Stevia is a non-caloric sweetener derived from the leaves of the plant Stevia rebaudiana, a shrub native to parts of South America. It has gained considerable global attention as a plant-based alternative to table sugar and artificial sweeteners. Its popularity stems from its intense sweetness, allowing consumers to reduce calorie and carbohydrate intake without sacrificing taste. The highly purified extract is now a common ingredient in beverages, food products, and tabletop sweeteners around the world.
Botanical Origin and Sweet Compounds
The Stevia plant, Stevia rebaudiana, is a tender perennial herb belonging to the Asteraceae family. Its native habitat is centered in the highlands of Paraguay and Brazil, where indigenous populations, such as the Guaraní people, have used the leaves for centuries to sweeten mate tea and medicines, referring to it as “sweet herb” (ka’a he’ẽ).
The intense sweet flavor originates from a collection of compounds called steviol glycosides, which are naturally produced within the leaves. The two most abundant glycosides are Stevioside and Rebaudioside A, but the plant can contain over 40 distinct sweet compounds. These compounds are significantly sweeter than sucrose; Rebaudioside A, for example, registers up to 450 times the sweetness of table sugar.
Extraction and Regulatory Status
The stevia sweetener used commercially is a highly purified extract, not simply the dried, crushed leaf. The industrial process begins by steeping dried stevia leaves in hot water, similar to brewing tea, to extract the steviol glycosides. This crude liquid extract then undergoes a multi-step purification process to remove non-sweet compounds, plant matter, and unwanted flavor components.
Purification techniques often involve ion-exchange chromatography and crystallization, sometimes using food-grade alcohol or methanol, to isolate the specific steviol glycosides. This results in a high-purity product, typically defined as containing at least 95% total steviol glycosides, which is the form approved for use as a general-purpose sweetener. Regulatory bodies like the U.S. Food and Drug Administration (FDA) have granted this high-purity extract “Generally Recognized as Safe” (GRAS) status. The FDA has not approved the use of whole stevia leaf or crude extracts in food. The Acceptable Daily Intake (ADI) for steviol glycosides is set at 4 milligrams per kilogram of body weight per day.
Metabolic Impact and Safety Profile
Stevia is a non-nutritive sweetener, meaning it provides virtually zero calories and has a zero glycemic index. Since the human digestive system cannot break down the steviol glycosides, they pass through the upper gastrointestinal tract without being absorbed or affecting blood sugar levels. In the colon, gut bacteria break down the glycosides into a compound called steviol, which is then absorbed, processed by the liver, and safely excreted.
Multiple studies confirm that consuming stevia does not significantly affect blood glucose or insulin levels in people managing their weight or diabetes. When substituted for sucrose, stevia intake results in lower postprandial glucose and insulin responses because it eliminates the caloric load of sugar. Furthermore, the notion that stevia negatively impacts the gut’s microbial community is largely unsupported by current human research. Studies on human subjects consuming stevia indicate a minimal or neutral effect on the composition and diversity of the gut microbiota.
Flavor Profile and Culinary Uses
Despite its intense sweetness, stevia extract has a unique flavor profile that consumers often describe as having a lingering, licorice-like taste or a slight bitterness. This aftertaste is less noticeable in highly purified extracts, such as those rich in Rebaudioside A (Reb A) or Rebaudioside M (Reb M), which are engineered to taste closer to sugar. The specific type of steviol glycoside and its purity level significantly influence the final sensory experience.
For cooking and baking, stevia is valued for its heat and pH stability, meaning it does not break down when heated. Substituting it directly for sugar in baked goods presents a challenge because sugar provides volume, texture, and aids in browning, properties that stevia does not offer. When using concentrated stevia, other ingredients must be added to replace the bulk necessary for proper structure and volume. To minimize the characteristic aftertaste, cooks can use complementary flavors like a pinch of salt, vanilla, or a splash of citrus juice.