Last verified: 17 days ago
L-Tryptophan
Also known as: Tryptophan, Trp, L-Trp, 2-amino-3-(1H-indol-3-yl)propanoic acid
Evidence under review. — Not yet rated
Essential amino acid that may help regulate appetite and blood sugar when combined with other nutrients.
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What it does
L-Tryptophan is an essential amino acid your body cannot make on its own — you must get it from food or supplements. Research in the provided studies suggests it can stimulate gut hormones like...
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Evidence quality
Evidence base hasn't been formally rated yet. See research below.
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Clinical dose
No established dose from provided studies
What the Science Says
L-Tryptophan is an essential amino acid your body cannot make on its own — you must get it from food or supplements. Research in the provided studies suggests it can stimulate gut hormones like GLP-1 and CCK that slow digestion and reduce appetite, particularly when combined with certain fatty acids. One small pediatric study also explored its use alongside melatonin for sleep support in children with neurodevelopmental disorders, though results were inconclusive.
What It Doesn't Do
Not proven to improve mood or depression on its own based on these studies. No evidence here it builds muscle or boosts athletic performance. The sleep benefits seen in studies used it combined with melatonin — tryptophan alone showed no significant sleep improvement. Don't expect it to work as a standalone blood sugar fix.
Evidence-Based Benefits
Reduces calorie intake by stimulating gut hormones that slow digestion, when delivered directly to the gut.
Weak EvidenceEffective at: No established oral dose from provided studies
Supporting studies (click to view on PubMed):
Combined with lauric acid, lowers post-meal blood sugar in men with type 2 diabetes by slowing gastric emptying.
Weak EvidenceEffective at: No established oral dose from provided studies
Supporting studies (click to view on PubMed):
When added to melatonin, may reduce nighttime movement in children with neurodevelopmental disorders.
Weak EvidenceEffective at: 20 mg combined with 1 mg melatonin in one small trial
Supporting studies (click to view on PubMed):
Absorption & Bioavailability
Unknown from provided studies — most research used intraduodenal (direct gut) infusion, which bypasses normal oral absorption. Oral bioavailability data not available in these papers.
Red Flags to Watch For
- Most positive findings used intraduodenal infusion, not oral supplements — results may not translate to pills or powders
- The sleep study had only 13 completers out of 26 enrolled — very small and high dropout rate
- Competing amino acids (like leucine) in protein-rich meals can block tryptophan's effects on appetite hormones
- Historical safety concern: a 1989 contaminated batch caused a serious condition called eosinophilia-myalgia syndrome — always buy from reputable, tested manufacturers
- No long-term safety data provided in these studies
Products Containing L-Tryptophan
See how L-Tryptophan is used in these analyzed products:
Elm & Rye Vegan Protein Blend
Supplement
Thorne Amino Complex Berry Powder NSF
Supplement
Double Wood Supplements Essential Amino Acids
Supplement
Optimum Nutrition 100% Gold Standard Whey
Supplement
Swolverine INTRA
Supplement
Juna Nightcap Sleep Gummies
Supplement
Performance Lab Sleep
Supplement
Kin Euphorics Dream Light Nightcap
Supplement
Frequently Asked Questions
What does L-Tryptophan do?
Essential amino acid that may help regulate appetite and blood sugar when combined with other nutrients.
What is the effective dose of L-Tryptophan?
No established dose from provided studies
Is L-Tryptophan safe?
Most positive findings used intraduodenal infusion, not oral supplements — results may not translate to pills or powders
What doesn't L-Tryptophan do?
Not proven to improve mood or depression on its own based on these studies.
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-05-25