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.
Every L-Tryptophan product we have scored
| # | Product | Score | Per serving |
|---|---|---|---|
| 1 | Nutricost L-Tryptophan Capsules | 94 A | $0.15 |
| 2 | Pure Encapsulations Cognitive Aminos | 91 A | $0.98 |
| 3 | Pure Encapsulations L-Tryptophan | 89 A | $1.61 |
| 4 | NOW Foods Double Strength L-Tryptophan | 88 A | $0.39 |
| 5 | NOW Foods L-Tryptophan | 88 A | $0.42 |
| 6 | Thorne RecoveryPro® | 85 A- | $3.67 |
| 7 | Thorne Amino Complex - Travel Packs - Berry | 85 A- | $1.20 |
| 8 | Thorne Amino Complex - Travel Packs - Lemon | 85 A- | $1.20 |
| 9 | Thorne Amino Complex - Berry | 84 A- | $1.47 |
| 10 | Thorne Amino Complex - Lemon | 84 A- | $1.47 |
| 11 | Onnit New MOOD (60 ct) | 84 A- | $2.00 |
| 12 | Bluebonnet Nutrition L-TRYPTOPHAN 500 mg | 82 A- | $0.60 |
Scored on dose accuracy, form, label transparency and third-party testing. Per-serving cost is list price divided by servings per container. No brand pays to be listed or ranked.
Common questions
How much L-Tryptophan should I take?
The typical range is 500-2000 mg daily. Safe long-term
When should I take L-Tryptophan?
Evening for sleep; any for mood. Small carb helps absorption.
Which form of L-Tryptophan is best?
Capsules — Common.
Is L-Tryptophan safe?
Commonly reported: Drowsiness, Nausea. Serious warnings: Serotonin syndrome with SSRIs. Safe
Which L-Tryptophan supplement scores highest?
Nutricost L-Tryptophan Capsules, at 94/100. Scored on dose accuracy, form, label transparency and third-party testing — no brand pays to be listed or ranked.
Primary uses
- Sleep
- Mood support
- Serotonin production
What systematic reviews concluded
Outcomes that systematic reviews of L-Tryptophan reached a verdict on: 3 with a benefit, 2 unclear. Each is quoted from a review and linked to it on PubMed. How these were read.
Reviews found a benefit (3)
“Trp supplementation, especially at ≥1 g can help improve sleep quality.” PMID 33942088
“This suggests that TRP intake may be an effective approach to decrease anxiety and increase positive mood in healthy individuals.” PMID 32272859
“Sodium intake and L-tryptophan supplementation demonstrated positive effects on fatigue reduction and recovery.” PMID 41059723
Not enough to say: aggressive behavior; violent/aggressive behavior treatment.
1 finding from reviews in specific patient groups (such as cancer, pregnancy or surgery) is not shown here.
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.
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
Check a full stack
Formulate's free interaction checker lets you paste in any combination of supplements and medications at once — every pairing flags severity, timing, and cited evidence.
Open the checkerWhere does L-Tryptophan fit in your stack?
Answer two questions and get a stack graded on research — every ingredient scored on the evidence behind it, not the marketing.
Build my stack2 questions · free · no account needed to start
Also on iPhone — get the free app
Evidence-based supplement guides, no spam
We send a short digest when new guides drop — nothing else. No affiliate pushes, no sponsored content, unsubscribe anytime.
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.