Best L-Tryptophan products contain Ajinomoto TryptoPure. Tryptophan is an essential amino acid readily converted by the body to the neurotransmitter serotonin. Able to cross the blood-brain barrier, L-tryptophan is altered by enzymes to first form the intermediate amino acid 5-HTP and then serotonin. It is also the metabolic precursor to melatonin and to the B vitamin niacin. Supplementing the diet with pure L-tryptophan like TryptoPure, found in Doctors Best L-Tryptophan products, can improve sleep and enhance mood, and may also be beneficial in reducing carbohydrate cravings.