View source for Biotin

{{Short description|Chemical compound and essential nutrient}}
{{good article}}
{{cs1 config|name-list-style=vanc|display-authors=3}}
{{Use American English|date=August 2025}}
{{Use mdy dates|date=December 2022}}
{{chembox
| Watchedfields = changed
| verifiedrevid = 443307462
| Name = Biotin
| Reference =
| ImageFile = Biotin skeletal.svg
| ImageClass = skin-invert-image
| ImageSize = 200
| ImageAlt = Skeletal formula of biotin
| ImageFile1 = Biotin-view-1-from-xtal-Mercury-3D-balls.png
| ImageClass1 = bg-transparent
| ImageSize1 = 150
| ImageAlt1 = Ball-and-stick model of the Biotin molecule
| PIN =5-[(3a''S'',4''S'',6a''R'')-2-Oxohexahydro-1''H''-thieno[3,4-''d'']imidazol-4-yl]pentanoic acid
| OtherNames = Vitamin B<sub>7</sub>
|Section1={{Chembox Identifiers
| IUPHAR_ligand = 4787
| DrugBank_Ref = {{drugbankcite|correct|drugbank}}
| DrugBank = DB00121
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 15956
| SMILES = O=C1N[C@@H]2[C@@H](SC[C@@H]2N1)CCCCC(=O)O
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 6SO6U10H04
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = D00029
| InChI = 1/C10H16N2O3S/c13-8(14)4-2-1-3-7-9-6(5-16-7)11-10(15)12-9/h6-7,9H,1-5H2,(H,13,14)(H2,11,12,15)/t6-,7-,9-/m0/s1
| InChIKey = YBJHBAHKTGYVGT-ZKWXMUAHBB
| SMILES1 = C1[C@H]2[C@@H]([C@@H](S1)CCCCC(=O)O)NC(=O)N2
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 857
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C10H16N2O3S/c13-8(14)4-2-1-3-7-9-6(5-16-7)11-10(15)12-9/h6-7,9H,1-5H2,(H,13,14)(H2,11,12,15)/t6-,7-,9-/m0/s1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = YBJHBAHKTGYVGT-ZKWXMUAHSA-N
| CASNo = 58-85-5
| CASNo_Ref = {{cascite|correct|CAS}}
| PubChem = 171548
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 149962
| RTECS =
  }}
|Section2={{Chembox Properties
| C=10 | H=16 | N=2 | O=3 | S=1
| Appearance = White crystalline needles
| Solubility = 22 mg/100 mL
| MeltingPtC = 232 to 233
| MeltingPt_notes = 
}}
|Section6={{Chembox Pharmacology
| ATCCode_prefix = A11
| ATCCode_suffix = HA05
}}
|Section7={{Chembox Hazards
| NFPA-H = 1
| NFPA-F = 1
| NFPA-R = 0
}}
}}
[[File:Biotin.gif|alt=3D space-filling model of Biotin rotating about an axis (GIF)|thumb|3D space-filling model of Biotin rotating about an axis (GIF)]]
'''Biotin''' (also known as '''vitamin B<sub>7</sub>''') is one of the [[B vitamins]] &ndash; a group of essential dietary [[micronutrient]]s.<ref name="ods">{{cite web|url=https://ods.od.nih.gov/factsheets/Biotin-HealthProfessional/|title=Biotin – Fact Sheet for Health Professionals|date=10 January 2022|publisher=Office of Dietary Supplements, US [[National Institutes of Health]]|access-date=3 August 2025}}</ref><ref name="lpi">{{cite web|title=Biotin |url=https://lpi.oregonstate.edu/mic/vitamins/biotin|publisher=Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis, OR|access-date=3 August 2025|date=2025}}</ref> Present in every living [[cell (biology)|cell]], it is involved as a [[Cofactor (biochemistry)|cofactor]] for [[enzyme]]s in numerous [[metabolism|metabolic processes]], both in humans and in other organisms, primarily related to the [[biochemistry]] of fats, carbohydrates, and [[amino acid]]s.<ref name=ods/><ref name=lpi/><ref name=PKIN2020Biotin>{{cite book |vauthors=Penberthy WT, Sadri M, Zempleni J |title = Present Knowledge in Nutrition, Eleventh Edition |chapter = Biotin |editor=BP Marriott |editor2=DF Birt |editor3=VA Stallings|editor4=AA Yates |publisher = Academic Press (Elsevier) |year=2020 |location = London, United Kingdom |pages = 289–304 |isbn=978-0-323-66162-1}}</ref>

When isolated, biotin is a white, needle-like crystalline solid.<ref name="pubchem">{{cite web|title=Biotin|url=https://pubchem.ncbi.nlm.nih.gov/compound/171548 |date=2 August 2025|access-date=3 August 2025|publisher=US National Library of Medicine}}</ref> Biotin is obtained from foods, particularly meats and [[liver]], and is sold as a [[dietary supplement]].<ref name=ods/>

The name ''biotin'', borrowed from the German {{Lang|de|biotin}}, derives from the Ancient Greek word {{lang|grc|{{linktext|βίοτος}}}} ({{Transliteration|grc|bíotos}}; 'life') and the suffix "-in" (a suffix used in chemistry usually to indicate 'forming').<ref name=Etymology>{{cite web|title=Biotin |url=https://www.etymonline.com/word/biotin|access-date=3 August 2025|date=2025|publisher=Online Etymology Dictionary}}</ref>

==Chemical description==
Biotin is classified as a [[heterocyclic compound]], with a sulfur-containing [[tetrahydrothiophene]] ring fused to a [[ureido]] group. A C5-carboxylic acid side chain is appended to the former ring. The ureido ring, containing the −N−CO−N− group, serves as the carbon dioxide carrier in carboxylation reactions.<ref>{{cite journal | vauthors = Waldrop GL, Holden HM, St Maurice M | title = The Enzymes of Biotin dependent CO₂ Metabolism: What Structures Reveal about Their Reaction Mechanisms | journal = Protein Science | volume = 21 | issue = 11 | pages = 1597–1619 | date = November 2012 | pmid = 22969052 | pmc = 3527699 | doi = 10.1002/pro.2156 }}</ref> Biotin is a [[coenzyme]] for five [[carboxylase]] enzymes, which are involved in the [[catabolism]] of [[amino acid]]s and [[fatty acid]]s, synthesis of [[fatty acid]]s, and [[gluconeogenesis]].<ref name=lpi/><ref name=PKIN2020Biotin /> [[Biotinylation]] of [[histone]] proteins in nuclear [[chromatin]] plays a role in chromatin stability and gene expression.<ref name=PKIN2020Biotin /><ref name=Xu2014>{{cite journal |vauthors=Xu YM, Du JY, Lau AT |title=Posttranslational modifications of human histone H3: an update |journal=Proteomics |volume=14 |issue=17–18 |pages=2047–2060 |date=September 2014 |pmid=25044606 |doi=10.1002/pmic.201300435 |s2cid=11293428 |url=}}</ref>

==Dietary recommendations==
The US National Academy of Medicine updated [[Dietary Reference Intake]]s for many vitamins in 1998.<ref name=ods/> At that time there was insufficient information to establish estimated average requirement or recommended dietary allowance, terms that exist for most vitamins. In instances such as this, the academy sets adequate intakes (AIs) with the understanding that at some later date, when the [[physiology|physiological]] effects of biotin are better understood, AIs will be replaced by more exact information. The biotin AIs for both males and females are:<ref name=ods/> 
<div style="float:left; padding: 1em;">
{| class="wikitable"
|+ Biotin Adequate Intakes (AIs)<ref name="DRItext">{{cite book | last1 = Institute of Medicine | title = Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline | chapter = Biotin | publisher = The National Academies Press| location = Washington, DC | pages = 374–89 | chapter-url = https://nap.nationalacademies.org/read/6015/chapter/13|date=2025 | access-date=3 August 2025 | isbn = 0-309-06554-2 | author1-link = Institute of Medicine }}</ref>
|-
! Age Group !! Biotin AI (μg/day)
|-
| 0 to 6 months || 5
|-
| 7 to 12 months || 6
|-
| 1 to 3 years || 8
|-
| 4 to 8 years || 12
|-
| 9 to 13 years || 20
|-
| 14 to 18 years || 25
|-
| 19 years and older || 30
|-
| Pregnant females (14 to 50 years) || 30
|-
| Lactating females (14 to 50 years) || 35
|}
</div>
Australia and New Zealand set AIs similar to the US.<ref name=AustNZ>{{cite web |url=http://www.nhmrc.gov.au/_files_nhmrc/file/publications/synopses/n35.pdf |title=National Health and Medical Research Council: Nutrient Reference Values for Australia and New Zealand |access-date=2010-02-19 |archive-url=https://web.archive.org/web/20170121003340/https://www.nhmrc.gov.au/_files_nhmrc/file/publications/synopses/n35.pdf |archive-date=2017-01-21 |url-status=dead }}</ref>

The [[European Food Safety Authority]] (EFSA) also identifies AIs, setting values at 40&nbsp;μg/day for adults, pregnancy at 40&nbsp;μg/day, and breastfeeding at 45&nbsp;μg/day. For children ages 1–17 years, the AIs increase with age from 20 to 35&nbsp;μg/day.<ref name=EFSA2017>{{cite web| title = Overview on Dietary Reference Values for the EU population as derived by the EFSA Panel on Dietetic Products, Nutrition and Allergies| year = 2017| url = https://www.efsa.europa.eu/sites/default/files/assets/DRV_Summary_tables_jan_17.pdf| access-date = August 30, 2017| archive-date = August 28, 2017| archive-url = https://web.archive.org/web/20170828082247/https://www.efsa.europa.eu/sites/default/files/assets/DRV_Summary_tables_jan_17.pdf| url-status = live}}</ref>

===Safety===
The US National Academy of Medicine estimates upper limits for vitamins and minerals when evidence for a true limit is sufficient. For biotin, however, there is no upper limit because the adverse effects of high biotin intake have not been determined.<ref name="DRItext" /> The EFSA also reviewed safety and reached the same conclusion as in the United States.<ref>{{cite web| title = Tolerable Upper Intake Levels For Vitamins And Minerals| publisher = European Food Safety Authority| year = 2006| url = http://www.efsa.europa.eu/sites/default/files/efsa_rep/blobserver_assets/ndatolerableuil.pdf| access-date = March 4, 2016| archive-date = March 16, 2016| archive-url = https://web.archive.org/web/20160316225123/http://www.efsa.europa.eu/sites/default/files/efsa_rep/blobserver_assets/ndatolerableuil.pdf| url-status = live}}</ref>

===Labeling regulations===
For US food and dietary supplement labeling purposes, the amount in a serving is expressed as a percent of daily value. For biotin labeling purposes, 100% of the daily value was 300&nbsp;μg/day, but as of May 27, 2016, it was revised to 30&nbsp;μg/day to agree with the adequate intake.<ref name="FedReg">{{cite web|url=https://www.gpo.gov/fdsys/pkg/FR-2016-05-27/pdf/2016-11867.pdf|title=Federal Register May 27, 2016 Food Labeling: Revision of the Nutrition and Supplement Facts Labels |archive-url=https://web.archive.org/web/20170922104400/https://www.gpo.gov/fdsys/pkg/FR-2016-05-27/pdf/2016-11867.pdf|archive-date=2017-09-22|url-status=live}}</ref><ref>{{cite web | title=Daily Value Reference of the Dietary Supplement Label Database (DSLD) | website=Dietary Supplement Label Database (DSLD) | url=https://www.dsld.nlm.nih.gov/dsld/dailyvalue.jsp | access-date=16 May 2020 | archive-date=7 April 2020 | archive-url=https://web.archive.org/web/20200407073956/https://dsld.nlm.nih.gov/dsld/dailyvalue.jsp | url-status=dead }}</ref> Compliance with the updated labeling regulations was required by January 1, 2020, for manufacturers with [[US$]]10&nbsp;million or more in annual food sales, and by January 1, 2021, for manufacturers with lower volume food sales.<ref name="FDAdelay">{{cite web | title=Changes to the Nutrition Facts Label | website=U.S. [[Food and Drug Administration]] (FDA) | date=27 May 2016 | url=https://www.fda.gov/food/food-labeling-nutrition/changes-nutrition-facts-label | access-date=16 May 2020 | archive-date=May 6, 2018 | archive-url=https://web.archive.org/web/20180506080421/https://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/LabelingNutrition/ucm385663.htm | url-status=dead }} {{PD-notice}}</ref><ref>{{cite web | title=Industry Resources on the Changes to the Nutrition Facts Label | website=U.S. [[Food and Drug Administration]] (FDA) | date=21 December 2018 | url=https://www.fda.gov/food/food-labeling-nutrition/industry-resources-changes-nutrition-facts-label | access-date=16 May 2020 | archive-date=December 25, 2020 | archive-url=https://web.archive.org/web/20201225063145/https://www.fda.gov/food/food-labeling-nutrition/industry-resources-changes-nutrition-facts-label | url-status=dead }} {{PD-notice}}</ref> A table of the old and new adult daily values is provided at [[Reference Daily Intake]].
{{clear}}

==Food sources ==
<div style="float:left; padding: 1em;">
{| class="wikitable"
|-
!Source<ref name=ods/>
!Amount<br /> (μg/100 g)
|-
|[[Beef]] liver || 31
|-
|[[Egg as food|Whole eggs]] || 10
|-
|[[Salmon]], pink, canned in water || 5
|-
|[[Pork]] chop || 4
|-
|[[Hamburger]] patty || 4
|-
|[[Sunflower seed]]s, roasted || 3
|-
|[[Sweet potato]], cooked || 2
|}
</div>
Biotin is stable at room temperature and is not destroyed by cooking.<ref name=lpi/> The dietary biotin intake in Western populations has been estimated to be in the range of 35 to 70 μg/day. Nursing infants ingest about 6 μg/day.<ref name=PKIN2020Biotin /> Biotin is available in dietary supplements, individually or as an ingredient in [[multivitamin]]s.<ref name=ods/><ref name=lpi/>

According to the Global Fortification Data Exchange, biotin deficiency is so rare that no countries require that foods be fortified.<ref name=Map>{{cite web|url=https://fortificationdata.org/map-number-of-nutrients/|title=Map: Count of Nutrients In Fortification Standards|website=Global Fortification Data Exchange|access-date=11 January 2011|archive-date=April 11, 2019|archive-url=https://web.archive.org/web/20190411123853/https://fortificationdata.org/map-number-of-nutrients/|url-status=live}}</ref>
{{clear}}

==Physiology==
Biotin is a water-soluble B vitamin.<ref name=ods/> Consumption of large amounts as a dietary supplement results in absorption, followed by excretion into urine as biotin.<ref name=ods/><ref name=lpi/> Consumption of biotin as part of a normal diet results in urinary excretion of biotin and biotin metabolites.<ref name=lpi/>

===Absorption===
Biotin in food is bound to proteins. Digestive enzymes reduce the proteins to biotin-bound peptides. The intestinal enzyme [[biotinidase]], found in pancreatic secretions and in the brush border membranes of all three parts of the [[small intestine]], frees biotin, which is then absorbed from the small intestine.<ref name=lpi/><ref name=PKIN2020Biotin /> When consumed as a biotin dietary supplement, absorption is nonsaturable, meaning that even very high amounts are absorbed effectively. Transport across the [[jejunum]] is faster than across the [[ileum]].<ref name=PKIN2020Biotin />

The large intestine [[microbiota]] synthesizes amounts of biotin estimated to be similar to the amount taken in the diet, and a significant portion of this biotin exists in the free (protein-unbound) form and, thus, is available for absorption. How much is absorbed in humans is unknown, although a review did report that human colon epithelial cells in vitro demonstrated an ability to uptake biotin.<ref name=Said2013>{{cite journal |vauthors=Said HM |title=Recent advances in transport of water-soluble vitamins in organs of the digestive system: a focus on the colon and the pancreas |journal=Am J Physiol Gastrointest Liver Physiol |volume=305 |issue=9 |pages=G601–10 |date=November 2013 |pmid=23989008 |pmc=3840235 |doi=10.1152/ajpgi.00231.2013 |url=}}</ref>

Once absorbed, [[sodium-dependent multivitamin transporter]] (SMVT) mediates biotin uptake into the liver.<ref name=PKIN2020Biotin /> SMVT also binds [[pantothenic acid]], so high intakes of either of these vitamins can interfere with the transport of the other.<ref>{{cite journal | vauthors = Chirapu SR, Rotter CJ, Miller EL, Varma MV, Dow RL, Finn MG | title = High specificity in response of the sodium-dependent multivitamin transporter to derivatives of pantothenic acid | journal = Current Topics in Medicinal Chemistry | volume = 13 | issue = 7 | pages = 837–42 | date = 31 March 2013 | pmid = 23578027 | doi = 10.2174/1568026611313070006 }}</ref>

===Metabolism and excretion===
Biotin [[catabolism]] occurs via two pathways. In one, the valeric acid sidechain is cleaved, resulting in bisnorbiotin. In the other path, the sulfur is oxidized, resulting in biotin sulfoxide. Urine content is proportionally about half biotin, plus bisnorbiotin, biotin sulfoxide, and small amounts of other metabolites.<ref name=PKIN2020Biotin />

===Factors that affect biotin requirements===
Chronic alcohol use is associated with a significant reduction in plasma biotin.<ref name=Said2011>{{cite journal |vauthors=Said HM |title=Intestinal absorption of water-soluble vitamins in health and disease |journal=Biochem J |volume=437 |issue=3 |pages=357–72 |date=August 2011 |pmid=21749321 |pmc=4049159 |doi=10.1042/BJ20110326 |url=}}</ref> Intestinal biotin uptake also appears to be sensitive to the effect of the anti-[[epilepsy]] drugs [[carbamazepine]] and [[primidone]].<ref name=Said2011 /> Relatively low levels of biotin have also been reported in the urine or plasma of patients who have had a partial [[gastrectomy]] or have other causes of [[achlorhydria]], as well as burn patients, elderly individuals, and athletes.<ref name=Combs>{{cite book| author = Combs GF | title= The Vitamins: Fundamental Aspects in Nutrition and Health | year= 2008| publisher= San Diego: Elsevier, Inc| isbn = 978-0-12-183493-7}}</ref> Pregnancy and [[lactation]] may be associated with an increased demand for biotin. In pregnancy, this may be due to a possible acceleration of biotin [[catabolism]], whereas, in lactation, the higher demand has yet to be elucidated. Recent studies have shown marginal biotin deficiency can be present in [[human gestation]], as evidenced by increased urinary excretion of [[beta-Hydroxy beta-methylbutyric acid|3-hydroxyisovaleric acid]], decreased urinary excretion of biotin and bisnorbiotin, and decreased plasma concentration of biotin.<ref name=PKIN2020Biotin />

==Biosynthesis==
Biotin, synthesized in plants, is essential to plant growth and development.<ref name=Maruyama>{{cite journal |vauthors=Maruyama J, Yamaoka S, Matsuo I, Tsutsumi N, Kitamoto K |title=A newly discovered function of peroxisomes: involvement in biotin biosynthesis |journal=Plant Signal Behav |volume=7 |issue=12 |pages=1589–93 |date=December 2012 |pmid=23073000 |pmc=3578898 |doi=10.4161/psb.22405 |bibcode=2012PlSiB...7.1589M |url=}}</ref> Bacteria also synthesize biotin,<ref name=Satiputra2016>{{cite journal |vauthors=Satiaputra J, Shearwin KE, Booker GW, Polyak SW |title=Mechanisms of biotin-regulated gene expression in microbes |journal=Synth Syst Biotechnol |volume=1 |issue=1 |pages=17–24 |date=March 2016 |pmid=29062923 |pmc=5640590 |doi=10.1016/j.synbio.2016.01.005 |url=}}</ref> and it is thought that bacteria resident in the large intestine may synthesize biotin that is absorbed and utilized by the host organism.<ref name=Said2013 />

Biosynthesis starts from two precursors, [[alanine]] and [[pimelic acid|pimeloyl]]-CoA. These form 7-keto-8-aminopelargonic acid (KAPA). KAPA is transported from plant peroxisomes to mitochondria where it is converted to 7,8-diaminopelargonic acid (DAPA) with the help of the enzyme, BioA. The enzyme dethiobiotin synthetase catalyzes the formation of the ureido ring via a DAPA carbamate activated with ATP, creating dethiobiotin with the help of the enzyme, BioD, which is then converted into biotin which is catalyzed by BioB.<ref name="Cronan, J. E 2020">{{cite journal |last1=Hu |first1=Yuanyuan |last2=Cronan |first2=John E. |date=2020-11-05 |title=α-proteobacteria synthesize biotin precursor pimeloyl-ACP using BioZ 3-ketoacyl-ACP synthase and lysine catabolism |journal=Nature Communications |language=en |volume=11 |issue=1 |pages=5598 |doi=10.1038/s41467-020-19251-5 |issn=2041-1723 |pmc=7645780 |pmid=33154364|bibcode=2020NatCo..11.5598H }}</ref> The last step is catalyzed by [[biotin synthase]], a radical SAM enzyme.  The sulfur is donated by an unusual [2Fe-2S] ferredoxin.<ref>{{cite book| doi = 10.1016/bs.mie.2018.06.003|chapter = Purification, Characterization, and Biochemical Assays of Biotin Synthase from ''Escherichia coli''|title = Radical SAM Enzymes|series = Methods in Enzymology|year = 2018|last1 = Cramer|first1 = Julia D.|last2 = Jarrett|first2 = Joseph T.|volume = 606|pages = 363–388|pmid = 30097099|isbn = 9780128127940}}</ref> Depending on the species of bacteria, Biotin can be synthesized via multiple pathways.<ref name="Cronan, J. E 2020" />

==Cofactor biochemistry==
The enzyme [[holocarboxylase synthetase]] covalently attaches biotin to five human [[carboxylase]] [[enzyme]]s:<ref name=PKIN2020Biotin />
* [[Acetyl-CoA carboxylase|Acetyl-CoA carboxylase alpha]] (ACC1)
* [[Acetyl-CoA carboxylase|Acetyl-CoA carboxylase beta]] (ACC2)
* [[Pyruvate carboxylase]] (PC)
* [[Methylcrotonyl-CoA carboxylase]] (MCC)
* [[Propionyl-CoA carboxylase]] (PCC)

For the first two, biotin serves as a [[Cofactor (biochemistry)|cofactor]] responsible for the transfer of [[bicarbonate]] to [[acetyl-CoA]], converting it to [[malonyl-CoA]] for [[fatty acid synthesis]]. PC participates in [[gluconeogenesis]]. MCC catalyzes a step in [[leucine]] metabolism. PCC catalyzes a step in the metabolism of [[propionyl-CoA]].<ref name=ods/><ref name=lpi/><ref name=PKIN2020Biotin /> Metabolic degradation of the [[biotinylation|biotinylated]] carboxylases leads to the formation of [[biocytin]]. This compound is further degraded by biotinidase to release biotin, which is then reutilized by holocarboxylase synthetase.<ref name=PKIN2020Biotin />

Biotinylation of [[histone]] proteins in nuclear chromatin is a [[posttranslational modification]] that plays a role in chromatin stability and gene expression.<ref name=PKIN2020Biotin /><ref name=Xu2014/>

==Deficiency==
{{main|Biotin deficiency}}
Primary biotin deficiency, meaning deficiency due to too little biotin in the diet, is rare because biotin is contained in many foods. Subclinical deficiency can cause mild symptoms, such as hair thinning, brittle fingernails, or skin rash, typically on the face.<ref name="DRItext" /><ref name=PKIN2020Biotin />

Aside from inadequate dietary intake (rare), biotin deficiency can be caused by a genetic disorder that affects biotin metabolism. The most common among these is [[biotinidase deficiency]]. Low activity of this enzyme causes a failure to recycle biotin from [[biocytin]]. Rarer are carboxylase and biotin transporter deficiencies.<ref name=PKIN2020Biotin /><ref name=Zempleni2008>{{cite journal | vauthors = Zempleni J, Hassan YI, Wijeratne SS |title = Biotin and biotinidase deficiency | journal = Expert Review of Endocrinology & Metabolism |volume = 3 |issue = 6 |pages = 715–24 |date = November 2008 | pmid = 19727438 |pmc = 2726758 |doi = 10.1586/17446651.3.6.715 }}</ref> Neonatal screening for biotinidase deficiency started in the United States in 1984, with many countries now also testing for this genetic disorder at birth. Treatment is a lifelong dietary supplement with biotin.<ref name=ods/> If biotinidase deficiency goes untreated, it can be fatal.<ref>{{cite journal |vauthors=Wolf B |title=Biotinidase deficiency and our champagne legacy |journal=Gene |volume=589 |issue=2 |pages=142–50 |date=September 2016 |pmid=26456103 |doi=10.1016/j.gene.2015.10.010 |url=}}</ref>

===Diagnosis===
Low serum and urine biotin are not sensitive indicators of inadequate biotin intake.<ref name=PKIN2020Biotin /> However, serum testing can be useful for confirmation of consumption of biotin-containing dietary supplements, and whether a period of refraining from supplement use is long enough to eliminate the potential for interfering with drug tests.<ref name=Luong2019/><ref name=Bowen2019/> Indirect measures depend on the biotin requirement for carboxylases. [[3-Methylcrotonyl-CoA]] is an intermediate step in the catabolism of the amino acid [[leucine]]. Without biotin, the pathway diverts to [[3-hydroxyisovaleric acid]]. Urinary excretion of this compound is an early and sensitive indicator of biotin deficiency.<ref name="DRItext" /><ref name=PKIN2020Biotin />

===Deficiency as a result of metabolic disorders===
[[Biotinidase deficiency]] is a deficiency of the enzyme that recycles biotin, due to an inherited genetic mutation.<ref name=ods/> Biotinidase catalyzes the cleavage of biotin from biocytin and biotinyl-peptides (the proteolytic degradation products of each holocarboxylase) and thereby recycles biotin.<ref name="DRItext" /> It is also important in freeing biotin from dietary protein-bound biotin.<ref name=Wolf1985/> Neonatal screening for biotinidase deficiency started in the United States in 1984,<ref name=Canda2020 /> which as of 2017 was reported as required in more than 30 countries.<ref name=Strovel2017/>

Profound biotinidase deficiency, defined as less than 10% of normal serum enzyme activity, which has been reported as 7.1 nmol/min/mL, has an incidence of 1 in 40,000 to 1 in 60,000, but with rates as high as 1 in 10,000 in countries with high incidence of consanguineous marriages (second cousin or closer). Partial biotinidase deficiency is defined as 10% to 30% of normal serum activity.<ref name=Canda2020>{{cite journal |vauthors=Canda E, Kalkan Uçar S, Çoker M |title=Biotinidase Deficiency: Prevalence, Impact And Management Strategies |journal=Pediatric Health Med Ther |volume=11 |issue= |pages=127–33 |date=2020 |pmid=32440248 |doi=10.2147/PHMT.S198656  |doi-broken-date=July 1, 2025  |doi-access=free|pmc=7211084 |url=}}</ref> Incidence data stems from government-mandated newborn screening.<ref name="Strovel2017">{{cite journal|last=Glynis|first=Ablon|date=November 2012|title=A Double-blind, Placebo-controlled Study Evaluating the Efficacy of an Oral Supplement in Women with Self-perceived Thinning Hair|journal=The Journal of Clinical and Aesthetic Dermatology|volume=5|issue=11|pages=28–34|pmid=23198010|pmc=3509882}}</ref> For profound deficiency, treatment is oral dosing with 5 to 20&nbsp;mg per day. Seizures are reported as resolving in hours to days, with other symptoms resolving within weeks.<ref name=Canda2020/> Treatment of partial biotinidase deficiency is also recommended even though some untreated people never manifest symptoms.<ref name=Canda2020 /> Lifelong treatment with supplemental biotin is recommended for both profound and partial biotinidase deficiency.<ref name=ods/>

Inherited metabolic disorders characterized by deficient activities of biotin-dependent carboxylases are termed [[multiple carboxylase deficiency]]. These include deficiencies in the enzymes [[holocarboxylase synthetase]].<ref name=ods/> [[Holocarboxylase synthetase deficiency]] prevents the body's cells from using biotin effectively and thus interferes with multiple carboxylase reactions.<ref name=Wolf1985>{{cite journal | vauthors = Wolf B, Grier RE, Secor McVoy JR, Heard GS | s2cid = 11554577 | title = Biotinidase deficiency: a novel vitamin recycling defect | journal = Journal of Inherited Metabolic Disease | volume = 8 | issue = Suppl 1 | pages = 53–8 | year = 1985 | pmid = 3930841 | doi = 10.1007/BF01800660 }}</ref> There can also be a genetic defect affecting the sodium-dependent multivitamin transporter protein.<ref name=Zempleni2008/>

Biochemical and clinical manifestations of any of these metabolic disorders can include [[Metabolic acidosis|ketolactic acidosis]], [[organic aciduria]], [[hyperammonemia]], rash, [[hypotonia]], [[seizure]]s, [[Intellectual disability|developmental delay]], [[alopecia]] and [[coma]].<ref name=PKIN2020Biotin />

==Use in biotechnology==
Chemically modified versions of biotin are widely used throughout the [[biotechnology]] industry to isolate proteins and non-protein compounds for biochemical [[assay]]s.<ref name=ThermoFisher>{{cite web |url=http://www.piercenet.com/browse.cfm?fldID=4DDCADD2-5056-8A76-4E7E-2E00843BE346 |title=Overview of Protein Labeling |publisher=[[Thermo Fisher Scientific]] |access-date=22 April 2012 |archive-date=September 26, 2012 |archive-url=https://web.archive.org/web/20120926034604/http://www.piercenet.com/browse.cfm?fldID=4DDCADD2-5056-8A76-4E7E-2E00843BE346 |url-status=live }}</ref> Because egg-derived [[avidin]] binds strongly to biotin with a [[dissociation constant]] ''K''<sub>d</sub> ≈ 10<sup>−15</sup>&nbsp;M,<ref name=Laitinen2006>{{cite journal | vauthors = Laitinen OH, Hytönen VP, Nordlund HR, Kulomaa MS | s2cid = 7180383 | title = Genetically engineered avidins and streptavidins | journal = Cellular and Molecular Life Sciences | volume = 63 | issue = 24 | pages = 2992–3017 | date = December 2006 | pmid = 17086379 | doi = 10.1007/s00018-006-6288-z | pmc = 11136427 }}</ref> biotinylated compounds of interest can be isolated from a sample by exploiting this highly stable interaction. First, the chemically modified biotin reagents are bound to the targeted compounds in a solution via a process called biotinylation. The choice of which chemical modification to use is responsible for the biotin reagent binding to a specific protein.<ref name=ThermoFisher /> Second, the sample is incubated with avidin bound to beads, then rinsed, removing all unbound proteins, while leaving only the biotinylated protein bound to avidin. Last, the biotinylated protein can be eluted from the beads with excess free biotin.<ref>{{cite journal | vauthors = Morag E, Bayer EA, Wilchek M | title = Immobilized nitro-avidin and nitro-streptavidin as reusable affinity matrices for application in avidin-biotin technology | journal = Anal Biochem | volume = 243 | issue = 2 | pages = 257–263 | date = Dec 1996 | pmid = 8954558 | doi = 10.1006/abio.1996.0514 }}</ref> The process can also utilize bacteria-derived [[streptavidin]] bound to beads, but because it has a higher dissociation constant than avidin, very harsh conditions are needed to elute the biotinylated protein from the beads, which often will denature the protein of interest.<ref name=Laitinen2006/>

==Interference with medical laboratory results==
When people are ingesting high levels of biotin in dietary supplements, a consequence can be clinically significant interference with [[diagnosis|diagnostic]] blood tests that use biotin-streptavidin technology. This methodology is commonly used to measure levels of hormones such as [[thyroid hormones]], and other analytes such as 25-hydroxyvitamin D. Biotin interference can produce both falsely normal and falsely abnormal results.<ref name=ods/><ref name=FDA2017>{{cite web|title=The FDA Warns that Biotin May Interfere with Lab Tests: FDA Safety Communication|date=28 November 2017|url=https://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/ucm586505.htm|publisher=US Food and Drug Administration|access-date=5 January 2021|archive-date=April 24, 2019|archive-url=https://web.archive.org/web/20190424073101/https://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/ucm586505.htm|url-status=dead}}</ref> In the US, biotin as a non-prescription dietary supplement is sold in amounts of 1 to 10&nbsp;mg per serving, with claims for supporting hair and nail health, and as 300&nbsp;mg per day as a possibly effective treatment for multiple sclerosis<ref name=Tryfonow2019/><ref name=Sedel2016/> (see [[Biotin#Research|§ Research]]). Overconsumption of 5&nbsp;mg/day or higher causes elevated concentration in plasma that interferes with biotin-streptavidin immunoassays in an unpredictable manner.<ref name=Luong2019>{{cite journal |vauthors=Luong JH, Vashist SK |title=Chemistry of Biotin-Streptavidin and the Growing Concern of an Emerging Biotin Interference in Clinical Immunoassays |journal=ACS Omega |volume=5 |issue=1 |pages=10–18 |date=January 2020 |pmid=31956746 |pmc=6963918 |doi=10.1021/acsomega.9b03013 |url=}}</ref><ref name=Bowen2019>{{cite journal |vauthors=Bowen R, Benavides R, Colón-Franco JM, Katzman BM, Muthukumar A, Sadrzadeh H, Straseski J, Klause U, Tran N |title=Best practices in mitigating the risk of biotin interference with laboratory testing |journal=Clin Biochem |volume=74 |issue= |pages=1–11 |date=December 2019 |pmid=31473202 |doi=10.1016/j.clinbiochem.2019.08.012 |url=|doi-access=free }}</ref> Healthcare professionals are advised to instruct patients to stop taking biotin supplements for 48 h or even up to weeks before the test, depending on the specific test, dose, and frequency of biotin uptake.<ref name=Luong2019/> Guidance for laboratory staff is proposed to detect and manage biotin interference.<ref name=Bowen2019/>

==History==
{{Further|Vitamin#History}}
In 1916, W. G. Bateman observed that a diet high in raw egg whites caused toxic symptoms in dogs, cats, rabbits, and humans.<ref>{{cite journal| vauthors = Bateman WG |date=June 1916|title=The Digestibility and Utilization of Egg Proteins|journal=Journal of Biological Chemistry|volume=26|pages=263–91|doi=10.1016/S0021-9258(18)87458-0|doi-access=free|url=https://archive.org/download/digestibilityuti00bate/digestibilityuti00bate_bw.pdf}}</ref> By 1927, scientists such as Margarete Boas and [[Helen Parsons]] had performed experiments demonstrating the symptoms associated with "egg-white injury." They had found that rats fed large amounts of egg whites as their only protein source exhibited neurological dysfunction, [[Alopecia|hair loss]], dermatitis, and eventually, death.<ref>{{cite journal | vauthors = Boas MA | title = The Effect of Desiccation upon the Nutritive Properties of Egg-white | journal = The Biochemical Journal | volume = 21 | issue = 3 | pages = 712–724.1 | date = 1927 | pmid = 16743887 | pmc = 1251968 | doi = 10.1042/bj0210712 }}</ref><ref>{{cite journal | vauthors = Parsons HT, Kelly E | journal = The Journal of Biological Chemistry | volume = 100 | date = 1933 | title = The Character of the Dermatitis-Producing Factor in Dietary Egg White as Shown by Certain Chemical Treatments | issue = 11 | pages = 377–379 | pmid = 7005763 | doi = 10.1111/j.1753-4887.1980.tb05948.x | s2cid = 86107167 }}</ref>

In 1936, Fritz Kögl and Benno Tönnis documented isolating a yeast growth factor in a journal article titled "{{Lang|de|Darstellung von krystallisiertem biotin aus eigelb|italic=no}}." (Representation of crystallized biotin from egg yolk).<ref>{{cite journal|last=Kögl and Tönnis|date=1936 |volume=242|issue=1–2|pages=43–73|doi=10.1515/bchm2.1936.242.1-2.43|title=Über das Bios-Problem. Darstellung von krystallisiertem Biotin aus Eigelb. 20. Mitteilung über pflanzliche Wachstumsstoffe|journal=Hoppe-Seyler's Zeitschrift für Physiologische Chemie}}</ref> The name ''biotin'' derives from the Greek word {{Transliteration|grc|bios}} ('to live') and the suffix "-in" (a general chemical suffix used in organic chemistry).<ref name=Etymology /> Other research groups, working independently, had isolated the same compound under different names. Hungarian scientist [[Paul Gyorgy]] began investigating the factor responsible for egg-white injury in 1933 and in 1939, was successful in identifying what he called "Vitamin H" (the H represents {{Lang|de|Haar und Haut}}, German for 'hair and skin').<ref>{{cite journal|last=György|first=P|date=December 1939|title=The Curative Factor (vitamin H) for Egg White Injury, with Particular Reference to Its Presence in Different Foodstuffs and in Yeast|journal=Journal of Biological Chemistry|volume=131|issue=2|pages=733–44|doi=10.1016/S0021-9258(18)73468-6|doi-access=free}}</ref><ref>{{cite journal|vauthors=György P, Kuhn R, Lederer E|date=December 1939|title=Attempts to Isolate the Factor (vitamin H) Curative of Egg White Injury|journal=Journal of Biological Chemistry|volume=131|issue=2|pages=745–59|doi=10.1016/S0021-9258(18)73469-8|doi-access=free}}</ref> Further chemical characterization of vitamin H revealed that it was water-soluble and present in high amounts in the liver.<ref>{{cite journal|last1=Birch|first1=TW|last2=György|first2=P|date=December 1939|title=Physicochemical Properties of the Factor (vitamin H) Curative of Egg White Injury|journal=Journal of Biological Chemistry|volume=131|issue=2|pages=761–66|doi=10.1016/S0021-9258(18)73470-4|doi-access=free}}</ref> After experiments performed with yeast and ''Rhizobium trifolii'', West and Wilson isolated a compound they called co-enzyme R.<ref>{{cite journal | vauthors = West PM, Wilson PW | title = The Relation of "coenzyme R" to Biotin | journal = Science | volume = 89 | issue = 2322 | pages = 607–8 | date = June 1939 | pmid = 17751623 | doi = 10.1126/science.89.2322.607 | bibcode = 1939Sci....89..607W | s2cid = 30138816 }}</ref><ref>{{cite journal|vauthors=DuVigneaud V, Hofmann K, Melville DB, György P|date=August 1941|title=Isolation of Biotin (vitamin H) from Liver|journal=Journal of Biological Chemistry|volume=140|issue=2|pages=643–51|doi=10.1016/S0021-9258(18)51355-7|doi-access=free}}</ref> By 1940, it was recognized that all three compounds were identical and were collectively given the name: biotin.<ref>{{cite journal | vauthors = György P, Rose CS, Hofmann K, Melville DB, DU Vigneaud V | title = A Further Note on the Identity of Vitamin H with Biotin | journal = Science | volume = 92 | issue = 2400 | pages = 609 | date = December 1940 | pmid = 17795447 | doi = 10.1126/science.92.2400.609 | bibcode = 1940Sci....92..609G }}</ref> Gyorgy continued his work on biotin and in 1941 published a paper demonstrating that egg-white injury was caused by the binding of biotin by [[avidin]].<ref>{{cite journal | vauthors = György P, Rose CS, Eakin RE, Snell EE, Williams RJ | title = Egg-White Injury as the Result of Nonabsorption or Inactivation of Biotin | journal = Science | volume = 93 | issue = 2420 | pages = 477–8 | date = May 1941 | pmid = 17757050 | doi = 10.1126/science.93.2420.477 | bibcode = 1941Sci....93..477G | jstor = 1668938 }}</ref><ref>{{cite journal | vauthors = Gyorgy P, Rose CS |date=1943|title=The Liberation of Biotin from the Avidin-Biotin Complex (AB)|journal=Experimental Biology and Medicine|volume=53|issue=1|pages=55–7|doi=10.3181/00379727-53-14183|s2cid=84419614}}</ref> Unlike for many vitamins, there is insufficient information to establish a recommended dietary allowance, so dietary guidelines identify an "adequate intake" based on best available science with the understanding that at some later date this will be replaced by more exact information.<ref name="DRItext"/><ref name=AustNZ/><ref name=EFSA2017 />

Using ''E. coli'', a biosynthesis pathway was proposed by Rolfe and Eisenberg in 1968. The initial step was described as a condensation of pimelyl-CoA and alanine to form 7-oxo-8-aminopelargonic acid. From there, they described a three-step process, the last being introducing a sulfur atom to form the tetrahydrothiophene ring.<ref>{{cite journal | vauthors = Rolfe B, Eisenberg MA | title = Genetic and biochemical analysis of the biotin loci of ''Escherichia coli'' K-12 | journal = Journal of Bacteriology | volume = 96 | issue = 2 | pages = 515–24 | date = August 1968 | pmid = 4877129 | pmc = 252325 | doi = 10.1128/JB.96.2.515-524.1968 }}</ref>

==Research==

===Multiple sclerosis===
High-dose biotin (300&nbsp;mg/day = 10,000 times [[Dietary Reference Intake|adequate intake]]) has been used in [[clinical trial]]s for treatment of [[multiple sclerosis]], a demyelinating autoimmune disease.<ref name=Tryfonow2019/><ref name=Sedel2016/> The hypothesis is that biotin may promote remyelination of the [[myelin]] sheath of nerve cells, slowing or even reversing neurodegeneration. The proposed mechanisms are that biotin activates acetyl-CoA carboxylase, a key rate-limiting enzyme during the synthesis of myelin, and by reducing axonal hypoxia through enhanced energy production.<ref name=Tryfonow2019>{{cite journal |vauthors=Tryfonos C, Mantzorou M, Fotiou D, Vrizas M, Vadikolias K, Pavlidou E, Giaginis C |title=Dietary Supplements on Controlling Multiple Sclerosis Symptoms and Relapses: Current Clinical Evidence and Future Perspectives |journal=Medicines  |volume=6 |issue=3 |date=September 2019 |page=95 |pmid=31547410 |pmc=6789617 |doi=10.3390/medicines6030095 |url=|doi-access=free }}</ref><ref name=Sedel2016>{{cite journal |vauthors=Sedel F, Bernard D, Mock DM, Tourbah A |title=Targeting demyelination and virtual hypoxia with high-dose biotin as a treatment for progressive multiple sclerosis |journal=Neuropharmacology |volume=110 |issue=Pt B |pages=644–53 |date=November 2016 |pmid=26327679 |doi=10.1016/j.neuropharm.2015.08.028 |url=|doi-access=free }}</ref> Clinical trial results are mixed; a 2019 review concluded that a further investigation of the association between multiple sclerosis symptoms and biotin should be undertaken,<ref name=Tryfonow2019/> whereas two 2020 reviews of a larger number of clinical trials reported no consistent evidence for benefits,<ref name=Motte2020>{{cite journal |vauthors=Motte J, Gold R |title=High-dose biotin in multiple sclerosis: the end of the road |journal=Lancet Neurol |volume=19 |issue=12 |pages=965–66 |date=December 2020 |pmid=33222766 |doi=10.1016/S1474-4422(20)30353-7 |s2cid=225049079 |url=}}</ref> and some evidence for increased disease activity and higher risk of relapse.<ref name=Goldschmidt2020>{{cite journal |vauthors=Goldschmidt CH, Cohen JA |title=The Rise and Fall of High-Dose Biotin to Treat Progressive Multiple Sclerosis |journal=Neurotherapeutics |volume=17 |issue=3 |pages=968–70 |date=July 2020 |pmid=32761325 |doi=10.1007/s13311-020-00907-5 |pmc=7609671 |url=|doi-access=free }}</ref>

===Hair, nails, skin===
In the United States, biotin is promoted as a [[dietary supplement]] for strengthening hair and [[fingernail]]s, though scientific data supporting these outcomes in humans are very weak.<ref name=lpi/><ref name=Cashman2010/><ref name=Patel2017/> A review of the fingernails literature reported brittle nail improvement as evidence from two pre-1990 clinical trials that had administered an oral dietary supplement of 2.5&nbsp;mg/day for several months, without a placebo control comparison group. There is no more recent clinical trial literature.<ref name=Cashman2010>{{cite journal |vauthors=Cashman MW, Sloan SB |title=Nutrition and nail disease |journal=Clin Dermatol |volume=28 |issue=4 |pages=420–5 |date=2010 |pmid=20620759 |doi=10.1016/j.clindermatol.2010.03.037 }}</ref>{{update inline|date=January 2025}} A review of biotin as a treatment for hair loss identified case studies of infants and young children with genetic defect biotin deficiency having improved hair growth after supplementation, but went on to report that "there have been no randomized, controlled trials to prove the efficacy of supplementation with biotin in normal, healthy individuals."<ref name=Patel2017>{{cite journal |vauthors=Patel DP, Swink SM, Castelo-Soccio L |title=A Review of the Use of Biotin for Hair Loss |journal=Skin Appendage Disord |volume=3 |issue=3 |pages=166–69 |date=August 2017 |pmid=28879195 |pmc=5582478 |doi=10.1159/000462981 }}</ref> Biotin is also incorporated into topical hair and skin products with similar claims.<ref>{{cite journal | vauthors = Fiume MZ | title = Final report on the safety assessment of biotin | journal = International Journal of Toxicology | volume = 20 | pages = 1–12 | year = 2001 | issue = Suppl 4 | doi = 10.1080/10915810160233712 | pmid = 11800048 }}</ref>

The [[Dietary Supplement Health and Education Act of 1994]] states that the US Food and Drug Administration must allow on the product label what are described as "Structure:Function" (S:F) health claims that ingredient(s) are essential for health. For example: Biotin helps maintain healthy skin, hair, and nails. If a S:F claim is made, the label must include the disclaimer "This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease."<ref>{{Citation |author1=Janet Rehnquist |author-link1=Janet Rehnquist |date=March 2003 |title=Department of Health and Human Services – Office of the Inspector General – Dietary Supplement Labels: Key Elements |publisher=[[United States Department of Health and Human Services]] |id=OEI-01-01-00120 |url=https://oig.hhs.gov/oei/reports/oei-01-01-00120.pdf |access-date=2 April 2013 |archive-date=November 18, 2004 |archive-url=https://web.archive.org/web/20041118061526/https://oig.hhs.gov/oei/reports/oei-01-01-00120.pdf |url-status=live }}</ref>

==Animals==
In cattle, biotin is necessary for hoof health. Lameness due to hoof problems is common, with herd prevalence estimated at 10 to 35%.<ref name=Langova2020/> Consequences of lameness include less food consumption, lower milk production, and increased veterinary treatment costs. Results after 4–6 months from supplementing biotin at 20&nbsp;mg/day into daily diet reduces the risk of lameness.<ref name=Langova2020>{{cite journal |vauthors=Langova L, Novotna I, Nemcova P, Machacek M, Havlicek Z, Zemanova M, Chrast V |title=Impact of Nutrients on the Hoof Health in Cattle |journal=Animals  |volume=10 |issue=10 |date=October 2020 |page=1824 |pmid=33036413 |pmc=7600182 |doi=10.3390/ani10101824 |url=|doi-access=free }}</ref><ref name=":0">{{cite journal |date=October 2005 |title=Biotin and lameness - A review |url=http://wrap.warwick.ac.uk/34343/ |journal=Cattle Practice |volume=13 |issue=Part 2 |pages=145–53 |access-date=May 17, 2022 |archive-date=May 17, 2022 |archive-url=https://web.archive.org/web/20220517224134/http://wrap.warwick.ac.uk/34343/ |url-status=live }}</ref> A review of controlled trials reported that supplementation at 20&nbsp;mg/day increased milk yield by 4.8%. The discussion speculated that this could be an indirect consequence of improved hoof health or a direct effect on milk production.<ref name=Chen2011>{{cite journal |vauthors=Chen B, Wang C, Wang YM, Liu JX |title=Effect of biotin on milk performance of dairy cattle: a meta-analysis |journal=J Dairy Sci |volume=94 |issue=7 |pages=3537–46 |date=July 2011 |pmid=21700041 |doi=10.3168/jds.2010-3764 |url=|doi-access=free }}</ref>

For horses, conditions such as chronic laminitis, cracked hooves, or dry, brittle feet incapable of holding shoes are a common problem. Biotin is a popular nutritional supplement. There are recommendations that horses need 15 to 25&nbsp;mg/day. Studies report biotin improves the growth of new hoof horn rather than improving the status of existing hoof, so months of supplementation are needed for the hoof wall to be completely replaced.<ref>{{cite web |url=https://ker.com/equinews/biotin-basics/ |title=Biotin Basics |date=4 November 2003 |website=Kentucky Equine Basics |access-date=18 January 2021 |archive-date=June 10, 2021 |archive-url=https://web.archive.org/web/20210610060936/https://ker.com/equinews/biotin-basics/ |url-status=live }}</ref>

==See also==
* [[Biotin deficiency]]
* [[Biotin sulfoxide]]
* [[Biotinidase deficiency]]
* [[Biotinylation]]
* [[Multiple carboxylase deficiency]]
* [[Photobiotin]]

==References==
{{Reflist}}

==External links==
* {{Commons category-inline}}

{{Vitamin}}
{{Enzyme cofactors}}
{{Authority control}}

[[Category:B vitamins]]
[[Category:Cofactors]]
[[Category:Ureas]]
[[Category:Carboxylic acids]]
[[Category:Thiolanes]]