Stevia leaf extract (rebiana)

"Natural" high-potency sweetener: "Diet," "no-sugar," "sugar-free" and other products, including beverages, packaged sweeteners, and various foods. Also called rebiana, stevioside, rebaudioside A, rebaudioside D, etc.; sold under such brand names as Truvia, Pure Via, and Sweet Leaf.

Stevia rebaudiana is a shrub (yerba dulce) that traditionally grew in Brazil, Paraguay, and even parts of Arizona. It is now grown commercially in California, China, southeast Asia, and elsewhere. Stevia leaves are about 30 times as sweet as sugar, and contain sweet substances called steviol glycosides that are 200–300 times sweeter than sugar. Among the sweetest ones are rebaudioside A, also called reb A or rebiana, and stevioside. Companies are racing to market better-tasting extracts that have been dubbed rebaudioside D, M, X, and others.

The food industry and many consumers who are trying to avoid sugar and artificial sweeteners have high hopes for stevia leaf extracts. Crude stevia leaf extracts have long been used in Japan and several other countries. One flaw though, is that many people perceive stevia leaf and its sweet derivatives to have an unpleasant aftertaste, which companies are trying feverishly to overcome.

In the 1990s, the FDA (and Canada and the European Union) rejected whole-leaf stevia and crude stevia extracts for use as a food ingredient. High dosages fed to rats reduced sperm production and increased cell proliferation in their testicles, which, at least at those dosages, could cause infertility or other problems. Pregnant hamsters that had been fed large amounts of a metabolite of stevioside called steviol had fewer and smaller offspring. In the laboratory, steviol can be converted into a mutagenic compound, which may promote cancer by causing mutations in the cells' DNA. FDA also was concerned that stevia might interfere with the absorption of carbohydrates and the conversion of food into energy within cells, as well as with effects on cardiovascular and renal systems.

In the early 2000s, Cargill and Merisant (a marketer of sugar substitutes) developed highly purified extracts of stevia that are 95 percent pure rebaudioside A and 200 times as sweet as sugar. Since then, other companies have also developed highly purified extracts of stevia, some containing rebaudioside A and some containing stevioside. Truvia and Pure Via are the brand names for packaged or tabletop sweeteners containing mostly rebaudioside A, also called rebiana, and SweetLeaf is the brand name for packaged sweeteners containing both rebiana and stevioside. Like other packaged sugar substitutes, packets of those products contain only a very small amount of the actual high-intensity sweetener (rebiana and/or stevioside in this case), since the tiny bits of powder would get lost in the packets if a carrier were not added. Thus, Truvia packets are mostly erythritol, PureVia mostly dextrose and cellulose powder, and SweetLeaf mostly inulin.

The one nagging concern (other than taste) about stevia leaf extracts is that they have not been adequately tested for cancer. Several (but not all) genetic tests found that rebiana-related substances caused mutations and other forms of genotoxicity. Because such findings may indicate a cancer risk, that should have spurred the FDA to require additional animal feeding studies.  Nevertheless, in late 2008 the FDA did not object to rebaudioside A as "generally recognized as safe" (GRAS) and since then has raised no objections to other steviol glycosides such as stevioside as GRAS. Companies quickly marketed a wide range of lower-calorie products sweetened with stevia leaf extracts, replacing some or all of the sugar or other high-potency sweeteners.

Some food and beverage companies are trying to mask the aftertaste of rebiana with various ingredients, including ERYTHRITOL or modest amounts of sugar. Meanwhile, companies are developing other natural sweeteners, such as MONK FRUIT EXTRACT, MONATIN, and others. Ultimately, those substances might play an important role in reducing the harm caused by the huge amounts of SUGAR and HIGH-FRUCTOSE CORN SYRUP that so many people are consuming.