Stevia
is a genus of about 240 species of herbs and shrubs in the sunflower family (Asteraceae), native
to subtropical and tropical regions from western North America to South America. The species Stevia
rebaudiana, commonly known as sweetleaf, sweet leaf, sugarleaf, or simply stevia, is widely grown for
its sweet leaves. As a sweetener and sugar substitute, stevia's taste has a slower onset and longer
duration than that of sugar, although some of its extracts may have a bitter or licorice-like aftertaste at
high concentrations.
With its steviol glycoside extracts having up to 300 times the sweetness of sugar, stevia has garnered
attention with the rise in demand for low-carbohydrate, low-sugar food alternatives. Because stevia has a
negligible effect on blood glucose, it is attractive as a natural sweetener to people on carbohydrate-
controlled diets.
The availability of stevia varies from country to country. In a few countries, it has been available as a
sweetener for decades or centuries; for example, stevia is widely used as a sweetener in Japan where it
has been available for decades. In some countries, stevia is restricted or banned. In other countries,
health concerns and political controversies have limited its availability; for example, the United States
banned stevia in the early 1990s unless labeled as a dietary supplement,[1][2] but in 2008
approved rebaudioside A extract as a food additive. Over the years, the number of countries in which
stevia is available as a sweetener has been increasing.
History and use
Steviol is the basic building block of stevia's sweet glycosides: Stevioside and rebaudioside A are constructed by replacing
the bottom hydrogen atom with glucose and the top hydrogen atom with two or three linked glucose groups, respectively.
The genus Stevia consists of 240[3] species of plants native to South America, Central America, and
Mexico, with several species found as far north asArizona, New Mexico, and Texas.[4] They were first
researched by Spanish botanist and physician Petrus Jacobus Stevus (Pedro Jaime Esteve),[5] from
whose surname originates the Latinized word stevia.[6] Human use of the sweet species S.
rebaudiana originated in South America. The leaves of the stevia plant have 30–45 times the sweetness
of sucrose (ordinary table sugar).[7] The leaves can be eaten fresh, or put in teas and foods.
In 1899, the Swiss botanist Moisés Santiago Bertoni, during his research in eastern Paraguay first
described the plant and the sweet taste in detail.[8] Only limited research was conducted on the topic until,
in 1931, two French chemists isolated the glycosides that give stevia its sweet taste.[9] These compounds
were named stevioside and rebaudioside, and are 250–300 times as sweet as sucrose, heat
stable, pH stable, and non-fermentable.[10]
The exact structure of the aglycone and the glycoside were published in 1955.
In the early 1970s, Japan began cultivating stevia as an alternative to artificial sweeteners such
as cyclamate and saccharin, which were suspectedcarcinogens. The plant's leaves, the aqueous extract
of the leaves, and purified steviosides are used as sweeteners. Since the Japanese firm Morita Kagaku
Kogyo Co., Ltd. produced the first commercial stevia sweetener in Japan in 1971,[11] the Japanese have
been using stevia in food products, soft drinks(including Coca Cola),[12] and for table use. Japan currently
consumes more stevia than any other country, with stevia accounting for 40% of the sweetener market.[13]
Today, stevia is cultivated and used in food elsewhere in east Asia, including in China (since
1984), Korea, Taiwan, Thailand, and Malaysia. It can also be found in Saint Kitts and Nevis, in parts
of South America (Brazil, Colombia, Peru, Paraguay, and Uruguay), Philippines [1] and in Israel. China is
the world's largest exporter of stevioside.[13]
Stevia species are found in the wild in semiarid habitats ranging from grassland to mountain terrain. They
do produce seeds, but only a small percentage of them germinate. Planting cloned stevia is a more
effective method of reproduction.
[edit]Medicinal use
For centuries, the Guaraní peoples of Paraguay, Bolivia and Brazil used stevia, which they called ka'a
he'ê ("sweet herb"), as a sweetener in yerba mate and medicinal teas for treating heartburn and other
ailments.[14] More recent medical research has shown promise in treating obesity[15] and hypertension.[16]
[17]
Stevia has a negligible effect on blood glucose, even enhancing glucose tolerance;[18] therefore, it is
attractive as a natural sweetener to diabetics and others on carbohydrate-controlled diets.[19]
Possible treatment of osteoporosis has been suggested by the patent application claim that eggshell
breakage can be reduced by 75% by adding a small percentage of stevia leaf powder to chicken feed.
[20]
It has also been suggested that pigs fed stevia extract had twice as much calcium content in their
meat, but these claims are unverified.[21]
