Vitamin C was introduced in Creatures 1 as a Water soluble vitamin, used to maintain healthy connective tissue. Despite this description, it was not included in any official COBs, or referenced anywhere in the genome, making it an unused chemical.
By Creatures 3/Docking Station, however, Vitamin C had the function of speeding up the conversion of antigens to antibodies, and it was contained in the Medicine maker's Vitamin Potion. It is described as Keeps bones healthy, aids in healing from injuries. In most C3/DS norns, Vitamin C has an infinite halflife, meaning it will not decay. The Panatreea Potion included with the fragile Treehugger Norns includes a large amount of Vitamin C.