Global Ingredient Risk Index Botanical

L-Theanine

N5-ethyl-L-glutamine

Also known as: L-theanine, theanine, Suntheanine, gamma-glutamylethylamide

23 მარ 2026

LOW RISK 1.5/10 How?

This ingredient is classified as unclassified risk (GIRI score: 1.5/10).

Known Safety Concerns

May potentiate sedative medications at high doses
Additive blood pressure lowering with antihypertensives
No established UL -- long-term very high dose data limited
Generally regarded as one of the safest supplement ingredients

Contraindications

May potentiate sedative medications at high doses
Additive blood pressure lowering with antihypertensives

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Information not yet available for this ingredient profile.

L-theanine is an amino acid found almost exclusively in tea leaves. It has a well-established safety profile at doses of 100-400 mg/day. It promotes relaxation without sedation and is commonly combined with caffeine to smooth its stimulant effects. No adverse effects have been documented at standard doses. No established UL.

Scientific Name: N5-ethyl-L-glutamine

Information not yet available for this ingredient profile.

SETI Score 50/100

Risk Level High risk

Scientific Confidence Low

Evidence Strength Limited

Key Benefit Botanical

Key Safety Concern May potentiate sedative medications at high doses

Evidence Reviewed 10 PubMed studies

Scientific Confidence Low

Based on study quality, consistency, and recency

Executive Summary — Ingredient Assessment

SETI Score 50/100

Risk Level High risk

Evidence Strength Limited

Main Benefit Botanical

Main Safety Concern May potentiate sedative medications at high doses

Ingredient L-Theanine

Scientific name N5-ethyl-L-glutamine

Scientific Evidence Overview

10 studies reviewed
0 high-quality studies (meta-analysis or RCT)
Main clinical benefit observed: Botanical
Evidence consistency: High consistency across studies (100%)

Safety Signals

May potentiate sedative medications at high doses
Additive blood pressure lowering with antihypertensives
No established UL -- long-term very high dose data limited
Generally regarded as one of the safest supplement ingredients

Evidence Strength Limited

Final Scientific Assessment

The available scientific evidence for L-Theanine indicates notable safety signals that warrant caution. Use should be considered carefully and monitored, particularly in sensitive populations or alongside other medications.

Ingredient L-Theanine

Evidence reviewed 10 peer-reviewed studies (last 10 years)

Scientific name N5-ethyl-L-glutamine

50 /100

Total SETI Score

High risk

Evidence quality	10/40
Evidence consistency	20/20
Safety signals	0/20
Study recency	10/10
Evidence transparency	10/10

Evidence Summary

10 studies reviewed
0 high-quality studies (meta-analysis or systematic review)
0 studies identified benefits or no safety concern (GREEN)
10 studies reported limited or advisory safety evidence (YELLOW)

Evidence Policy

Only peer-reviewed scientific literature indexed in PubMed or comparable databases is included in this evaluation. Commercial websites, blogs, and marketing materials are excluded. All references include direct traceable links to source documents.

Last updated: 23 მარ 2026, 18:47

Evidence Distribution

10 Other / unclassified

Observational / other LOW evidence YELLOW
Beneath the Surface: Root Metabolites Driving Shoot Agronomic Traits in Tea Plant (Camellia sinensis L.). ↗

PMID 41848094 ↗

Journal J Agric Food Chem

Year 2026

Study type Observational / other

Evidence strength LOW evidence

PubMed link https://pubmed.ncbi.nlm.nih.gov/41848094/

Huang Y et al.. Beneath the Surface: Root Metabolites Driving Shoot Agronomic Traits in Tea Plant (Camellia sinensis L.).. J Agric Food Chem. 2026. PMID:41848094.
Observational / other LOW evidence YELLOW
Clinical assessment of blood glucose responses to 300-mg dose of L-theanine, an amino acid unique to green tea, in a fixed-sequence, two-period… ↗

PMID 41845544 ↗

Journal J Pharm Health Care Sci

Year 2026

Study type Observational / other

Evidence strength LOW evidence

PubMed link https://pubmed.ncbi.nlm.nih.gov/41845544/

Yamaura S et al.. Clinical assessment of blood glucose responses to 300-mg dose of L-theanine, an amino acid unique to green tea, in a fixed-sequence, two-period trial.. J Pharm Health Care Sci. 2026. PMID:41845544.
Observational / other LOW evidence YELLOW
A microbial L-theanine-BCAT2 axis rewires host BCAA catabolism. ↗

PMID 41840166 ↗

Journal Sci China Life Sci

Year 2026

Study type Observational / other

Evidence strength LOW evidence

PubMed link https://pubmed.ncbi.nlm.nih.gov/41840166/

Fang X et al.. A microbial L-theanine-BCAT2 axis rewires host BCAA catabolism.. Sci China Life Sci. 2026. PMID:41840166.
Observational / other LOW evidence YELLOW
New and emerging treatments for anxiety disorders. ↗

PMID 41839508 ↗

Journal BMJ

Year 2026

Study type Observational / other

Evidence strength LOW evidence

PubMed link https://pubmed.ncbi.nlm.nih.gov/41839508/

Zbozinek TD et al.. New and emerging treatments for anxiety disorders.. BMJ. 2026. PMID:41839508.
Observational / other LOW evidence YELLOW
Combined and Separate Pretreatments with L-Theanine and Aerobic Exercise Modulate Cognitive Decline Following Chronic Neuroinflammation in Rats Exposed to Lipopolysaccharide. ↗

PMID 41828356 ↗

Journal Int J Mol Sci

Year 2026

Study type Observational / other

Evidence strength LOW evidence

PubMed link https://pubmed.ncbi.nlm.nih.gov/41828356/

Hadzhipetrov GK et al.. Combined and Separate Pretreatments with L-Theanine and Aerobic Exercise Modulate Cognitive Decline Following Chronic Neuroinflammation in Rats Exposed to Lipopolysaccharide.. Int J Mol Sci. 2026. PMID:41828356.
Observational / other LOW evidence YELLOW
L-theanine as a sustainable feed additive: Evaluating impacts on animal health and production efficiency. ↗

PMID 41802656 ↗

Journal Microb Pathog

Year 2026

Study type Observational / other

Evidence strength LOW evidence

PubMed link https://pubmed.ncbi.nlm.nih.gov/41802656/

Wu S et al.. L-theanine as a sustainable feed additive: Evaluating impacts on animal health and production efficiency.. Microb Pathog. 2026. PMID:41802656.
Observational / other LOW evidence YELLOW
Pharmacological effects and molecular targets of L-theanine in cardiovascular diseases and comorbidities. ↗

PMID 41796839 ↗

Journal Eur J Pharmacol

Year 2026

Study type Observational / other

Evidence strength LOW evidence

PubMed link https://pubmed.ncbi.nlm.nih.gov/41796839/

Garcu00eda-Niu00f1o WR et al.. Pharmacological effects and molecular targets of L-theanine in cardiovascular diseases and comorbidities.. Eur J Pharmacol. 2026. PMID:41796839.
Observational / other LOW evidence YELLOW
Comparative evaluation of l-theanine synthetases coupled with PPK2 based ATP regeneration under buffer-free and Mn(2u202f+) optimized conditions. ↗

PMID 41762940 ↗

Journal Enzyme Microb Technol

Year 2026

Study type Observational / other

Evidence strength LOW evidence

PubMed link https://pubmed.ncbi.nlm.nih.gov/41762940/

Yu K et al.. Comparative evaluation of l-theanine synthetases coupled with PPK2 based ATP regeneration under buffer-free and Mn(2u202f+) optimized conditions.. Enzyme Microb Technol. 2026. PMID:41762940.
Observational / other LOW evidence YELLOW
Antidepressant Mechanisms of L-Theanine in Tea Based on Network Pharmacology, Molecular Docking, and Molecular Dynamics Simulations. ↗

PMID 41683141 ↗

Journal Foods

Year 2026

Study type Observational / other

Evidence strength LOW evidence

PubMed link https://pubmed.ncbi.nlm.nih.gov/41683141/

Shi Y et al.. Antidepressant Mechanisms of L-Theanine in Tea Based on Network Pharmacology, Molecular Docking, and Molecular Dynamics Simulations.. Foods. 2026. PMID:41683141.
Observational / other LOW evidence YELLOW
Kiperin Mind Focus supplement mitigates chronic stress-induced neuroinflammation and molecular dysregulation and improves stress-related affective and exploratory behaviors in rats. ↗

PMID 41695889 ↗

Journal Front Integr Neurosci

Year 2025

Study type Observational / other

Evidence strength LOW evidence

PubMed link https://pubmed.ncbi.nlm.nih.gov/41695889/

Karcioglu Batur L et al.. Kiperin Mind Focus supplement mitigates chronic stress-induced neuroinflammation and molecular dysregulation and improves stress-related affective and exploratory behaviors in rats.. Front Integr Neurosci. 2025. PMID:41695889.

Q × L × D × S × 10 = 1.5 / 10

The GIRI Score is the product of four independently computed evidence components, each normalised to 0–1, then scaled to 0–10. Every component is derived exclusively from peer-reviewed references and regulatory data — no editorial judgement is applied.

0 of 10 approved references (score saturates at 10). More peer-reviewed studies = stronger evidence base.

Method: Q = number of approved references ÷ 10 (capped at 1.0)

50%

Limited — mostly case reports or animal studies

Method: L = mean study-level weight across approved references. Level 1 (meta-analysis / systematic review) = 1.0; Level 2 (RCT) = 0.8; Level 3 (cohort/case-control) = 0.6; Level 4 (case report) = 0.4; Level 5 (animal / in-vitro) = 0.2.

Benefit

Risk

50%

Mixed or neutral — roughly equal benefit and risk signals

Method: D = (sum of risk-scored references − sum of benefit-scored references) ÷ total evidence score, then scaled from [−1, 1] to [0, 1]. 0.0 = pure benefit; 0.5 = neutral; 1.0 = pure risk.

50%

One or more monitoring-level safety signals active

Method: S = 0.5 (neutral baseline) + sum of active signal severity deltas ÷ 10. Severity deltas: Critical = +2.0, High = +1.5, Moderate = +1.0, Low = +0.5. Capped at 1.0.

0Q × 5L × 5D × 5S = 1.5 / 10

Final GIRI Score for L-Theanine. Risk level thresholds: Low 0–3.0 · Moderate 3.0–5.5 · High 5.5–7.5 · Critical 7.5–10.

Full methodology & data sources

The GIRI Score is computed entirely from structured data — no editorial scoring or subjective weighting is applied at any step.

References: Only approved references are counted. Each reference is assigned an evidence level (L1–L5) and a direction (risk / neutral / benefit) by the reference manager or AI classifier.
Safety Signals: Sourced from regulatory agencies (FDA, EMA, Health Canada, TGA, and others) and pharmacovigilance databases. Only active signals count toward the score.
Formula version: GIRI Score v3.7.0 — Q × L × D × S × 10.
Limitations: The score reflects published evidence and recorded signals as of the last update date. It is not a clinical risk assessment and should not replace advice from a qualified healthcare professional.

LOW RISK 1.5/10

Based on available regulatory signals and scientific evidence, this ingredient presents a low safety concern under normal conditions of use.

LOW
0–3.0

MODERATE
3.0–5.5

HIGH
5.5–7.5

CRITICAL
7.5–10

1.5

The score pin shows exactly where this ingredient falls on the fixed risk scale.

What drove the Low classification for L-Theanine

A score of 1.5 places this ingredient in the Low band. Thresholds: Low 0–3.0 · Moderate 3.0–5.5 · High 5.5–7.5 · Critical 7.5–10.

0 approved references.

Limited — mostly case reports or animal studies (Level 4–5).

Neutral or mixed — benefit and risk signals roughly balanced.

No active signals — S component is at neutral baseline (0.5), contributing no extra risk weight.

No major regulatory restrictions or advisories recorded across monitored jurisdictions (FDA, EMA, Health Canada, TGA, and others).

How are the Low / Moderate / High / Critical thresholds defined?

The four risk levels are fixed score bands. A score is assigned to exactly one level based on where it falls:

Level	Score	Meaning
LOW	0.0 – 2.9	Sparse or predominantly beneficial evidence. No active safety alerts.
MODERATE	3.0 – 5.4	Mixed signals — some risk alongside benefit. Caution at high doses or in sensitive groups.
HIGH	5.5 – 7.4	Multiple studies or regulatory alerts documenting adverse effects. Professional oversight recommended.
CRITICAL	7.5 – 10	Regulatory restrictions in one or more major jurisdictions. Serious documented harm. Avoid without specialist supervision.

Thresholds are fixed constants (GIRI_Score_Utils::LEVEL_THRESHOLDS). They do not change per ingredient and are never subject to editorial adjustment.

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L-Theanine

Safety Profile

Known Safety Concerns

Contraindications

Interactions

Evidence and Scientific Findings

Ingredient Overview

Biological and Chemical Classification

Mechanism of Action

Clinical Evidence of Effectiveness

Pharmacokinetics

Recommended Dosage

SETI — Scientific Evidence Transparency Index

Executive Summary — Ingredient Assessment

Evidence Summary

Evidence Policy

Evidence Distribution

Score Transparency

Risk Level Classification

What drove the Low classification for L-Theanine

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