Aspartic acid. Molecular model of the amino acid aspartic acid. Its chemical formula is C4.H7.N.O4. Atoms are represented as spheres and are colour- coded: carbon (blue), hydrogen (gold), oxygen (red) and nitrogen (dark blue). Amino acids are the building blocks of proteins. Aspartic acid is a non-essential amino acid. It can be synthesised by the body and so does not need to come from the diet. Aspartic acid plays an important role in nerve function, as it stimulates NMDA receptors (proteins that guard nerve cells' ion channels), exciting the nerve cells in the brain and making them resistant to fatigue. It also participates in gluconeogenesis, where glucose (a type of sugar used by the body for energy) is formed from simple molecules such as pyruvate and lactic acid.