human supplement-effect evidence.Closer to a research marker than a directly felt benefit.Animal or cell-study clue — not a human effect probability.Open metrics>
Animal or cell research
1 studiesTier-C
Animal or Cell-Study Clue
Some positive signal observedResearch marker focusSupplement context
This is an early research clue, not direct human supplement-effect evidence.
Closer to a research marker than a directly felt benefit.
Animal or cell-study clue — not a human effect probability.
Open metrics
>Animal, cell, or mechanism-only findings
No effect-rate metric is shown because this should be read as research context, not as a general supplement effect.
Evidence score
27.5
Score reflects signal strength. Tier also considers paper count, repetition, and study context.
Recent research
Updated This Month10 new papers
10 new papers were added in this period. No new risk signal was identified.
What's new
10 new papers were added.No new risk signal was identified.
Most notable recent finding
This is the most meaningful new study in the latest update.
Why it mattersIt ranked highest among the newly collected papers for this ingredient in the latest update.
View paperStudy dosage range (reference only)
Lower dose
25
mg/dayHigher dose
400
mg/dayDosages used in research papers, shown as reference context.
Not personal dosing instructions, recommendations, or safety limits.
Key cautions to review
Standalone side-effect signals and combination cautions are listed separately.
Caution index
0.3
Caution band: Low
Caution signals
0
Side effects + combos + curated rules
Key precautions
No combination caution signal is clear enough to show right now. This does not guarantee safety.
1 combo signals and 0 added-signal combos shown below.
Standalone side effects, combination cautions, and positive combos are separated below.
Combinations studied together
The group showed a positive signal, but individual contributions are hard to isolate. Not a stack recommendation.
+CaffeineCombined intake of L-theanine (6 mg/kg) and caffeine significantly improved guard, draw, and take-out shooting performance in elite curling athletes compared to placebo (all p < 0.001).
Evidence summaries
Paper IDs and full lists are private. Only study types and summaries are shown.
Key Evidence #2
observationalPublic scholarly dataCitation signal: 100
It is shown that L-theanine not only reduces anxiety but also attenuates the blood-pressure increase in high-stress-response adults.
Key Evidence #3
observationalPublic scholarly dataCitation signal: 48
This preliminary study did not support the efficacy of L-theanine in the treatment of anxiety symptoms in GAD, and further studies to explore the application of the amino acid in sleep disturbance are warranted.
3 more summariesLimited representative sample by study type.>
Public scholarly dataCitation signal: 38
observational[Abstract]: We examined the acute effects of l-theanine, caffeine and their combination on sustained attention, inhibitory control and overall cognition in boys with attention deficit hyperactivity disorder (ADHD). l-Theanine (2.5 mg/kg), caffeine (2.0 mg/kg),
Public scholarly dataCitation signal: 38
observationalIt is indicated that l-theanine may contribute to improving attention, thus enhancing working memory and executive functions, in men and women aged 50–69 years.
Public scholarly dataCitation signal: 26
observationalIt can be concluded that L-theanine helped to improve the undesirable manifestations of stress in cats in as soon as 15 days, though better results could be seen after 30 days of administration.
L-Theanine
arrow_backBack to listEvidence score: 67.4|Caution index: 0.3