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 deficiency and excess
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.
- Vitamin F was the designation originally given to essential fatty acids that the body cannot manufacture. They were "de-vitaminized" because they are fatty acids. Fatty acids are a major component of fats.
- Although there is no Vitamin S, the suggestion has been made that salicylic acid may qualify for the criteria needed to be defined as a vitamin, and that in this case the designation "Vitamin S" could be used to describe it.
- The sedative Ketamine is often called Vitamin K when used as a recreational drug.
- Vitamin V is a colloquialism for Viagra.
- Herbalists and naturopaths have named various herbs and chemicals "vitamins", even though they are not, including Vitamin T and Vitamin U.
- Some authorities say that Ubiquinone, also called Coenzyme Q10, is a vitamin. Ubiquinone is manufactured in small amounts by the body, like Vitamin D.
- Colloquially, the word vitamin is often used to refer to vitamin supplements , products, often in pill form, that contain or more purified vitamins which are used to supplement the vitamin content of a diet.
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.