Our MITOcare add·on L-tryptophan L-tryptophan is obtained from natural fermentation. L-tryptophan is one of the essential amino acids. The body cannot produce it itself and must therefore obtain it from food. In the body, L-tryptophan acts as a building block for various proteins, but is also involved in the formation of hormones. In the intestine, L-tryptophan passes into the blood, of which a small proportion can usually cross the blood-brain barrier and thus reach the central nervous system. A sufficient supply of L-tryptophan enables the body to further synthesise part of it into 5-HTP, which in turn is the precursor for the happiness hormone serotonin.