Healthvit L-Tryptophane 500MG | 60 Capsules L-tryptophan is an amino acid, a protein building block that can be found in many plant and animal proteins. L-tryptophan is called an essential amino acid because the body cant make it. It must be acquired from food. L-tryptophan is an amino acid, a protein building block that can be found in many plant and animal proteins. L-tryptophan is called an “essential” amino acid because the body can’t make it. It must be acquired from food. L-tryptophan is naturally found in animal and plant proteins. L-tryptophan is considered an essential amino acid because our bodies can’t make it. It is important for the development and functioning of many organs in the body. After absorbing L-tryptophan from food, our bodies convert it to 5-HTP (5-hyrdoxytryptophan), and then to serotonin