Vitamin C (ascorbic acid), a reducing agent, is necessary to maintain the enzyme prolyl hydroxylase in an active form, most likely by keeping its iron atom in a reduced state. The precursor molecule to the protein collagen, procollagen, contains an unusual amino acid sequence in that every third amino acid is a glycine and contains a high frequency of two amino acids not found in any other proteins - hydroxyproline and hydroxylysine. These latter two amino acids are converted from proline and lysine, respectively, after the procollagen molecule has been synthesized. The hydroxylation of proline and lysine in procollagen is carried out by the enzyme prolyl hydroxylase using vitamin C as a cofactor.

A vitamin C deficiency results in an underhydroxylation of proline and lysine in collagen which results in a lower melting temperature of the resulting collagen fibers which causes a breakdown of the protein collagen needed for connective tissue, bones and dentin, the major portion of teeth. Collagen is a cementing material that binds cells together, and is an essential connective tissue protein in the body. Whenever the body is wounded, collagen glues the separated tissues together to form a scar.

A lack of collagen causes the walls of the body's blood capillaries to break down and hemorrhaging occurs in cells throughout the body. When capillaries lose the "glue" that holds them together, symptoms of scurvy appear.

An affected person becomes weak and has joint pain. Internal hemorrhages cause black-and-blue marks to appear on the skin. At the first visible signs of scurvy, raised red spots appear on the skin around the hair follicles of the legs, buttocks, arms and back. When the tiny capillaries of the hair follicles hemorrhage, the hair-producing cells do not receive the nourishment needed for the hairs to grow normally. Consequently, the skin becomes flecked with small lesions that begin to appear on the body after about five months on a diet deficient in vitamin C. These lesions were the "spots" that James Lind observed on the skin of his sick men. Gums hemorrhage and their tissue becomes weak and spongy. Dentin, which lies below the enamel and is part of the root of teeth, breaks down. Teeth loosen and eating becomes difficult and painful. A Treatise on the Scurvy 

James Lind's observation that citrus fruits contained something that counteracted the ravages of scurvy was followed by his development of a method for the concentration and preservation of citrus fruit juices for use at sea. In 1795, the British Royal Navy provided a daily ration of lime or lemon juice to all its men. English sailors to this day are called "limeys", for lime was the term used at the time for both lemons and limes. It was not until 1932, that W.A. Waugh and C.G. King at the University of Pittsburgh, and Albert Szent-Gyorgyi, a Hungarian scientist, isolated and synthesized ascorbic acid, or vitamin C.

Curiously, only primates and guinea pigs are unable to manufacture vitamin C on their own, having lost the genetic information necessary for the production of this important cofactor. ** (Also Fruit-Bats See Below)