Vitamins are organic molecules (or a set of closely related molecules called vitamers) that are essential to an organism in small quantities for proper metabolic function. These essential nutrients cannot be synthesized in the organism in sufficient quantities for survival, and therefore must be obtained through consumption. For example, vitamin C can be synthesized by some species but not by others; it is not considered a vitamin in the first instance but is in the second. Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, there are eight vitamers of vitamin E: four tocopherols and four tocotrienols.
The other essential nutrients are minerals, essential fatty acids, essential amino acids, and choline.
Major health organizations list thirteen vitamins:
Vitamin A (all-trans-retinols, all-trans-retinyl-esters, as well as all-trans-β-carotene and other provitamin A carotenoids) Vitamin B1 (thiamine) Vitamin B2 (riboflavin) Vitamin B3 (niacin) Vitamin B5 (pantothenic acid) Vitamin B6 (pyridoxine) Vitamin B7 (biotin) Vitamin B9 (folic acid and folates) Vitamin B12 (cobalamins) Vitamin C (ascorbic acid and ascorbates) Vitamin D (calciferols) Vitamin E (tocopherols and tocotrienols) Vitamin K (phylloquinones, menaquinones, and menadiones)
Some writers include choline as a vitamin.
Vitamins have diverse biochemical functions. Vitamin A acts as a regulator of cell and tissue growth and differentiation. Vitamin D provides a hormone-like function, regulating mineral metabolism for bones and other organs. The B complex vitamins function as enzyme cofactors (coenzymes) or the precursors for them. Vitamins C and E function as antioxidants. Both deficient and excess intake of a vitamin can potentially cause clinically significant illness, although excess intake of water-soluble vitamins is less likely to do so.
All the vitamins were discovered between 1910 and 1948. Historically, when intake of vitamins from the diet was lacking, the results were vitamin deficiency diseases. Then, starting in 1935, commercially produced tablets of yeast-extract vitamin B complex and semi-synthetic vitamin C became available. This was followed in the 1950s by the mass production and marketing of vitamin supplements, including multivitamins, to prevent vitamin deficiencies in the general population. Governments have mandated the addition of some vitamins to staple foods such as flour or milk, referred to as food fortification, to prevent deficiencies. Recommendations for folic acid supplementation during pregnancy reduced the risk of infant neural tube defects.
List of vitamins Vitamin Vitamers Solubility U.S. recommended dietary allowances per day (ages 19–70) Deficiency disease(s) Overdose syndrome/symptoms Food sources References A retinol (retinal, retinoic acid, retinoids), carotenoids (alpha-carotene, beta-carotene, gamma-carotene), xanthophyll, beta-cryptoxanthin 900 μg/700 μg vitamin A deficiency hypervitaminosis A fish, liver, dairy products, orange or ripe yellow fruits, leafy vegetables, carrots B B1 thiamine, thiamine monophosphate, thiamine pyrophosphate 1.2 mg/1.1 mg beriberi, Wernicke–Korsakoff syndrome pork, wholemeal grains, brown rice, vegetables, potatoes B2 riboflavin, flavin mononucleotide, flavin adenine dinucleotide 1.3 mg/1.1 mg ariboflavinosisdairy products, meat, liver, refined grains B3 nicotinic acid, niacinamide, nicotinamide riboside 16 mg/14 mg pellagra vasodilation, gastrointestinal symptoms, electrolyte imbalances, liver damagemeat, fish, eggs, vegetables, mushrooms, tree nuts B5 pantothenic acid, panthenol, pantethine 5 mg/5 mg paresthesia diarrheameat, vegetables, seeds, yeast B6 pyridoxine, pyridoxamine, pyridoxal 1.3–1.7 mg/1.2–1.5 mg anemia, neurological symptoms, dermatitis, cheilosis, glossitis neuropathymeat, vegetables, tree nuts, bananas B7 biotin 30 μg/30 μg biotin deficiencyraw egg yolk, liver, vegetables B9 folates, folic acid 400 μg/400 μg folate deficiency may mask symptoms of vitamin B12 deficiencyleafy vegetables, legumes, lentils, cereal, liver B12 cyanocobalamin, hydroxocobalamin, methylcobalamin, adenosylcobalamin 2.4 μg/2.4 μg vitamin B12 deficiency anemia fish, eggs, milk productsC ascorbic acid 90 mg/75 mg scurvy gastrointestinal symptomsfruits and vegetables, liverDD1 mixture of molecular compounds of ergocalciferol with lumisterol, 1:1 15 μg/15 μg vitamin D deficiency hypervitaminosis D D2ergocalciferol Finger millet, mushrooms, seeds, soya bean, Colocasia leaves, yeastD3cholecalciferol fatty fish, fish liver oils, eggs, milk productsD422-dihydroergocalciferol D5sitocalciferol E tocopherols, tocotrienols 15 mg/15 mg vitamin E deficiency bleedingmany fruits and vegetables, nuts, seeds, seed oilsK K1 phylloquinone AI: 110 μg/120 μg vitamin K deficiency skin rash, gastrointestinal symptoms leafy green vegetablesK2menaquinone poultry and eggs, nattō, beef, pork, or fish
History Etymology The term "vitamin" was derived from "vitamine", a portmanteau coined from "vital amine" in 1912 by the biochemist Casimir Funk and his friend Max Nierenstein, Reader of Biochemistry at Bristol University,Funk, C. and Dubin, H. E. (1922). The Vitamines. Baltimore: Williams and Wilkins Company. while Funk was working at the Lister Institute of Preventive Medicine. The word "vitamine" is coined on p. 342: "It is now known that all these diseases, with the exception of pellagra, can be prevented and cured by the addition of certain preventative substances; the deficient substances, which are of the nature of organic bases, we will call "vitamines"; and we will speak of a beri-beri or scurvy vitamine, which means a substance preventing the special disease." Funk created the name from vital and amine as suggested by Nierenstein, because it appeared that these organic micronutrient food factors that prevent beriberi and perhaps other similar dietary-deficiency diseases were required for life, hence "vital", and were chemical amines, hence "amine", as in the case of thiamine. In 1920, Jack Cecil Drummond proposed that the final "e" be dropped to deemphasize the "amine" reference, hence "vitamin", after researchers began to suspect that not all "vitamines" (in particular, vitamin A) had an amine component. The name "vitamin" soon became synonymous with Hopkins' "accessory factors".
Understanding before science The value of eating certain foods to maintain health was recognized long before vitamins were identified in modern science. The ancient Egyptians 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 advance of ocean voyages during the Age of Discovery resulted in prolonged periods without access to fresh fruits and vegetables, and made illnesses from vitamin deficiency common among ships' crews. Cited in
+ The discovery dates of the vitamins Year of discovery Vitamin 1913 Vitamin A (Retinol) 1910 Vitamin B1 (Thiamine) 1920 Vitamin C (Ascorbic acid) 1920 Vitamin D (Calciferol) 1920 Vitamin B2 (Riboflavin) 1922 Vitamin E (Tocopherol) 1929 Vitamin K1 (Phylloquinone) 1931 Vitamin B5 (Pantothenic acid) 1934 Vitamin B6 (Pyridoxine) 1936 Vitamin B7 (Biotin) 1936 Vitamin B3 (Niacin) 1941 Vitamin B9 (Folic acid) 1948 Vitamin B12 (Cobalamins)
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; Portuguese and Spanish sailors had independently known about the disease they acquired and how it was reduced after eating oranges and vegetables such as yams and turnips. In 1753, Lind published his Treatise on the Scurvy, which recommended using lemons and limes to avoid scurvy, which was adopted by the British Royal Navy. This led to the nickname limey for British sailors. However, during the 19th century, limes grown in the West Indies were substituted for lemons; these were subsequently found to be much lower in vitamin C. As a result, Arctic expeditions continued to be plagued by scurvy and other deficiency diseases. In the early 20th century, when Robert Falcon Scott made his two expeditions to the Antarctic, the prevailing medical theory was that scurvy was caused by "tainted" canned food.
In 1881, Russian medical doctor Nikolai Lunin studied the effects of scurvy at the University of Tartu. He fed mice an artificial mixture of all the separate constituents of milk known at that time, namely the proteins, fats, carbohydrates, and salts. 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. A similar result by Cornelis Adrianus Pekelharing appeared in Dutch medical journal Nederlands Tijdschrift voor Geneeskunde in 1905, but it was not widely reported.
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 was endemic 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 battleships; 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 a kind of polyneuritis that was the equivalent of beriberi. 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.
Scientific study breakthrough 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 (later Orizanin). 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 complexes like it.
Nobel Prizes for vitamin research The Nobel Prize for Chemistry for 1928 was awarded to Adolf Windaus "for his studies on the constitution of the sterols and their connection with vitamins", the first person to receive an award mentioning vitamins, even though it was not specifically about vitamin D.