Stevia comes from the leaves of Stevia rebaudiana, a small shrub in the sunflower family native to Paraguay and Brazil. The leaves contain naturally occurring sweet compounds called steviol glycosides, which are 200 to 300 times sweeter than table sugar. These compounds are extracted, purified, and often blended with bulking agents to create the white powder or liquid drops you find on store shelves.
The Plant Behind the Sweetener
Stevia rebaudiana is a perennial shrub that grows naturally in the Amambay region of northeastern Paraguay. It belongs to the Asteraceae family, making it a relative of sunflowers, daisies, and chamomile. The plant has been used as a food and medicine in South America for centuries, long before it became a mainstream sugar substitute. It grows low to the ground, rarely exceeding two or three feet tall, and its small serrated leaves are the part that matters for sweetness.
The Sweet Compounds Inside the Leaves
The sweetness in stevia leaves comes from a group of molecules called steviol glycosides. These are naturally produced by the plant and concentrated in its leaves. The two most abundant are stevioside and rebaudioside A (often labeled “Reb A” on products). In their refined form, stevioside is 150 to 300 times sweeter than sugar, while rebaudioside A ranges from 250 to 450 times sweeter.
Chemically, steviol glycosides are built on a backbone called steviol, with sugar molecules attached to it. That structure is what makes them taste sweet to your tongue. Despite the intense sweetness, these compounds contribute zero calories because your body processes them very differently than it processes sugar.
How Stevia Goes From Leaf to Packet
Commercial stevia production starts with dried stevia leaves steeped in hot water, similar to brewing tea. This water extraction pulls the steviol glycosides out of the leaf material. The liquid then goes through a series of filtration steps to remove plant matter, pigments, and other non-sweet compounds. After filtration, the extract is further purified and crystallized into a white powder.
The FDA requires that steviol glycosides reach a minimum purity of 95% to qualify as Generally Recognized as Safe (GRAS). Some products, particularly those built around rebaudioside A, meet an even higher 97% purity threshold. This is why the stevia you buy looks nothing like a green leaf. It has been refined down to essentially pure sweet compounds.
What Else Is in the Packet
Pure steviol glycosides are so intensely sweet that you’d need only a tiny speck to sweeten a cup of coffee. That’s impractical, so manufacturers add bulking agents to give stevia products a usable volume. The most common fillers include:
- Erythritol: a sugar alcohol with almost no calories, frequently paired with stevia in brands like Truvia
- Dextrose: a simple sugar (technically glucose) used in small amounts for bulk, found in packets like Stevia in the Raw
- Inulin: a plant fiber sometimes used as a filler in stevia blends
- Mannitol: another sugar alcohol occasionally used in baking-oriented stevia products
These bulking agents can make up the majority of the packet by weight. If you flip over a stevia product and see erythritol or dextrose listed as the first ingredient, that’s normal. The actual stevia extract is present in very small quantities because so little is needed. This also explains why some stevia products have a few calories per serving even though steviol glycosides themselves are calorie-free: the filler contributes a small amount of energy.
Whole Leaf vs. Purified Extract
There are three forms of stevia you might encounter. Green leaf stevia is the least processed: dried, ground leaves sold as a green powder. It tastes sweet but also grassy and herbal. Crude stevia extract is a partially refined dark liquid or brown powder. And purified steviol glycosides are the white crystalline product found in most commercial sweeteners.
Only the highly purified form (95% or greater steviol glycoside content) has FDA GRAS status. Whole-leaf stevia and crude extracts have not received the same approval because they contain a broader mix of plant compounds that haven’t been as thoroughly studied for safety at high intake levels. You can still buy whole-leaf stevia as a dietary supplement, but it won’t carry the same regulatory standing as the refined version.
How Your Body Processes It
Steviol glycosides pass through your stomach and small intestine completely intact. Your digestive enzymes can’t break apart the specific chemical bonds holding these molecules together. Once they reach your colon, gut bacteria (primarily from the Bacteroidaceae family) strip away the sugar molecules attached to the steviol backbone. The freed steviol is then absorbed into your bloodstream, converted into a compound called steviol glucuronide by your liver, and excreted in your urine. This entire process takes roughly 12 to 72 hours.
Because the sweet compounds aren’t absorbed in the upper digestive tract where calories are typically extracted, stevia contributes no energy to your diet. Your body treats it more like a fiber that passes through than like a sugar it can use for fuel.