- any of a group of organic substances essential in small quantities to normal metabolism, found in minute amounts in natural foodstuffs or sometimes produced synthetically: deficiencies of vitamins produce specific disorders.
- any of a group of substances that are essential, in small quantities, for the normal functioning of metabolism in the body. They cannot usually be synthesized in the body but they occur naturally in certain foods: insufficient supply of any particular vitamin results in a deficiency disease
1920, originally vitamine (1912) coined by Polish biochemist Casimir Funk (1884-1967), from Latin vita “life” (see vital) + amine, because they were thought to contain amino acids. The terminal -e formally was stripped off when scientists learned the true nature of the substance; -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 the same time (1920).
- 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.
- Any of various organic compounds that are needed in small amounts for normal growth and activity of the body. Most vitamins cannot be synthesized by the body, but are found naturally in foods obtained from plants and animals. Vitamins are either water-soluble or fat-soluble. Most water-soluble vitamins, such as the vitamin B complex, act as catalysts and coenzymes in metabolic processes and energy transfer and are excreted fairly rapidly. Fat-soluble vitamins, such as vitamins A, D, and E are necessary for the function or structural integrity of specific body tissues and membranes and are retained in the body.
Complex organic compounds that are needed in small amounts by the body for normal growth and metabolism. An important part of a balanced diet, vitamins occur naturally in foods and may be added to processed foods to increase their nutritional value. Many vitamins have been identified, and each plays a specific role in the functioning of the body. For example, vitamin C is needed for the proper healing of wounds and broken bones; vitamin A helps the body resist infection. Some vitamins are so important that without them certain diseases or conditions could develop. For example, a deficiency of vitamin D may cause rickets, and a deficiency of vitamin B12 could result in a form of anemia.