This one’s going to get interesting in unexpected ways. I generally like to indulge my curiosities with a little research and on this day, it began with my interest in whether or not sucralose (Splenda) is actually a bad thing and to learn about how and why Stevia might be a better alternative. Sucralose is an artificial sweetener and, as you may know, that’s a no-go on this anti-inflammatory diet I’m trialing for psoriatic arthritis (read more about that here).

Suffice to say, I was surprised! I’ll go ahead and put your suspense to rest, I do plan to buy Stevia after I run out of Splenda. As to the purpose of this article, there is a lot of science involved in mass producing the desired stevia compounds! It’s wild out here, y’all! As a healthy human, I thoroughly appreciate things that are just simple and natural. But you don’t become a pharmacist without having a love for science. It’s just cool. Honestly, my healthy human side is a little bothered by what I learned, but my sciency pharmacist side understands that it’s the same end result. You’ll see what I mean.

Stevia rebaudiana, commonly known as stevia, is a plant native to Paraguay and Brazil. Its leaves have been used for centuries by indigenous cultures as a natural sweetener, and in recent decades, stevia has gained widespread popularity globally as a sugar substitute. It is especially favored for being zero-calorie and non-glycemic, making it a common choice for people with diabetes or those trying to reduce their sugar intake.

This guide explores stevia from a biochemical, botanical, and commercial production perspective. The discussion will cover stevia’s sweet compounds, the processes used in its production, and the debate surrounding the use of whole-leaf stevia in food and beverages.

1. The Botany of Stevia (Stevia rebaudiana)

Stevia is a herbaceous perennial plant in the Asteraceae family, which also includes daisies and sunflowers. While there are more than 200 species of stevia, Stevia rebaudiana is the most notable for its sweet-tasting leaves.

Plant Characteristics:

• Height: Typically grows to 1-3 feet (30-90 cm) in height.
• Leaves: The leaves are the key part of the plant, where steviol glycosides (the compounds responsible for its sweetness) are found. These compounds can be 50-300 times sweeter than sucrose (table sugar).
• Climate: Stevia thrives in warm climates with full sunlight and well-drained soil.
• Flowers: Stevia produces small white flowers, but the flowers are not typically involved in its use as a sweetener.

2. Biochemistry: The Sweet Compounds of Stevia

The sweetness in stevia is mainly attributed to a group of compounds known as steviol glycosides. These are glycosides, meaning they are sugar molecules bound to non-sugar components.

Key Steviol Glycosides:

1. Stevioside: The most abundant steviol glycoside found in stevia. It is about 50-100 times sweeter than sucrose but often has a slight bitter aftertaste.
2. Rebaudioside A (Reb A): The most commonly used steviol glycoside in commercial stevia products. It is about 200-300 times sweeter than sucrose and has a cleaner taste without much bitterness.
3. Rebaudiosides B, C, D, E, and F: These are less commonly used, but they are found in smaller quantities in the stevia plant and have varying sweetness levels and flavors.
4. Dulcoside A: Another sweet compound found in smaller quantities.

Chemical Structure:

• Steviol aglycone: The aglycone (non-sugar portion) of steviol glycosides is a terpenoid compound called steviol. Terpenoids are a large group of naturally occurring organic compounds derived from isoprene units (compounds made up of five carbon atoms). Steviol itself is composed of 20 carbon atoms and forms the core structure of these glycosides.
• Glycosidic Bond: The sweetness of stevia comes from the glycosidic bonds linking sugar molecules (such as glucose, rhamnose, and xylose) to the steviol aglycone. When these glycosides are consumed, digestive enzymes break the glycosidic bonds, releasing steviol.

Mechanism of Sweetness:

• Absorption: After stevia is consumed, the glycosides are absorbed into the bloodstream, but since they are not metabolized by digestive enzymes, they do not raise blood sugar levels. The steviol molecule is absorbed and then converted into steviol glucuronide by the liver, which is then excreted via urine.
• No Impact on Blood Sugar: Unlike sugar or other sweeteners, steviol glycosides have no significant impact on blood glucose levels, which is why stevia is considered safe for individuals with diabetes.

3. Commercial Production of Stevia

The commercial production of stevia typically involves two main methods: traditional extraction from the plant and biotechnological production using genetically engineered microorganisms. Both processes extract and purify the sweet compounds, mainly rebaudioside A, to make stevia available as a sweetener in various products.

A. Traditional Plant Extraction:

1. Harvesting: Once the stevia plant matures (typically after about 3-4 months), the leaves are harvested, as they contain the highest concentration of steviol glycosides just before flowering.
2. Drying and Grinding: The leaves are dried and then ground to facilitate the extraction of the sweet compounds.
3. Extraction: The dried leaves are subjected to a process where water or ethanol is used as a solvent to extract the steviol glycosides.
4. Purification: After extraction, the mixture is purified using techniques like chromatography (a method that separates different compounds based on their chemical properties) and filtration.
5. Concentration: The purified extract is then concentrated into either a liquid or powder form, which can be used as a sweetener.

B. Biotechnological Production:

1. Genetic Engineering: In this method, genetically engineered microorganisms such as Escherichia coli (E. coli) or Saccharomyces cerevisiae (baker’s yeast) are used to produce steviol glycosides. The genes responsible for producing steviol glycosides are inserted into the DNA of these microorganisms.
2. Fermentation: The engineered microorganisms are cultured in large fermentation tanks, where they are fed simple sugars (like glucose from corn or sugarcane). During fermentation, these microorganisms produce steviol glycosides.
3. Purification: Once fermentation is complete, the steviol glycosides are extracted from the microbial culture and purified through methods such as centrifugation and chromatography.
4. Final Product: After purification, the steviol glycosides (mainly rebaudioside A) are formulated into a sweetener product.

Sustainability:

• Biotechnological production of stevia using fermentation has become an increasingly popular method because it is more sustainable and cost-effective than traditional plant extraction. It also allows for scalability and the production of high-purity stevia extracts.

4. The Whole Leaf Debate: Is it Safe for Consumption?

While purified stevia extracts, particularly rebaudioside A, are widely used in food and beverages, the use of whole stevia leaves or crude stevia extracts in commercial food products has been a topic of debate.

Regulatory Concerns:

• FDA (U.S. Food and Drug Administration): The FDA has approved highly purified steviol glycosides, like rebaudioside A, as Generally Recognized As Safe (GRAS) for use in food and beverages. However, the FDA has not approved the use of whole stevia leaves or crude stevia extracts in food due to concerns over the safety of certain compounds, such as stevioside and rebaudioside C, which are found in the whole leaf. These compounds have not been fully evaluated for safety in long-term consumption.
• EFSA (European Food Safety Authority): Similar to the FDA, EFSA has approved purified steviol glycosides but has not allowed the use of whole stevia leaves or crude extracts in food.

Health Concerns with Whole Stevia Leaves:

• Some studies have suggested that consuming large amounts of whole stevia leaves might lead to the accumulation of steviol, which could affect kidney function. However, this is largely theoretical, and no significant adverse effects have been reported in moderate use.
• Traditional Use: In regions like South America and Japan, the whole stevia leaf has been used in herbal teas and as a sweetener for centuries. While traditional use does not equate to modern regulatory approval, many argue that whole-leaf stevia is safe when consumed in reasonable quantities.

5. Conclusion

Stevia is a natural sweetener with a complex biochemical profile, primarily due to the presence of steviol glycosides, which provide its sweet taste. These compounds, particularly rebaudioside A, are non-caloric and do not raise blood sugar, making stevia a popular choice for those following low-carb or diabetic diets.

Commercial production of stevia involves both traditional extraction methods and biotechnological fermentation, with the latter offering a more sustainable and scalable option for producing high-purity stevia extracts. While purified extracts like rebaudioside A are GRAS and widely used in food, the use of whole stevia leaves remains controversial and is not approved for use in food products by regulatory bodies like the FDA and EFSA due to concerns over safety in large quantities.

Overall, stevia continues to be a safe, zero-calorie alternative to sugar for many, though its long-term health effects and use of whole-leaf products remain areas of ongoing research and regulatory discussion.

So you see what I mean, right? That one completely caught me off guard! But like I said, I do still plan to make the switch to Stevia just because it’s believed to be less inflammatory than sucralose. We’re just trying to live our best lives over here without pain or injuries! I wish you the same!