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A Vitamin is an organic molecule required by a living organism in minute amounts for proper health. An organism deprived of all sources of a particular vitamin will eventually suffer from disease symptoms specific to that vitamin.

Vitamins can be classified as either water soluble, which means they dissolve easily in water, or fat soluble, which means they are absorbed through the intestinal tract with the help of lipids.

In general, an organism must obtain vitamins or their metabolic precursors from outside the body, most often from the organism's diet. Examples of vitamins that the human body can derive from precursors include vitamin A, which can be produced from beta carotene; niacin from the amino acid tryptophan; and vitamin D through exposure of skin to ultraviolet light.

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 merely promote health, but are not strictly essential.

The word vitamin was coined by the Polish biochemist Casimir 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.

Contents 1 History 2 Human vitamins 2.1 Vitamin deficiency and excess 3 Pseudo-vitamins 4 Colloquial usage of the term 5 Non-human vitamins 6 See also 7 References 8 External links

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 caused by a vitamin A deficiency. In 1747, the Scottish surgeon James Lind discovered that citrus foods helped prevent scurvy, a particularly deadly disease in which collagen is not properly formed, and characterized by poor wound healing, bleeding of the gums, and severe pain. In 1753, Lind published his Treatise on the Scurvy. His discovery, however, was not widely accepted. In the Royal Navy's Arctic expeditions in the 19th century, for example, it was widely believed that scurvy was prevented by good hygiene on board ship, regular exercise, and maintaining the morale of the crew, rather than by a diet of fresh food, so that Navy expeditions continued to be plagued by scurvy. At the time Robert Falcon Scott made his two expeditions to the Antarctic in the early 20th century, the prevailing medical theory was that scurvy was caused by "tainted" canned food.

In 1881, Russian surgeon Nikolai Lunin fed mice upon an artificial mixture of all the separate constituents of milk known at that time, namely the proteins, fats, carbohydrates, and salts. They died, while the mice fed by milk itself developed normally. He made a conclusion that "a natural food such as milk must therefore contain besides these known principal ingredients small quantities of unknown substances essential to life" [1] However, his conclusion was rejected by other researchers who were unable to reproduces his results. One difference was that he used table sugar (sucrose), while other researchers used milk sugar (lactose) which still contained small amounts of vitamin B.

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 are necessary to the human body. When Casimir Funk isolated the water-soluble complex of micronutrients whose bioactivity 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 already 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. Initially, lipid from fish oil was used to cure rickets in rats, and the fat-soluble nutrient was called "antirachitic A". The irony here is that the first "vitamin" bioactivity ever isolated, which cured rickets, was initially called vitamine A, this bioactivity is now called vitamin D, which is subject to the semantic debate that vitamin D is not truly a vitamin because it is a steroid derivative. What we now call "vitamin A" was identified in fish oil because it was inactivated by ultraviolet light. Most of what we now recognize as the water-soluble organic micronutrients were initially referred to as just one entity, "vitamin B".

Human vitamins

In humans, there are thirteen vitamins, divided into two groups, the four fat soluble vitamins (A, D, E and K) and the nine water soluble vitamins (eight B vitamins and vitamin C).

Vitamin Name	Chemical Name	Solubility	Deficiency Disease	Overdose	Example Estimated Average Daily Requirements (M,19-30)[2]
Vitamin A	Retinol	Fat	Night-blindness, Keratomalacia	25,000 IUs	620μg
Vitamin B1	Thiamine	Water	Beriberi	n/a	1mg
Vitamin B2	Riboflavin	Water	Ariboflavinosis	n/a	1.1mg
Vitamin B3	Niacin	Water	Pellagra	2,500 mg	12mg
Vitamin B5	Pantothenic acid	Water	Paresthesias	n/a
Vitamin B6	Pyridoxine	Water	n/a	400 mg	1.1 mg
Vitamin B7	Biotin	Water	n/a	n/a	30 μg
Vitamin B9	Folic acid	Water	n/a	1,000 µg	320 μg
Vitamin B12	Cyanocobalamin	Water	Pernicious anemia	n/a	2 μg
Vitamin C	Ascorbic acid	Water	Scurvy	n/a	75 mg
Vitamin D1	Lamisterol	Fat	Rickets	50,000 IUs	2 μg for all Vitamin D
Vitamin D2	Ergocalciferol	Fat	Rickets	See above.	2 μg for all Vitamin D
Vitamin D3	Calciferol	Fat	Rickets	See above.	2 μg for all Vitamin D
Vitamin D4	Dihydrotachysterol	Fat	Rickets	See above.	2 μg for all Vitamin D
Vitamin D5	7-dehydrositosterol	Fat	Rickets	See above.	2 μg for All Vitamin D
Vitamin E	Tocopherol	Fat	n/a	50,000 IUs	12 mg
Vitamin K	Naphthoquinone	Fat	n/a	n/a	75 μg

Some of the vitamins are known by other names in older literature. Vitamin B₂ is also referred to as Vitamin G. Vitamin B₇, or Biotin is also referred to as Vitamin H. Vitamin B₉, or Folic Acid is also referred to as Vitamin M. Vitamin B₃ is also referred to as "Vitamin PP", a name derived from the obsolete term "pellagra-preventing factor". Many other essential dietary substances were originally called vitamins and are now classified differently.

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.

Pseudo-vitamins

• 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 which, like water, are needed by the body in large quantities and thus do not fit the definition of vitamins which are needed only in trace amounts.
• 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. However as salicylic acid is not required in humans for normal existence it cannot be truly classified as a vitamin.
• 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.
• Pangamic acid and the related substance dimethylglycine are sometimes referred to as Vitamin B₁₅.
• Laetrile is sometimes referred to as Vitamin B₁₇. Both pangamic acid and laetrile were first proposed as vitamins by Ernst T. Krebs; neither are recognized by the medical community as vitamins.
• Flavonoids are sometimes called Vitamin P.
• A few substances were once thought to be B-complex vitamins and are referred to as B-vitamins in older literature, including B₄ (Adenine) and B₈, but are no longer recognized as such.

Colloquial usage of the term

• Likewise, Vitamin A and Vitamin C are sometimes used as slang terms for alcoholic beverages and caffeine, respectively.
• Biotin is sometimes referred to as Vitamin H.
• Vitamin I is a colloquialism for ibuprofen.
• Vitamin J has been used to refer to Jägermeister, which is a herbal liquor exported from Germany.
• The sedative Ketamine is often called Vitamin K when used as a recreational drug.
• Vitamin Love is mentioned in the Patti Page song, "I Don't Care if the Sun Don't Shine", referring to love itself.
• Vitamin W is a colloquialism for water.
• Vitamin V is a colloquialism for Viagra, Vitamin Z for Zoloft, and Vitamin R for Ritalin, especially when implying that these drugs are overprescribed (or, as a hyperbole, taken as commonly as vitamins).
• Colloquially, the word vitamin is often used to refer to vitamin supplements, products, often in pill form, that contain one or more purified vitamins which are used to supplement the vitamin content of a diet.

Non-human vitamins

Different organisms need different trace organic substances. Most mammals need, with few exceptions, the same vitamins as humans. One notable exception is Vitamin C (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. Housecats require the nutrient taurine; this makes it a vitamin for them, but not for humans as they can manufacture their own taurine, although like any internally formed nutrient, taking it directly usually has no harmful effects if done within reason.

See also

• Pharmacology
• Vitamin poisoning
• Dietary minerals

References

• STEDMAN'S MEDICAL DICTIONARY. Ed. Maureen Barlow Pugh et.al. 27th ed. Baltimore: Lippincott Williams & Wilkins, 2000.
• Donatelle, Rebecca J. Health: The Basics. 6th ed. San Francisco: Pearson Education, Inc. 2005.
• Funk, C. and H. E. Dubin. The Vitamines. Baltimore: Williams and Wilkins Company, 1922.
• The History of Vitamin Discovery. Retrieved 1 Feb 2005.
• Bellis, Mary. History of Vitamins. Retrieved 1 Feb 2005.
• Challem, Jack (1997). The Past, Present and Future of Vitamins. Retrieved 1 Feb 2005.
• Leonhardt, David (2004). Vitamin A - The Glow in the Dark Vitamin. Retrieved 1 Feb 2005.

External links

• USDA RDA chart in PDF format
• The lab which discovered the enzyme associated with PQQ
• A Brief Update on Ubiquinone (Coenzyme Q10), Journal of Orthomolecular Medicine 2000; 15(2):63-68.
• Vitamins Chart
• Vitamins (Co- Enzymes)
• News and information on vitamins
• Vitamins, minerals and supplements
• Health Canada Dietary Reference Intakes Reference Chart for Vitamins

Vitamins
All B vitamins | All D vitamins
Retinol (A) | Thiamine (B1) | Riboflavin (B2) | Niacin (B3) | Pantothenic acid (B5) | Pyridoxine (B6) | Biotin (B7) | Folic acid (B9) | Cyanocobalamin (B12) | Ascorbic acid (C) | Ergocalciferol (D2) | Cholecalciferol (D3) | Tocopherol (E) | Naphthoquinone (K)

This article is based on the article "Vitamins" from Wikipedia - the free encyclopedia created and edited by online user community. This article is distributed under the terms of GNU Free Documentation License. Here you find the list of authors of this article. The article can only edited within Wikipedia. Edit this article in Wikipedia.

This article is about minerals in the geologic sense; for nutrient minerals see dietary mineral; for the band see Mineral (band).

Minerals are natural compounds formed through geological processes. The term "mineral" encompasses not only the material's chemical composition but also the mineral structures. Minerals range in composition from pure elements and simple salts to very complex silicates with thousands of known forms (organic compounds are usually excluded). The study of minerals is called mineralogy.

Contents 1 Mineral definition and classification 1.1 Minerals and rocks 1.2 Physical properties of minerals 1.3 Chemical properties of minerals 1.3.1 Silicate class 1.3.2 Carbonate class 1.3.3 Sulfate class 1.3.4 Halide class 1.3.5 Oxide class 1.3.6 Sulfide class 1.3.7 Phosphate class 1.3.8 Element class 2 See also 3 External links 4 References

Mineral definition and classification

To be classified as a "true" mineral, a substance must be a solid and have a crystal structure. It must also be an inorganic, naturally-occurring, homogenous substance with a defined chemical composition. The chemical composition may vary between end members of a mineral system. For example the plagioclase feldspars comprise a continuous series from sodium-rich albite (NaAlSi₃O₈) to calcium-rich anorthite (CaAl₂Si₂O₈) with four recognized intermediate compositions between. Mineral-like substances that don't strictly meet the definition are sometimes classified as mineraloids. Other natural-occurring substances are Nonminerals. Industrial minerals is a commercial term and refers to commercially valuable mined materials (see also Minerals and Rocks section below).

A crystal structure is the orderly geometric spatial arrangement of atoms in the internal structure of a mineral. There are 14 basic lattice arrangements of atoms in three dimensions in the six crystal systems, and all crystal structures currently recognized fit in one of these 14 arrangements. This crystal structure is based on regular internal atomic or ionic arrangement that is often visible as the mineral form. Even when the mineral grains are too small to see or are irregularly shaped the crystal structure can be determined by x-ray analysis and/or optical microscopy.

Chemistry and crystal structure define together a mineral. In fact, two or more minerals may have the same chemical composition, but differ in crystal structure (these are known as polymorphs). For example, pyrite and marcasite are both iron sulfide. Similarly, some minerals have different chemical compositions, but the same crystal structure: for example, halite (made from sodium and chlorine), galena (made from lead and sulfur) and periclase (made from magnesium and oxygen) all share the same cubic crystal structure.

Crystal structure greatly influences a mineral's physical properties. For example, though diamond and graphite have the same composition (both are pure carbon), graphite is very soft, while diamond is the hardest of all known minerals.

There are currently just over 4,000 known minerals, according to the International Mineralogical Association, which is responsible for the approval of and naming of new mineral species found in nature.

Minerals and rocks

A mineral is a naturally occurring, inorganic substance with a definite chemical composition and a crystalline structure. A rock is an aggregate of one or more minerals. (A rock may also include organic remains.) The specific minerals in a rock can vary a lot. Some minerals, like quartz, mica or feldspar are common, while others have been found in only one or two locations worldwide. Over half of the mineral species known are so rare that they have only been found in a handful of samples, and many are known from only one or two small grains.

Commercially valuable minerals and rocks are refered to as industrial minerals.

Physical properties of minerals

Classifying minerals can range from simple to very difficult. A mineral can be identified by several physical properties, some of them being sufficient for full identification without equivocation. In other cases, minerals can only be classified by more complex chemical or X-ray diffraction analysis; these methods, however, can be costly, time-consuming, and even risk damaging the sample.

Physical properties commonly used are :

• Crystal structure and habit: See the above discussion of crystal structure. A mineral may show good crystal habit or form, or it may be massive, granular or compact with only microscopically visible crystals.
• Hardness: the physical hardness of a mineral is usually measured according to the Mohs scale of mineral hardness.
• Luster indicates the way a mineral's surface interacts with light and can range from dull to glassy (vitreous).
• Color indicates the appearance of the mineral in reflected light or transmitted light for translucent minerals (i.e. what it looks like to the naked eye).
• Streak refers to the color of the powder a mineral leaves after rubbing it on an unglazed porcelain streak plate.
• Cleavage describes the way a mineral may come apart or cleave in different ways. In thin section, cleavage is visible as thin parallel lines across a mineral.
• Fracture describes how a mineral breaks when broken contrary to its natural cleavage planes.
• Specific gravity relates the mineral mass to the mass of an equal volume of water, namely the density of the material.
• Other properties: fluorescence (response to ultraviolet light), magnetism, radioactivity, tenacity (response to mechanical induced changes of shape or form), and reactivity to dilute acids.

Chemical properties of minerals

Minerals may be classified according to chemical composition. They are here categorized by anion group. The list below is in approximate order of their abundance in the Earth's crust. The list follows the Dana classification system.

Silicate class

The largest group of minerals by far are the silicates, which are composed largely of silicon and oxygen, with the addition of ions such as aluminium, magnesium, iron, and calcium. Some important rock-forming silicates include the feldspars, quartz, olivines, pyroxenes, amphiboles, garnets, and micas.

Carbonate class

The carbonate minerals consist of those minerals containing the anion (CO₃)^2- and include calcite and aragonite (both calcium carbonate), dolomite (magnesium/calcium carbonate) and siderite (iron carbonate). Carbonates are commonly deposited in marine settings when the shells of dead planktonic life settle and accumulate on the sea floor. Carbonates are also found in evaporitic settings (e.g. the Great Salt Lake, Utah) and also in karst regions, where the dissolution and reprecipitation of carbonates leads to the formation of caves, stalactites and stalagmites. The carbonate class also includes the nitrate and borate minerals.

Sulfate class

Sulfates all contain the sulfate anion, in the form SO₄^2-. Sulfates commonly form in evaporitic settings where highly saline waters slowly evaporate, allowing the formation of both sulfates and halides at the water-sediment interface. Sulfates also occur in hydrothermal vein systems as gangue minerals along with sulfide ore minerals. Another occurrence is as secondary oxidation products of original sulfide minerals. Common sulfates include anhydrite (calcium sulfate), celestite (strontium sulfate), barite (barium sulfate), and gypsum (hydrated calcium sulfate). The sulfate class also includes the chromate, molybdate, selenate, sulfite, tellurate, and tungstate minerals.

Halide class

The halides are the group of minerals forming the natural salts and include fluorite (calcium fluoride), halite (sodium chloride), sylvite (potassium chloride), and sal ammoniac (ammonium chloride). Halides, like sulfates, are commonly found in evaporitic settings such as playa lakes and landlocked seas such as the Dead Sea and Great Salt Lake. The halide class includes the fluoride, chloride, and iodide minerals.

Oxide class

Oxides are extremely important in mining as they form many of the ores from which valuable metals can be extracted. They commonly occur as precipitates close to the Earth's surface, oxidation products of other minerals in the near surface weathering zone, and as accessory minerals in igneous rocks of the crust and mantle. Common oxides include hematite (iron oxide), magnetite (iron oxide), chromite (chromium oxide), spinel (magnesium aluminium oxide - a common component of the mantle), rutile (titanium dioxide), and ice (hydrogen oxide). The oxide class includes the oxide and the hydroxide minerals.

Sulfide class

Many sulfides are economically important as metal ores. Common sulfides include pyrite (iron sulfide - commonly known as fools' gold), chalcopyrite (copper iron sulfide) and galena (lead sulfide). The sulfide class also includes the selenides, the tellurides, the arsenides, the antimonides, the bismuthinides, and the sulfosalts (sulfur and a second anion such as arsenic).

Phosphate class

The phosphate mineral group actually includes any mineral with a tetrahedral unit AO₄ where A can be phosphorus, antimony, arsenic or vanadium. By far the most common phosphate is apatite which is an important biological mineral found in teeth and bones of many animals. The phosphate class includes the phosphate, arsenate, vanadate, and antimonate minerals.

Element class

The Elemental group includes metals and intermetallic elements (gold, silver, copper), semi-metals and non-metals (antimony, bismuth, graphite, sulfur). This group also includes natural alloys, such as electrum (a natural alloy of gold and silver), phosphides, silicides, nitrides and carbides (which are usually only found naturally in a few rare meteorites).

See also

• A list of minerals with associated Wikipedia articles
• A comprehensive list of minerals
• Industrial minerals
• Mineral water, water containing minerals or other dissolved substances that alter its taste or give it therapeutic value
• Mineral wool
• Mining
• Norman L. Bowen
• Quarrying

External links

• Mineral gallery
• Minerals.net
• mindat.org mineral database
• Webmineral.com
• a directory of on-line databases related to mineralogy and crystallography

References

• Photo glossary of volcano terms from the USGS Volcano Hazards Program

This article is based on the article "Minerals" from Wikipedia - the free encyclopedia created and edited by online user community. This article is distributed under the terms of GNU Free Documentation License. Here you find the list of authors of this article. The article can only edited within Wikipedia. Edit this article in Wikipedia.