1. Any of various unrelated organic substances that occur in many foods in small amounts and which are necessary in trace amounts for the normal metabolic functioning of the body. They may be water-soluble or fat-soluble.
2. An organic substance essential in small quantities to the metabolism in most animals.

Vitamins are found in minute quantities in food, in some cases are produced by the body, and are also produced synthetically.

3. Any of various fat-soluble or water-soluble organic substances essential in minute amounts for normal growth and activity of the body and obtained naturally from plant and animal foods.
4. Any of a group of complex organic substances found in minute quantities in most natural foodstuffs, and closely associated with the maintenance of normal physiological functions in man and animals.
5. Etymology: originally it was vitamine (1912) as coined by Polish biochemist Casimir Funk (1884-1967), from Latin vita, "life" + amine, because vitamins were thought to contain amino acids.

The terminal -e was formally deleted when scientists learned the true nature of the vitamin substance. The suffix -in was acceptable because it was used for neutral substances of undefined composition. The lettering system of nomenclature (Vitamin A, B, C, etc.) was introduced at about the same time the suffix change was made.

Loss of vitamin content in food products because of vitamin instability; especially, in oxidation and during heating.

Methods of preserving foods add to the loss of vitamins. Pickling, salting, curing, or fermenting processes usually cause complete loss of vitamin C.

Commercial canning destroys frokm 50% to 85% of vitamin C contained in peas, lima beans, spinach, and asparagus. Pasteurization, unless special precautions are observed, causes a loss of from 30% to 60% of the vitamin C.

Organic substances needed in very small quantities by the body for normal growth and maintenance of life, and which play a catalytic and regulatory role in the body's metabolism.