Stevia

Stevia(/ˈstiːviə,ˈstɛviə/)is a sweetsugar substitutethat is about 50 to 300 timessweeterthansugar.It isextractedfrom the leaves ofStevia rebaudiana, a plant native to areas ofParaguayandBrazil.The active compounds in stevia aresteviol glycosides(mainlysteviosideandrebaudioside).Stevia is heat-stable,pH-stable, and notfermentable.Humans cannot metabolize theglycosidesin stevia, and it therefore has zerocalories. Its taste has a slower onset and longer duration than that of sugar, and at high concentrations some of its extracts may have anaftertastedescribed aslicorice-like orbitter. Stevia is used in sugar- and calorie-reduced food and beverage products as an alternative for variants with sugar.
The legal status of stevia as afood additiveordietary supplementvaries from country to country. In theUnited States, certain high-puritystevia glycosideextracts have beengenerally recognized as safe(GRAS) and may be lawfully marketed and added to food products, but stevia leaf and crude extracts do not have GRAS orFood and Drug Administration(FDA) approval for use in food.TheEuropean UnionapprovedStevia rebaudianaadditives in 2011.InJapan, stevia has been widely used as a sweetener for decades.
The plantStevia rebaudianahas been used for centuries by theGuaraní peoplesof South America, who called itka'a he'ê("sweet herb").The leaves have been used traditionally for hundreds of years in both Paraguay and Brazil to sweeten local teas, and as a "sweet treat".The genus was named for the Spanish botanist and physicianPedro Jaime Esteve(Petrus James Stevus, 1500–1556) a professor of botany at theUniversity of Valencia.
In 1899, Swiss botanistMoisés Santiago Bertoni, while conducting research in eastern Paraguay, first described the plant and the sweet taste in detail.Only limited research was conducted on the topic until, in 1931, two French chemists isolated theglycosidesthat give stevia its sweet taste.
During the 1990s, the United StatesFood and Drug Administration(FDA) received two petitions requesting that stevia be classified asgenerally recognized as safe(GRAS), but the FDA "disagreed with [the] conclusions [detailed in the petitions]".Stevia remained banned for all uses until theDietary Supplement Health and Education Act of 1994, after which the FDA revised its stance and permitted stevia to be used as adietary supplement, although still not as a food additive.In 1999, prompted by early studies, theEuropean Commissionbanned stevia's use in food products within the European Union pending further research.In 2006 and 2016, research data compiled in the safety evaluations released by theWorld Health Organizationfound no adverse effects.
In December 2008, the FDA gave a "no objection" approval for GRAS status toTruviaandPureVia,both of which userebaudioside Aderived from theStevia rebaudianaplant.However, the FDA said that these products are not stevia, but a highly purifiedStevia rebaudiana-extract product.In 2015, the FDA still regarded stevia as "not an approved food additive", and stated that it "has not been affirmed as GRAS in the United States due to inadequate toxicological information".In June 2016, theU.S. Customs and Border Protectionissued an order of detention for stevia products made in China based on information that the products were made usingprison labor.Certain high-puritystevia glycosideextracts have beengenerally recognized as safe(GRAS) and may be lawfully marketed and added to food products.
Use of stevia as a sweetener began in Japan,with theaqueousextractof the leaves yielding purified steviosides developed as sweeteners. Japanese firmMorita Kagaku Kogyoclaims they were the first, in 1971, to commercialize stevia sweetener production.
In the mid-1980s, stevia was commonly used in U.S.natural foodsandhealth foodindustries, as a noncaloric natural sweetener for teas and weight-loss blends.The makers of the synthetic sweetenerNutraSweet(at the time Monsanto) asked the FDA to require testing of stevia extracts.In 2007,the Coca-Cola Companyannounced plans to obtain approval for itsStevia-derived sweetener,Rebiana, for use as a food additive within the United States by 2009, as well as plans to market Rebiana-sweetened products in 12 countries that allow stevia's use as a food additive.
In May 2008, Coca-Cola andCargillannounced the availability of Truvia, a consumer-brandSteviasweetener containingerythritoland Rebiana,which the FDA permitted as a food additive in December 2008.Coca-Cola announced intentions to release stevia-sweetened beverages in late December 2008.From 2013 onwards,Coca-Cola Life, containing stevia as a sweetener, was launched in various countries around the world.
Shortly afterward,PepsiCoandPure Circleannounced PureVia, their brand ofStevia-based sweetener, but withheld release of beverages sweetened withrebaudioside Auntil receipt of FDA confirmation. Since the FDA permitted Truvia and PureVia, both the Coca-Cola Company and PepsiCo have introduced products that contain their new sweeteners.
Rebaudioside A has the leastbitternessof all the steviol glycosides in theStevia rebaudianaplant. To produce steviol glycosides commercially,Stevia rebaudianaplants are dried and subjected to a hot waterextractionprocess.This crude extract contains about 50% rebaudioside A. The various glycosides are separated and purified viacrystallizationtechniques, typically usingethanolormethanolassolvent.The dried extract contains no less than 95% steviol glycosides.
Stevia rebaudianaextracts and derivatives are produced industrially and marketed under different trade names.
Glycosides are molecules that contain glucose residues bound to other non-sugar substances calledaglycones(molecules with other sugars arepolysaccharides). Preliminary experiments deduce that the tongue'staste receptorsreact to the glycosides and transduce the sweet taste sensation and the lingering bitter aftertaste by direct activation of sweet and bitter receptors.
According tobasic research, steviol glycosides and steviol interact with aprotein channelcalledTRPM5, potentiating the signal from the sweet or bitter receptors, amplifying the taste of other sweet, bitter and umami tastants.Thesynergeticeffect of the glycosides on the sweet receptor and TRPM5 explains the sweetness sensation. Some steviol glycosides (rebaudioside A) are perceived sweeter than others (stevioside).
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.
A three-dimensional map of theproteinsproduced 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.
A 2010 review found that the use ofStevia rebaudianasweeteners as replacements for sugar might benefit children, people withdiabetes, and those wishing to lower their intake of calories.
Although both steviol and rebaudioside A have been found to bemutagenicin laboratoryin vitrotesting,these effects have not been demonstrated for the doses and routes of administration to which humans are exposed.Two 2010 review studies found no health concerns withStevia rebaudianaor its sweetening extracts.
Used as anextract, stevia leaves have been used traditionally in Paraguay as a women'scontraceptive, administered as a daily drink. The effect has been tested in rats, finding a 57–79 percent reduction in fertility compared with thecontrol group, the lowered fertility continuing after withdrawal of the drug for up to two months.
The WHO's Joint Experts Committee on Food Additives has approved, based on long-term studies, anacceptable daily intakeof steviol glycoside of up to 4 mg/kg of body mass.In 2010, TheEuropean Food Safety Authorityestablished an acceptable daily intake of 4 mg/kg of steviol, in the form of steviol glycosides. Meanwhile, theMemorial Sloan Kettering Cancer Centerwarns that "steviol at high dosages may have weak mutagenic activity,"and a review "conducted for" theCenter for Science in the Public Interestnotes that there are no published carcinogenicity results for rebaudioside A (or stevioside).
In August 2019, the US FDA placed an import alert onStevialeaves and crude extracts – which do not haveGRASstatus – and on foods or dietary supplements containing them due to concerns about safety and potential fortoxicity.
The plant may be grown legally in most countries, although some countries restrict its use as a sweetener. The legally allowed uses and maximum dosage of the extracts and derived products vary widely from country to country.