L-dopa (L-3,4-dihydroxyphenylalanine) is a non-essential amino acid that can be found in some foods and herbs, and it's also made inside the human body by using another amino acid, L-tyrosine. L-dopa's most important function is that it acts as a precursor to the neurotransmitter dopamine and other important neurotransmitters.*
A neurotransmitter is a natural, biological chemical that helps transmit nerve signals in the body.
The most common natural source of L-dopa is a bean plant called Mucuna Pruriens, or velvet bean. Most supplemental forms of L-dopa are extracted from Mucuna Pruriens.