Stevia

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Stevia
A young Stevia rebaudiana plant
Scientific classification
Kingdom: Plantae Division: Magnoliophyta Class: Magnoliopsida Order: Asterales Family: Asteraceae Genus: Stevia
Species
About 150 species, including: Stevia eupatoria Stevia ovata Stevia plummerae Stevia rebaudiana Stevia salicifolia Stevia serrata

Stevia (also called sweetleaf, sweet leaf or sugarleaf) is a genus of about 150 species of herbs and shrubs in the sunflower family (Asteraceae), native to subtropical and tropical South America and Central America. As a sweetener, stevia's sweet taste has a slower onset and longer duration than that of sugar, although some of its extracts may have a bitter or liquorice-like aftertaste at high concentrations.

With its 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. Stevia also has shown promise in medical research for treating such conditions as obesity^[1] and high blood pressure.^[2][3] Stevia has negligible effect on blood glucose, therefore it is attractive as a natural sweetener to diabetics and others on carbohydrate-controlled diets. However, health and political controversies have limited stevia's availablility in many countries; for example, the United States banned it in the early 1990s. Stevia is widely used as a sweetener in Japan, and it is now available in the US and Canada as a dietary supplement, although not as a food additive.

[edit] History and use

For centuries, the Guaraní tribes of Paraguay and Brazil used Stevia species, primarily S. rebaudiana which they called ka'a he'ê ("sweet herb"), as a sweetener in yerba mate and medicinal teas for treating heartburn and other ailments.

In 1931, two French chemists isolated the glycosides that give stevia its sweet taste.^[4] These extracts were named stevioside and rebaudioside. These compounds are 250–300 times sweeter than sucrose (ordinary table sugar), heat stable, pH stable, and non-fermentable.^[5]

In the early 1970s, Japan began cultivating stevia as an alternative to artificial sweeteners such as cyclamate and saccharin, suspected carcinogens. The plant's leaves, the aqueous extract of the leaves, and purified steviosides are used as sweeteners. Stevia sweeteners have been produced commercially in Japan since 1977 and are widely used in food products, soft drinks (including Coca Cola^[6]), and for table use. Japan currently consumes more stevia than any other country; there, stevia accounts for 40% of the sweetener market.

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 part of South America (Brazil, Paraguay, and Uruguay) and in Israel. China is the world's largest exporter of stevioside.

Stevia species are found in the wild in semi-arid habitats ranging from grassland to mountain terrain. Stevia does produce seeds, but only a small percentage of them germinate. Planting cloned stevia is a more effective method of reproduction.

[edit] Controversies

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.

[edit] Health controversy

A 1985 study reported that steviol, a breakdown product from stevioside and rebaudioside (two of the sweet steviol glycosides in the stevia leaf) is a mutagen in the presence of a liver extract of pre-treated rats^[7] — but this finding has been criticized on procedural grounds that the data were mishandled in such a way that even distilled water would appear mutagenic.^[8] More recent animal tests have shown mixed results in terms of toxicology and adverse effects of stevia extract, with some tests finding steviol to be a weak mutagen^[9] while others find no safety issues.^[10] Although more recent studies appear to establish the safety of stevia, government agencies have expressed concerns over toxicity, citing a lack of sufficient conclusive research.^[11][12]

Whole foods proponents draw a distinction between consuming (and safety testing) only parts, such as stevia extracts and isolated compounds like stevioside, versus the whole herb. In his book Healing With Whole Foods, Paul Pitchford cautions, "Obtain only the green or brown [whole] stevia extracts or powders; avoid the clear extracts and white powders, which, highly refined and lacking essential phyto-nutrients, cause imbalance". However, this statement is not backed by published scientific evidence, other than the general findings about refined foods being less beneficial.

In 2006, the World Health Organization (WHO) performed a thorough evaluation of recent experimental studies of stevioside and steviols conducted on animals and humans, and concluded that "stevioside and rebaudioside A are not genotoxic in vitro or in vivo and that the genotoxicity of steviol and some of its oxidative derivatives in vitro is not expressed in vivo."^[13] The report also found no evidence of carcinogenic activity. Furthermore, the report noted that "stevioside has shown some evidence of pharmacological effects in patients with hypertension or with type-2 diabetes"^[13] but concluded that further study was required to determine proper dosage.

Indeed, millions of Japanese people have been using stevia for over thirty years with no reported or known harmful effects. Similarly, stevia leaves have been used for centuries in South America spanning multiple generations in ethnomedical tradition as a treatment of type II diabetes.

[edit] Political controversy

In 1991, at the request of an anonymous complaint, the United States Food and Drug Administration labeled stevia as an "unsafe food additive" and restricted its import. The FDA's stated reason was "toxicological information on stevia is inadequate to demonstrate its safety."^[14] This ruling was controversial, as stevia proponents pointed out that this designation violates the FDA's own guidelines, under which any natural substance used prior to 1958 with no reported adverse effects should be generally recognized as safe (GRAS).

Stevia occurs naturally, requiring no patent to produce it. As a consequence, since the import ban in 1991, marketers and consumers of stevia have shared a belief that the sweetener industry pressured the FDA to keep stevia out of the United States. Arizona congressman Jon Kyl, for example, called the FDA action against stevia "a restraint of trade to benefit the artificial sweetener industry."^[15] To date, the FDA has never revealed the source of the original complaint in its responses to requests filed under the Freedom of Information Act.

The FDA requires proof of safety before recognizing a food additive as safe. A similar burden of proof is required for the FDA to ban a substance or label it unsafe. Nevertheless, stevia remained banned until after the 1994 Dietary Supplement Health and Education Act forced the FDA in 1995 to revise its stance to permit stevia to be used as a dietary supplement, although not as a food additive — a position that stevia proponents regard as contradictory because it simultaneously labels stevia as safe and unsafe, depending on how it is sold.^[16]

[edit] Availability

Stevia may be grown legally.

Stevia has been grown on an experimental basis in Ontario since 1987 for the purpose of determining the feasibility of growing the crop commercially. In the United States, it is legal to import, grow, sell, and consume Stevia products if contained within or labeled for use as a dietary supplement, but not as a food additive. Stevia has also been approved as a dietary supplement in Australia and Canada. In Japan and South American countries, stevia may also be used as a food additive.

Although unresolved questions remain concerning whether metabolic processes can produce a mutagen from stevia in animals, let alone in humans, the early studies nevertheless prompted the European Commission to ban stevia's use in food in the European Union pending further research.^[17] It is also banned in Singapore and Hong Kong.^[18] More recent data compiled in the safety evaluation released by the World Health Organization in 2006^[13] suggest that these policies may be obsolete.

[edit] Names in other countries

Both the sweetener and the stevia plant Stevia rebaudiana bertoni (also known as Eupatorium rebaudianum bertoni) are known and pronounced as "stévia" in English-speaking countries as well as in France, Germany, Italy, Portugal, and Sweden — although some of these countries also use other terms as shown below. Similar pronunciations occur in Japan (sutebia or ステビア in katakana), and in Thailand (satiwia). In some countries (India, for example) the name translates literally as "sweet leaf." Below are some names for the stevia plant in various regions of the world:

• Afrikaans-speaking countries: heuningblaar (honey leaf)
• China: 甜菊 (tian jü – sweet chrysanthemum), 甜菊叶 (tian jü ye – stevia leaf)
• English-speaking countries: candy leaf, sugar leaf, sweetleaf (USA), sweet honey leaf (Australia), sweet herb of Paraguay
• German speaking countries (also Switzerland): Süßkraut, Süßblatt, Honigkraut
• Hungary: jázmin pakóca
• India: madhu parani (Marathi), madhu patra (Sanskrit), seeni tulsi (Tamil), madhu patri (Telugu)
• Japan: アマハステビア (amaha sutebia)
• Portuguese-speaking countries: capim doce, erva doce, estévia (Brazil), folhas da stévia
• Spanish-speaking countries: hierba / yerba dulce, estevia, ka´a he´ê (Guaraníes, Natives of Paraguay)
• Thailand: satiwia, หญ้าหวาน (ya wan, or sweet grass in Bangkok)

[edit] See also

• Asteraceae
• Glycoside
• Sugar substitute

[edit] Notes and references

Look up Stevia in Wiktionary, the free dictionary.

1. ^ PubMed research articles related to treatments of obesity
2. ^ PubMed research articles on stevia's effects on blood pressure
3. ^ PubMed articles on stevia's use in treating hypertension
4. ^ Bridel, M.; Lavielle, R. (1931). "Sur le principe sucre des feuilles de kaa-he-e (stevia rebaundiana B)". Academie des Sciences Paris Comptes Rendus (Parts 192): 1123-1125. 
5. ^ Brandle, Jim (2004-08-19). FAQ - Stevia, Nature's Natural Low Calorie Sweetener (HTML). Agriculture and Agri-Food Canada. Retrieved on November 8, 2006.
6. ^ Taylor, Leslie (2005). The Healing Power of Natural Herbs. Garden City Park, NY: Square One Publishers, Inc., (excerpted at weblink). ISBN 0-7570-0144-0. 
7. ^ Pezzuto, JM; Compadre CM, Swanson SM, Nanayakkara D, Kinghorn AD (April 1985). "Metabolically activated steviol, the aglycone of stevioside, is mutagenic". Proc Natl Acad Sci U.S.A. 82 (8): 2478-82. 
8. ^ Procinska, E; Bridges BA, Hanson JR (March 1991). "Interpretation of results with the 8-azaguanine resistance system in Salmonella typhimurium: no evidence for direct acting mutagenesis by 15-oxosteviol, a possible metabolite of steviol". Mutagenesis 6 (2): 165-7.  – article text is reproduced here.
9. ^ Matsui, M; Matsui K, Kawasaki Y, Oda Y, Noguchi T, Kitagawa Y, Sawada M, Hayashi M, Nohmi T, Yoshihira K, Ishidate M Jr, Sofuni T (November 1996). "Evaluation of the genotoxicity of stevioside and steviol using six in vitro and one in vivo mutagenicity assays". Mutagenesis 11 (6): 573-9. 
10. ^ Klongpanichpak, S; Temcharoen P, Toskulkao C, Apibal S, Glinsukon T (September 1997). "Lack of mutagenicity of stevioside and steviol in Salmonella typhimurium TA 98 and TA 100". J Med Assoc Thai 80 (Suppl 1): S121-8. 
11. ^ European Commission Scientific Committee on Food (June 1999). Opinion on Stevia Rebaudiana Bertoni plants and leaves
12. ^ Food Standards Agency (August 2000). FSA note on Stevia and stevioside
13. ^ ^{a b c} Benford, D.J.; DiNovi, M., Schlatter, J. (2006). "Safety Evaluation of Certain Food Additives: Steviol Glycosides" (PDF – 18 MB). WHO Food Additives Series 54: 140. 
14. ^ Food and Drug Administration (1995, rev 1996, 2005). Import Alert #45-06: "Automatic Detention of Stevia Leaves, Extract of Stevia Leaves, and Food Containing Stevia"
15. ^ Kyl, John (R-Arizona) (1993). Letter to former FDA Commissioner David Aaron Kessler about the 1991 stevia import ban.
16. ^ McCaleb, Rob (1997). Controversial Products in the Natural Foods Market (HTML). Herb Research Foundation. Retrieved on November 8, 2006.
17. ^ European Commission Scientific Committee on Food (June 1999). Opinion on Stevioside as a Sweetener
18. ^ Simon LI (Legislative Council Secretariat Research and Library Services Division) (27 March 2002). Fact Sheet: Stevioside

[edit] Further reading

• Pitchford, Paul (2002). Healing With Whole Foods: Asian Traditions and Modern Nutrition (3rd ed.). Berkeley: North Atlantic Books (ISBN 1-55643-430-8).
• May, James (2003). The Miracle of Stevia. New York, NY: Twin Stream Books (ISBN 0-7582-0220-2).
• Kirkland, James (1999). Sugar-Free Cooking with Stevia. Arlington, TX: Crystal Health Pub. (ISBN 1-928906-11-7).
• Goettomoeller, Jeffrey (1999). Stevia Sweet Recipes: Sugar-Free-Naturally. Bloomingdale, IL: Vital Health Pub. (ISBN 1-890612-13-8).
• Sahelian, Ray (1999). The Stevia Cookbook. Garden City Park, NY: Avery (ISBN 0-89529-926-7).

[edit] External links

• SteviaInfo.com - Stevia Research Studies, News, Recipes and Background Information
• Center for Science in the Public Interest article Stevia: A Bittersweet Tale
• Center for Science in the Public Interest article
• Hong Kong Legislative Council Secretariat (PDF file)
• Journal review article on Stevia's safety
• Stevia: Not Ready For Prime Time
• Stevia - Health and History Information
• Multilingual Multiscript plant name database has terms for the Stevia plant in different languages
• Article by Daniel Mowrey, Ph.D. in assoc. with Health Freedom Resources (http://www.healthfree.com/).
• Diabetes Health - Article on Stevia and Diabetes.
• http://www.eustas.org/ - European Stevia Association