L-Tryptophan is an essential amino acid that is necessary for making proteins. It is naturally found in red meat, poultry, eggs, and dairy.

L-tryptophan is important for many organs in the body. L-tryptophan is not made by the body and must be consumed from the diet. After absorbing L-tryptophan from food, the body converts some of it to 5-HTP and then to serotonin. Serotonin is a hormone that transmits signals between nerve cells. Changes in serotonin levels in the brain can affect mood.

People use L-tryptophan for severe PMS symptoms, depression, insomnia, and many other conditions.