amino acid Amino Acids Oral

L-Tryptophan

An essential amino acid that is a direct precursor to the neurotransmitter serotonin and the sleep hormone melatonin.

Sci.L-Tryptophan l-tryptophan Tryptophan Trp (S)-Tryptophan
1 form
Oral

About L-Tryptophan

L-Tryptophan is an essential aromatic amino acid that cannot be synthesized by the human body and must be obtained from the diet. It serves as a critical metabolic precursor for several important compounds, most notably the neurotransmitter serotonin and the hormone melatonin. It is also a precursor for the synthesis of niacin via the kynurenine pathway, and is incorporated into various structural and functional proteins throughout the body.

Official resources

Fact sheets from the NIH Office of Dietary Supplements related to this ingredient group.

Dietary Supplement Label Database

Ingredient group data in NutriNav is aligned with the NIH Dietary Supplement Label Database (DSLD).

DSLD group id
199

At a glance

Suggested daily

The Recommended Dietary Allowance (RDA) for adults is set at 5 mg per kg of body weight per day, approximately 350 mg for a 70 kg individual.

Max safe daily

No official UL has been established, but caution is advised with high-dose supplements due to historical associations with eosinophilia-myalgia syndrome.

Approval status

supplement

Compare All Forms

1 form

Compare supplement forms of L-Tryptophan by absorption quality and what your body actually gets from each:

High Moderate Low
Form Absorption Steps to absorb Notes Action
L-Tryptophan
  • CAS: 73-22-3
  • Label category: Synthetic (Fermentation)
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Type: Amino Acids

Building blocks of proteins. Essential amino acids must be obtained from diet, while non-essential can be synthesized by the body.

Absorption: Amino acids are generally well-absorbed. Some forms (like citrulline) are more effective than others (like arginine).

Interactions: Generally safe but high doses can cause digestive issues. Some amino acids can affect neurotransmitter levels.

Watch out for

Possible interactions or cautions — talk to a healthcare provider if unsure.

  • May interact with antidepressants, particularly SSRIs, and sedatives.

Potential Benefits

Benefits associated with L-Tryptophan forms:

Sleep Quality Mood Support Mood Enhancement Sleep aid

Potential Side Effects

Side effects associated with L-Tryptophan forms:

Drowsiness How serious: Mild Gastrointestinal issues How serious: medium

What does the research say?

L-Tryptophan has been studied for its role in serotonin production, sleep regulation, and mood enhancement. Research indicates its importance in mental health and sleep disorders.