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Vitamins are a class of essential nutrients that cannot be synthesized (either at all or in sufficient quantities) by a given animal organism and must be taken (in trace quantities) with food for that organism's continued good health. Humans require 13 different vitamins. The term vitamin is not used for other classes of essential nutrients including 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.

The name 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.

History
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 cased 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"&mdash;in addition to proteins, carbohydrates, fats, etc.&mdash;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.

Throughout the early 1900s, scientists were able to isolate and identify a number of vitamins by depriving animals of them.

Solubility
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. Unlike food, water, and&mdash;for aerobic organisms&mdash;air, an organism can survive for some time without vitamins, although prolonged vitamin deficit results in a disease state.

Vitamin deficiency diseases
Vitamins were first recognised by the diseases that occur from a lack of certain foods; for example, the British Royal Navy's observation that limes were effective in preventing scurvy led to the discovery of vitamin C. Several diseases are caused by a lack of adequate vitamin intake. These can become severe, even life-threatening. Most vitamin deficiencies are simply called after the name of the vitamin, such as vitamin K deficiency disease.

About names
The usage of names in the format "vitamin letter" and "vitamin letter number" is diminishing. This is especially true for vitamins H, M, B1, B2, B3, and B5, which are usually called by their proper chemical names.

On the other hand, vitamins D and E are still usually called by their symbolic names, and A and K don't even have proper chemical names (since they are mixtures of chemicals). The names ascorbic acid and vitamin C are used with similar frequency.

Non-vitamins
Several medicines and herbs are given vitamin names, although they aren't considered such by the medical community.


 * Vitamin V is a colloquialism for Viagra.
 * Vitamin T
 * Vitamin U

New vitamin discoveries
On April 24, 2003 a research team led by Takafumi Kato of the Japanese Institute of Physical and Chemical Research confirmed that pyrroloquinoline quinone (PQQ), a substance originally discovered in 1979, can be categorised as a vitamin in mice.

Some authorities say that Ubiquinone, also called Coenzyme Q, is a vitamin (See ref.) Ubiquinone is manufactured by the body, so other authorities dispute this. However most humans need about 500mg/day, but manufacture less as they age. Ubiquinone's primary action is as an antioxidant many times more powerful than Vitamin E, and one of its most important roles is to prevent oxidative damage to mitochondria, the cellular organelles that power human metabolism. Many authorities say that Ubiquinone supplementation has value to treat or prevent some symptoms and diseases of aging.

Non-human vitamins
Different organisms need different trace organic substances. The list of vitamins in this article refers to humans. Most mammals need, with few exceptions, the same vitamins (except that most species don't need ascorbic acid in their diet as they synthesize their own). The further apart from mammals a species is, the more diverse the organisms' requirements become. For example, some bacteria need adenine. Pyrroloquinoline quinone (PQQ) was reported as a vitamin for mice in 2003.