L-Tryptophan
L‑Tryptophan
Snapshot
L‑Tryptophan is an essential amino acid precursor to serotonin and melatonin, supporting mood regulation, restful sleep, and cognitive performance.
What is L‑Tryptophan?
L‑Tryptophan (2S)-2-amino-3-(1H-indol-3-yl)propanoic acid is a proteinogenic amino acid that the body cannot synthesize and must obtain through diet. It serves as the precursor for neurotransmitters and hormones critical to mental and sleep health.
Where It Comes From
Dietary sources include turkey, chicken, eggs, dairy products, nuts, seeds (especially pumpkin and sesame), bananas, and soy products. L‑Tryptophan is also available as a standalone supplement or within balanced amino acid blends.
Key Nutrients & Compounds
Supplemental L‑Tryptophan provides the free-form amino acid that is converted by the body into 5‑hydroxytryptophan (5‑HTP) and then into serotonin and melatonin, supporting neurotransmission and circadian rhythm regulation.
Health Benefits
L‑Tryptophan enhances mood by boosting serotonin synthesis; promotes deeper, more restorative sleep via melatonin production; may improve cognitive focus and stress resilience; and supports healthy appetite regulation.
Recommended Dosage
Typical supplemental doses range from 500 mg to 2 g daily, taken 30–60 minutes before bedtime for sleep support or with meals for mood benefits. Start at the lower end and adjust based on individual response.
How to Use It
Take L‑Tryptophan in capsule or powder form with water or a light snack. For sleep support, consume roughly one hour before bedtime on an empty or lightly fed stomach.
Who Should Use It?
Individuals experiencing mild mood disturbances, sleep difficulties, jet lag, or appetite dysregulation; those seeking natural support for serotonin and melatonin pathways.
Possible Interactions or Cautions
May interact with antidepressant or sedative medications; risk of serotonin syndrome if combined with SSRIs or MAO inhibitors. People with liver disease or those pregnant or nursing should consult a healthcare provider before use.
Final Thoughts
L‑Tryptophan is a versatile amino acid that underpins key neurotransmitter and hormone pathways, making it valuable for mood balance, quality sleep, and overall wellbeing.
Scientific Studies
Fernstrom JD. Effects of tryptophan depletion and supplementation on neurotransmitter synthesis and function. J Nutr. 2012;142(6):1142S–1149S. https://doi.org/10.3945/jn.111.149361
Markus CR, Firk C, Gerhardt C, Kloek J, Smolders GF. Effect of the alpha‑lactalbumin fraction of whey protein on brain tryptophan availability and stress‑induced mood disturbances in young adults. Am J Clin Nutr. 2000;71(6):1536–1541. https://doi.org/10.1093/ajcn/71.6.1536
Hartmann E. The effects of L‑tryptophan on sleepiness and on sleep. J Psychiatr Res. 1982;17(2):107–113. https://doi.org/10.1016/0022-3956(82)90007-1