Vitamin C has many functions that benefit the human body: it forms and maintains collagen, it metabolizes tryptophan, it acts as an antioxidant, it acts as a detoxifier, it can treat infections, and it helps increase thyroid hormones and decrease cholesterol. These functions are summarized below.
 

Vitamin C helps in the formation and maintenance if collagen. Collagen is the building block of connective tissues such as skin, ligaments, cartilage, vertebral discs, joint linings, capillary walls, bones, and teeth. This triple-helical protein has an amino acid called 4-hydroxyproline that is rarelly found elswere in the body. The reaction that goes on in the body is the conversion of proline to 4-hydroxyproline. The function of vitamin C is to keep the catalyst of this conversion from deactivating. Collagen is very important, because it helps heal wounds and maintain healthy blood vessels.

Vitamin C, in the presence of tryptophan, forms serotinin, which is a neurotransmitter that is an important brain chemical.

The oxidation of water-soluble molecules create free radicals. Vitamin C is an antioxidant that helps prevent the oxidation of these water-soluble molecules. Vitamin C can also protect the fat-soluble vitamins such as vitamins A and E and also some B vitamins from oxidation.
 

Vitamin C (ascorbic acid) is a detoxifier that reduces the toxicity of common drugs such as cortisone, aspirin, and insulin. It can also reduce the toxicity of some heavy metals such as lead, mercury, and arsenic.

Vitamin C is shown to stimulate the immune system. This means that it can help in treatment and prevention of infections and other diseases. Vitamin C increases the production of lymphocytes, which are the white blood cells that are important in antibody production. As an example of vitamin C's ability to treat infections, it is shown to prevent or minimize the effects of the common cold.
 

Vitamin C (ascorbic acid) helps thyroid hormone production, helps metabolize cholesterol, and assists in removing cholesterol deposits from the arterial walls.