DOPA, 3,4-dihydroxyphenylalanine, is an amino acid produced in the sympathetic nervous system and adrenal glands by hydroxylation of tyrosine. It occurs naturally in several beans, notably velvet beans (Mucuna pruriens), and can be made synthetically. DOPA is the metabolic precursor of dopamine and an intermediate in the biosynthesis of adrenaline and noradrenaline. In medicine its levorotatory form, L-DOPA, is the cornerstone therapy for Parkinson’s disease. Foods containing it are of interest to researchers studying dietary sources of neurotransmitter precursors. Supplement marketers sometimes overstate its benefits, so consumers should rely on clinical evidence.