Stevia

Stevia
Stevia rebaudiana flowers.
Stevia rebaudiana flowers.
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Asterales
Family: Asteraceae
Tribe: Eupatorieae
Genus: Stevia
Cav.
Species

About 150 species, including:
Stevia eupatoria
Stevia ovata
Stevia plummerae
Stevia rebaudiana
Stevia salicifolia
Stevia serrata

Stevia is a genus of about 240 species of herbs and shrubs in the sunflower family (Asteraceae), native to subtropical and tropical South America and Central America. The species Stevia rebaudiana Bertoni, commonly known as sweetleaf, sweet leaf, sugarleaf, or simply stevia, is widely grown for its sweet leaves. As a 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 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 a negligible effect on blood glucose, even enhancing glucose tolerance;[4] therefore, it is attractive as a natural sweetener to diabetics and others on carbohydrate-controlled diets.[5] However, health and political controversies have limited stevia's availability in many countries; for example, the United States banned it in the early 1990s unless labeled as a supplement. 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. Rebiana is the trade name for a stevia-derived sweetener being developed jointly by The Coca-Cola Company and Cargill with the intent of marketing in several countries and gaining regulatory approval in the US and EU. Truvia is Cargill's consumer brand of Rebiana-based sweetener, while PureVia is PepsiCo's brand of stevia-based sweetener.

Contents

History and use

The genus Stevia consists of 240[6] species of plants native to South America, Central America, and Mexico, with several species found as far north as Arizona, New Mexico, and Texas.[7] Human use of the sweet species originated in South America. 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. The leaves of the stevia plant have 30–45 times the sweetness of sucrose (ordinary table sugar).[8]

The Swiss botanist Moisés Santiago Bertoni first described the plant and the sweet taste in detail.[9] But only limited research was conducted on the topic, until in 1931, two French chemists isolated the glycosides that give stevia its sweet taste.[10] These compounds were named stevioside and rebaudioside, and are 250–300 times sweeter than sucrose, heat stable, pH stable, and non-fermentable.[11]

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 are suspected carcinogens. 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,[12] the Japanese have been using stevia in food products, soft drinks (including Coca Cola),[13] and for table use. Japan currently consumes more stevia than any other country, with stevia accounting for 40% of the sweetener market.[14]

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) and in Israel. China is the world's largest exporter of stevioside.[14]

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.

Availability

Stevia has been grown on an experimental basis in Ontario, Canada 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, New Zealand[15] and Canada. Since 2008 it is approved as a sweetener for food and beverages in Australia and New Zealand.[16] In Japan and South American countries, stevia may also be used as a food additive. Stevia is currently banned for use in food in the European Union.[17] It is also banned in Singapore and Hong Kong.[18]

Rebiana is the trade name for a patent-pending, calorie-free, food and beverage sweetener derived from stevia and developed jointly by The Coca-Cola Company and Cargill. In May 2007, Coca-Cola announced plans to obtain approval for its use as a food additive within the United States by 2009. Coca-Cola has also announced plans to market rebiana-sweetened products in 12 countries that allow stevia's use as a food additive. The two companies are conducting their own studies in an effort to gain regulatory approval in the United States and the European Union.[19][20] In May 2008, Cargill announced the availability of Truvia, a consumer brand of Rebiana.[21] PepsiCo and the Whole Earth Sweetener Company also announced PureVia, their brand of stevia-based sweetener.[22]

The U.S. ingredient firm Blue California claims to have developed an economical industrial production process for isolating Rebaudioside A, a sweet compound derived from stevia, using a "more economical and proprietary process". The company expects to go into industrial scale production in 2008. The isolation process for Rebaudioside A results in a product that delivers the desired sweetness without a bitter aftertaste.[23]

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.

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[24] — but this finding was criticized on procedural grounds that the data were mishandled in such a way that even distilled water would appear mutagenic.[25] Over the following years bioassay, cell culture, and animal studies have shown mixed results in terms of toxicology and adverse effects of stevia constituents, but in general, they have not been found to be harmful. While reports have emerged finding steviol and stevioside to be weak mutagens,[26][27] the bulk of studies show an absence of harmful effects.[28][29] In a 2008 review, 14 of 16 studies cited showed no genotoxic activity for stevioside, 11 of 15 studies showed genotoxic activity for steviol, and no studies showed genotoxicity for Rebaudioside A. Nevertheless, even if a chemical can cause DNA damage in the controlled conditions of a bioassay (e.g., in bacteria, in mammalian cell cultures) it is a fundamentally different question whether it causes cancer in intact organisms (e.g., rodents, humans) or is teratogenic (i.e., causes birth defects). No evidence for stevia constitutents causing cancer or birth defects has been found.[28][29]

Other studies have shown stevia improves insulin sensitivity in rats[30] and may even promote additional insulin production,[31] helping to reverse diabetes and metabolic syndrome.[32] Preliminary human studies show stevia can help reduce hypertension[33] although another study has shown it has no effect on hypertension.[34] Indeed, millions of Japanese have been using stevia for over thirty years with no reported or known harmful effects.[35] Similarly, stevia leaves have been used for centuries in South America spanning multiple generations in ethnomedical tradition as a treatment of type II diabetes.[36]

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."[37] 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"[37] but concluded that further study was required to determine proper dosage.

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.[38] However, professionals in pharmacognosy, as well as physicians and science journalists disagree that whole foods are necessarily beneficial over extracted components, and may even be harmful.[39][40]

Political controversy

The stevia plant may be grown legally in most countries, although some countries restrict or ban its use as a sweetener.

In 1991, at the request of an anonymous complaint, the United States Food and Drug Administration (FDA) 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."[41] This ruling was controversial, as stevia proponents pointed out that this designation violated 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 FDA acted in response to industry pressure.[15] Arizona congressman Jon Kyl, for example, called the FDA action against stevia "a restraint of trade to benefit the artificial sweetener industry."[42] Citing privacy issues, the FDA has not revealed the source of the original complaint in its responses to requests filed under the Freedom of Information Act.[15]

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.[43]

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] Singapore and Hong Kong have banned it also.[18] However, more recent data compiled in the safety evaluation released by the World Health Organization in 2006[37] suggest that these policies may be obsolete.

Names in other countries

Both the sweetener and the stevia plant Stevia rebaudiana Bertoni (also known as Eupatorium rebaudianum Bertoni[44]) are known simply as "stevia" (pronounced /ˈstɛviə/) in English-speaking countries as well as in France, Germany, Italy, Portugal, Israel, Norway 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:[45]

See also

Notes and references

  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. ↑ Curi R, Alvarez M, Bazotte RB, Botion LM, Godoy JL, Bracht A (1986). "Effect of Stevia rebaudiana on glucose tolerance in normal adult humans". Braz. J. Med. Biol. Res. 19 (6): 771–4. PMID 3651629. 
  5. ↑ Gregersen S, Jeppesen PB, Holst JJ, Hermansen K (January 2004). "Antihyperglycemic effects of stevioside in type 2 diabetic subjects". Metab. Clin. Exp. 53 (1): 73–6. PMID 14681845. http://linkinghub.elsevier.com/retrieve/pii/S0026049503003871. 
  6. ↑ "Stevia". Flora of North America.
  7. ↑ "Stevia Cav.". USDA PLANTS.
  8. ↑ European Commission Scientific Committee on Food (1999-06-17). "Opnion on Stevia Rebaudiana plants and leaves" (PDF). Press release. Retrieved on 2008-01-27.
  9. ↑ Bertoni, Moisés Santiago (1899). ".". Revista de Agronomia de l’Assomption 1: 35. 
  10. ↑ 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): 1123–5. 
  11. ↑ Brandle, Jim (2004-08-19). "FAQ - Stevia, Nature's Natural Low Calorie Sweetener" (HTML). Agriculture and Agri-Food Canada. Retrieved on 2006-11-08.
  12. ↑ "Stevia" (HTML). Morita Kagaku Kogyuo Co., Ltd. (2004). Retrieved on 2007-11-06.
  13. ↑ Taylor, Leslie (2005). The Healing Power of Natural Herbs. Garden City Park, NY: Square One Publishers, Inc.. pp. (excerpted at weblink). ISBN 0-7570-0144-0. http://rain-tree.com/stevia.htm. 
  14. ↑ 14.0 14.1 Jones, Georgia (September 2006). "Stevia" (HTML). NebGuide: University of Nebraska–Lincoln Institute of Agriculture and Natural Resources. Retrieved on 2007-05-04.
  15. ↑ 15.0 15.1 15.2 Hawke, Jenny (February-March 2003). "The Bittersweet Story of the Stevia Herb" (PDF). Nexus magazine 10 (2). https://www.dormanpub.com/articles/PDFs/FFF_March_2003.pdf. Retrieved on 2008-07-09. 
  16. ↑ Stevia gets Australian approval for food and beverages
  17. ↑ 17.0 17.1 European Commission Scientific Committee on Food (June 1999). Opinion on Stevioside as a Sweetener
  18. ↑ 18.0 18.1 Simon LI (Legislative Council Secretariat Research and Library Services Division) (27 March 2002). Fact Sheet: Stevioside
  19. ↑ Stanford, Duane D. (2007-05-31). "Coke and Cargill teaming on new drink sweetener", Atlanta Journal-Constitution. Retrieved on 2007-05-31. 
  20. ↑ Etter, Lauren and McKay, Betsy (2007-05-31). "Coke, Cargill Aim For a Shake-Up In Sweeteners", Wall Street Journal. Retrieved on 2007-06-01. 
  21. ↑ "Truvia information". Retrieved on 2008-05-15.
  22. ↑ "PureVia". Retrieved on 2008-10-18.
  23. ↑ Lorraine Heller (2007-11-15). "US firm claims cheap, industrial stevia production", Food Navigator USA. Retrieved on 2007-11-01. 
  24. ↑ 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. PMID 3887402. PMC: 397582. http://www.pnas.org/cgi/pmidlookup?view=long&pmid=3887402. 
  25. ↑ 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. PMID 2056919. http://mutage.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=2056919.  – article text is reproduced here.
  26. ↑ Matsui M, Matsui K, Kawasaki Y, et al (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. PMID 8962427. 
  27. ↑ Nunes AP, Ferreira-Machado SC, Nunes RM, Dantas FJ, De Mattos JC, Caldeira-de-Araújo A (2007). "Analysis of genotoxic potentiality of stevioside by comet assay". Food Chem Toxicol 45 (4): 662-6. doi:10.1016/j.fct.2006.10.015. PMID 17187912. 
  28. ↑ 28.0 28.1 Geuns JM (2003). "Stevioside". Phytochemistry 64 (5): 913-21. doi:10.1016/S0031-9422(03)00426-6. PMID 14561506. 
  29. ↑ 29.0 29.1 Brusick DJ (2008). "A critical review of the genetic toxicity of steviol and steviol glycosides". Food Chem Toxicol 46 (7): S83-S91. doi:10.1016/j.fct.2008.05.002. PMID 18556105. 
  30. ↑ Lailerd N, Saengsirisuwan V, Sloniger JA, Toskulkao C, Henriksen EJ (January 2004). "Effects of stevioside on glucose transport activity in insulin-sensitive and insulin-resistant rat skeletal muscle". Metab. Clin. Exp. 53 (1): 101–7. doi:10.1016/j.metabol.2003.07.014. PMID 14681850. http://linkinghub.elsevier.com/retrieve/pii/S0026049503003883. 
  31. ↑ Jeppesen PB, Gregersen S, Rolfsen SE, et al (March 2003). "Antihyperglycemic and blood pressure-reducing effects of stevioside in the diabetic Goto-Kakizaki rat". Metab. Clin. Exp. 52 (3): 372–8. doi:10.1053/meta.2003.50058. PMID 12647278. 
  32. ↑ Dyrskog SE, Jeppesen PB, Colombo M, Abudula R, Hermansen K (September 2005). "Preventive effects of a soy-based diet supplemented with stevioside on the development of the metabolic syndrome and type 2 diabetes in Zucker diabetic fatty rats". Metab. Clin. Exp. 54 (9): 1181–8. doi:10.1016/j.metabol.2005.03.026. PMID 16125530. 
  33. ↑ Hsieh MH, Chan P, Sue YM, et al (November 2003). "Efficacy and tolerability of oral stevioside in patients with mild essential hypertension: a two-year, randomized, placebo-controlled study". Clin Ther 25 (11): 2797–808. doi:10.1016/S0149-2918(03)80334-X. PMID 14693305. 
  34. ↑ Ferri LA, Alves-Do-Prado W, Yamada SS, Gazola S, Batista MR, Bazotte RB (September 2006). "Investigation of the antihypertensive effect of oral crude stevioside in patients with mild essential hypertension". Phytother Res 20 (9): 732–6. doi:10.1002/ptr.1944. PMID 16775813. 
  35. ↑ "Products and Markets - Stevia" ([HTML]). Food and Agriculture Organization of the United Nations - Forestry Department. Retrieved on 2007-05-04.
  36. ↑ Abudula R, Jeppesen PB, Rolfsen SE, Xiao J, Hermansen K (October 2004). "Rebaudioside A potently stimulates insulin secretion from isolated mouse islets: studies on the dose-, glucose-, and calcium-dependency". Metab. Clin. Exp. 53 (10): 1378–81. doi:10.1016/j.metabol.2004.04.014. PMID 15375798. http://linkinghub.elsevier.com/retrieve/pii/S0026049504002100. 
  37. ↑ 37.0 37.1 37.2 Benford, D.J.; DiNovi, M., Schlatter, J. (2006). "Safety Evaluation of Certain Food Additives: Steviol Glycosides" (PDF – 18 MB). WHO Food Additives Series (World Health Organization Joint FAO/WHO Expert Committee on Food Additives (JECFA)) 54: 140. http://whqlibdoc.who.int/publications/2006/9241660546_eng.pdf. 
  38. ↑ "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". Pitchford, Paul (2002). Healing With Whole Foods: Asian Traditions and Modern Nutrition (3rd ed.). Berkeley, CA: North Atlantic Books. ISBN 1-55643-430-8. 
  39. ↑ Tyler, Varro E (1999-08-31). "False Tenets of Paraherbalism" (HTML). Quackwatch, Inc.. Retrieved on 2008-09-30.
  40. ↑ Goldacre, Ben (2007-10-06). "The problem with herbalists" (HTML). Guardian News and Media Limited. Retrieved on 2008-09-30.
  41. ↑ 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"
  42. ↑ Kyl, John (R-Arizona) (1993). Letter to former FDA Commissioner David Aaron Kessler about the 1991 stevia import ban, quoted at herbalremedies.com.
  43. ↑ McCaleb, Rob (1997). "Controversial Products in the Natural Foods Market" (HTML). Herb Research Foundation. Retrieved on 2006-11-08.
  44. ↑ "Asteraceae Eupatorium rebaudianum Bertoni". International Plant Names Index.
  45. ↑ The Multilingual Multiscript plant name database has terms for the Stevia plant in various languages.

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