Stevia: What's Left After You Process a 'Natural' Sweetener

The stevia plant has been used in South America for centuries. Indigenous Guarani people chewed the leaves for sweetness. By the 20th century, Japan was using stevia extracts in foods while the US was still sorting out its regulatory stance.

Today, stevia is in everything from protein bars to Vitamin Water. The marketing calls it “natural.” The FDA has something more specific to say about that.

The Plant vs. The Product

Stevia rebaudiana is a small shrub native to Paraguay and Brazil. Its leaves are intensely sweet because they contain compounds called steviol glycosides. The main ones are stevioside and rebaudioside A (Reb-A).

What you buy at the grocery store is not dried and ground leaves. It’s a white powder that went through a multi-step extraction process: the leaves are dried, steeped in hot water, filtered, and then the glycosides are separated from the plant material using ion exchange resins or other processes. The resulting pure steviol glycoside extract is 200 to 400 times sweeter than sugar.

That process is legal, safe, and necessary to get a consistent, shelf-stable product. But calling the result “natural” requires a loose definition of the word. The same can be said about most food ingredients that start in a plant and end up in a package.

The FDA’s Position: Purified Extracts Only

Here’s something most stevia marketing quietly omits: the FDA has not approved whole-leaf stevia as a food additive.

The GRAS designation (Generally Recognized as Safe) covers purified steviol glycosides. Not the leaves. Not crude extracts.

The FDA’s concern with whole-leaf stevia involves other compounds in the plant beyond the glycosides, including diterpene compounds that haven’t been as extensively evaluated. The regulatory approval is specific to the purified extract form.

This is largely an academic distinction for consumers — nobody is selling you raw stevia leaves at scale — but it matters for understanding what “FDA-approved natural sweetener” actually means.

Reb-A, Stevioside, and Reb-M: What the Labels Mean

Not all steviol glycosides taste the same.

Stevioside is the most abundant glycoside in the plant, but it has a pronounced bitterness and a licorice-like aftertaste at higher concentrations. This is the main real-world complaint about stevia products.

Rebaudioside A (Reb-A) is less abundant in the plant but has a much cleaner sweetness with less aftertaste. Most commercial stevia products are specifically formulated with high Reb-A content. If a product says “99% Reb-A,” that’s a quality indicator: they’ve removed most of the stevioside and kept the cleaner-tasting compound.

Rebaudioside M (Reb-M) is newer to the market. It has an even cleaner taste profile that comes closest to table sugar. The interesting thing about Reb-M: it’s present in stevia leaves only in trace amounts. Most commercial Reb-M is produced by fermenting ferulic acid (from rice bran) using engineered yeast that produces the mogroside structure through a biosynthetic pathway. This Reb-M can technically be called a “natural flavor” under FDA definitions because the process starts with a natural substrate — but no stevia plant was meaningfully involved.

It’s a perfect illustration of how “natural” works in food regulation: the word describes origin, not process.

What Research Shows on Health Effects

The safety case for purified steviol glycosides is solid. EFSA’s 2010 comprehensive review covered multiple toxicological studies and found no evidence of carcinogenicity, genotoxicity, or reproductive toxicity at relevant doses. The ADI was set at 4 mg/kg/day of steviol equivalents.

Two areas of active research:

Blood pressure. Some studies suggest steviol glycosides may modestly lower blood pressure at doses of 3 to 4 mg/kg/day. The effect sizes are small and inconsistent across studies. For most people eating normal amounts in food, the blood pressure effect isn’t clinically significant. It’s an interesting pharmacological property, not a treatment claim.

Gut microbiome. Animal studies at high doses show changes in gut bacteria composition. Human data is limited and doesn’t establish the same effects at dietary levels. This is an open question in the research, not a settled concern.

Blood glucose. Consistent finding across studies: steviol glycosides do not raise blood glucose. They don’t stimulate insulin in the way sugar does. This is one reason stevia is popular in products marketed to people managing diabetes or watching glycemic load.

The Taste Problem Is Real

No amount of regulatory approval fixes an aftertaste that people don’t like. And a significant portion of the population finds stevia’s flavor profile off-putting.

The perception is partly genetic — variations in taste receptor genes affect how strongly people perceive the bitterness in stevioside. This is similar to how some people taste cilantro as soapy and others don’t.

Practical strategies: choose high-Reb-A or Reb-M products, use stevia in hot applications where some flavor compounds volatilize, blend it with small amounts of sugar or other sweeteners to round out the profile, and expect variation between brands since glycoside extraction quality differs.

What “Natural” Actually Tells You

Stevia’s “natural” positioning is more defensible than many food ingredients that claim the label. The sweet compounds do come from a plant, the production process doesn’t introduce synthetic chemicals into the final product, and there are no artificial colorings or preservatives involved.

But the white crystalline powder in a Truvia packet is not stevia leaves. It’s a highly purified extract that went through industrial processing. That processing is fine — it’s what makes the product consistent, stable, and concentrated enough to be useful. The “natural” label just describes where the raw material came from, not how much it was transformed to get to your coffee.

That’s true of most “natural” food ingredients. Stevia is at least honest about its plant origin.