L-Aspartic Acid is thought to help promote a robust metabolism, and is sometimes used to treat fatigue and depression. Aspartic acid plays an important role in the citric acid cycle, or krebs cycle, during which other amino acids and biochemical, such as asparagine, arginine, lysine, methionine, threonine, and isoleucine are synthesized. Aspartic acid keeps your mind sharp by increasing concentrations of nicotinamide adenine dinucleotide (NADH) in the brain, it to boost the production of neurotransmitters and chemicals needed for normal mental functioning. It also removes excess toxins from the cells, particularly ammonia, which is very damaging to the brain and nervous system as well as the liver.