Editing Biotin (section)

===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=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>