A vitamin is an organic compound that cannot be synthesized (at all; or in quantities that meet all needs) by a given organism and must be taken (in trace quantities) with food for that organism's continued good health. The name was invented 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. This is now known to be incorrect, but the name stuck. The term vitamin is not used for inorganic trace nutritional requirements (these are dietary minerals) or for essential fatty acids or for essential amino acids.

Table of contents
1 Introduction
2 Vitamin deficiency diseases
3 Is vitamin D a real vitamin?
4 Vitamins A and K
5 Names
6 Whatever Happened to Vitamin F?
7 Non-human vitamins


Vitamins were first recognised by the diseases that occur from a lack of certain foods; for example, the British Royal Navy recognised that a constituent of limes prevented scurvy (one result of not having enough vitamin C over an extended period of time), so limes were added to the diet of sailors. Vitamin D prevents rickets, and so forth.

Vitamins can be divided in two groups by their solubility in water:

Water-soluble vitamins

Fat-soluble vitamins 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 – for aerobic organisms – air, an organism can survive for some time without vitamins, although prolonged vitamin deficit results in a disease state.

Vitamin deficiency diseases

Several diseases are caused by a lack of adequate vitamin intake. These can become severe, even life-threatening.

Some vitamin deficiency diseases include:

Deficient vitaminDisease
         A         night blindness
         B1         beriberi
         B2         ariboflavinosis
         B12         pernicious anaemia
         niacin         pellagra
         C         scurvy
         D         rickets

Other vitamin deficiencies are simply called after the name of the vitamin, like vitamin K deficiency disease.

Is vitamin D a real vitamin?

Vitamin D is synthetized by human body, but in quantities that are not always sufficient. The level of synthesis depends on exposure to sunlight, so in winter and in polar areas it acts more like a vitamin, and in summer and in equatorial areas it acts less like a vitamin. So it's usually treated as a vitamin, but one that isn't required in some areas and seasons.

Vitamins A and K

Neither vitamin A nor vitamin K is a single chemical substance, but all derivatives fulfill the same functions in organisms (or are converted into the active form by the organism), so taking just one of the derivatives is sufficient for good health. The derivatives differ in chemical structure and level of activity.


Some obsolete vitamin names:
  • Vitamin B - actually a complex of several vitamins: B-number, H, and M.
  • Vitamin G - another name for riboflavin (vitamin B2)

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.

Whatever Happened to Vitamin F?

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.

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). The further we go from mammals, the more diverse organisms' requirements become. For example, some bacteria need adenine.

See pharmacology.

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