Editing Stevia (section)

==Mechanism of action==
[[File:Steviol structure.svg|thumb|right|180px|[[Steviol]], the basic building block of stevia's [[steviol glycoside|sweet glycosides]] ]]

Glycosides are molecules that contain glucose residues bound to other non-sugar substances called [[aglycones]] (molecules with other sugars are [[polysaccharide]]s). Preliminary experiments deduce that the tongue's [[taste receptor]]s react to the glycosides and transduce the sweet taste sensation and the lingering bitter aftertaste by direct activation of sweet and bitter receptors.<ref>{{cite journal |last1=Hellfritsch |first1=C. |last2=Brockhoff |first2=A. |last3=Stähler |first3=F. |last4=Meyerhof |first4=W. |last5=Hofmann |first5=T. |title=Human psychometric and taste receptor responses to steviol glycosides |journal=Journal of Agricultural and Food Chemistry |date=11 July 2012 |volume=60 |issue=27 |pages=6782–6793 |pmid=22616809 |doi=10.1021/jf301297n|bibcode=2012JAFC...60.6782H }}</ref>

According to [[basic research]], steviol glycosides and steviol interact with a [[protein channel]] called [[TRPM5]], potentiating the signal from the sweet or bitter receptors, amplifying the taste of other sweet, bitter and umami tastants.<ref>{{cite journal |last1=Philippaert |first1=K. |last2=Pironet |first2=A. |last3=Mesuere |first3=M. |last4=Sones |first4=W. |last5=Vermeiren |first5=L. |last6=Kerselaers |first6=S. |last7=Pinto |first7=S. |last8=Segal |first8=A. |last9=Antoine |first9=N. |last10=Gysemans |first10=C. |last11=Laureys |first11=J. |last12=Lemaire |first12=K. |last13=Gilon |first13=P. |last14=Cuypers |first14=E. |last15=Tytgat |first15=J. |last16=Mathieu |first16=C. |last17=Schuit |first17=F. |last18=Rorsman |first18=P. |last19=Talavera |first19=K. |last20=Voets |first20=T. |last21=Vennekens |first21=R. |display-authors=6 |date=31 March 2017 |title=Steviol glycosides enhance pancreatic beta-cell function and taste sensation by potentiation of TRPM5 channel activity |journal=Nature Communications |volume=8 |pages=14733 |pmid=28361903 |doi=10.1038/ncomms14733 |pmc=5380970|bibcode=2017NatCo...814733P }}</ref> The [[synergy|synergetic]] effect of the glycosides on the sweet receptor and TRPM5 explains the sweetness sensation. Some steviol glycosides (rebaudioside&nbsp;A) are perceived sweeter than others (stevioside).<ref>{{cite journal |pmid=24206531 |year=2013 |last1=Well |first1=C. |last2=Frank |first2=O. |last3=Hofmann |first3=T. |title=Quantitation of sweet steviol glycosides by means of a HILIC-MS/MS-SIDA approach|journal=Journal of Agricultural and Food Chemistry |volume=61 |issue=47 |pages=11312–11320 |doi=10.1021/jf404018g|bibcode=2013JAFC...6111312W }}</ref>

Steviol is processed by intestinal microflora and is also taken up into the bloodstream, further metabolised by the liver to steviol glucuronide and several other metabolites, and excreted in the urine.<ref>{{cite journal |last1=Geuns |first1=J.M. |last2=Buyse |first2=J. |last3=Vankeirsbilck |first3=A. |last4=Temme |first4=E.H. |last5=Compernolle |first5=F. |last6=Toppet |first6=S. |title=Identification of steviol glucuronide in human urine |journal=Journal of Agricultural and Food Chemistry |date=5 April 2006 |volume=54 |issue=7 |pages=2794–2798 |pmid=16569078 |doi=10.1021/jf052693e|bibcode=2006JAFC...54.2794G }}</ref><ref name="Joint FAO/WHO2016" />{{rp|56–57}}

A three-dimensional map of the [[protein]]s produced by the stevia plant, showing the crystalline structures that produce both the sensation of sweetness and bitter aftertaste in the sweetener, was reported in 2019.<ref>{{cite web |url=https://cen.acs.org/biological-chemistry/natural-products/enzyme-makes-stevia-sweet/97/i24 |title=This enzyme is what makes stevia so sweet |website=Chemical & Engineering News |language=en |access-date=2019-08-22}}</ref>