Vitamins are organic chemicals that a given living organism requires in trace quantities for good health, but which the organism cannot synthesize, and therefore must obtain from its diet. The term vitamin does not encompass other essential nutrients such as dietary minerals, essential fatty acids or essential amino acids. Nor is it used for the large number of other nutrients that are merely health-furthering, but not strictly essential. Humans require 13 different vitamins.
The word vitamin was coined by the Polish biochemist Kazimierz Funk in 1912. Vita in Latin is life and the -amin suffix is short for amine; at the time it was thought that all vitamins were amines. Though this is now known to be incorrect, the name has stuck.
The value of eating certain foods to maintain health was recognized long before vitamins were identified. The ancient Egyptians knew that feeding a patient liver would help cure night blindness, now known to be caused by a Vitamin A deficiency. In 1747, the Scottish surgeon James Lind discovered that citrus foods helped prevent scurvy, a particularly deadly disease characterized by bleeding and severe pain. In 1753, Lind published his Treatise on the Scurvy.
In 1905, William Fletcher discovered that eating unpolished rice instead of polished helped prevent the disease beriberi. The following year, Frederick Hopkins postulated that foods contained "accessory factors"—in addition to proteins, carbohydrates, fats, etc.—that were necessary to the human body. When Kazimierz Funk isolated the chemical that Fletcher had identified, he proposed that it be named "Vitamine". The name soon became synonymous with Hopkins' "accessory factors", and by the time it was shown that not all vitamins were amines, the word was ubiquitous. In 1920, Jack Cecil Drummond proposed that the final "e" be dropped, to deemphasize the "amine" reference, after the discovery that Vitamin C had no amine component, and the name has been "vitamin" ever since.
Throughout the early 1900s, scientists were able to isolate and identify a number of vitamins by depriving animals of them.
|Vitamin name||Water/fat soluble||Notes|
|Biotin||Water||Also known as Vitamin B7 or Vitamin H.|
|Folate||Water||Discovered by Lucy Wills in 1933. Also known as Folic Acid or Vitamin M|
|Niacin||Water||Discovered by Conrad Elvehjem in 1937. Deficiency causes pellagra. Also known as Vitamin B3, Vitamin P or Vitamin PP (for prevents pellagra).|
|Pantothenic acid||Water||Discovered by Roger Williams in 1933. Also known as Vitamin B5.|
|Riboflavin||Water||Discovered by D. T. Smith and E. G. Hendrick in 1926. Deficiency causes ariboflavinosis . Also known as Vitamin B2 or Vitamin G.|
|Thiamin||Water||Discovered by Kazimierz Funk in 1912. Deficiency causes beriberi. Also known as Vitamin B1.|
|Vitamin A (Retinoids)||Fat||Discovered by Elmer V. McCollum and M. Davis between 1912 and 1914. Deficiency causes night-blindness. Not a single chemical, but a group of chemicals derived from Retinol.|
|Vitamin B6 (Pyridoxine, pyridoxamine, or pyridoxal )||Water||Discovered by Paul Gyorgy in 1934.|
|Vitamin B12 (Cobalamin)||Water||Discovered by Karl Folkers and Alexander Todd in 1948. Deficiency causes pernicious anaemia. It is the only water-soluble vitamin that can be stored for extended periods of time in the human body.|
|Vitamin C (Ascorbic acid)||Water||Identified by James Lind in 1747. Rediscovered by A. Hoist and T. Froelich in 1912. Deficiency causes scurvy.|
|Vitamin D (Calciferol)||Fat||Discovered by Edward Mellanby in 1922. Deficiency causes rickets. Synthesized in small amounts by the body depending on exposure to sunlight.|
|Vitamin E (Tocopherol)||Fat||Discovered by Herbert Evans and Katherine Bishop in 1922.|
|Vitamin K (Naphthoquinoids)||Fat||Discovered by Henrik Dam in 1929. Not a single chemical, but a group of chemicals derived from Naphthoquinone. Deficiency impairs blood coagulation.|
An organism can survive for some time without vitamins, although prolonged vitamin deficit results in a disease state, often painful and potentially deadly. Body stores for different vitamins can vary widely; an adult may be deficient in Vitamins A or B12 for a year or more before developing a deficiency condition, while Vitamin B1 stores may only last a couple of weeks.
Fat-soluble vitamins may be stored in the body and can cause toxicity when taken in excess. Water-soluble vitamins are not stored in the body, with the exception of Vitamin B12, which is stored in the liver.
The usage of letters and numbers as vitamin names has been diminishing for the past few decades. The names in the above chart are those that the USDA uses.
Different organisms need different trace organic substances. Most mammals need, with few exceptions, the same vitamins as humans. One notable exception is ascorbic acid; most mammals can synthesize this. The less related a species is to mammals, the more different the organisms' requirements become. For example, some bacteria need adenine. Pyrroloquinoline quinone (PQQ) was reported as a vitamin for mice in 2003. In general, plants can synthesize all the organic substances they need and therefore, do not require any vitamins.