Stevia

Stevia is a natural, non-caloric sweetener derived from the leaves of Stevia rebaudiana, a plant native to Paraguay and Brazil. Its sweetness is produced by steviol glycosides—primarily stevioside and rebaudioside A—which are 50 to 300 times sweeter than sucrose. These compounds are heat-stable, pH-stable and resistant to fermentation, making stevia suitable for a wide range of culinary and industrial applications. Humans cannot metabolise steviol glycosides, so they contribute no caloric value. Their sweetness has a slower onset and longer duration than sugar, and concentrated extracts may impart a bitter or liquorice-like aftertaste.

Origins and Early Use

For centuries the Guaraní people of South America have used the leaves of Stevia rebaudiana, known locally as kaa he or “sweet herb”, to sweeten teas and medicinal preparations. The plant was named for the sixteenth-century Spanish botanist Pedro Jaime Esteve. Scientific interest began in 1899 when the Swiss botanist Moisés Santiago Bertoni described the plant and its sweet properties. The active sweet compounds were isolated in 1931 by French chemists, laying the groundwork for later commercial development.

Regulatory History

Stevia’s regulatory status has varied internationally. In the United States early petitions for stevia to be recognised as generally recognised as safe (GRAS) were rejected, and until 1994 it was prohibited in foods. After the Dietary Supplement Health and Education Act, stevia could be sold as a dietary supplement but still not as a food additive. High-purity steviol glycoside extracts—such as those used in Truvia and PureVia—were granted GRAS status in 2008; however, crude stevia leaf and unrefined extracts remain unapproved for food use.
In 1999 the European Commission banned stevia pending further research. Subsequent evaluations by the World Health Organization in 2006 and 2016 found no safety concerns at recommended intake levels. The European Union approved steviol glycosides as food additives in 2011. Japan has used stevia widely since the 1970s, and several other countries—including China, the UK and many in South America—permit or actively support its use.
Acceptable daily intake levels established by international authorities typically allow up to 4 mg of steviol equivalents per kilogram of body weight.

Commercial Development and Uses

Japan was the first country to commercialise stevia sweeteners, with Morita Kagaku Kogyo producing purified steviosides from the early 1970s. By the mid-1980s stevia was marketed in the United States through natural food outlets as a plant-based sweetener. Large beverage companies later developed proprietary stevia-derived sweeteners: Coca-Cola and Cargill launched Truvia in 2008, while PepsiCo introduced PureVia. These products blend rebaudioside A with erythritol to improve flavour. Since the approval of steviol glycosides as food additives, numerous reduced-sugar beverages have incorporated stevia, including Coca-Cola Life in several international markets.

Extraction and Industrial Processing

Commercial production begins with harvesting and drying Stevia rebaudiana leaves. The sweet glycosides are extracted using hot water, producing a crude extract containing roughly half rebaudioside A. Purification is achieved via crystallisation, typically with ethanol or methanol as solvents, yielding products containing at least 95% steviol glycosides. Different trade names identify various refined preparations of these glycosides.
Rebaudioside A is considered the least bitter and most sugar-like of the steviol glycosides. More recently, biotechnology approaches have enabled the production of alternative glycoside profiles using microbial fermentation to enhance sweetness or reduce aftertaste.

Mechanism of Action

Steviol glycosides consist of a steviol backbone bound to multiple glucose units. When consumed, they interact with the sweet taste receptors on the tongue and may also activate certain bitter receptors, explaining the characteristic bitterness in some extracts. Basic research indicates that these compounds modulate the TRPM5 ion channel, which amplifies sweet, bitter and umami taste signals. This contributes to their perceived intensity and lingering sweetness.
In the body steviol glycosides are not broken down by human digestive enzymes. Intestinal microflora cleave the glycosidic bonds to release steviol, which is absorbed, converted in the liver to steviol glucuronide and excreted in the urine.

Safety and Health Considerations

Scientific reviews generally support the safety of steviol glycosides at typical consumption levels. Although steviol and rebaudioside A demonstrate mutagenicity in some in vitro assays, in vivo studies have not shown harmful effects at human-relevant doses. Reviews published in 2010 reported no significant health concerns, and international food safety authorities have reached similar conclusions.
Stevia leaves have been used traditionally in Paraguay as a contraceptive when consumed daily. Animal studies have reported reduced fertility in rats receiving high doses of leaf extracts, with effects persisting briefly after treatment. These findings pertain to whole-leaf preparations rather than purified steviol glycosides.

Global Acceptance and Future Perspectives

With broad regulatory approval for high-purity steviol glycosides and growing consumer demand for natural, low-calorie sweeteners, stevia has become a prominent ingredient in sugar-reduced foods and beverages. Continued refinement of extraction technologies and advances in metabolic engineering aim to improve flavour profiles by producing glycosides with less bitterness and more sugar-like taste. Interest also continues in exploring potential health benefits, particularly for individuals managing calorie intake or metabolic disorders.