Some amino acids have properties similar to neurotransmitters.
This makes them useful in treating anxiety and depression. Gamma-aminobutyric acid, or GABA, is a natural antianxiety chemical and is often found in low levels in depressed people. L-tryptophan is a precursor to the synthesis of serotonin, and so it too is vital for combating depression and maintaining emotional balance. Tyrosine is a precursor of norepinephrine and dopamine, two neurochemicals that are involved in mood. D-phenylalanine is another important amino acid that has been associated with depression.