113-409: Vitamin B 4 is a former designation given to several distinct chemical compounds, none of which is currently considered a true vitamin : Choline is synthesized by the human body, but not sufficiently to maintain good health, and is now considered an essential dietary nutrient. Adenine is a nucleobase synthesized by the human body. Carnitine
226-450: A hydroxyl group that can donate a hydrogen atom to reduce free radicals , and a hydrophobic side chain that allows for penetration into biological membranes. Both natural and synthetic tocopherols are subject to oxidation, so dietary supplements are esterified , creating tocopheryl acetate for stability purposes. Population studies have suggested that people who consumed foods with more vitamin E, or who chose on their own to consume
339-543: A vitamin . Many biological functions have been postulated, including a role as a fat-soluble antioxidant . In this role, vitamin E acts as a radical scavenger, delivering a hydrogen (H) atom to free radicals. At 323 kJ / mol , the O-H bond in tocopherols is about 10% weaker than in most other phenols . This weak bond allows the vitamin to donate a hydrogen atom to the peroxyl radical and other free radicals , minimizing their damaging effect. The thus-generated tocopheryl radical
452-867: A 2S rather than 2R configuration at the molecules' single chiral center, but unlike synthetic dl-alpha-tocopherol, the marketed tocotrienol dietary supplements are extracted from palm oil or rice bran oil. Tocotrienols are not essential nutrients; government organizations have not specified an estimated average requirement or recommended dietary allowance. A number of health benefits of tocotrienols have been proposed, including decreased risk of age-associated cognitive impairment, heart disease and cancer. Reviews of human research linked tocotrienol threatment to improved biomarkers for inflammation and cardiovascular disease , although those reviews did not report any information on clinically significant diease outcomes. Biomarkers for other diseases were not affected by tocotrienol supplementation. Vitamin E may have various roles as
565-631: A 32% decrease in the incidence of prostate cancer, but the SELECT trial of selenium or vitamin E for prostate cancer enrolled men ages 55 or older and reported relative risk 17% higher for the vitamin group. For colorectal cancer , a systematic review of randomized clinical trials and the large SELECT trial reported no statistically significant change in relative risk. The Women's Health Study reported no significant differences for incidences of all types of cancer, cancer deaths, or specifically for breast, lung or colon cancers. Potential confounding factors are
678-735: A concern that co-administration of vitamin E could counter the mechanisms of anti-cancer radiation therapy and some types of chemotherapy, and so advises against its use in these patient populations. The references it cited reported instances of reduced treatment adverse effects, but also poorer cancer survival, raising the possibility of tumor protection from the intended oxidative damage by the treatments. The U.S. National Academy of Medicine updated estimated average requirements (EARs) and recommended dietary allowances (RDAs) for vitamin E in 2000. RDAs are higher than EARs so as to identify amounts that will cover people with higher than average requirements. Adequate intakes (AIs) are identified when there
791-514: 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
904-462: A deficiency disease. Even minor deficiencies may cause permanent damage. 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 . For
1017-472: A dietary supplement in amounts in excess of 300 mg/day may lead to interactions with aspirin , warfarin , tamoxifen and cyclosporine A in ways that alter function. For aspirin and warfarin, high amounts of vitamin E may potentiate anti-blood clotting action. In multiple clinical trials, vitamin E lowered blood concentration of the immunosuppressant medication, cyclosporine A. The US National Institutes of Health , Office of Dietary Supplements, raises
1130-431: A fourteenth, choline . 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
1243-844: A human trial as 540 mg/day, used an uncertainty factor of 2 to derive an upper limit of half of that, then rounded to 300 mg/day. The People's Republic of China publishes dietary guidelines without specifics for individual vitamins or minerals. The United Kingdom recommends 4 mg/day for adult men and 3 mg/day for adult women. The Japan National Institute of Health and Nutrition set adult AIs at 6.5 mg/day (females) and 7.0 mg/day (males), and 650–700 mg/day (females), and 750–900 mg/day (males) for upper limits (amounts depending on age). India recommends an adult intake of 7.5–10 mg/day and does not set an upper limit. The World Health Organization recommends that adults consume 10 mg/day. Consumption tends to be below these recommendations. A worldwide summary reported
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#17328592156211356-518: A maximum daily dosage referred to as the tolerable upper intake level (UL or Upper Limit). Vitamin products above these regulatory limits are not considered supplements and should be registered as prescription or non-prescription ( over-the-counter drugs ) due to their potential side effects. The European Union, United States and Japan establish ULs. Dietary supplements often contain vitamins, but may also include other ingredients, such as minerals, herbs, and botanicals. Scientific evidence supports
1469-450: A means of disposing of excess vitamin E. Alpha-tocopherol transfer protein is coded by the TTPA gene on chromosome 8. The binding site for RRR-α-tocopherol is a hydrophobic pocket with a lower affinity for beta-, gamma-, or delta-tocopherols, or for the stereoisomers with an S configuration at the chiral 2 site. Tocotrienols are also a poor fit because the double bonds in the phytic tail create
1582-457: A median dietary intake of 6.2 mg/d for alpha-tocopherol. For U.S. food and dietary supplement labeling purposes, the amount in a serving is expressed as a percent of daily value. For vitamin E labeling purposes 100% of the daily value was 30 international units, but as of 27 May 2016, it was revised to 15 mg to bring it into agreement with the RDA. A table of the old and new adult daily values
1695-600: A median of 22.1 μmol/L for serum α-tocopherol, and defined α-tocopherol deficiency as less than 12 μmol/L. It cited a recommendation that serum α-tocopherol concentration be ≥30 μmol/L to optimize health benefits. In contrast, the U.S. Dietary Reference Intake text for vitamin E concluded that a plasma concentration of 12 μmol/L was sufficient to achieve normal ex vivo hydrogen peroxide-induced hemolysis. A 2014 review defined less than 9 μmol/L as deficient, 9-12 μmol/L as marginal, and greater than 12 μmol/L as adequate. Regardless of which definition
1808-469: 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
1921-407: A multicellular organism. Using the genetic blueprint inherited from its parents, a fetus develops 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 , bone , and muscle . If there is serious deficiency in one or more of these nutrients, a child may develop
2034-521: A non-significant 2% increase in all-cause mortality when alpha-tocopherol was the only supplement used. The same journal article reported a statistically significant 3% increase for results when alpha-tocopherol was used in combination with other nutrients (vitamin A, vitamin C, beta-carotene, selenium). A Cochrane review concluded that there were no changes seen for risk of developing age-related macular degeneration (AMD) from long-term vitamin E supplementation and that supplementation may slightly increase
2147-582: A number of different disorders. Some vitamins have documented acute or chronic toxicity at larger intakes, which is referred to as hypertoxicity. The European Union and the governments of several countries have established Tolerable upper intake levels (ULs) for those vitamins which have documented toxicity (see table). The likelihood of consuming too much of any vitamin from food is remote, but excessive intake ( vitamin poisoning ) from dietary supplements does occur. In 2016, overdose exposure to all formulations of vitamins and multi-vitamin/mineral formulations
2260-667: A prescription. 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
2373-1101: A progressive neurodegenerative disorder known as ataxia with vitamin E deficiency (AVED) despite consuming normal amounts of vitamin E. Large amounts of alpha-tocopherol as a dietary supplement are needed to compensate for the lack of α-TTP. Bariatric surgery as a treatment for obesity can lead to vitamin deficiencies. Long-term follow-up reported a 16.5% prevalence of vitamin E deficiency. There are guidelines for multivitamin supplementation, but adherence rates are reported to be less than 20%. Vitamin E deficiency due to either malabsorption or metabolic anomaly can cause nerve problems due to poor conduction of electrical impulses along nerves due to changes in nerve membrane structure and function. In addition to ataxia, vitamin E deficiency can cause peripheral neuropathy , myopathies , retinopathy , and impairment of immune responses. The amounts of alpha-tocopherol, other tocopherols and tocotrienols that are components of dietary vitamin E, when consumed from foods, do not appear to cause any interactions with drugs. Consumption of alpha-tocopherol as
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#17328592156212486-483: A rice-based diet, and that the symptoms were reversed when the chickens were switched to whole-grain rice. He called this "the anti-beriberi factor", which was later identified as vitamin B 1 , thiamine. 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
2599-423: A rigid configuration that is a mismatch with the α-TTP pocket. A rare genetic defect of the TTPA gene results in people exhibiting a progressive neurodegenerative disorder known as ataxia with vitamin E deficiency (AVED) despite consuming normal amounts of vitamin E. Large amounts of alpha-tocopherol as a dietary supplement are needed to compensate for the lack of α-TTP. The role of α-TTP is to move α-tocopherol to
2712-527: A single chiral center , which exists at the 2' chromanol ring carbon, at the point where the isoprenoid tail joins the ring. The other two corresponding centers in the phytyl tail of the corresponding tocopherols do not exist as chiral centers for tocotrienols due to unsaturation (C-C double bonds) at these sites. Tocotrienols extracted from plants are always dextrorotatory stereoisomers, signified as d-tocotrienols. In theory, levorotatory forms of tocotrienols (l-tocotrienols) could exist as well, which would have
2825-526: 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. In 1942, when flour enrichment with nicotinic acid began, a headline in the popular press said "Tobacco in Your Bread." In response, the Council on Foods and Nutrition of
2938-532: 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. There
3051-415: A variety of health conditions is mixed. Vitamin E can also interact with some medications and other supplements. Vitamin E has been studied as a treatment for skin health and skin ageing, immune function, and managing conditions like cardiovascular disease or Alzheimer's disease (AD), or certain types of cancer. Most studies have found limited or inconclusive benefits and the potential for some risks. It
3164-434: A vitamin E dietary supplement , had lower incidence of cardiovascular diseases , cancer , dementia , and other diseases. However, placebo -controlled clinical trials using alpha-tocopherol as a supplement, with daily amounts as high as 2,000 mg per day, could not always replicate these findings. In the United States vitamin E supplement use peaked around 2002, but had declined by more than half by 2006. Declining use
3277-434: A vitamin E dietary supplement reported an increased risk of lung cancer for those consuming more than 215 mg/day. For prostate cancer , there are also conflicting results. A meta-analysis based on serum alpha-tocopherol content reported an inverse correlation in relative risk, but a second meta-analysis of observational studies reported no such relationship. A large clinical trial with male tobacco smokers and reported
3390-444: 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 1913 and 1948. Historically, when intake of vitamins from 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
3503-482: Is European Union equivalent of RDA; higher for adults than for children, and may be even higher for women who are pregnant or lactating. For Thiamin and Niacin the PRIs are expressed as amounts per MJ of calories consumed. MJ = megajoule = 239 food calories. UL or Upper Limit Tolerable upper intake levels. ND ULs have not been determined. NE EARs have not been established. In those who are otherwise healthy, there
Vitamin B4 - Misplaced Pages Continue
3616-461: Is RRR-alpha tocopherol, referred to as d-alpha-tocopherol. The synthetic has 73.5% of the potency of the natural. Manufacturers of dietary supplements and fortified foods for humans or domesticated animals convert the phenol form of the vitamin to an ester using either acetic acid or succinic acid because the esters are more chemically stable, providing for a longer shelf-life. A worldwide summary of more than one hundred human studies reported
3729-415: Is a lipid-soluble antioxidant functioning within the glutathione peroxidase pathway, and protecting cell membranes from oxidation by reacting with lipid radicals produced in the lipid peroxidation chain reaction . This removes the free radical intermediates and prevents the oxidation reaction from continuing. The oxidized α-tocopheroxyl radicals produced in this process may be recycled back to
3842-418: 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 B 1 , and inhibits the enzymes that use thiamine. Each vitamin is typically used in multiple reactions, and therefore most have multiple functions. Vitamins are essential for the normal growth and development of
3955-519: Is about 7 mg/d but plasma concentrations are in the range of 11–37 μmol/L. Affinity of α-TTP for vitamin E vitamers Vitamin E has been suggested as a supplement for helping many health conditions, mostly due to its antioxidant activity and potential to protect cells from oxidative damage. In the US, the vitamin is widely available as an over-the-counter supplement, however, medical evidence supporting its effectiveness and safety for treating or preventing
4068-796: Is an essential dietary nutrient for certain worms, but not for humans. References [ edit ] ^ Zeisel SH, da Costa KA (November 2009). "Choline: an essential nutrient for public health" . Nutrition Reviews . 67 (11): 615–23. doi : 10.1111/j.1753-4887.2009.00246.x . PMC 2782876 . PMID 19906248 . ^ Reader V (1930). "The assay of vitamin B(4)" . The Biochemical Journal . 24 (6): 1827–31. doi : 10.1042/bj0241827 . PMC 1254803 . PMID 16744538 . ^ Bender DA (29 January 2009). A Dictionary of Food and Nutrition . Oxford University Press. p. 521 . ISBN 978-0-19-157975-2 . [REDACTED] Index of chemical compounds with
4181-460: Is classified as an essential nutrient for humans. Various government organizations recommend that adults consume between 3 and 15 mg per day, while a 2016 worldwide review reported a median dietary intake of 6.2 mg per day. Sources rich in vitamin E include seeds, nuts, seed oils , peanut butter , vitamin E-fortified foods and dietary supplements. Symptomatic vitamin E deficiency
4294-432: Is created and from that the beta- compounds. Biosynthesis takes place in the plastids . As to why plants synthesize tocochromanols, the major reason appears to be for antioxidant activity. Different parts of plants, and different species, are dominated by different tocochromanols. The predominant form in leaves, and hence leafy green vegetables, is α-tocopherol. Location is in chloroplast membranes, in close proximity to
4407-448: Is different from Wikidata All set index articles Vitamin 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. Essential nutrients cannot be synthesized in the organism in sufficient quantities for survival, and therefore must be obtained through
4520-432: Is excreted by the liver via bile into the intestinal lumen, where it will either be reabsorbed or excreted via feces, and all of the vitamin E vitamers are metabolized and then excreted via urine. Upon reaching the liver, RRR-alpha-tocopherol is preferentially taken up by alpha-tocopherol transfer protein (α-TTP). All other forms are degraded to 2'-carboxethyl-6-hydroxychromane (CEHC), a process that involves truncating
4633-431: Is important. Fat-soluble vitamins are absorbed through the gastrointestinal tract with the help of lipids (fats). Vitamins A and D can accumulate in the body, which can result in dangerous hypervitaminosis . Fat-soluble vitamin deficiency due to malabsorption is of particular significance in cystic fibrosis . Anti-vitamins are chemical compounds that inhibit the absorption or actions of vitamins. For example, avidin
Vitamin B4 - Misplaced Pages Continue
4746-725: 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. A 2018 meta-analysis found no evidence that intake of vitamin D or calcium for community-dwelling elderly people reduced bone fractures. Europe has 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
4859-403: Is more γ-tocopherol than α-tocopherol, but for safflower, sunflower and olive oils the reverse is true. Of the commonly used food oils, palm oil is unique in that tocotrienol content is higher than tocopherol content. Seed tocochromanols content is also dependent on environmental stressors. In almonds, for example, drought or elevated temperature increase α-tocopherol and γ-tocopherol content of
4972-504: Is most often recommended to obtain vitamin E through a balanced diet because high-dose supplementation may have health risks. There is evidence that the sale of dietary supplement vitamin E has decreased by up to 33% following a report showing little or no effect of vitamin E in preventing cancer or cardiovascular disease. Two meta-analyses concluded that as a dietary supplement, vitamin E neither improved nor impaired all-cause mortality. A meta-analysis of long-term clinical trials reported
5085-484: 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
5198-424: Is no discrimination among the vitamin E vitamers during absorption. Bile is necessary for chylomicron formation, so disease conditions such as cystic fibrosis result in biliary insufficiency and vitamin E malabsorption. When consumed as an alpha-tocopheryl acetate dietary supplement, absorption is promoted when consumed with a fat-containing meal. Unabsorbed vitamin E is excreted via feces. Additionally, vitamin E
5311-401: Is not sufficient information to set EARs and RDAs. The EAR for vitamin E for women and men ages 14 and up is 12 mg/day. The RDA is 15 mg/day. As for safety, tolerable upper intake levels ("upper limits" or ULs) are set for vitamins and minerals when evidence is sufficient. Hemorrhagic effects in rats were selected as the critical endpoint to calculate the upper limit via starting with
5424-411: Is provided at Reference Daily Intake . European Union regulations require that labels declare energy, protein, fat, saturated fat, carbohydrates, sugars, and salt. Voluntary nutrients may be shown if present in significant amounts. Instead of daily values, amounts are shown as percent of reference intakes (RIs). For vitamin E, 100% RI was set at 12 mg in 2011. The international unit measurement
5537-421: Is rare, is usually caused by an underlying problem with digesting dietary fat rather than from a diet low in vitamin E. Deficiency can cause neurological disorders . Tocopherols and tocotrienols both occur in α (alpha), β (beta), γ (gamma), and δ (delta) forms, as determined by the number and position of methyl groups on the chromanol ring. All eight of these vitamers feature a chromane double ring, with
5650-423: Is recycled to tocopherol by a redox reaction with a hydrogen donor, such as vitamin C . Vitamin E affects gene expression and is an enzyme activity regulator, such as for protein kinase C (PKC) – which plays a role in smooth muscle growth – with vitamin E participating in deactivation of PKC to inhibit smooth muscle growth. Photosynthesizing plants, algae and cyanobacteria synthesize tocochromanols,
5763-418: Is seen in observational studies. A large clinical trial reported no difference in bladder cancer cases between treatment and placebo. An inverse relationship between dietary vitamin E and lung cancer was reported in observational studies, but a large clinical trial in male tobacco smokers reported no impact on lung cancer between treatment and placebo, and a trial which tracked people who chose to consume
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#17328592156215876-443: Is synthesized from a mixture of toluene and 2,3,5-trimethyl-hydroquinone that reacts with isophytol to all-rac-alpha-tocopherol, using iron in the presence of hydrogen chloride gas as catalyst. The reaction mixture obtained is filtered and extracted with aqueous caustic soda. Toluene is removed by evaporation and the residue (all rac-alpha-tocopherol) is purified by vacuum distillation." The natural alpha tocopherol extracted from plants
5989-508: Is synthesized from the amino acid tryptophan . Vitamin C can be synthesized by some species but not by others. Vitamin B 12 is the only vitamin or nutrient not available from plant sources. The Food Fortification Initiative lists countries which have mandatory fortification programs for vitamins folic acid, niacin, vitamin A and vitamins B 1 , B 2 and B 12 . The body's stores for different vitamins vary widely; vitamins A, D, and B 12 are stored in significant amounts, mainly in
6102-508: 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. Vitamin E The term Vitamin E refers to a group of eight molecular-structure related compounds that include four tocopherols and four tocotrienols . The tocopherols function as fat-soluble antioxidants which may help protect cell membranes from reactive oxygen species . Vitamin E
6215-446: Is the most biologically active. The U.S. Department of Agriculture (USDA), Agricultural Research Services, maintains a food composition database. The last major revision was Release 28, September 2015. In addition to the naturally occurring sources shown in the table, certain ready-to-eat cereals, infant formulas, liquid nutrition products and other foods are fortified with alpha-tocopherol. Tocotrienols occur in some foods sources,
6328-436: Is used, vitamin E deficiency is rare in humans, occurring as a consequence of abnormalities in dietary fat absorption or metabolism rather than from a diet low in vitamin E. Cystic fibrosis and other fat malabsorption conditions can result in low serum vitamin E. One example of a genetic abnormality in metabolism is mutations of genes coding for alpha-tocopherol transfer protein (α-TTP). Humans with this genetic defect exhibit
6441-591: The American Medical Association approved of the Food and Nutrition Board 's new names niacin and niacin amide for use primarily by non-scientists. It was thought appropriate to choose a name to dissociate nicotinic acid from nicotine , to avoid the perception that vitamins or niacin-rich food contains nicotine, or that cigarettes contain vitamins. The resulting name niacin was derived from ni cotinic ac id + vitam in . Researchers also focused on
6554-489: The Lister Institute of Preventive Medicine . Funk created the name from vital and amine , 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". This was true of thiamine , but after it was found that vitamin C and other such micronutrients were not amines,
6667-579: 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. 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
6780-586: The diet . 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 term vitamin does not include the three other groups of essential nutrients : minerals , essential fatty acids , and essential amino acids . Major health organizations list thirteen vitamins: Some sources include
6893-434: The liver , and an adult's diet may be deficient in vitamins A and D for many months and B 12 in some cases for years, before developing a deficiency condition. However, vitamin B 3 (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
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#17328592156217006-491: The European Union (same concept as RDAs), followed by what three government organizations deem to be the safe upper intake. RDAs are set higher than EARs to cover people with higher than average needs. Adequate Intakes (AIs) are set when there is not sufficient information to establish EARs and RDAs. Governments are slow to revise information of this nature. For the U.S. values, with the exception of calcium and vitamin D, all of
7119-581: The Nobel Prize in Physiology and Medicine "...for their discoveries concerning the primary physiological and chemical visual processes in the eye." Wald's contribution was discovering the role vitamin A had in the process. 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 ,
7232-409: The active reduced form through reduction by other antioxidants , such as ascorbate , retinol or ubiquinol . Other forms of vitamin E have their own unique properties; for example, γ-tocopherol is a nucleophile that can react with electrophilic mutagens . The four tocotrienols (alpha, beta, gamma, delta) are similar in structure to the four tocopherols, with the main difference being that
7345-533: The beneficial effects of which are questionable. As one example, in the 1950s, the Wonder Bread company sponsored the Howdy Doody television show, with host Buffalo Bob Smith telling the audience, "Wonder Bread builds strong bodies 8 ways", referring to the number of added nutrients . The term "vitamin" was derived from "vitamine", a portmanteau coined in 1912 by the biochemist Casimir Funk while working at
7458-448: The benefits of dietary supplements for persons with certain health conditions. 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. Most countries place dietary supplements in
7571-592: The chances of developing late AMD. Two meta-analyses reported lower vitamin E blood levels in AD people compared to healthy, age-matched people. However, a review of vitamin E supplementation trials concluded that there was insufficient evidence to state that supplementation reduced the risk of developing AD or slowed the progression of AD. In a 2022 update of an earlier report, the United States Preventive Services Task Force recommended against
7684-438: The chemical family of compounds made up of four tocopherols and four tocotrienols; in a nutrition context this family is referred to as Vitamin E. Biosynthesis starts with formation of the closed-ring part of the molecule as homogentisic acid (HGA). The side chain is attached (saturated for tocopherols , polyunsaturated for tocotrienols ). The pathway for both is the same, so that gamma- is created and from that alpha-, or delta-
7797-613: The chemistry of flavins , which led to the identification of lactoflavin . For their investigations on carotenoids, flavins and vitamins A and B 2 , they both received the Nobel Prize in Chemistry in 1937. 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 activity counter to scurvy in his long-established guinea pig scorbutic assay. In 1937, Szent-Györgyi
7910-405: The data date to 1997–2004. All values are consumption per day: EAR US Estimated Average Requirements. RDA US Recommended Dietary Allowances; higher for adults than for children, and may be even higher for women who are pregnant or lactating. AI US and EFSA Adequate Intake; AIs established when there is not sufficient information to set EARs and RDAs. PRI Population Reference Intake
8023-491: The essential vitamins, notably vitamins D and E. Well-researched human vitamin deficiencies involve thiamine (beriberi), niacin ( pellagra ), vitamin C (scurvy), folate (neural tube defects) and vitamin D (rickets). In much of the developed world these deficiencies are rare due to an adequate supply of food and the addition of vitamins to common foods. In addition to these classical vitamin deficiency diseases, some evidence has also suggested links between vitamin deficiency and
8136-467: The first person to receive an award mentioning vitamins, even though it was not specifically about vitamin D. The Nobel Prize in Physiology or Medicine for 1929 was awarded to Christiaan Eijkman and Frederick Gowland Hopkins for their contributions to the discovery of vitamins. Thirty-five years earlier, Eijkman had observed that chickens fed polished white rice developed neurological symptoms similar to those observed in military sailors and soldiers fed
8249-401: The form of vitamin E used in prospective studies and the amounts. Synthetic, racemic mixtures of vitamin E isomers are not bioequivalent to natural, non-racemic mixtures, yet are widely used in clinical trials and as dietary supplement ingredients. One review reported a modest increase in cancer risk with vitamin E supplementation while stating that more than 90% of the cited clinical trials used
8362-457: The former have hydrophobic side chains with three carbon-carbon double bonds, whereas the tocopherols have saturated side chains. For alpha(α) -tocotrienol each of the three "R" sites has a methyl group (CH 3 ) attached. For beta(β) -tocotrienol: R1 = methyl group, R2 = H, R3 = methyl group. For gamma(γ) -tocotrienol: R1 = H, R2 = methyl group, R3 = methyl group. For delta(δ) -tocotrienol: R1 = H, R2 = H, R3 = methyl group. Tocotrienols have only
8475-403: The functions of the human body. 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
8588-519: The hydrophobic tail which differs between tocopherol and tocotrienol. The synthesis of the specific tail is dependent on which molecule it originates from. In a tocopherol, its prenyl tail emerges from the geranylgeranyl diphosphate (GGDP) group, while the phytyl tail of a tocotrienol stems from a phytyl diphosphate. The synthetic product is all-rac-alpha-tocopherol, also referred to as dl-alpha tocopherol. It consists of eight stereoisomers (RRR, RRS, RSS, RSR, SRR, SSR, SRS and SSS) in equal quantities. "It
8701-406: 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"). The name soon became synonymous with Hopkins' "accessory factors", and, by the time it was shown that not all vitamins are amines , the word
8814-482: The lowest-observed-adverse-effect-level. The result was a human upper limit set at 1000 mg/day. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes . The European Food Safety Authority (EFSA) refers to the collective set of information as dietary reference values, with population reference intakes (PRIs) instead of RDAs, and average requirements instead of EARs. AIs and ULs are defined
8927-496: 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. In the European Union, the Food Supplements Directive requires that only those supplements that have been proven safe can be sold without
9040-446: The most part, vitamins are obtained from the diet, but some are acquired by other means: for example, microorganisms in the gut flora produce vitamin K and biotin; and one form of vitamin D is synthesized in skin cells when they are exposed to a certain wavelength of ultraviolet light present in sunlight . Humans can produce some vitamins from precursors they consume: for example, vitamin A is synthesized from beta carotene ; and niacin
9153-444: The need to ensure adequate nutrition, especially to compensate for what was lost in the manufacture of 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 led to an obsessive consumption of vitamins and multi-vitamins,
9266-532: 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
9379-634: The nuts. The same article mentions that drought increases the tocopherol content of olives, and heat likewise for soybeans. Vitamin E biosynthesis occurs in the plastid and goes through two different pathways: the Shikimate pathway and the Methylerythritol Phosphate pathway (MEP pathway). The Shikimate pathway generates the chromanol ring from the Homogentisic Acid (HGA) and the MEP pathway produces
9492-443: The percentage losses of various nutrients from food types and cooking methods. Some vitamins may become more "bio-available" – that is, usable by the body – when foods are cooked. 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
9605-480: The photosynthetic process. The function is to protect against damage from the ultraviolet radiation of sunlight. Under normal growing conditions the presence of α-tocopherol does not appear to be essential, as there are other photo-protective compounds, and plants that through mutations have lost the ability to synthesize α-tocopherol demonstrate normal growth. However, under stressed growing conditions such as drought, elevated temperature or salt-induced oxidative stress,
9718-421: The phytic tail of the molecule, then either sulfated or glycuronidated. This renders the molecules water-soluble and leads to excretion via urine. Alpha-tocopherol is also degraded by the same process, to 2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychromane (α-CEHC), but more slowly because it is partially protected by α-TTP. Large intakes of α-tocopherol result in increased urinary α-CEHC, so this appears to be
9831-481: The plants' physiological status is superior if it has the normal synthesis capacity. Seeds are lipid-rich, to provide energy for germination and early growth. Tocochromanols protect the seed lipids from oxidizing and becoming rancid. The presence of tocochromanols extends seed longevity, and promotes successful germination and seedling growth. Gamma-tocopherol dominates in seeds of most plant species, but there are exceptions. For canola, corn and soy bean oils, there
9944-415: The plasma membrane of hepatocytes (liver cells), where it can be incorporated into newly created very low density lipoprotein (VLDL) molecules. These convey α-tocopherol to cells in the rest of the body. As an example of a result of the preferential treatment, the US diet delivers approximately 70 mg/d of γ-tocopherol and plasma concentrations are on the order of 2–5 μmol/L; meanwhile, dietary α-tocopherol
10057-423: The prefixes alpha- (α-), beta- (β-), gamma- (γ-), and delta- (δ-). For alpha(α)-tocopherol each of the three "R" sites has a methyl group (CH 3 ) attached. For beta(β)-tocopherol: R1 = methyl group, R2 = H, R3 = methyl group. For gamma(γ)-tocopherol: R1 = H, R2 = methyl group, R3 = methyl group. For delta(δ)-tocopherol: R1 = H, R2 = H, R3 = methyl group. The same configurations exist for the tocotrienols, except that
10170-474: The responsibility of the European Food Safety Authority . Tocotrienols and tocopherols, the latter including the stereoisomers of synthetic alpha-tocopherol, are absorbed from the intestinal lumen, incorporated into chylomicrons , and secreted into the portal vein , leading to the liver. Absorption efficiency is estimated at 51% to 86%, and that applies to all of the vitamin E family – there
10283-1463: The richest being palm oil , but to a lesser extent rice bran oil , barley , oats , and certain seeds, nuts and grains, and the oils derived from them. Vitamin E is fat soluble, so dietary supplement products are usually in the form of the vitamin, esterified with acetic acid to generate tocopheryl acetate , and dissolved in vegetable oil in a softgel capsule. For alpha-tocopherol, amounts range from 100 to 1000 IU per serving. Smaller amounts are incorporated into multi-vitamin/mineral tablets. Gamma-tocopherol and tocotrienol supplements are also available from dietary supplement companies. The latter are extracts from palm oil. The World Health Organization does not have any recommendations for food fortification with vitamin E. The Food Fortification Initiative does not list any countries that have mandatory or voluntary programs for vitamin E. Infant formulas have alpha-tocopherol as an ingredient. In some countries, certain brands of ready-to-eat cereals, liquid nutrition products and other foods have alpha-tocopherol as an added ingredient. Various forms of vitamin E are common food additive in oily food, used to deter rancidity caused by peroxidation. Those with an E number include: These E numbers include all racemic forms and acetate esters thereof. Commonly found on food labels in Europe and some other countries, their safety assessment and approval are
10396-401: The same as in the United States. For women and men ages 10 and older, the PRIs are set at 11 and 13 mg/day, respectively. PRI for pregnancy is 11 mg/day, for lactation 11 mg/day. For children ages 1–9 years the PRIs increase with age from 6 to 9 mg/day. The EFSA used an effect on blood clotting as a safety-critical effect. It identified that no adverse effects were observed in
10509-457: The same name This set index article lists chemical compounds articles associated with the same name. If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Vitamin_B4&oldid=1255369851 " Category : Set index articles on chemistry Hidden categories: Articles with short description Short description
10622-413: The synthetic form ( all-racemic or all-rac vitamin E, also dl-tocopherol) is equal parts of eight stereoisomers RRR, RRS, RSS, SSS, RSR, SRS, SRR and SSR with progressively decreasing biological equivalency, so that 1.36 mg of dl-tocopherol is considered equivalent to 1.0 mg of d-tocopherol, the natural form. Rephrased, the synthetic has 73.5% of the potency of the natural. Alpha-tocopherol
10735-428: The synthetic tocopheryl acetate, is sold as a popular dietary supplement, either by itself or incorporated into a multivitamin product, and in oils or lotions for use on skin. The nutritional content of vitamin E is defined by equivalency to 100% RRR-configuration α-tocopherol activity. The molecules that contribute α-tocopherol activity are four tocopherols and four tocotrienols, within each group of four identified by
10848-442: The unsaturated side chain has three carbon-carbon double bonds whereas the tocopherols have a saturated side chain. In addition to distinguishing tocopherols and tocotrienols by position of methyl groups, the tocopherols have a phytyl tail with three chiral points or centers that can have a right or left orientation. The naturally occurring plant form of alpha-tocopherol is RRR-α-tocopherol, also referred to as d-tocopherol, whereas
10961-426: 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, but may be consuming less than the recommended amounts; a national food and supplement survey conducted in the US over 2003–2006 reported that over 90% of individuals who did not consume vitamin supplements were found to have inadequate levels of some of
11074-410: The use of vitamin E supplements for the prevention of cardiovascular disease or cancer, concluding there was insufficient evidence to assess the balance of benefits and harms, yet also concluding with moderate certainty that there is no net benefit of supplementation. As for literature on different types of cancer, an inverse relationship between dietary vitamin E and kidney cancer and bladder cancer
11187-572: The water when a vegetable is boiled, and are then lost when the water is discarded. In setting human nutrient guidelines, government organizations do not necessarily agree on amounts needed to avoid deficiency or maximum amounts to avoid the risk of toxicity. For example, for vitamin C, recommended intakes range from 40 mg/day in India to 155 mg/day for the European Union. The table below shows U.S. Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for vitamins, PRIs for
11300-571: The word was shortened to "vitamin" in English. 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
11413-510: 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 B 3 (niacin), though he described it as "anti-beri-beri-factor" (which would today be called thiamine or vitamin B 1 ). Funk proposed
11526-466: Was already ubiquitous. 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) have an amine component. 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",
11639-689: 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 1938, Richard Kuhn was awarded the Nobel Prize in Chemistry for his work on carotenoids and vitamins, specifically B 2 and B 6 . Five people have been awarded Nobel Prizes for direct and indirect studies of vitamin B 12 : George Whipple , George Minot and William P. Murphy (1934), Alexander R. Todd (1957), and Dorothy Hodgkin (1964). In 1967, George Wald , Ragnar Granit and Haldan Keffer Hartline were awarded
11752-529: 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
11865-648: 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 risk of infant neural tube defects . from plant origin as provitamin A / all- trans -beta-carotene: orange, ripe yellow fruits, leafy vegetables, carrots, pumpkin, squash, spinach The value of eating certain foods to maintain health
11978-414: 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
12091-543: Was originally started in 2000, when forms of Vitamin E other than alpha-tocopherol was dropped from dietary calculations by the IOM. The UL amount disregards any conversion. The EFSA has never used an IU unit, and their measurement only considers RRR-alpha-tocopherol. Of the different forms of vitamin E, gamma-tocopherol ( γ-tocopherol ) is the most common form found in the North American diet, but alpha-tocopherol ( α-tocopherol )
12204-474: Was recognized long before vitamins were identified. 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. In 1747,
12317-518: Was reported by 63,931 individuals to the American Association of Poison Control Centers with 72% of these exposures in children under the age of five. In the US, analysis of a national diet and supplement survey reported that about 7% of adult supplement users exceeded the UL for folate and 5% of those older than age 50 years exceeded the UL for vitamin A. The USDA has conducted extensive studies on
12430-499: 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
12543-566: Was the common staple food of the middle class, beriberi resulting from lack of vitamin B 1 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
12656-534: Was theorized to be due to publications of meta-analyses that showed either no benefits or actual negative consequences from high-dose vitamin E. Vitamin E was discovered in 1922, isolated in 1935, and first synthesized in 1938. Because the vitamin activity was first identified as essential for fertilized eggs to result in live births (in rats), it was given the name "tocopherol" from Greek words meaning birth and to bear or carry . Alpha-tocopherol, either naturally extracted from plant oils or, most commonly, as
12769-429: Was used by the United States in 1968–2016. 1 IU is the biological equivalent of about 0.667 mg d (RRR)-alpha-tocopherol (2/3 mg exactly), or of 0.90 mg of dl-alpha-tocopherol, corresponding to the then-measured relative potency of stereoisomers. In May 2016, the measurements have been revised, such that 1 mg of "Vitamin E" is 1 mg of d-alpha-tocopherol or 2 mg of dl-alpha-tocopherol. The change
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