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    Amino AcidsSynthetic

    L-Tryptophan

    Also known as: Tryptophan

    Essential amino acid hydroxylated to 5-HTP by tryptophan hydroxylase, decarboxylated to serotonin, then N-acetylated and methylated to melatonin in the pineal.

    Last reviewed: 2026-06-23 · 1 indexed study

    Evidence Score
    62/100
    SleepMoodSerotonin precursor
    Data Completeness3/4 · 75%
    Evidence ScoreDosageSafetyLinked Studies

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    Overview

    L-Tryptophan is the essential amino acid precursor to serotonin and melatonin; supplementation supports sleep onset, mood, and circadian regulation.

    Mechanism & Function

    Mechanism of Action

    Supplies precursor for serotonin and melatonin synthesis; competes with large neutral AAs for blood-brain barrier transport.

    Physiological Role

    Useful for sleep onset insomnia, mood support, and post-exercise mood/recovery; effects depend on insulin (which clears competing LNAAs) — best taken with carbohydrate.

    Primary Pathways

    Tryptophan hydroxylaseSerotonin synthesisMelatonin synthesisKynurenine pathway

    Performance / Health Relevance

    RCTs support sleep latency and mood benefits; effective doses vary 0.5–3 g.

    Evidence Review

    Overall62/100
    Human Clinical70/100
    Meta-Analysis58/100
    Mechanistic78/100
    Real-World62/100
    Safety80/100

    Practical Use & Dosage

    Minimum Effective Dose
    500 mg
    Optimal Range
    1–2 g pre-bed (sleep) or split (mood)
    Upper / Caution Level
    ~3 g/day
    Timing
    With carbohydrate, 60 min pre-bed
    Best Format
    Powder, capsule
    Bioavailability
    Moderate — competes for LNAA transporter.
    Absorption Considerations
    Active intestinal transport; brain uptake enhanced by insulin-driven LNAA clearance.

    Safety & Interactions

    Side Effects

    • •Mild drowsiness
    • •Nausea
    • •Headache

    Contraindications

    • SSRI/MAOI use
    • Carcinoid syndrome

    Drug Interactions

    • •SSRIs
    • •MAOIs
    • •Triptans
    • •SAM-e

    Who Should Avoid

    • •Concurrent serotonergic agents — risk of serotonin syndrome

    Monitoring

    None routine in healthy users.

    Frequently Asked Questions

    Auto-generated from indexed evidence — dosage, safety, interactions, and more.

    When is L-Tryptophan typically used or indicated?

    L-Tryptophan is most commonly used for: Sleep, Mood, Serotonin precursor. Useful for sleep onset insomnia, mood support, and post-exercise mood/recovery; effects depend on insulin (which clears competing LNAAs) — best taken with carbohydrate.

    How does L-Tryptophan work?

    Supplies precursor for serotonin and melatonin synthesis; competes with large neutral AAs for blood-brain barrier transport.

    What is the recommended dose of L-Tryptophan?

    The optimal range is 1–2 g pre-bed (sleep) or split (mood). with a minimum effective dose of 500 mg. Best taken: With carbohydrate, 60 min pre-bed. Upper / caution level: ~3 g/day.

    What are the side effects of L-Tryptophan?

    Reported side effects include: Mild drowsiness; Nausea; and Headache. Monitoring: None routine in healthy users.

    Does L-Tryptophan interact with medications?

    Known or theoretical interactions: SSRIs; MAOIs; Triptans; and SAM-e. Always check with a clinician before combining with prescription medication.

    Who should avoid L-Tryptophan?

    L-Tryptophan is generally not recommended for: Concurrent serotonergic agents — risk of serotonin syndrome; SSRI/MAOI use; and Carcinoid syndrome.

    How strong is the evidence for L-Tryptophan?

    Evidence level: Moderate (overall score 62/100), based on 1 indexed study on SuppIndex.

    Research & References (1)

    L-Tryptophan in the treatment of insomnia: meta-analysis

    Meta-Analysis2022Moderate
    PubMed

    Tryptophan significantly reduced sleep latency and improved subjective sleep quality.

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    Research Overview

    Moderate Evidence
    1Total Studies
    0Human Trials
    1Meta-Analyses
    2022Latest Study
    0Animal / In Vitro
    0Athlete Studies
    Primary data sourceMixed
    Pooled evidence (meta-analysis / systematic review)Yes

    Cite this ingredient

    One-click citation export in APA, MLA, Chicago, BibTeX, or HTML. The URL below is stable and safe to link.

    Stable URL

    https://thesuppindex.com/ingredients/l-tryptophan

    SuppIndex. (2026). L-Tryptophan: Evidence summary, dosage and clinical studies. Retrieved October 16, 2026, from https://thesuppindex.com/ingredients/l-tryptophan

    Based on 1 indexed studies · Evidence level: Moderate.

    Goal Ratings

    Sleep
    Stress
    Recovery

    Stack Compatibility

    Pair with carbohydrate, magnesium, glycine for sleep.

    MagnesiumGlycineCarbohydrate