Definition: The term "isosuccinic" refers to a type of amino acid that is found in the body's metabolism. Isosuccinic acid is an essential amino acid for muscle and bone growth, as well as for maintaining healthy skin and hair. Isosuccinic acid has three isomers: 3-isocoumarin (1R), 3-isobutyric acid (2R), and 3-isopropyl-cyclodithiogalactopyranos