The Distinction: Refined Stevia vs. the Whole Plant
First, it is crucial to clarify the distinction between the highly-refined stevia products sold commercially and the raw Stevia rebaudiana plant itself. The sweet taste most consumers associate with stevia comes from steviol glycosides extracted from the plant's leaves. These compounds are intensely sweet, but they are not fructooligosaccharides (FOS). The refinement process used to produce these sweeteners isolates the glycosides, and the resulting product is free of FOS.
However, a different part of the stevia plant—the roots and stems—contains fructan-type polysaccharides, including fructooligosaccharides. These are a type of soluble dietary fiber with prebiotic properties that are distinct from the sweetening compounds of the leaves. In fact, some manufacturers intentionally add FOS derived from other plant sources, like chicory root, to commercial stevia products to enhance the sweetening and provide additional prebiotic benefits. This is why some people may associate the two, but it is important to remember that FOS is not naturally present in the refined leaf extract used for sweetening.
What Exactly Are Fructooligosaccharides (FOS)?
Fructooligosaccharides (FOS) are a form of soluble dietary fiber composed of short chains of fructose units. As prebiotics, they are not digested in the small intestine but instead travel to the large intestine where they selectively feed beneficial gut bacteria like Bifidobacterium and Lactobacillus. This fermentation process produces short-chain fatty acids (SCFAs), which are important for gut health.
Common natural sources of FOS include:
- Chicory root
- Onions and garlic
- Jerusalem artichokes
- Asparagus
- Bananas
- Yacon root
While FOS can also be sourced from the stems and roots of the Stevia rebaudiana plant, this is not the primary commercial method, as it requires processing different parts of the plant than those used for sweetener production. The prebiotic effects and low-calorie nature of FOS have led to its widespread use in functional foods, beverages, and dietary supplements.
Comparing Refined Stevia Sweetener and Fructooligosaccharides (FOS)
To fully understand the difference, it is helpful to compare the primary function, source, and nutritional impact of refined stevia extract and fructooligosaccharides (FOS).
| Feature | Refined Stevia Sweetener | Fructooligosaccharides (FOS) |
|---|---|---|
| Primary Function | Zero-calorie, non-glycemic sweetener | Prebiotic fiber, low-calorie sweetener |
| Primary Source | Steviol glycosides extracted from the Stevia rebaudiana leaves | Inulin hydrolysis or synthesis from sucrose, found in roots/stems of the stevia plant |
| Effect on Blood Sugar | Does not raise blood sugar levels | Does not cause a spike in blood sugar levels |
| Nutritional Classification | Non-nutritive sweetener | Soluble dietary fiber |
| Impact on Gut Health | Generally safe for gut bacteria, minimal effect | Promotes growth of beneficial gut bacteria |
| Calorie Content | Zero calories per serving | Low-calorie (approx. 1.5 calories per gram) |
The Role of Stevia-FOS Blends
As mentioned, some products on the market combine stevia extract with FOS to leverage the benefits of both ingredients. For example, a commercial blend may use stevia extract for intense sweetness and FOS as a bulking agent and soluble fiber source. This strategy provides a product that is both zero-sugar and beneficial for gut health. This hybrid approach caters to the increasing demand for natural, functional food ingredients. While the stevia itself doesn't contain FOS, its use in conjunction with FOS is a practical application in the food industry.
Choosing Between Stevia and FOS
When considering which to use, the choice depends on your specific health goals.
- For pure zero-calorie sweetness: If your main objective is to replace sugar without any calories or carbohydrates, a pure stevia leaf extract or a steviol glycoside-based product is the ideal choice. It is well-suited for managing weight and blood sugar levels without the prebiotic effects of FOS.
- For gut health: If you want to increase your intake of prebiotics to support beneficial gut flora, FOS is the better option. While it also has a mild sweetness, its primary benefit is feeding probiotic bacteria. Some people may experience gastrointestinal distress with large doses of FOS, such as gas or bloating, so it is often recommended to start with a small amount.
- For a combined approach: If you are looking for a powerful sweetener with added fiber, a blend containing both stevia and FOS might be appropriate. These products offer the best of both worlds, providing strong sweetness while supporting digestive health. It is important to check the product label for the specific ingredients and proportions.
Conclusion
In summary, the question of whether stevia contains fructooligosaccharides is a nuanced one. Refined stevia leaf extract, the ingredient used in most commercial sweeteners, does not contain FOS. However, the raw Stevia rebaudiana plant's roots and stems are a proven source of FOS. This distinction is critical for consumers. While stevia is a zero-calorie, non-glycemic sweetener, FOS functions as a prebiotic fiber with a low-calorie profile. Their distinct properties and sourcing methods mean they serve different purposes, though they can be combined in commercial products to provide dual benefits. Understanding these differences allows for a more informed choice based on individual dietary needs and health priorities.
Authoritative Reference
- A new natural source for obtainment of inulin and fructo-oligosaccharides from Stevia rebaudiana (Bertoni) stems. This article from PubMed documents the extraction of FOS from the stems of the stevia plant. https://pubmed.ncbi.nlm.nih.gov/28193409/
