The ABC of Vitamins

Liz Harvey:   


This web page provides an overview to the subject of vitamins, giving details of the history of their discovery, their main properties and functions in the body, and as food additives, principal sources and deficiency diseases resulting from a lack of a vitamin in the diet. I decided to carry out a project on this subject because it has always been avoided in past teaching, and I wanted to know more about it.

What are vitamins?

Vitamins are one type of ‘micronutrient’, substances that are used by the body in tiny amounts, and yet are vital in the diet of higher animals, which have often lost the ability to synthesize them. For an account of the discovery of vitamins, and the proof of their importance, go to history.

The word ‘vitamin’ means literally: vital amine, or amine of life. This is because the first vitamin discovered was thiamine, a complicated amino acid. We now know that vitamins have a variety of different structures, and are not all amines or amino acids, indeed thiamine is the only amine vitamin. However, in general, vitamins can be described as organic molecules which an organism requires for metabolic processes. Each vitamin has its own function, and cannot be replaced by any other substance. A compound may be a vitamin for one species, and yet not for another, if it can be produced in the body of the latter. An example is Vitamin C in humans, which can readily be synthesized by many other organisms.

Vitamins can be divided into two main groups: Water soluble (including Vitamin C and the B complex vitamins) and Fat soluble (including vitamins A, D, E and K). Fat soluble vitamins are found mostly in fish oils and meats, but also in some vegetables. Water soluble vitamins are found in meat, dairy products, carbohydrate rich food and fruit and vegetables. Perhaps the main reason for the importance of vitamins in the body is their use as precursors to coenzymes; complex non-protein organic compounds that help the action of enzymes. Without coenzymes many of the body’s primary functions would fail. Vitamins are just one of a number of materials which also include minerals and fatty acids, that work together synergistically to catalyze cell metabolism reactions.