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A vitamin (vita in Latin is life and -amin suffix is short form of amine) is a organic compound that cannot be synthesized (at all or in quantities that fulfill all needs) by a given organism and must be taken (in trace quantities) with food for that organism's continued good health. Name was invented by Polish biochemist Kazimierz Funk in 1912, who proposed that name for semi-hypothetical substances he thought can be found in some kinds of food.

Vitamins were first recognised by the diseases that occurred from the lack of certain foods; the British Royal Navy recognised that a constituent of limes prevented scurvy (one possible 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, as follows.

Water-soluble vitamins:

• Ascorbic Acid (Vitamin C)
• Thiamin (Vitamin B1)
• Riboflavin (Vitamin B2)
• Niacin (Vitamin B3) (also called Nicotinic Acid or Vitamin P -- for Pellagra preventing)
• Pantothenic acid (Vitamin B5)
• Pyridoxine (Vitamin B6)
• Cobalamin Vitamin B12
• Biotin (Vitamin H)
• Folic acid (Vitamin M)

Fat-soluble vitamins:

• Retinol and derivatives) (Vitamin A)
• Calciferol- see below (Vitamin D)
• Tocopherol (Vitamin E)
• Naphthoquinone (and derivatives) (Vitamin K)

Unlike food, water, and--for aerobic organisms--air, an organism can survive quite some time without vitamins, although prolonged vitamin deficit results in a disease state. Organic vitamins are contrasted with other trace nutritional requirements that are inorganic in nature, referred to as minerals.

Vitamin Deficiency Diseases

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

Some vitamin deficiency diseases:

Deficiency in Vitamin A causes night blindness

Deficiency in Vitamin B1 causes beriberi

Deficiency in Vitamin B2 causes ariboflavinosis

Deficiency in Vitamin B12 causes pernicious anemia

Deficiency in Niacin causes pellagra

Deficiency in Vitamin C causes scurvy

Deficiency in Vitamin D causes 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. Level of synthesis depends on sun activity, so in winter and in polar areas it's more like a vitamin, and in summer and in equatorial areas it's 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 fulfil the same function in organism, so taking just one of derivatives is required for good health. Derivatives differ only by level of activity.

Names

Some obsolete vitamin names:

• Vitamin B - actually complex of a few vitamins: B-number, H and M.

• Vitamin G - another name for Riboflavin (Vitamin B2)

Usage of names '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 with their symbolic names, and A and K don't even have proper chemical names.

The names Ascorbic Acid and Vitamin C are used with similar frequency.

It's very probable that in some distant future, all vitamins will be named with common chemical names. We can see this evolution in case of Ascorbic Acid nowadays.

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 (but the majority of them 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.