is an organic compound
and an essential nutrient
that an organism
requires in limited amounts. An organic chemical compound (or related set of compounds) is called a vitamin when the organism cannot synthesize
the compound in sufficient quantities, and it must be obtained through the diet; thus, the term vitamin
is conditional upon the circumstances and the particular organism. For example, ascorbic acid
(one form of vitamin C
) is a vitamin for humans, but not for most other animals. Vitamin D is essential only for people who do not have adequate skin exposure to sunlight, as ultraviolet light promotes synthesis in skin cells. Supplementation is important for the treatment of certain health problems, but there is little evidence of nutritional benefit when used by otherwise healthy people.
By convention the term vitamin
does not include other essential nutrient
s, such as dietary minerals
, essential fatty acid
s and essential amino acid
s. Thirteen vitamins are universally recognized at present. Vitamins are classified by both biological and chemical activity, and not their structure. Thus, each vitamin refers to a number of vitamer
compounds that all show the biological activity associated with a particular vitamin. Such a set of chemicals is grouped under an alphabetized vitamin "generic descriptor" title, such as " vitamin A
", which includes the compounds retinal
, and four known carotenoid
s. Vitamers by definition are convertible to the active form of the vitamin in the body, and are sometimes inter-convertible to one another, as well.
Vitamins have diverse biochemical functions. Some, such as vitamin D
, have hormone-like functions as regulators of mineral metabolism, or regulators of cell and tissue growth and differentiation (such as some forms of vitamin A). Others function as antioxidants
(e.g., vitamin E
and sometimes vitamin C
). The largest number of vitamins, the B complex
vitamins, function as enzyme cofactor
s ( coenzymes
) or the precursors
for them; coenzymes help enzyme
s in their work as catalyst
s in metabolism
. In this role, vitamins may be tightly bound to enzymes as part of prosthetic group
s: For example, biotin
is part of enzymes involved in making fatty acid
s. They may also be less tightly bound to enzyme catalysts as coenzymes, detachable molecules that function to carry chemical groups
or electrons between molecules. For example, folic acid
may carry methyl
, and methylene
groups in the cell. Although these roles in assisting enzyme-substrate reactions are vitamins' best-known function, the other vitamin functions are equally important.
Until the mid-1930s, when the first commercial yeast-extract vitamin B complex and semi-synthetic vitamin C supplement tablets were sold, vitamins were obtained solely through food intake, and changes in diet (which, for example, could occur during a particular growing season) usually greatly altered the types and amounts of vitamins ingested. However, vitamins have been produced as commodity chemicals
and made widely available as inexpensive semisynthetic and synthetic-source multivitamin
dietary and food supplements and additives, since the middle of the 20th century. Study of structural activity, function and their role in maintaining health is called vitaminology.
List of vitamins
Each vitamin is typically used in multiple reactions, and therefore most have multiple functions.Kutsky, R.J. (1973). Handbook of Vitamins and Hormones. New York: Van Nostrand Reinhold,
Vitamins are essential for the normal growth and development of a multicellular organism. Using the genetic blueprint inherited from its parents, a fetus
begins to develop
from the nutrients it absorbs. It requires certain vitamins and minerals to be present at certain times. These nutrients facilitate the chemical reactions that produce among other things, skin
, and muscle
. If there is serious deficiency in one or more of these nutrients, a child may develop a deficiency disease. Even minor deficiencies may cause permanent damage.Gavrilov, Leonid A. (10 February 2003) Pieces of the Puzzle: Aging Research Today and Tomorrow
For the most part, vitamins are obtained with food, but a few are obtained by other means. For example, microorganisms in the intestine — commonly known as " gut flora
" — produce vitamin K and biotin, while one form of vitamin D is synthesized in the skin
with the help of the natural ultraviolet
wavelength of sunlight
. Humans can produce some vitamins from precursors they consume. Examples include vitamin A
, produced from beta carotene
, and niacin
, from the amino acid tryptophan
Once growth and development are completed, vitamins remain essential nutrients for the healthy maintenance of the cells, tissues, and organs that make up a multicellular organism; they also enable a multicellular life form to efficiently use chemical energy provided by food it eats, and to help process the proteins, carbohydrates, and fats required for cellular respiration
In those who are otherwise healthy, there is little evidence that supplements have any benefits with respect to cancer
or heart disease
. Vitamin A and E supplements not only provide no health benefits for generally healthy individuals, but they may increase mortality, though the two large studies that support this conclusion included smokers
for whom it was already known that beta-carotene
supplements can be harmful. While other findings suggest that vitamin E toxicity is limited to only a specific form when taken in excess.
The European Union and other countries of Europe have regulations that define limits of vitamin (and mineral) dosages for their safe use as dietary supplements. Most vitamins that are sold as dietary supplements are not supposed to exceed a maximum daily dosage referred to as the Tolerable upper intake level
(ULs). Vitamin products above these regulatory limits are not considered supplements and should be registered as prescription or non-prescription ( over-the-counter drug
s) due to their potential side effects. The European Union, United States, Japan and some other countries each set ULs. S. Getman (March 2011). EU Regulations on food supplements, health foods, herbal medicines
. US Commercial Service. Retrieved February 2014.Schweizerische Eidgenossenschaft. Bundesrecht 817.022.104. Verordnung des EDI über Speziallebensmittel vom 23. Nov. 2005
Art. 22 Nahrungsergänzungsmittel. (in German)
, mineral oil
, polyethylene glycol
, and carnauba wax
s often contain vitamins, but may also include other ingredients, such as minerals, herbs, and botanicals. Scientific evidence supports the benefits of dietary supplements for persons with certain health conditions. Use and Safety of Dietary Supplements
NIH office of Dietary Supplements. In some cases, vitamin supplements may have unwanted effects, especially if taken before surgery, with other dietary supplements or medicines, or if the person taking them has certain health conditions. They may also contain levels of vitamins many times higher, and in different forms, than one may ingest through food.Higdon, Jane (2011) Vitamin E recommendations at Linus Pauling Institute's Micronutrient Information Center
Effect of cooking
has conducted extensive studies on the percentage losses of various nutrients from different food types and cooking methods.
It should be noted however that some vitamins may become more "bio-available" – that is, usable by the body – when foods are cooked.
Comparison of Vitamin Levels in Raw Foods vs. Cooked Foods
. Beyondveg.com. Retrieved on 3 August 2013.
The table below shows whether various vitamins are susceptible to loss from heat—such as heat from boiling, steaming, frying, etc. The effect of cutting vegetables can be seen from exposure to air and light. Water-soluble vitamins such as B and C dissolve into the water when a vegetable is boiled, and are then lost when the water is discarded. Effects of Cooking on Vitamins (Table)
. Beyondveg.com. Retrieved on 3 August 2013.
Humans must consume vitamins periodically but with differing schedules, to avoid deficiency
. The body's
stores for different vitamins vary widely; vitamins A, D, and B12 are stored in significant amounts, mainly in the liver
, and an adult's diet may be deficient in vitamins A and D for many months and B12 in some cases for years, before developing a deficiency condition. However, vitamin B3 (niacin and niacinamide) is not stored in significant amounts, so stores may last only a couple of weeks. For vitamin C, the first symptoms of scurvy
in experimental studies of complete vitamin C deprivation in humans have varied widely, from a month to more than six months, depending on previous dietary history that determined body stores.
Deficiencies of vitamins are classified as either primary or secondary. A primary deficiency occurs when an organism does not get enough of the vitamin in its food. A secondary deficiency may be due to an underlying disorder that prevents or limits the absorption or use of the vitamin, due to a "lifestyle factor", such as smoking, excessive alcohol consumption, or the use of medications that interfere with the absorption or use of the vitamin. People who eat a varied diet are unlikely to develop a severe primary vitamin deficiency. In contrast, restrictive diets have the potential to cause prolonged vitamin deficits, which may result in often painful and potentially deadly disease
Well-known human vitamin deficiencies involve thiamine ( beriberi
), niacin ( pellagra
), vitamin C ( scurvy
), and vitamin D ( rickets
). In much of the developed world, such deficiencies are rare; this is due to (1) an adequate supply of food and (2) the addition of vitamins and minerals to common foods ( fortification
). In addition to these classical vitamin deficiency diseases, some evidence has also suggested links between vitamin deficiency and a number of different disorders.
Some vitamins have documented side effects
that tend to be more severe with a larger dosage. The likelihood of consuming too much of any vitamin from food is remote, but overdosing ( vitamin poisoning
) from vitamin supplementation does occur. Acute symptoms can include nausea, vomiting and diarrhea.Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. National Academy Press, Washington, DC, 2001. In the United States, the Institute of Medicine of the National Academies has established Tolerable upper intake levels
(ULs) for those vitamins which have documented side effects at high intakes. In the European Union the European Food Safety Authority
has also set ULs. ULs from the two organizations do not always match.
In 2014, overdose exposure to all formulations of vitamins and multi-vitamin/mineral formulations was reported by 68,058 individuals to the American Association of Poison Control Centers
with 73% of these exposures in children under the age of five.
Vitamins are classified as either water
-soluble or fat-soluble
. In humans there are 13 vitamins: 4 fat-soluble (A, D, E, and K) and 9 water-soluble (8 B vitamins and vitamin C). Water-soluble vitamins dissolve easily in water and, in general, are readily excreted from the body, to the degree that urinary output is a strong predictor of vitamin consumption. Because they are not as readily stored, more consistent intake is important. Fat-soluble vitamins are absorbed through the intestinal tract
with the help of lipid
s (fats). Because they are more likely to accumulate in the body, they are more likely to lead to hypervitaminosis
than are water-soluble vitamins. Fat-soluble vitamin regulation is of particular significance in cystic fibrosis
The value of eating a certain food to maintain health was recognized long before vitamins were identified. The ancient Egypt
ians knew that feeding liver
to a person may help with night blindness
, an illness now known to be caused by a vitamin A
deficiency. The advancement of ocean voyages during the Renaissance
resulted in prolonged periods without access to fresh fruits and vegetables, and made illnesses from vitamin deficiency common among ships' crews.
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, causing poor wound healing, bleeding of the gums
, severe pain, and death.Jack Challem (1997). Past, Present and Future of Vitamins"
In 1753, Lind published his Treatise on the Scurvy
, which recommended using lemon
s and lime
s to avoid scurvy
, which was adopted by the British Royal Navy
. This led to the nickname limey
for British sailors. Lind's discovery, however, was not widely accepted by individuals in the Royal Navy's Arctic
expeditions in the 19th century, where it was widely believed that scurvy could be prevented by practicing good hygiene
, regular exercise, and maintaining the morale
of the crew while on board, rather than by a diet of fresh food. As a result, Arctic expeditions continued to be plagued by scurvy and other deficiency disease
s. In the early 20th century, when Robert Falcon Scott
made his two expeditions to the Antarctic
, the prevailing medical theory at the time was that scurvy was caused by "tainted" canned food
During the late 18th and early 19th centuries, the use of deprivation studies allowed scientists to isolate and identify a number of vitamins. Lipid from fish oil
was used to cure rickets
s, and the fat-soluble nutrient was called "antirachitic A". Thus, the first "vitamin" bioactivity ever isolated, which cured rickets, was initially called "vitamin A"; however, the bioactivity of this compound is now called vitamin D
.Bellis, Mary. Production Methods The History of the Vitamins
. Retrieved 1 February 2005. In 1881, Russia
n surgeon Nikolai Lunin studied the effects of scurvy at the University of Tartu
in present-day Estonia. 1929 Nobel lecture
. Nobelprize.org. Retrieved on 3 August 2013. He fed mice
an artificial mixture of all the separate constituents of milk
known at that time, namely the protein
s, and salt
s. The mice that received only the individual constituents 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." However, his conclusions were rejected by his advisor, Gustav von Bunge
, even after other students reproduced his results. A similar result by Cornelius Pekelharing
appeared in a Dutch medical journal in 1905, but it was not widely reported.
ians knew that feeding a person liver
may help with night blindness
In East Asia
, where polished white rice
was the common staple food of the middle class, beriberi
resulting from lack of vitamin B1 was endemic
. In 1884, Takaki Kanehiro
, a British trained medical doctor of the Imperial Japanese Navy
, observed that beriberi
among low-ranking crew who often ate nothing but rice, but not among officers who consumed a Western-style diet. With the support of the Japanese navy, he experimented using crews of two battleship
s; one crew was fed only white rice, while the other was fed a diet of meat, fish, barley, rice, and beans. The group that ate only white rice documented 161 crew members with beriberi and 25 deaths, while the latter group had only 14 cases of beriberi and no deaths. This convinced Takaki and the Japanese Navy that diet was the cause of beriberi, but they mistakenly believed that sufficient amounts of protein prevented it. That diseases could result from some dietary deficiencies was further investigated by Christiaan Eijkman
, who in 1897 discovered that feeding unpolished rice
instead of the polished variety to chickens helped to prevent beriberi in the chickens. The following year, Frederick Hopkins
postulated that some foods contained "accessory factors" — in addition to proteins, carbohydrates, fats etc.
— that are necessary for the functions of the human body. Hopkins and Eijkman were awarded the Nobel Prize for Physiology or Medicine
in 1929 for their discoveries.
In 1910, the first vitamin complex was isolated by Japanese scientist Umetaro Suzuki
, who succeeded in extracting a water-soluble complex of micronutrients from rice bran and named it aberic acid
). He published this discovery in a Japanese scientific journal. When the article was translated into German, the translation failed to state that it was a newly discovered nutrient, a claim made in the original Japanese article, and hence his discovery failed to gain publicity. In 1912 Polish-born biochemist Casimir Funk
, working in London, isolated the same complex of micronutrients and proposed the complex be named "vitamine". It was later to be known as vitamin B3 (niacin), though he described it as "anti-beri-beri-factor" (which would today be called thiamine or vitamin B1). Funk proposed the hypothesis that other diseases, such as rickets, pellagra, coeliac disease, and scurvy could also be cured by vitamins. Max Nierenstein
a friend and reader of Biochemistry at Bristol University reportedly suggested the "vitamine" name (from "vital amine").).Funk, C. and Dubin, H. E. (1922). The Vitamines
. Baltimore: Williams and Wilkins Company. The name soon became synonymous with Hopkins' "accessory factors", and, by the time it was shown that not all vitamins are amine
s, the word was already ubiquitous. In 1920, Jack Cecil Drummond
proposed that the final "e" be dropped to deemphasize the "amine" reference, after researchers began to suspect that not all "vitamines" (in particular, vitamin A
) have an amine component.
In 1930, Paul Karrer
elucidated the correct structure for beta-carotene
, the main precursor of vitamin A, and identified other carotenoids
. Karrer and Norman Haworth
confirmed Albert Szent-Györgyi's discovery of ascorbic acid
and made significant contributions to the chemistry of flavins
, which led to the identification of lactoflavin
. For their investigations on carotenoids, flavins and vitamins A and B2, they both received the Nobel Prize in Chemistry
in 1937.Nobelprize.org. The Official Website of the Nobel Prize. Paul Karrer-Biographical
. Retrieved 8 January 2013.
In 1931, Albert Szent-Györgyi
and a fellow researcher Joseph Svirbely
suspected that "hexuronic acid" was actually vitamin C
, and gave a sample to Charles Glen King
, who proved its anti- scorbutic
activity in his long-established guinea pig
scorbutic assay. In 1937, Szent-Györgyi was awarded the Nobel Prize in Physiology or Medicine
for his discovery. In 1943, Edward Adelbert Doisy
and Henrik Dam
were awarded the Nobel Prize in Physiology or Medicine for their discovery of vitamin K
and its chemical structure. In 1967, George Wald
was awarded the Nobel Prize (along with Ragnar Granit
and Haldan Keffer Hartline
) for his discovery that vitamin A could participate directly in a physiological process.
The term vitamin
was derived from "vitamine", a compound word
coined in 1912 by the Polish biochemist Kazimierz Funk
when working at the Lister Institute of Preventive Medicine
. The name is from vital
, meaning amine
of life, because it was suggested in 1912 that the organic micronutrient food factors that prevent beriberi
and perhaps other similar dietary-deficiency diseases might be chemical amines. This was true of thiamine
, but after it was found that other such micronutrients were not amines the word was shortened to vitamin in English.
Society and culture
Once discovered, vitamins were actively promoted in articles and advertisements in McCall's
, Good Housekeeping
, and other media outlets. Marketers enthusiastically promoted cod-liver oil
, a source of Vitamin D, as "bottled sunshine", and bananas as a “natural vitality food". They promoted foods such as yeast
cakes, a source of B vitamins, on the basis of scientifically-determined nutritional value, rather than taste or appearance. World War II
researchers focused on the need to ensure adequate nutrition, especially in processed foods
. Robert W. Yoder
is credited with first using the term vitamania
, in 1942, to describe the appeal of relying on nutritional supplements rather than on obtaining vitamins from a varied diet of foods. The continuing preoccupation with a healthy lifestyle has led to an obsessive consumption of additives the beneficial effects of which are questionable.
Most countries place dietary supplement
s in a special category under the general umbrella of foods
, not drugs. As a result, the manufacturer, and not the government, has the responsibility of ensuring that its dietary supplement products are safe before they are marketed. Regulation of supplements varies widely by country. In the United States
, a dietary supplement is defined under the Dietary Supplement Health and Education Act
of 1994. Legislation
. Fda.gov (15 September 2009). Retrieved on 2010-11-12. There is no FDA approval process for dietary supplements, and no requirement that manufacturers prove the safety or efficacy of supplements introduced before 1994. The Food and Drug Administration
must rely on its Adverse Event Reporting System to monitor adverse events that occur with supplements.
In 2007, the US Code of Federal Regulations
(CFR) Title 21, part III took effect, regulating Good Manufacturing Practices (GMPs) in the manufacturing, packaging, labeling, or holding operations for dietary supplements. Even though product registration is not required, these regulations mandate production and quality control standards (including testing for identity, purity and adulterations) for dietary supplements.U.S. Food and Drug Administration. CFR – Code of Federal Regulations Title 21
. Retrieved 16 February 2014. In the European Union, the Food Supplements Directive
requires that only those supplements that have been proven safe can be sold without a prescription. not EUR-Lex – 32002L0046 – EN
. Eur-lex.europa.eu. Retrieved on 12 November 2010.
For most vitamins, pharmacopoeial standards
have been established. In the United States, the United States Pharmacopeia
(USP) sets standards for the most commonly used vitamins and preparations thereof. Likewise, monographs of the European Pharmacopoeia
(Ph.Eur.) regulate aspects of identity and purity for vitamins on the European market.
The reason that the set of vitamins skips directly from E to K is that the vitamins corresponding to letters F–J were either reclassified over time, discarded as false leads, or renamed because of their relationship to vitamin B, which became a complex of vitamins.
The German-speaking scientists who isolated and described vitamin K (in addition to naming it as such) did so because the vitamin is intimately involved in the coagulation of blood following wounding (from the German
). At the time, most (but not all) of the letters from F through to J were already designated, so the use of the letter K was considered quite reasonable.Bennett, David. Every Vitamin Page
. All Vitamins and Pseudo-Vitamins. Vitamins and minerals – names and facts
. pubquizhelp.34sp.com The table nomenclature of reclassified vitamins
lists chemicals that had previously been classified as vitamins, as well as the earlier names of vitamins that later became part of the B-complex.
There are other missing B vitamins which were reclassified or determined not to be vitamins. For example, B9 is folic acid
and five of the folates are in the range B11 through B16, forms of other vitamins already discovered, not required as a nutrient by the entire population (like B10, PABA
for internal use B Vitamins
. NeuroSoup (2013-04-15). Retrieved on 2015-11-30.), biologically inactive, toxic, or with unclassifiable effects in humans, or not generally recognised as vitamins by science, Vitamins: What Vitamins Do I Need?
. Medical News Today. Retrieved on 2015-11-30. such as the highest-numbered, which some naturopath
practitioners call B21 and B22. There are also nine lettered B complex vitamins (e.g. Bm). There are other D vitamins now recognised as other substances, which some sources of the same type number up to D7. The controversial cancer treatment laetrile
was at one point lettered as vitamin B17. There appears to be no consensus on any vitamins Q, R, T, V, W, X, Y or Z, nor are there substances officially designated as Vitamins N or I, although the latter may have been another form of one of the other vitamins or a known and named nutrient of another type.
Anti-vitamins are chemical compounds that inhibit the absorption or actions of vitamins. For example, avidin
is a protein in raw egg whites that inhibits the absorption of biotin
; it is deactivated by cooking. Pyrithiamine, a synthetic compound, has a molecular structure similar to thiamine, vitamin B1
, and inhibits the enzyme
s that use thiamine.
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