Safety Profile
Known Safety Concerns
- 1989 EMS outbreak -- 37 deaths from contaminated product
- Serotonin syndrome risk with SSRIs, MAOIs, or triptans
- FDA revoked ban only in 2005 -- quality control critical
- Sedation -- do not combine with CNS depressants
Contraindications
- 1989 EMS outbreak -- 37 deaths from contaminated product
- Serotonin syndrome risk with SSRIs, MAOIs, or triptans
Interactions
Information not yet available for this ingredient profile.
Evidence and Scientific Findings
Ingredient Overview
L-tryptophan is a serotonin precursor used for sleep and mood support. A contaminated batch caused an outbreak of eosinophilia-myalgia syndrome (EMS) in 1989 killing 37 people and disabling thousands, leading to an FDA recall. Modern pharmaceutical-grade tryptophan is purified and considered safer, but the FDA revoked its ban only in 2005. Serotonin syndrome risk exists when combined with SSRIs or MAOIs.
Biological and Chemical Classification
- Scientific Name
- L-Tryptophan
Mechanism of Action
Information not yet available for this ingredient profile.
Clinical Evidence of Effectiveness
Information not yet available for this ingredient profile.
Pharmacokinetics
Information not yet available for this ingredient profile.
Recommended Dosage
Information not yet available for this ingredient profile.
SETI — Scientific Evidence Transparency Index
Executive Summary — Ingredient Assessment
- 10 studies reviewed
- 0 high-quality studies (meta-analysis or RCT)
- Main clinical benefit observed: Metabolic
- Evidence consistency: High consistency across studies (100%)
- 1989 EMS outbreak -- 37 deaths from contaminated product
- Serotonin syndrome risk with SSRIs, MAOIs, or triptans
- FDA revoked ban only in 2005 -- quality control critical
- Sedation -- do not combine with CNS depressants
The available scientific evidence for L-Tryptophan indicates notable safety signals that warrant caution. Use should be considered carefully and monitored, particularly in sensitive populations or alongside other medications.
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: 25 მარ 2026, 12:48
Evidence Distribution
-
Observational / other LOW evidence YELLOWA synthetic Bacillus compound agent enhances cotton yield and fiber quality by regulating rhizosphere microbes and metabolites. ↗Wang Q et al.. A synthetic Bacillus compound agent enhances cotton yield and fiber quality by regulating rhizosphere microbes and metabolites.. Front Plant Sci. 2026. PMID:41877974.PMID 41877974 ↗Journal Front Plant SciYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41877974/
-
Observational / other LOW evidence YELLOWCharacterization and hemocompatibility of poly (N-acryloyl-L-tryptophan) nanoparticles as targeting delivery carriers for vinblastine. ↗Zhou Z et al.. Characterization and hemocompatibility of poly (N-acryloyl-L-tryptophan) nanoparticles as targeting delivery carriers for vinblastine.. J Biomater Appl. 2026. PMID:41869752.PMID 41869752 ↗Journal J Biomater ApplYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41869752/
-
Observational / other LOW evidence YELLOWArbuscular Mycorrhizal Fungi Enhance Growth and Defense Against Spodoptera litura in Lactuca sativa. ↗Liu R et al.. Arbuscular Mycorrhizal Fungi Enhance Growth and Defense Against Spodoptera litura in Lactuca sativa.. Plant Cell Environ. 2026. PMID:41859818.PMID 41859818 ↗Journal Plant Cell EnvironYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41859818/
-
Observational / other LOW evidence YELLOWKynurenine promotes porcine intestinal epithelial cell proliferation by activating the AHR-MST1-YAP1 axis. ↗Hu Z et al.. Kynurenine promotes porcine intestinal epithelial cell proliferation by activating the AHR-MST1-YAP1 axis.. J Anim Sci Biotechnol. 2026. PMID:41845541.PMID 41845541 ↗Journal J Anim Sci BiotechnolYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41845541/
-
Observational / other LOW evidence YELLOWArtemether and Euphorbia Factor L9 suppress kynurenine production through distinct effects on Tryptophan metabolism. ↗Capatina AL et al.. Artemether and Euphorbia Factor L9 suppress kynurenine production through distinct effects on Tryptophan metabolism.. Biochem J. 2026. PMID:41823303.PMID 41823303 ↗Journal Biochem JYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41823303/
-
Observational / other LOW evidence YELLOWDiscovery of diketopiperazine alkaloids from anu00a0endophytic Kitasatospora sp. by heterologous expression. ↗Wang G et al.. Discovery of diketopiperazine alkaloids from anu00a0endophytic Kitasatospora sp. by heterologous expression.. J Antibiot (Tokyo). 2026. PMID:41820597.PMID 41820597 ↗Journal J Antibiot (Tokyo)Year 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41820597/
-
Observational / other LOW evidence YELLOWModular co-culture engineering of Escherichia coli and Saccharomyces cerevisiae for de novo biosynthesis of tryptophol from glucose. ↗Fu Z et al.. Modular co-culture engineering of Escherichia coli and Saccharomyces cerevisiae for de novo biosynthesis of tryptophol from glucose.. Bioresour Technol. 2026. PMID:41812804.PMID 41812804 ↗Journal Bioresour TechnolYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41812804/
-
Observational / other LOW evidence YELLOWSolvent-mediated organocatalytic browning of biogenic indoles enables the formation of zwitterionic nanoparticles. ↗Hu TM et al.. Solvent-mediated organocatalytic browning of biogenic indoles enables the formation of zwitterionic nanoparticles.. RSC Adv. 2026. PMID:41809077.PMID 41809077 ↗Journal RSC AdvYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41809077/
-
Observational / other LOW evidence YELLOWCo-application of Acinetobacter calcoaceticus and L-tryptophan enhances growth, physiology, and yield in bitter gourd. ↗Azhar MZ et al.. Co-application of Acinetobacter calcoaceticus and L-tryptophan enhances growth, physiology, and yield in bitter gourd.. 3 Biotech. 2026. PMID:41808727.PMID 41808727 ↗Journal 3 BiotechYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41808727/
-
Observational / other LOW evidence YELLOWThe quasi-liquid layer thickness controls clathrate hydrates' growth rate. ↗Cai X et al.. The quasi-liquid layer thickness controls clathrate hydrates' growth rate.. Proc Natl Acad Sci U S A. 2026. PMID:41805569.PMID 41805569 ↗Journal Proc Natl Acad Sci U S AYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41805569/
Score Transparency
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)
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.
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.
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.
Final GIRI Score for L-Tryptophan. 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.
Risk Level Classification
Based on available regulatory signals and scientific evidence, this ingredient presents a moderate safety concern. Caution is advised, particularly at high doses or in sensitive populations.
0–3.0
3.0–5.5
5.5–7.5
7.5–10
The score pin shows exactly where this ingredient falls on the fixed risk scale.
What drove the Moderate classification for L-Tryptophan
A score of 4.5 places this ingredient in the Moderate 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.