Aspartic acid is one of the building-block amino acids that are responsible for synthesizing proteins and regulating hormones in the human body.Aspartic acid comes in two forms: L-aspartic acid and D-aspartic acid.

L-aspartic acid becomes part of proteins synthesized in the body and is responsible for encouraging the production of antibodies that support the function of the body’s immune system. D-aspartic acid is not used to synthesize proteins. It is typically found in the pituitary gland and the testes, and is involved in the regulation, release, and synthesis of testosterone and luteinizing hormone (LH), which is responsible for regulating when a woman’s ovaries release an egg during her menstrual cycle and encouraging sperm production in men.

Aspartic acid is involved in the synthesis of four essential amino acids in humans: methionine, threonine, isoleucine, and lysine. Methionine is used in the metabolism; threonine is used in the central nervous system, the cardiovascular system, and the immune system; isoleucine is used in energy regulation; lysine is used in growth and muscle turnover.