Stevioside is a steviol glycoside naturally extracted from the leaves of the Stevia rebaudiana plant, a species native to regions of Paraguay and Brazil. Its main application is as a high-intensity, zero-calorie sweetener within the food industry.
Chemical Profile and Properties
Stevioside is a glycoside, meaning it consists of a glucose component linked to a non-sugar molecule called steviol. This molecular arrangement contributes to its potent sweetening capacity, estimated to be 100 to 300 times sweeter than sucrose, commonly known as table sugar. Its high sweetness potency allows for very small quantities to be used to achieve desired sweetness levels in various products.
Despite its intense sweetness, stevioside has a distinctive taste profile that includes a slightly bitter or licorice-like aftertaste. This characteristic can become more pronounced at higher concentrations, affecting the overall flavor experience of foods and beverages. The presence of fewer glucosyl groups in its structure is associated with a longer bitter aftertaste.
Other steviol glycosides also exist in the Stevia rebaudiana plant, with varying sweetness intensities and taste profiles. For instance, Rebaudioside A (Reb A) is another prominent steviol glycoside often favored in commercial applications. Reb A is perceived to have a cleaner taste with less of the bitter aftertaste than stevioside, making it a popular choice for formulators seeking to minimize off-notes in their products.
Metabolic Pathway and Bodily Interaction
When consumed, stevioside passes through the human digestive system without being absorbed in the upper gastrointestinal tract. This is because human digestive enzymes are unable to break down its beta-glycosidic bonds. Stevioside then passes largely intact into the colon, where it encounters the diverse community of gut bacteria.
Within the colon, specific gut microbiota play a significant role in metabolizing stevioside. These bacteria break down the stevioside molecule by cleaving off its glucose units. This process leaves behind the non-sugar molecule, steviol.
Steviol is then absorbed into the bloodstream from the colon. Once in circulation, it is transported to the liver for further metabolic processing. In the liver, steviol is conjugated with glucuronic acid to form steviol glucuronide, its primary metabolite. This modified compound is then excreted from the body primarily through urine, with a small amount also in feces.
Since the glucose units are utilized by gut bacteria and not absorbed as free sugars, stevioside consumption results in a negligible impact on blood glucose levels and insulin response. This makes it a suitable sweetener for individuals managing blood sugar levels, such as those with diabetes. Research also suggests potential effects of stevioside and its steviol metabolite on blood pressure and insulin sensitivity.
Regulatory Status and Daily Intake
High-purity steviol glycosides, including stevioside, are recognized as Generally Recognized as Safe (GRAS) by the U.S. Food and Drug Administration (FDA) for use as a general-purpose sweetener in various food products. This GRAS status applies specifically to highly purified extracts containing at least 95% steviol glycosides. It is important to note that this recognition does not extend to whole-leaf stevia or crude stevia extracts, which have not undergone the same rigorous safety evaluations.
The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has also established an Acceptable Daily Intake (ADI) for steviol glycosides. The ADI represents the amount of a substance that can be consumed daily over a lifetime without posing an appreciable health risk. For steviol glycosides, the ADI is set at 4 milligrams per kilogram of body weight per day, expressed as steviol equivalents.
To put this into perspective, for an average adult weighing 60 kilograms (approximately 132 pounds), the ADI translates to a maximum daily intake of 240 milligrams of steviol equivalents. This value accounts for the metabolic conversion of various steviol glycosides to steviol in the body.