Amino Acid
L-Tryptophan
Also known as: TRP, Tryptophan
Essential amino acid precursor to serotonin and melatonin. Supports mood and sleep through 5-HTP pathway.
Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.
Primary uses
- Sleep
- Mood support
- Serotonin production
How it works
- Converted to 5-HTP then serotonin
- Serotonin converted to melatonin
- Rate-limited by tryptophan hydroxylase
Dosage
- Typical range
- 500-2000 mg daily
- Timing
- Evening for sleep; any for mood
- With food
- Small carb helps absorption
- Duration
- Safe long-term
- Special populations
- Sleep issues, mood support
Forms
- Capsules
Safety
Common side effects
- Drowsiness
- Nausea
Contraindications
- MAOIs
- Use caution with SSRIs
Products containing L-Tryptophan
Top-scoring supplements in our catalog that list L-Tryptophan on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.
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Known interactions
Evidence notes
Serotonin and melatonin precursor
Grade B: Some human trials support key claims; further confirmation needed.
L-Tryptophan compared head-to-head
Related in Amino Acid
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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Individual needs and risks vary — consult a professional before starting, stopping, or combining supplements, especially if you are pregnant or nursing, taking medication, or managing a health condition.