* Amino Acid Supplement L-Aspartic acid plays a vital role in energy production. It is one of the components necessary to move high energy NADH molecules from the main body of a cell to its mitochondria, or primary energy-production areas. Once there, the NADH is used to generate ATP, the energy fuel that powers all the cell"s activities. Besides helping with energy production, L-Aspartic acid is a major excitatory neurotransmitter.