Vitamin C, also known as ascorbic acid, is the prince of vitamins and the first dietary substance associated with curing a disease known as scurvy, a deadly and painful illness that was prevalent before James Lind, MD, discovered the cure in 1747. He established that the absence of a compound in the diet was the cause of scurvy. Lind died in 1794 at 78, and the following year, the British Admiralty adopted the use of citrus foods as the prevention of scurvy. In 1935, vitamin C was synthesized in pure form.
Vitamin C is also an important part of a variety of bodily functions, ranging from bone formation to scar tissue repair. It is the major water-soluble antioxidant, it destroys free radicals, it plays a critical role in hydroxylation reactions that are essential for the formation of collagen, and carnitine synthesis uses vitamin C as a reducing agent. It is directly involved in the formation of norepinephrine and serotonin, two important substances needed for the proper function of the nervous system; and it is also involved in the synthesis of hormones, hormone-releasing factors and neurotransmitters.
The chemistry of vitamin C
The chemistry of vitamin Ca and its role in the body can be more easily understood if you remember that it is a reducing agent. This means that it donates hydrogen to other compounds. Vitamin C is formed from glucose in the bodies of most animals, except primates and guinea pigs. Humans lack the enzyme L-gulonolactone oxidase, which converts glucose to ascorbic acid. Although other enzymes are also required for the conversion, this one is definitely lacking. Take a look at the vitamin C molecule in Figure 1. It is a simple sugar molecule with a slight modification. The important parts of this figure are the two OH groups (hydroxyl groups) on the vitamin C molecule. It is the loss of the hydrogen atoms from these OHs that makes vitamin C a hydrogen donor and, therefore, a reducing agent.