L-Tryptophan
Vitamins & MineralsCAS: 73-22-3
This is what the ingredient is.
L-Tryptophan is an essential amino acid and precursor to serotonin and melatonin.
Here is why it shows up on the label.
Used for protein fortification and as dietary supplement for sleep and mood support.
Here is what food agencies say.
FDA GRAS for food use. History of supplement-related contamination issues in 1989 resolved.
Here is what research has found.
Essential amino acid. 1989 eosinophilia-myalgia outbreak was traced to contaminated batch, not tryptophan itself.
Here are a few things worth knowing.
Generally safe in food. Supplement use should be monitored. May interact with serotonin-affecting medications.
Sources
- FDA CFR 21
- CDC Investigation Report
- EFSA Scientific Opinion
How to read this page
We publish plain facts about this ingredient so a label is easier to read. This is not medical advice, and it is not a recommendation to buy, avoid, or use anything. For a personal health question, talk with a clinician who knows your history.
v1.0Updated 9/12/2026