Stevia sweeteners are built around compounds called steviol glycosides, naturally occurring molecules found in the leaves of the stevia plant. These glycosides are 250 to 350 times sweeter than sugar, contain zero calories, and pass through your digestive tract without being broken down or absorbed. But what you find inside a packet of stevia at the grocery store is quite different from what exists in the raw leaf.
The Sweet Compounds in the Leaf
The stevia plant (Stevia rebaudiana) produces its intense sweetness through a group of compounds called steviol glycosides, which make up roughly 8% to 20% of the dried leaf’s weight. The four most abundant are Rebaudioside A (Reb A), Stevioside, Rebaudioside C, and Dulcoside A. Of these, Reb A and Stevioside are the dominant players in commercial sweeteners because they deliver the most sweetness with the least off-flavor.
Not all of these compounds taste the same. Stevioside, the most plentiful glycoside in many plant varieties, carries a noticeable bitter and licorice-like aftertaste. Reb A is cleaner-tasting but still not a perfect match for sugar. Newer stevia products use rarer glycosides like Rebaudioside M, which has a faster sweetness onset, less bitterness, and almost no lingering aftertaste. The concentration of each glycoside varies dramatically between plant varieties. Large-scale screening of stevia genotypes has found stevioside content ranging from 2 to 125 milligrams per gram of dry leaf, and Reb A ranging from 2.5 to 164 milligrams per gram.
What’s in the Raw Leaf vs. the Extract
Raw stevia leaves contain more than just sweetness. They’re a source of vitamin C (about 15 mg per 100 grams), vitamin B2, folic acid, and minerals including zinc, iron, calcium, potassium, and magnesium. The leaves also contain fiber, proteins, and various plant compounds common in herbs.
Almost none of this survives the extraction process. Commercial stevia sweeteners use only the isolated glycosides, not the whole leaf. The FDA drew a clear line here in 2008: highly purified steviol glycosides (at least 95% purity) received Generally Recognized as Safe status for use as a general purpose sweetener in food. Whole stevia leaves and crude leaf extracts did not receive that same designation for food use, though they’ve been allowed in dietary supplements since 1995.
How the Glycosides Are Extracted
The extraction process is simpler than you might expect. Dried stevia leaves are steeped in water, much like making tea. The resulting liquid contains the dissolved glycosides along with plant pigments, proteins, and other soluble compounds. That liquid then goes through filtration steps to remove everything except the sweet glycosides. Some methods use specialized membranes that allow only molecules below a certain size to pass through, effectively straining out the unwanted material. The final product is a white, crystalline powder of nearly pure steviol glycosides.
What Else Is in That Packet
Here’s the part most people don’t realize: the stevia extract itself makes up a tiny fraction of what’s in a retail stevia product. Because the glycosides are hundreds of times sweeter than sugar, you’d need only a microscopic amount per serving. That’s far too little powder to measure with a spoon or pour from a packet, so manufacturers add bulking agents to give the product volume and a texture similar to sugar.
The most common fillers include:
- Erythritol: A sugar alcohol with almost zero calories that also helps reduce the bitterness and astringency of stevia. It adds a rounded sweetness and earlier onset of sweet flavor. This is the primary ingredient in many popular brands like Truvia.
- Dextrose: A simple sugar derived from corn. It does contain calories (about 4 per gram), though the amount per packet is small. Stevia In The Raw uses dextrose as its bulking agent.
- Maltodextrin: A starchy carbohydrate also derived from corn, used in powdered stevia blends and baking formulations.
- Inulin: A plant-based fiber sometimes used in stevia products marketed as “natural” or high-fiber.
Some products also include “natural flavors” to mask the residual bitterness that even purified Reb A can leave behind. Liquid stevia drops typically skip the bulking agents and use water or vegetable glycerin as a base instead, making them closer to pure stevia extract. If you want the fewest added ingredients, liquid drops or products listing only stevia extract and erythritol are your simplest options.
Why Different Stevia Products Taste Different
The taste difference between stevia brands comes down to which glycosides they use and what they’re blended with. First-generation stevia products relied heavily on Reb A, which is relatively easy to extract in large quantities but carries that characteristic bitter, licorice-like finish. Many people who say they “don’t like stevia” have only tried Reb A-based products.
Newer formulations use minor glycosides like Rebaudioside M and Rebaudioside D, which trained taste panels have found to be significantly cleaner. Reb M in particular shows faster sweetness onset, reduced bitterness and astringency, and minimal lingering aftertaste. Blending Reb M with Reb D further improves sweetness intensity and reduces bitter lingering. Blending with erythritol above 1% concentration contributes additional sweetness and a more rounded flavor profile. These blends represent the current state of the art in making stevia taste closer to sugar.
Zero Calories and No Blood Sugar Impact
Steviol glycosides cannot be broken down or absorbed by your digestive tract, which is why stevia extract has zero calories and does not raise blood sugar. Your gut bacteria do eventually break the glycosides into steviol, which is then processed by the liver and excreted. But this happens without generating usable energy for your body.
The bulking agents are a different story. Erythritol contributes roughly 0.2 calories per gram (compared to sugar’s 4 calories per gram) and has no effect on blood sugar. Dextrose and maltodextrin, on the other hand, are carbohydrates that do raise blood sugar and contain calories. The amounts per serving are small, typically under 4 calories per packet, which allows manufacturers to round down to zero on the label. But if you’re using stevia heavily throughout the day or managing diabetes closely, the choice of bulking agent matters. Reading the ingredient list, not just the front label, tells you what you’re actually consuming.