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{{Short description|Red-orange pigment of the terpenoids class}} |
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{{DISPLAYTITLE:''beta''-Carotene}} |
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{{Distinguish|beta-keratin}} |
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{{cs1 config|name-list-style=vanc|display-authors=6}} |
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{{Use dmy dates|date=February 2024}} |
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{{DISPLAYTITLE:β-Carotene}} |
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{{Chembox |
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{{Chembox |
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| Verifiedfields = changed |
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| Verifiedfields = changed |
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| Watchedfields = changed |
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| Watchedfields = changed |
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| verifiedrevid = 396298885 |
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| verifiedrevid = 458441983 |
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| Name = β-Carotene |
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| Name = β-Carotene |
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| ImageFile = Beta-Carotin.svg |
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| ImageFile = Beta-Carotin.svg |
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| ImageClass = skin-invert-image |
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| ImageFile_Ref = {{Chemboximage|correct|??}} |
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| ImageFile_Ref = {{Chemboximage|correct|??}} |
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| ImageSize = 244 |
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| ImageSize = 250 |
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| ImageName = Structural formula of beta-carotene ((1E,3E,5E,7E,9E,11E,13E,15E,17E)-octadeca-1,3,5,7,9,11,13,15,17-nonen) |
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| ImageAlt = Skeletal formula |
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| ImageFile2 = BetaCarotene-3d.png |
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| ImageCaption = ] |
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| ImageFile2_Ref = {{Chemboximage|correct|??}} |
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| ImageFile1 = Beta-carotene-from-xtal-3D-bs-17.png |
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| ImageSize2 = 244 |
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| ImageClass1 = bg-transparent |
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| ImageName2 = Stick model of beta-carotene ((1E,3E,5E,7E,9E,11E,13E,15E,17E)-octadeca-1,3,5,7,9,11,13,15,17-nonen) |
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| ImageFile1_Ref = {{Chemboximage|correct|??}} |
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| IUPACName = ''beta'',''beta''-Carotene |
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| ImageSize1 = 250 |
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| SystematicName = <!-- 1,3,3-Trimethyl-2-cyclohex-1-ene --> |
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| ImageAlt1 = Ball-and-stick model |
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| OtherNames = Betacarotene<br /> |
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| ImageCaption1 = ]<ref name="Hursthouse">{{ cite journal | url = https://dx.doi.org/10.5517/cc8j3mh | title = CSD Entry: CARTEN02 | website = ]: Access Structures | year = 2004 | publisher = ] | doi = 10.5517/cc8j3mh | access-date = 9 July 2022 | first1 = M. B. | last1 = Hursthouse | first2 = S. C. | last2 = Nathani | first3 = G. P. | last3 = Moss }}</ref><ref name="Senge">{{ cite journal | title = Structure and Conformation of Photosynthetic Pigments and Related Compounds 3. Crystal Structure of β-Carotene | first1 = Mathias O. | last1 = Senge | first2 = Häkon | last2 = Hope | first3 = Kevin M. | last3 = Smith | journal = ] | year = 1992 | volume = 47 | issue = 5–6 | pages = 474–476 | doi = 10.1515/znc-1992-0623 | s2cid = 100905826 | doi-access = free }}</ref> |
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β-Carotene<ref name='Scifinder'>{{cite web|url=https://scifinder.cas.org |title=SciFinder - CAS Registry Number 7235-40-7|accessdate=Oct. 21, 2009 }}</ref><br /> |
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| ImageFile2 = Beta-carotene-from-xtal-3D-sf.png |
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Food Orange 5<br /> |
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| ImageClass2 = bg-transparent |
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1,1'-(3,7,12,16-Tetramethyl-1,3,5,7,9,11,13,15,17-octadecanonaene-1,18-diyl)bis |
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| ImageFile2_Ref = {{Chemboximage|correct|??}} |
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| Section1 = {{Chembox Identifiers |
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| CASNo = 7235-40-7 |
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| ImageSize2 = 250 |
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| ImageAlt2 = Space-filling model |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| ImageCaption2 = ]<ref name=Hursthouse/><ref name=Senge/> |
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| PubChem = 573 |
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| ImageFile3 = Β-Carotene powder.jpg |
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| PubChem_Ref = {{Pubchemcite|correct|PubChem}} |
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| ImageSize3 = 250 |
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| ChemSpiderID = 4444129 |
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| IUPACName = β,β-Carotene |
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| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}} |
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| SystematicName = 1,1′-bis(2,6,6-trimethylcyclohex-1-ene) |
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| UNII = 01YAE03M7J |
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| OtherNames = Betacarotene <small>(])</small>, β-Carotene,<ref name='Scifinder'>{{cite web|url=https://scifinder.cas.org |title=SciFinder – CAS Registry Number 7235-40-7|access-date=21 October 2009}}</ref> Food Orange 5, Provitamin A |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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|Section1={{Chembox Identifiers |
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| ChEMBL = 1293 |
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| CASNo = 7235-40-7 |
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| ChEMBL_Ref = {{ebicite|changed|EBI}} |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| ATCCode_prefix = A11 |
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| PubChem = 5280489 |
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| ATCCode_suffix = CA02 |
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| ChemSpiderID = 4444129 |
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| ChEBI_Ref = {{ebicite|changed|EBI}} |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| UNII = 01YAE03M7J |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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| ChEMBL = 1293 |
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| ChEMBL_Ref = {{ebicite|correct|EBI}} |
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| ChEBI_Ref = {{ebicite|correct|EBI}} |
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| ChEBI = 17579 |
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| ChEBI = 17579 |
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| Beilstein = 1917416 |
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| SMILES = CC(C=CC=C(C)C=CC1=C(C)CCCC1(C)C)=CC=CC=C(C)C=CC=C(C)C=CC1=C(C)CCCC1(C)C |
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| KEGG = C02094 |
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| StdInChI = 1S/C40H56/c1-31(19-13-21-33(3)25-27-37-35(5)23-15-29-39(37,7)8)17-11-12-18-32(2)20-14-22-34(4)26-28-38-36(6)24-16-30-40(38,9)10/h11-14,17-22,25-28H,15-16,23-24,29-30H2,1-10H3/b12-11+,19-13+,20-14+,27-25+,28-26+,31-17+,32-18+,33-21+,34-22+ |
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| 3DMet = B00389 |
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| StdInChI_Ref = {{stdinchicite|changed|chemspider}} |
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| SMILES = CC2(C)CCCC(\C)=C2\C=C\C(\C)=C\C=C\C(\C)=C\C=C\C=C(/C)\C=C\C=C(/C)\C=C\C1=C(/C)CCCC1(C)C |
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| StdInChIKey = OENHQHLEOONYIE-JLTXGRSLSA-N |
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| StdInChI = 1S/C40H56/c1-31(19-13-21-33(3)25-27-37-35(5)23-15-29-39(37,7)8) 17-11-12-18-32(2)20-14-22-34(4)26-28-38-36(6)24-16-30-40(38,9) 10/h11-14,17-22,25-28H,15-16,23-24,29-30H2,1-10H3 |
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| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}} |
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| StdInChI_Ref = {{stdinchicite|changed|chemspider}} |
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| StdInChIKey = OENHQHLEOONYIE-UHFFFAOYSA-N |
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| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}} |
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| EINECS = 230-636-6 |
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}} |
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|Section2={{Chembox Properties |
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| C=40 | H=56 |
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| Appearance = Dark orange crystals |
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| Density = 1.00 g/cm<sup>3</sup><ref name=r1/> |
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| MeltingPtC = 183 |
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| MeltingPt_ref =<ref name=r1>{{cite book | editor= Haynes, William M. | year = 2011 | title = CRC Handbook of Chemistry and Physics | edition = 92nd | publisher = ] | isbn = 978-1439855119|page=3.94| title-link = CRC Handbook of Chemistry and Physics }}</ref> |
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| MeltingPt_notes = <br /> decomposes<ref name=sigma /> |
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| BoilingPtC = 654.7 |
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| BoilingPt_notes = <br /> at 760 mmHg (101324 Pa) |
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| Solubility = Insoluble |
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| SolubleOther = Soluble in ], ], ], ]<br /> Insoluble in ] |
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| Solubility1 = 4.51 g/kg (20 °C)<ref name="pubchem">{{cite web |title=Beta-carotene |url=https://pubchem.ncbi.nlm.nih.gov/compound/5280489 |publisher=PubChem, US National Library of Medicine |access-date=31 January 2024 |date=27 January 2024}}</ref> = 5.98 g/L (given BCM density of 1.3266 g/cm<sup>3</sup> at 20°C) |
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| Solvent1 = dichloromethane |
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| Solubility2 = 0.1 g/L |
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| Solvent2 = hexane |
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| LogP = 14.764 |
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| VaporPressure = 2.71·10<sup>−16</sup> mmHg |
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| RefractIndex = 1.565 |
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}} |
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|Section6={{Chembox Pharmacology |
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| ATCCode_prefix = A11 |
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| ATCCode_suffix = CA02 |
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| ATC_Supplemental = {{ATC|D02|BB01}} |
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}} |
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|Section7={{Chembox Hazards |
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| GHSPictograms = {{GHS07}} |
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| GHSSignalWord = Warning |
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| HPhrases = {{H-phrases|315|319|412}} |
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| PPhrases = {{P-phrases|264|273|280|302+352|305+351+338|321|332+313|337+313|362|501}} |
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| NFPA-H = 0 |
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| NFPA-F = 1 |
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| NFPA-R = 0 |
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| FlashPtC = 103 |
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| FlashPt_ref = <ref name=sigma>], . Retrieved on 27 May 2014.</ref> |
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}} |
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}} |
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| Section2 = {{Chembox Properties |
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| C = 40 |
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| H = 56 |
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| ExactMass = 536.438201792 g mol<sup>-1</sup> |
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| Appearance = Dark orange crystals |
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| Density = 0.94(6) g cm<sup>-3</sup> |
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| MeltingPtCL = 180 |
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| MeltingPtCH = 182 |
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| BoilingPtCL = 633 |
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| BoilingPtCH = 677 |
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| Boiling_notes = at 760 Torr<ref name="Scifinder"/> |
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| LogP = 14.764}} |
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| Section3= {{Chembox Hazards |
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| FlashPt = 103 °C<ref name='Sigmaldrich'>{{cite web|url=http://www.sigmaaldrich.com/catalog/ProductDetail.do?lang=en&N4=22040|FLUKA&N5=SEARCH_CONCAT_PNO|BRAND_KEY&F=SPEC|title=22040 β-Carotene BioChemika, purum, ≥97.0% (UV)|accessdate=Oct. 21, 2009 }}</ref>}} |
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}} |
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}} |
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'''β-Carotene''' is a strongly-coloured red-orange ] abundant in plants and fruits. It is an ] and chemically is classified as a ] and specifically as a ] (isoprenoid), reflecting its derivation from ] units. β-Carotene is biosynthesized from ].<ref name=Kirk/> |
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It is a member of the ]s, which are tetraterpenes, synthesized biochemically from eight isoprene units and thus having 40 carbons. Among this general class of carotenes, β-Carotene is distinquished by having beta-rings at both ends of the molecule. |
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'''β-Carotene''' (''beta''-carotene) is an ], strongly colored red-orange ] abundant in fungi,<ref name=":0">{{cite journal|last1=Lee|first1=Soo Chan|last2=Ristaino|first2=Jean B.|last3=Heitman|first3=Joseph|date=13 December 2012|title=Parallels in Intercellular Communication in Oomycete and Fungal Pathogens of Plants and Humans|journal=PLOS Pathogens|volume=8|issue=12|pages=e1003028|doi=10.1371/journal.ppat.1003028 |doi-access=free|pmid=23271965|pmc=3521652}}</ref> plants, and fruits. It is a member of the ]s, which are ]s (isoprenoids), synthesized biochemically from eight ] units and thus having 40 ]s. |
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Carotene is the substance in ] that colours them orange and is the most common form of carotene in plants. When used as a food colouring, it has the ] E160a.<ref name="isbn0-471-73518-3">{{cite book |author=Milne, George W. A. |title=Gardner's commercially important chemicals: synonyms, trade names, and properties |publisher=Wiley-Interscience |location=New York |year=2005 |pages= |isbn=0-471-73518-3 |oclc= |doi= |accessdate=}}</ref><sup>p119</sup> |
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Dietary β-carotene is a pro] compound, converting in the body to ] (vitamin A).<ref name="lpi">{{cite web |title=α-Carotene, β-Carotene, β-Cryptoxanthin, Lycopene, Lutein, and Zeaxanthin |url=https://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/carotenoids |publisher=Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis |access-date=31 January 2024 |date=October 2023}}</ref> In foods, it has rich content in ]s, ], ], and ].<ref name=lpi/> It is used as a ] and may be prescribed to treat ], an inherited condition of sunlight sensitivity.<ref name="mlp">{{cite web |title=Beta-carotene |url=https://medlineplus.gov/druginfo/natural/999.html |publisher=MedlinePlus, National Library of Medicine, US National Institutes of Health |access-date=31 January 2024 |date=27 January 2023}}</ref> |
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The structure was deduced by Karrer et al. in 1930.<ref>{{cite journal |
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| title = Pflanzenfarbstoffe XXV. Über die Konstitution des Lycopins und Carotins |
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| author = P. Karrer, A. Helfenstein, H. Wehrli, A. Wettstein |
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| journal = ] |
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| volume = 13 |
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| issue = |
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| pages = 1084–1099 |
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| year = 1930 |
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| url = |
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| doi = 10.1002/hlca.19300130532 }}</ref> In nature, β-carotene is a precursor (inactive form) to ] via the action of ].<ref name=Kirk>{{cite journal |
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| title = Vitamin A in Kirk-Othmer Encyclopedia of Chemical Technology |
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| author = Susan D. Van Arnum |
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| publisher = John Wiley |
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| location = New York |
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| issue = 45 |
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| pages =99–107 |
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| year = 1998 |
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| url = |
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| doi = 10.1002/0471238961.2209200101181421.a01}}</ref> |
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β-carotene is the most common carotenoid in plants.<ref name=lpi/> When used as a ], it has the ] E160a.<ref name="isbn0-471-73518-3">{{cite book |author=Milne, George W. A. |title=Gardner's commercially important chemicals: synonyms, trade names, and properties |publisher=Wiley-Interscience |location=New York |year=2005 |isbn=978-0-471-73518-2 }}</ref>{{rp|119}} The structure was deduced in 1930.<ref>{{cite journal | title = Pflanzenfarbstoffe XXV. Über die Konstitution des Lycopins und Carotins | vauthors = Karrer P, Helfenstein A, Wehrli H | author4 = Wettstein, A. | journal = ] | volume = 13 | issue = 5 | pages = 1084–1099 | year = 1930 | doi = 10.1002/hlca.19300130532 }}</ref> |
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Isolation of β-carotene from fruits abundant in carotenoids is commonly done using column ]. The separation of β-carotene from the mixture of other carotenoids is based on the polarity of a compound. β-Carotene is a non-polar compound, so it is separated with a non-polar solvent such as ].<ref>{{cite journal |
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| doi = 10.1021/jf980405r |
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| title = Carotenoids from Guava (Psidium guajava L.): Isolation and Structure Elucidation |
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| author = Mercadante, A.Z., Steck, A., Pfander, H. |
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| journal = J. Agric. Food Chem. |
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| volume = 47 |
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| issue = |
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1| pages = 145–151 |
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| year = 1999 |
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| pmid = 10563863}}</ref> Being highly ], it is deeply colored, and as a ] lacking functional groups, it is very ]. |
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Isolation of β-carotene from fruits abundant in carotenoids is commonly done using column ]. It is industrially extracted from richer sources such as the algae '']''.<ref name=us4439629>{{cite patent |
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==Pro-vitamin A activity== |
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| country = United States |
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Plant carotenoids are the primary dietary source of pro-vitamin A worldwide, with β-carotene as the most well-known pro-vitamin A carotenoid. Others include ] and ]. Carotenoid absorption is restricted to the duodenum of the small intestine and dependent on Class B scavenger receptor (SR-B1) membrane protein, which are also responsible for the absorption of ] (alpha-tocopherol).<ref>{{cite journal |last= van Bennekum |first= A |year= 2005 |title= Class B scavenger receptor-mediated intestinal absorption of dietary β-carotene and cholesterol.|journal= Biochemistry.|volume= 44|issue= 11|pages= 4517–25 | pmid = 15766282 | doi = 10.1021/bi0484320}}</ref> One molecule of β-carotene can be cleaved by the intestinal enzyme ''beta,beta-carotene 15,15'-monooxygenase'' into two molecules of vitamin A.<ref>{{cite journal | title = Conversion of beta-carotene to retinal pigment | journal = Vitamins and hormones | year = 2007 | first = HK | last = Biesalski | coauthors = Chichili GR, Frank J, von Lintig J, Nohr D. | volume = 75 | pages = 117–30| id = | accessdate = 2011-08-30 | pmid=17368314}}</ref> |
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| number = 4439629 |
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| status = expired |
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| title = Extraction Process for Beta-Carotene |
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| pubdate = 27 March 1984 |
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| gdate = |
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| fdate = 6 November 1981 |
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| pridate = |
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| inventor = Rüegg, Rudolf |
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| invent1 = |
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| invent2 = |
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| assign1 = Hoffmann-La Roche Inc. |
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| assign2 = |
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| class = |
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}}</ref> The separation of β-carotene from the mixture of other carotenoids is based on the polarity of a compound. β-Carotene is a non-polar compound, so it is separated with a non-polar solvent such as ].<ref>{{cite journal | vauthors = Mercadante AZ, Steck A, Pfander H | title = Carotenoids from guava (Psidium guajava l.): isolation and structure elucidation | journal = Journal of Agricultural and Food Chemistry | volume = 47 | issue = 1 | pages = 145–51 | date = January 1999 | pmid = 10563863 | doi = 10.1021/jf980405r }}</ref> Being highly ], it is deeply colored, and as a ] lacking functional groups, it is ]. |
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==Provitamin A activity== |
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Absorption efficiency is estimated to be between 9-22%. The absorption and conversion of carotenoids may depend on the form that the β-carotene is in (cooked vs. raw vegetables, in a supplement), intake of fats and oils at the same time, and current stores of vitamin A and β-carotene in the body. Researchers list the following factors that determine the pro-vitamin A activity of carotenoids:<ref>{{cite journal |doi= 10.1024/0300-9831.72.1.40 |last= Tanumihardjo |first= SA |year= 2002 |title= Factors influencing the conversion of carotenoids to retinol: bioavailability to bioconversion to bioefficacy|journal= Int J Vit Nutr Res|volume= 72|issue= 1|pages= 40–5 | pmid = 11887751}}</ref> |
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Plant carotenoids are the primary dietary source of ] A worldwide, with β-carotene as the best-known provitamin A carotenoid.<ref name=lpi/> Others include ] and ].<ref name=lpi/> Carotenoid absorption is restricted to the ] of the ]. One molecule of β-carotene can be cleaved by the intestinal enzyme ''β,β-carotene 15,15'-monooxygenase'' into two molecules of vitamin A.<ref name=lpi/><ref>{{cite book | title = Conversion of β-carotene to retinal pigment | year = 2007 | vauthors =Biesalski HK, Chichili GR, Frank J, von Lintig J, Nohr D | volume = 75 | pages = 117–30| pmid=17368314 | doi = 10.1016/S0083-6729(06)75005-1 | series = Vitamins & Hormones | isbn = 978-0-12-709875-3}}</ref><ref>{{cite journal |vauthors=Eroglu A, Harrison EH |title=Carotenoid metabolism in mammals, including man: formation, occurrence, and function of apocarotenoids |journal=J Lipid Res |volume=54 |issue=7 |pages=1719–30 |date=July 2013 |pmid=23667178 |pmc=3679377 |doi=10.1194/jlr.R039537 |doi-access=free |url=}}</ref> |
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==Absorption, metabolism and excretion== |
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* Species of carotenoid |
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As part of the digestive process, food-sourced carotenoids must be separated from plant cells and incorporated into lipid-containing micelles to be bioaccessible to intestinal ].<ref name=lpi/> If already extracted (or synthetic) and then presented in an oil-filled dietary supplement capsule, there is greater bioavailability compared to that from foods.<ref name=PKIN2020Carotenoids/> |
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* Molecular linkage |
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* Amount in the meal |
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* Matrix properties |
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* Effectors |
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* Nutrient status |
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* Genetics |
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* Host specificity |
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* Interactions between factors |
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At the enterocyte cell wall, β-carotene is taken up by the membrane transporter protein scavenger receptor class B, type 1 (SCARB1). Absorbed β-carotene is then either incorporated as such into ]s or first converted to retinal and then retinol, bound to ], before being incorporated into chylomicrons.<ref name=lpi/> The conversion process consists of one molecule of β-carotene cleaved by the enzyme ], which is encoded by the BCO1 gene, into two molecules of retinal.<ref name=lpi/> When plasma retinol is in the normal range the gene expression for SCARB1 and BCO1 are suppressed, creating a feedback loop that suppresses β-carotene absorption and conversion.<ref name=PKIN2020Carotenoids/> |
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===Symmetric and asymmetric cleavage=== |
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In the molecule chain between the two cyclohexyl rings β-carotene cleaves either symmetrically or asymmetrically. Symmetric cleavage with the enzyme ''beta,beta-carotene-15,15'-dioxygenase'' requires the antioxidant alpha-tocopherol.<ref>{{cite journal |
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| title = Alpha and omega of carotenoid cleavage |
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| author = Lakshman,MR |
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| journal = ] |
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| volume = 134 |
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| issue = 2 |
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| pages = 241S-245S |
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| year = 2004 |
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| pmid = 14704327 |
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}}</ref> This symmetric cleavage gives two equivalent retinal molecules and each retinal molecule further reacts to give retinol (]) and retinoic acid. Beta-carotene is also asymmetrically cleaved into two asymmetric products. The product of asymmetric cleavage is β-] (8',10',12'). Asymmetric cleavage reduces the level of retinoic acid significantly.<ref>{{cite journal |
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| title = Identification and Characterization of a Mammalian Enzyme Catalyzing the Asymmetric Oxidative Cleavage of Provitamin A |
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| author = Kiefer, C., Hessel, S., Lampert, S.M., Vogt, K., Lederer, M.O., Breithaupt, D.E., von Lintig, J. |
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| journal = The Journal of Biological Chemistry |
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| volume = 276 |
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| issue = 17 |
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| pages = 14110–14116 |
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| pmid = 11278918 |
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| year = 2001 |
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| doi = 10.1074/jbc.M011510200}}</ref> |
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The majority of chylomicrons are taken up by the liver, then secreted into the blood repackaged into ]s (LDLs).<ref name=lpi/> From these circulating lipoproteins and the chylomicrons that bypassed the liver, β-carotene is taken into cells via receptor SCARB1. Human tissues differ in expression of SCARB1, and hence β-carotene content. Examples expressed as ng/g, wet weight: liver=479, lung=226, prostate=163 and skin=26.<ref name=PKIN2020Carotenoids/> |
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===Conversion factors=== |
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Once taken up by peripheral tissue cells, the major usage of absorbed β-carotene is as a precursor to retinal via symmetric cleavage by the enzyme beta-carotene 15,15'-dioxygenase, which is encoded by the BCO1 gene.<ref name=lpi/> A lesser amount is metabolized by the mitochondrial enzyme beta-carotene 9',10'-dioxygenase, which is encoded by the BCO2 gene. The products of this asymmetric cleavage are two ] molecules and rosafluene. BCO2 appears to be involved in preventing excessive accumulation of carotenoids; a BCO2 defect in chickens results in yellow skin color due to accumulation in subcutaneous fat.<ref name="Babino2015">{{cite journal |vauthors=Babino D, Palczewski G, Widjaja-Adhi MA, Kiser PD, Golczak M, von Lintig J |title=Characterization of the Role of β-Carotene 9,10-Dioxygenase in Macular Pigment Metabolism |journal=J Biol Chem |volume=290 |issue=41 |pages=24844–57 |date=October 2015 |pmid=26307071 |pmc=4598995 |doi=10.1074/jbc.M115.668822 |url=|doi-access=free }}</ref><ref name=Wu2016>{{cite journal |vauthors=Wu L, Guo X, Wang W, Medeiros DM, Clarke SL, Lucas EA, Smith BJ, Lin D |title=Molecular aspects of β, β-carotene-9', 10'-oxygenase 2 in carotenoid metabolism and diseases |journal=Exp Biol Med (Maywood) |volume=241 |issue=17 |pages=1879–1887 |date=November 2016 |pmid=27390265 |pmc=5068469 |doi=10.1177/1535370216657900 |url=}}</ref> |
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Until recently, vitamin A activity in foods was expressed as international units (IU). This is still the measurement generally used on food and supplement labels. However, it is difficult to calculate the total vitamin A activity in the diet in terms of IU, because both the absorption and conversion of carotenoids, as compared with retinol, are variable. The unit retinol equivalent (RE) was developed by the Food and Agriculture Organization of the United Nations/] (FAO/WHO) in 1967.<ref>{{cite book|last= Food and Agriculture Organization/World Health Organization|first= |authorlink= |coauthors= |year= 1967 |month= |title= Requirement of Vitamin A, Thiamine, Riboflavin and Niacin.|location= Rome |volume= |series= FAO Food and Nutrition Series B }}</ref> More recently in 2001, the US Institute of Medicine proposed retinol activity equivalents (RAE) for their Dietary Reference Intakes.<ref>{{cite book |title= Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium and Zinc|year= 2001|publisher= National Academy Press|location= Washington, DC}}</ref> |
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==Conversion factors== |
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====International Units==== |
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For counting dietary vitamin A intake, β-carotene may be converted either using the newer retinol activity equivalents (RAE) or the older international unit (IU).<ref name=lpi/> |
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1 RE = 3.33 IU vitamin A activity from retinol |
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===Retinol activity equivalents (RAEs)=== |
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Since 2001, the US Institute of Medicine uses retinol activity equivalents (RAE) for their Dietary Reference Intakes, defined as follows:<ref name=lpi/><ref name=DRI_A>{{cite book|title=Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium and Zinc|year=2001|publisher=National Academy Press|location=(free download)|doi=10.17226/10026|pmid=25057538|isbn=978-0-309-07279-3|author1=Institute of Medicine (US) Panel on Micronutrients|s2cid=44243659}}</ref> |
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* 1 μg RAE = 1 μg retinol from food or supplements |
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* 1 μg RAE = 2 μg all-''trans''-β-carotene from supplements |
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* 1 μg RAE = 12 μg of all-''trans''-β-carotene from food |
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* 1 μg RAE = 24 μg α-carotene or β-cryptoxanthin from food |
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RAE takes into account carotenoids' variable absorption and conversion to vitamin A by humans better than and replaces the older retinol equivalent (RE) (1 μg RE = 1 μg retinol, 6 μg β-carotene, or 12 μg α-carotene or β-cryptoxanthin).<ref name=DRI_A /> RE was developed 1967 by the United Nations/] Food and Agriculture Organization (FAO/WHO).<ref>{{cite book|publisher= Food and Agriculture Organization/World Health Organization|year= 1967 |title= Requirement of Vitamin A, Thiamine, Riboflavin and Niacin|location=Rome |series= FAO Food and Nutrition Series B}}</ref> |
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1 RE = 10 IU vitamin A activity from β-carotene |
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===International Units=== |
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(In Canada, Health Canada sets 1 RE = 6.667 IU from β-carotene.<ref name="hc-sc.gc.ca">, Natural Health Product Monograph, ]</ref>) |
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Another older unit of vitamin A activity is the international unit (IU).<ref name=lpi/> Like retinol equivalent, the international unit does not take into account carotenoid variable absorption and conversion to vitamin A by humans, as well as the more modern retinol activity equivalent. Food and supplement labels still generally use IU, but IU can be converted to the more useful retinol activity equivalent as follows:<ref name=DRI_A /> |
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* 1 μg RAE = 3.33 IU retinol |
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* 1 IU retinol = 0.3 μg RAE |
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* 1 IU β-carotene from supplements = 0.3 μg RAE |
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* 1 IU β-carotene from food = 0.05 μg RAE |
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* 1 IU α-carotene or β-cryptoxanthin from food = 0.025 μg RAE1 |
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==Dietary sources== |
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====Retinol Equivalents (REs)==== |
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The average daily intake of β-carotene is in the range 2–7 mg, as estimated from a pooled analysis of 500,000 women living in the US, Canada, and some European countries.<ref>{{cite journal |vauthors = Koushik A, Hunter DJ, Spiegelman D, Anderson KE, Buring JE, Freudenheim JL, Goldbohm RA, Hankinson SE, Larsson SC, Leitzmann M, Marshall JR, McCullough ML, Miller AB, Rodriguez C, Rohan TE, Ross JA, Schatzkin A, Schouten LJ, Willett WC, Wolk A, Zhang SM, Smith-Warner SA | title = Intake of the major carotenoids and the risk of epithelial ovarian cancer in a pooled analysis of 10 cohort studies | journal = International Journal of Cancer | volume = 119 | issue = 9 | pages = 2148–54 | date = November 2006 | pmid = 16823847 | doi = 10.1002/ijc.22076 | s2cid = 22948131 | doi-access = free }}</ref> Beta-carotene is found in many foods and is sold as a ].<ref name=lpi/> β-Carotene contributes to the orange color of many different fruits and vegetables. ]ese ] (''Momordica cochinchinensis'' Spreng.) and crude ] are particularly rich sources, as are yellow and orange fruits, such as ], ], ], and ], and orange ] such as ] and ]es.<ref name=lpi/> |
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1 RE = 1 µg retinol |
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The color of β-carotene is masked by ] in green ]s such as ], ], sweet potato leaves, and sweet ] leaves.<ref name=lpi/><ref>{{cite journal | vauthors = Kidmose U, Edelenbos M, Christensen LP, Hegelund E | title = Chromatographic determination of changes in pigments in spinach (Spinacia oleracea L.) during processing | journal = Journal of Chromatographic Science | volume = 43 | issue = 9 | pages = 466–72 | date = October 2005 | pmid = 16212792 | doi = 10.1093/chromsci/43.9.466 | doi-access = free }}</ref> |
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1 RE = 6 µg β-carotene |
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(In Canada, Heath Canada sets 1 RE = 2 µg β-carotene.<ref name="hc-sc.gc.ca"/>) |
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The U.S. Department of Agriculture lists foods high in β-carotene content:<ref>{{cite web|url=https://ods.od.nih.gov/pubs/usdandb/VitA-betaCarotene-Content.pdf#search=%22beta-carotene%22 |title=USDA National Nutrient Database for Standard Reference, Release 28 |date=28 October 2015 |access-date=5 February 2022}}</ref> |
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1 RE = 12 µg other provitamin A carotenoids |
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{| class="wikitable" style="float:right; clear:right; width:18em; text-align:center;" |
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====Retinol Activity Equivalents (RAEs)==== |
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1 RAE = 1 µg retinol |
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1 RAE = 2 µg all-''trans''-β-carotene as a supplement |
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1 RAE = 12 µg of all-''trans''-β-carotene in a food matrix |
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1 RAE = 24 µg other provitamin A carotenes in a food matrix |
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==Sources in the diet== |
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β-Carotene contributes to the orange color of many different fruits and vegetables. ]ese ] (''Momordica Cochinchinensis'' Spreng.) and crude ] are particularly rich sources, as are yellow and orange fruits, such as ], ] and ], orange ] such as ] and ] and in green ] such as ], ], ] leaves, and ]. Vietnamese gac and crude ] have by far the highest content of β-carotene of any known fruit or vegetable, 10 times higher than carrots for example. However, gac is quite rare and unknown outside its native region of SE Asia, and crude ] is typically processed to remove the cartenoids before sale to improve the color and clarity. |
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The average daily intake of β-carotene is in the range 2–7 mg, as estimated from a pooled analysis of 500,000 women living in the USA, Canada and some European countries.<ref>{{cite journal |doi=10.1002/ijc.22076 |last=Koushik |first=A. |coauthors= Hunter DJ, Spiegelman D, Anderson KE, Buring JE, Freudenheim JL, Goldbohm RA, Hankinson SE, Larsson SC, Leitzmann M, Marshall JR, McCullough ML, Miller AB, Rodriguez C, Rohan TE, Ross JA, Schatzkin A, Schouten LJ, Willett WC, Wolk A, Zhang SM, Smith-Warner SA.|year=2006 |title=Intake of the major carotenoids and the risk of epithelial ovarian cancer in a pooled analysis of 10 cohort studies. |journal=Int J Cancer |volume=119 |issue=9 |pages=2148–54 |pmid=16823847 }}</ref> |
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The U.S. Department of Agriculture lists the following 10 foods to have the highest β-carotene content per serving.<ref name='Nutrient list'>{{cite web|url=http://www.ars.usda.gov/Services/docs.htm?docid=17477 |title=USDA National Nutrient Database for Standard Reference, Release 21 |accessdate=2009-07-24 }}</ref> |
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: |
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{| class="wikitable" border="1" |
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|- |
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|- |
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! Item |
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! Food |
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! Beta-carotene |
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! Grams per serving |
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Milligrams |
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! Serving size |
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per 100 g |
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! Milligrams β-carotene per serving |
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! Milligrams β-carotene per 100 g |
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|- |
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|- |
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| ], skinned, boiled |
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| Carrot juice, canned |
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| 236 |
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| 9.4 |
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|- |
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| 1 cup |
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| ] juice |
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| 22.0 |
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| 9.3 |
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| 9.3 |
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|- |
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|- |
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| Carrots, raw or boiled |
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| Pumpkin, canned, without salt |
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| 245 |
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| 9.2 |
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| 1 cup |
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| 17.0 |
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| 6.9 |
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|- |
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|- |
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| ], boiled |
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| Sweet potato, cooked, baked in skin, without salt |
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| 146 |
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| 8.8 |
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| 1 potato |
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| 16.8 |
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| 11.5 |
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|- |
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|- |
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| ], canned |
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| Sweet potato, cooked, boiled, without skin |
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| 156 |
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| 6.9 |
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| 1 potato |
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| 14.7 |
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| 9.4 |
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|- |
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| Spinach, frozen, chopped or leaf, cooked, boiled, drained, without salt |
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| 190 |
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| 1 cup |
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| 13.8 |
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| 7.2 |
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|- |
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| Carrots, cooked, boiled, drained, without salt |
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| 156 |
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| 1 cup |
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| 13.0 |
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| 8.3 |
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|- |
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|- |
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| Spinach, canned, drained solids |
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| ], canned |
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| 214 |
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| 1 cup |
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| 12.6 |
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| 5.9 |
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| 5.9 |
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|- |
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|- |
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| Sweet potato, canned, vacuum pack |
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| 255 |
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| 1 cup |
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| 12.2 |
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| 4.8 |
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|- |
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| Carrots, frozen, cooked, boiled, drained, without salt |
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| 146 |
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| 1 cup |
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| 12.0 |
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| 8.2 |
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|- |
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| Collards, frozen, chopped, cooked, boiled, drained, without salt |
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| 170 |
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| 1 cup |
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| 11.6 |
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| 6.8 |
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|} |
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===No dietary requirement=== |
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Government and non-government organizations have not set a dietary requirement for β-carotene.<ref name=PKIN2020Carotenoids/> |
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== Side effects == |
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== Side effects == |
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Excess β-carotene is predominantly stored in the fat tissues of the body.<ref name=lpi/> The most common side effect of excessive β-carotene consumption is ], a physically harmless condition that presents as a conspicuous ] ] tint arising from deposition of the carotenoid in the outermost layer of the ].<ref name=lpi/><ref name=mlp/><ref name=PKIN2020Carotenoids>{{cite book |vauthors=von Lintig J |title = Present Knowledge in Nutrition, Eleventh Edition |chapter = Carotenoids |editor=BP Marriott |editor2=DF Birt |editor3=VA Stallings|editor4=AA Yates |publisher = Academic Press (Elsevier) |year=2020 |location = London, United Kingdom |pages = 531–49 |isbn=978-0-323-66162-1}}</ref><ref name=PKIN2020VitA>{{cite book |vauthors=Blaner WS |title = Present Knowledge in Nutrition, Eleventh Edition |chapter = Vitamin A |editor=BP Marriott |editor2=DF Birt |editor3=VA Stallings|editor4=AA Yates |publisher = Academic Press (Elsevier) |year=2020 |location = London, United Kingdom |pages = 73–92 |isbn=978-0-323-66162-1}}</ref> |
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===Carotenosis=== |
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The most common side effect of excessive β-carotene consumption is ], a physically harmless condition that presents as a conspicuous orange skin tint arising from deposition of the carotenoid in the outermost layer of the ].<ref>{{cite journal | author=Stahl W, Heinrich U, Jungmann H, et al. | title=Increased Dermal Carotenoid Levels Assessed by Noninvasive Reflection Spectrophotometry Correlate with Serum Levels in Women Ingesting Betatene | journal=Journal of Nutrition | volume=128 | issue=5 | pages=903–7 | year=1998 | pmid=9567001 }}</ref> Chronic, high doses of β-carotene supplements have been associated with increased rate of ] among those who ].<ref>{{cite journal |author=Tanvetyanon T, Bepler G |title=Beta-carotene in multivitamins and the possible risk of lung cancer among smokers versus former smokers: a meta-analysis and evaluation of national brands |journal=Cancer |volume=113 |issue=1 |pages=150–7 |year=2008 |month=July |pmid=18429004 |doi=10.1002/cncr.23527 |url=}}</ref> Additionally, supplemental β-carotene may increase the risk of prostate cancer, ], and cardiovascular and total mortality in people who smoke cigarettes or have a history of high-level exposure to asbestos.<ref>, MedlinePlus</ref> |
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], also referred to as carotenemia, is a benign and reversible medical condition where an excess of dietary carotenoids results in orange discoloration of the outermost skin layer.<ref name=lpi/> It is associated with a high blood β-carotene value. This can occur after a month or two of consumption of beta-carotene rich foods, such as carrots, carrot juice, tangerine juice, mangos, or in Africa, red palm oil. β-carotene dietary supplements can have the same effect. The discoloration extends to palms and soles of feet, but not to the ], which helps distinguish the condition from ]. Carotenodermia is reversible upon cessation of excessive intake.<ref>{{cite journal |vauthors=Maharshak N, Shapiro J, Trau H |title=Carotenoderma--a review of the current literature |journal=Int J Dermatol |volume=42 |issue=3 |pages=178–81 |date=March 2003 |pmid=12653910 |doi=10.1046/j.1365-4362.2003.01657.x |s2cid=27934066 |url=|doi-access=free }}</ref> Consumption of greater than 30 mg/day for a prolonged period has been confirmed as leading to carotenemia.<ref name=PKIN2020Carotenoids/><ref>{{cite journal|vauthors=Nasser Y, Jamal Z, Albuteaey M |title=Carotenemia |journal=StatPearls |volume= |issue= |pages= |date= 11 August 2021 |pmid=30521299 |doi=10.1007/s00253-001-0902-7|s2cid=22232461 }}</ref> |
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===No risk for hypervitaminosis A=== |
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β-Carotene is stored in the liver and many other organs ("golden ovaries"). Rat studies show that the body cannot convert such stored β-carotene into vitamin A, even if a deficit develops. Heavy consumption of synthetic β-carotene additive from a variety of foods, plus from natural sources, may result in saturating the liver's storage capacity for fat soluble vitamins, so that reserves of other fat soluble vitamins, e.g. vitamin D and vitamin A, are not created - in countries far from the Equator, the summer storage of vitamin D, to be drawn upon during the darker winter, may be particularly important, not least in preventing osteoporosis and other vitamin D-deficiency related problems. In many cases the food color ] can be used instead of β-carotene, and is not deposited in the body. |
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At the ] cell wall, β-carotene is taken up by the membrane transporter protein scavenger receptor class B, type 1 (SCARB1). Absorbed β-carotene is then either incorporated as such into chylomicrons or first converted to retinal and then retinol, bound to ], before being incorporated into chylomicrons. The conversion process consists of one molecule of β-carotene cleaved by the enzyme ], which is encoded by the BCO1 gene, into two molecules of retinal. When plasma retinol is in the normal range the gene expression for SCARB1 and BCO1 are suppressed, creating a feedback loop that suppresses absorption and conversion. Because of these two mechanisms, high intake will not lead to ].<ref name=PKIN2020Carotenoids/> |
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===Drug interactions=== |
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β-Carotene has a high tendency to oxidize, more so than most food fats, and may thus to some extent hasten oxidation more than other food colours such as annatto. |
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β-Carotene can interact with medication used for lowering ].<ref name=lpi/> Taking them together can lower the effectiveness of these medications and is considered only a moderate interaction.<ref name=lpi/> ]s and ]s can decrease absorption of β-carotene.<ref>{{cite web | last=Meschino Health | title=Comprehensive Guide to Beta-Carotene | url=http://www.meschinohealth.com/books/beta_carotene| access-date = 29 May 2012}}</ref> Consuming alcohol with β-carotene can decrease its ability to convert to retinol and could possibly result in ].<ref>{{cite journal | vauthors = Leo MA, Lieber CS | title = Alcohol, vitamin A, and beta-carotene: adverse interactions, including hepatotoxicity and carcinogenicity | journal = The American Journal of Clinical Nutrition | volume = 69 | issue = 6 | pages = 1071–85 | date = June 1999 | pmid = 10357725 | doi = 10.1093/ajcn/69.6.1071 | doi-access = free }}</ref> |
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===β-Carotene and lung cancer in smokers=== |
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===β-Carotene and lung cancer in smokers=== |
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Chronic high doses of β-carotene supplementation increases the probability of lung cancer in ]<ref name=lpi/><ref>{{cite journal | vauthors = Tanvetyanon T, Bepler G | title = Beta-carotene in multivitamins and the possible risk of lung cancer among smokers versus former smokers: a meta-analysis and evaluation of national brands | journal = Cancer | volume = 113 | issue = 1 | pages = 150–7 | date = July 2008 | pmid = 18429004 | doi = 10.1002/cncr.23527 | s2cid = 33827601 | doi-access = free }}</ref> while its natural vitamer, retinol, increases lung cancer in smokers and nonsmokers. The effect is specific to supplementation dose as no ] damage has been detected in those who are exposed to cigarette smoke and who ingest a physiological dose of β-carotene (6 mg), in contrast to high pharmacological dose (30 mg).<ref name=lpi/><ref>{{cite journal | doi = 10.1351/pac200274081461 | title = Beta-carotene and lung cancer | author = Russel, R.M. | journal = ] | volume = 74 | issue = 8 | pages = 1461–1467 | year = 2002| citeseerx = 10.1.1.502.6550 | s2cid = 15046337 }}</ref> |
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Increases in lung cancer have been attributed to the tendency of β-carotene to oxidize,<ref>{{cite journal | vauthors = Hurst JS, Saini MK, Jin GF, Awasthi YC, van Kuijk FJ | title = Toxicity of oxidized beta-carotene to cultured human cells | journal = Experimental Eye Research | volume = 81 | issue = 2 | pages = 239–43 | date = August 2005 | pmid = 15967438 | doi = 10.1016/j.exer.2005.04.002 }}</ref> yet based on the pharmacokinetics of β-carotene absorption and transport through the intestine and the lack of specific β-carotene transporters, it is unlikely that β-carotene reaches the lung of smokers in sufficient quantities.<ref>{{Cite journal |last1=Babino |first1=Darwin |last2=Palczewski |first2=Grzegorz |last3=Widjaja-Adhi |first3=M. Airanthi K. |last4=Kiser |first4=Philip D. |last5=Golczak |first5=Marcin |last6=von Lintig |first6=Johannes |date=2015-10-09 |title=Characterization of the Role of β-Carotene 9,10-Dioxygenase in Macular Pigment Metabolism |journal=The Journal of Biological Chemistry |volume=290 |issue=41 |pages=24844–24857 |doi=10.1074/jbc.M115.668822 |doi-access=free |issn=1083-351X |pmc=4598995 |pmid=26307071}}</ref> Additional research is required to understand the link between the increased risk of cancer and all-cause mortality following β-carotene supplementation. |
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High dose β-Carotene supplementation increases the probability of lung cancer in cigarette smokers(15). The effect is specific to supplementation dose as no lung damage has been detected in those who are exposed to cigarette smoke and who ingest a physiologic dose of β-carotene (6 mg), in contrast to high pharmacologic dose (30 mg). Therefore, the ] from β-carotene is based on both cigarette smoke and high daily doses of β-carotene.<ref>{{cite journal |
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| doi = 10.1351/pac200274081461 |
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| title = Beta-carotene and lung cancer. |
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| author = Russel, R.M. |
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| journal = ] |
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| volume = 74 |
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| issue = 8 |
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| pages = 1461–1467 |
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| year = 2002}}</ref> |
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Additionally, supplemental, high-dose β-carotene may increase the risk of ], ], and cardiovascular and total mortality irrespective of smoking status.<ref name=lpi/><ref name=mlp/> |
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There have been at least two suggestions for the mechanism for the observed harmful effect of high-dose β-carotene supplementation in this group. None has so-far gained wide acceptance. |
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== Industrial sources == |
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A common explanation of the high dose effect is that when ] is liganded to RAR-beta (Retinoic Acid Receptor beta), the complex binds ] (Activator Protein 1). ] is a transcription factor that binds to DNA and in downstream events promote cell proliferation. Therefore, in the presence of ], the retinoic acid:RAR-beta complex binds to ] and inhibit AP-1 from binding to DNA. In that case, ] is no longer expressed, and cell proliferation does not occur. Cigarette smoke increases the asymmetric cleavage of β-carotene, decreasing the level of ] significantly. This can lead to a higher level of cell proliferation in smokers, and consequently, a higher probability of lung cancer. |
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β-carotene is industrially made either by total synthesis (see {{section link|Retinol|Industrial synthesis |
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}}) or by extraction from biological sources such as vegetables, microalgae (especially ''Dunaliella salina''), and genetically-engineered microbes. The synthetic path is low-cost and high-yield.<ref name="singh">{{cite journal |last1=Singh |first1=Rahul Vikram |last2=Sambyal |first2=Krishika |title=An overview of β-carotene production: Current status and future prospects |journal=Food Bioscience |date=June 2022 |volume=47 |pages=101717 |doi=10.1016/j.fbio.2022.101717|s2cid=248252973 }}<!-- some weird allegation of the two versions not being identical in cancer potential (also found in doi:10.1093/fqsafe/fyy004), I call BS. --></ref> |
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==Research== |
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Another β-carotene breakdown product suspected of causing cancer at high dose is ''trans''-β-apo-8'-carotenal (common ]), which has been found in one study to be mutagenic and genotoxic in cell cultures which do not respond to β-carotene itself.<ref>{{cite journal |author=Alija AJ, Bresgen N, Sommerburg O, Siems W, Eckl PM |title=Cytotoxic and genotoxic effects of β-carotene breakdown products on primary rat hepatocytes |journal=Carcinogenesis |volume=25 |issue=5 |pages=827–31 |year=2004 |pmid=14688018 |doi=10.1093/carcin/bgh056 |url=http://carcin.oxfordjournals.org/cgi/content/full/25/5/827}}</ref> |
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Medical authorities generally recommend obtaining beta-carotene from food rather than dietary supplements.<ref name=lpi/> A 2013 meta-analysis of ]s concluded that high-dosage (≥9.6 mg/day) beta-carotene supplementation is associated with a 6% increase in the risk of all-cause ], while low-dosage (<9.6 mg/day) supplementation does not have a significant effect on mortality.<ref name=Bjelakovic2014>{{cite journal | vauthors = Bjelakovic G, Nikolova D, Gluud C | title = Meta-regression analyses, meta-analyses, and trial sequential analyses of the effects of supplementation with beta-carotene, vitamin A, and vitamin E singly or in different combinations on all-cause mortality: do we have evidence for lack of harm? |journal = PLOS ONE| volume = 8 |issue = 9 |pages = e74558 |date = 2013 |pmid = 24040282 |pmc = 3765487 | doi = 10.1371/journal.pone.0074558 | bibcode = 2013PLoSO...874558B | doi-access = free }}</ref> Research is insufficient to determine whether a minimum level of beta-carotene consumption is necessary for human health and to identify what problems might arise from insufficient beta-carotene intake.<ref name=Impli>{{cite book|last1=Stargrove|first1=Mitchell|title= Herb, nutrient, and drug interactions : clinical implications and therapeutic strategies|date=20 December 2007|publisher=Mosby|isbn=978-0323029643|edition=1}}</ref> However, a 2018 meta-analysis mostly of ] found that both dietary and ] beta-carotene are associated with a lower risk of all-cause mortality. The highest circulating beta-carotene category, compared to the lowest, correlated with a 37% reduction in the risk of all-cause mortality, while the highest dietary beta-carotene intake category, compared to the lowest, was linked to an 18% decrease in the risk of all-cause mortality.<ref name="pmid30239557">{{cite journal| vauthors=Jayedi A, Rashidy-Pour A, Parohan M, Zargar MS, Shab-Bidar S| title=Dietary Antioxidants, Circulating Antioxidant Concentrations, Total Antioxidant Capacity, and Risk of All-Cause Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Observational Studies. | journal=Adv Nutr | year= 2018 | volume= 9 | issue= 6 | pages= 701–716 | pmid=30239557 | doi=10.1093/advances/nmy040 | pmc=6247336}}</ref> |
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===Macular degeneration=== |
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== Compendial status == |
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{{Main|Macular degeneration}} |
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* ] <ref name=ib29>{{cite web |
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Age-related macular degeneration (AMD) represents the leading cause of irreversible blindness in elderly people. AMD is an oxidative stress, retinal disease that affects the macula, causing progressive loss of central vision.<ref name="DiCarlo2021">{{cite journal |vauthors=Di Carlo E, Augustin AJ |title=Prevention of the Onset of Age-Related Macular Degeneration |journal=J Clin Med |volume=10 |issue=15 |date=July 2021 |page=3297 |pmid=34362080 |pmc=8348883 |doi=10.3390/jcm10153297 |url=|doi-access=free }}</ref> β-carotene content is confirmed in human retinal pigment epithelium.<ref name=PKIN2020Carotenoids/> Reviews reported mixed results for observational studies, with some reporting that diets higher in β-carotene correlated with a decreased risk of AMD whereas other studies reporting no benefits.<ref name="Gorus2017">{{cite journal |vauthors=Gorusupudi A, Nelson K, Bernstein PS |title=The Age-Related Eye Disease 2 Study: Micronutrients in the Treatment of Macular Degeneration |journal=Adv Nutr |volume=8 |issue=1 |pages=40–53 |date=January 2017 |pmid=28096126 |pmc=5227975 |doi=10.3945/an.116.013177 |url=}}</ref> Reviews reported that for intervention trials using only β-carotene, there was no change to risk of developing AMD.<ref name=lpi/><ref name="Gorus2017"/><ref>{{cite journal |vauthors=Evans JR, Lawrenson JG |title=Antioxidant vitamin and mineral supplements for preventing age-related macular degeneration |journal=Cochrane Database Syst Rev |volume=2017 |issue= 7|pages=CD000253 |date=July 2017 |pmid=28756617 |pmc=6483250 |doi=10.1002/14651858.CD000253.pub4 |url=}}</ref> |
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}}</ref> {{Clarify|date=February 2010}} |
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==See also== |
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===Cancer=== |
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A meta-analysis concluded that supplementation with β-carotene does not appear to decrease the risk of cancer overall, nor specific cancers including: pancreatic, colorectal, prostate, breast, melanoma, or skin cancer generally.<ref name=lpi/><ref name=Druesne2010>{{cite journal | vauthors = Druesne-Pecollo N, Latino-Martel P, Norat T, Barrandon E, Bertrais S, Galan P, Hercberg S | title = Beta-carotene supplementation and cancer risk: a systematic review and metaanalysis of randomized controlled trials | journal = International Journal of Cancer | volume = 127 | issue = 1 | pages = 172–84 | date = July 2010 | pmid = 19876916 | doi = 10.1002/ijc.25008 | s2cid = 24850769 | doi-access = free }}</ref> High levels of β-carotene may increase the risk of lung cancer in current and former smokers.<ref name=lpi/><ref>{{cite journal | vauthors = Misotti AM, Gnagnarella P | title = Vitamin supplement consumption and breast cancer risk: a review | journal = ecancermedicalscience | volume = 7 | pages = 365 | date = October 2013 | pmid = 24171049 | pmc = 3805144 | doi = 10.3332/ecancer.2013.365 }}</ref> Results are not clear for thyroid cancer.<ref>{{cite journal | vauthors = Zhang LR, Sawka AM, Adams L, Hatfield N, Hung RJ | title = Vitamin and mineral supplements and thyroid cancer: a systematic review | journal = European Journal of Cancer Prevention | volume = 22 | issue = 2 | pages = 158–68 | date = March 2013 | pmid = 22926510 | doi = 10.1097/cej.0b013e32835849b0 | s2cid = 35660646 }}</ref> |
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===Cataract=== |
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A ] looked at supplementation of β-carotene, vitamin C, and vitamin E, independently and combined, on people to examine differences in risk of ], cataract extraction, progression of cataract, and slowing the loss of visual acuity. These studies found no evidence of any protective effects afforded by β-carotene supplementation on preventing and slowing age-related cataract.<ref name=Cochrane2012>{{cite journal | vauthors = Mathew MC, Ervin AM, Tao J, Davis RM | title = Antioxidant vitamin supplementation for preventing and slowing the progression of age-related cataract | journal = The Cochrane Database of Systematic Reviews | volume = 2012 | issue = 6 | pages = CD004567 | date = June 2012 | pmid = 22696344 | pmc = 4410744 | doi = 10.1002/14651858.CD004567.pub2 }}</ref> A second meta-analysis compiled data from studies that measured diet-derived serum beta-carotene and reported a not statistically significant 10% decrease in cataract risk.<ref>{{cite journal | vauthors = Cui YH, Jing CX, Pan HW | title = Association of blood antioxidants and vitamins with risk of age-related cataract: a meta-analysis of observational studies | journal = The American Journal of Clinical Nutrition | volume = 98 | issue = 3 | pages = 778–86 | date = September 2013 | pmid = 23842458 | doi = 10.3945/ajcn.112.053835 | doi-access = free }}</ref> |
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===Erythropoietic protoporphyria=== |
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High doses of β-carotene (up to 180 mg per day) may be used as a treatment for ], a rare inherited disorder of sunlight sensitivity, without toxic effects.<ref name=lpi/><ref name=mlp/> |
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=== Food drying === |
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Foods rich in carotenoid dyes show discoloration upon drying. This is due to ] of carotenoids, possibly via ] and oxidation reactions.<ref>{{cite journal |last1=Song |first1=Jiangfeng |last2=Wang |first2=Xiaoping |last3=Li |first3=Dajing |last4=Liu |first4=Chunquan |date=18 December 2017 |title=Degradation kinetics of carotenoids and visual colour in pumpkin (Cucurbita maxima L.) slices during microwave-vacuum drying |journal=International Journal of Food Properties |language=en |volume=20 |issue=sup1 |pages=S632–S643 |doi=10.1080/10942912.2017.1306553 |s2cid=90336692 |issn=1094-2912|doi-access=free }}</ref> |
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== See also == |
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==References== |
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== References == |
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{{Reflist}} |
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<references/> |
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==External links== |
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* - Fatty Acids and Carotenoids in Gac (Momordica Cochinchinensis Spreng) Fruit. |
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* - Foods high in vitamin A or beta-carotene |
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{{Carotenoids}} |
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{{Carotenoids}} |
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{{Vitamin}} |
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{{Vitamin}} |
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{{Emollients and protectives}} |
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{{Terpenoids}} |
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{{Authority control}} |
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{{DEFAULTSORT:Carotene, Beta-}} |
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{{DEFAULTSORT:Carotene, Beta-}} |
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