Levodopa, or L-DOPA is an amino acid. In the body of mammals, it is sythesized from Tyrosine. It also occurs in different plants. As such it can be used as a dietary supplement. L-Dopa is the precursor to the neurotransmitters dopamine, norepiphedrine and epiphedrine, which are part of a group known as Catecholamines. L-dopa can also be used as a drug for diseases such as Parkinson's disease. The substance used in the drug is usually called Levodopa, and the naturally occurring substance is called L-Dopa.