What Defines an Ultra-Processed Food?
To understand if stevia qualifies as an ultra-processed food (UPF), one must first grasp the NOVA classification system, developed by Brazilian researchers. This system categorizes foods based on the extent and purpose of industrial processing, not just nutritional content. The four NOVA groups are:
- Group 1: Unprocessed or minimally processed foods. Edible parts of plants or animals altered only by basic methods like washing, cutting, drying, or freezing (e.g., fresh fruit, raw vegetables, dried beans).
- Group 2: Processed culinary ingredients. Substances like oils, salt, and sugar derived from Group 1 foods via processes like pressing, milling, and refining.
- Group 3: Processed foods. Relatively simple products made by combining Group 1 and 2 ingredients. Examples include canned vegetables in brine or cheeses made with salt.
- Group 4: Ultra-processed foods (UPF). Industrial formulations made mostly from extracted food components, often with five or more ingredients. These contain additives for cosmetic purposes (flavors, colors, sweeteners) and use industrial techniques rarely replicated at home. Examples include soda, packaged snacks, and sweetened cereals.
The Processing of Commercial Stevia Products
While the stevia plant ($Stevia~rebaudiana$) is natural, the journey from leaf to the sachet on your table is a long one. Commercial sweeteners are made from purified steviol glycoside extracts, most commonly Rebaudioside A (Reb A), which can be 200–400 times sweeter than sugar. The multi-stage industrial process involves:
- Harvesting and drying: Stevia leaves are picked and dried.
- Water extraction: The dried leaves are steeped in hot water, similar to making tea, to extract the sweet compounds.
- Filtration and separation: The liquid extract is filtered to separate the leaves and other plant matter.
- Purification: The extract is further purified using methods like crystallization, often involving food-grade alcohol.
- Drying and crystallization: The final purified glycosides are dried to form a powder or granules.
The Role of Additives and Blends
Crucially, many popular stevia products are not just pure extracts. They are blends that combine the potent extract with bulking agents to make them easier to measure and use. Common additives include:
- Erythritol: A sugar alcohol that provides bulk and a cooling sensation.
- Maltodextrin: A starch-derived powder used as a filler.
- Natural Flavors: Vague terms that can mask the lingering aftertaste of some steviol glycosides.
The presence of these industrial substances and additives, combined with the extensive processing to create a new "food-like" product, firmly places most commercial stevia products into the ultra-processed category under NOVA.
The Whole Leaf Distinction
There is a critical difference between refined stevia extracts and the whole leaf stevia plant. Green leaf stevia, the least processed form, is made from simply drying and grinding the leaves. This form is used as a dietary supplement in the US, but has not been approved as a sweetener in processed foods due to a lack of research on its safety. Whole leaf stevia is not an ultra-processed food and retains the plant's natural complexity, though many find its flavor to be different and stronger than the purified extracts.
Health Implications of Ultra-Processed Foods
The concern around UPFs extends beyond just processing. Research suggests a high intake of UPFs is linked to numerous health issues, including:
- Higher risk of obesity and type 2 diabetes.
- Increased risk of heart disease and stroke.
- Potential disruption of the gut microbiome.
These effects may stem from UPFs being hyper-palatable, calorie-dense, and low in fiber and nutrients, leading to overconsumption. The additives and industrial processing themselves may also play a role. While stevia extracts do not contribute calories like sugar, they are often added to UPF products (like diet soda or flavored yogurt) that still lack the nutritional benefits of whole foods and contribute to a high UPF intake.
The Stevia Processing Spectrum
| Feature | Whole Leaf Stevia | Commercial Stevia Extract/Blend |
|---|---|---|
| Starting Material | Dried Stevia leaves | Dried Stevia leaves |
| Processing Steps | Harvested, dried, and ground | Water extraction, filtration, purification (often with alcohol), crystallization, blending |
| Sweetening Compound | Natural steviol glycosides in their whole-plant ratio | Isolated steviol glycosides (e.g., Reb A, Reb M) |
| Common Additives | None | Erythritol, maltodextrin, dextrose, natural flavors |
| FDA Status (US) | Not approved as a food additive | Approved as "Generally Recognized as Safe" (GRAS) |
| NOVA Classification | Minimally processed (NOVA 1) | Ultra-processed (NOVA 4) |
| Appearance | Greenish powder | White powder or liquid |
Conclusion: A Nuanced Perspective on Stevia's Processing Status
To conclude, whether Stevia is an ultra-processed food depends entirely on its form. Whole leaf stevia, used as a supplement, is minimally processed and retains the plant's full chemical profile. Conversely, the popular white powder and liquid stevia products sold commercially are definitively ultra-processed. The extensive industrial extraction, purification, and use of additional ingredients to create these consumer-friendly sweeteners fit the criteria for a Group 4 food in the NOVA system. Ultimately, a balanced diet emphasizing whole, minimally processed foods, whether sweetened with a pure extract sparingly or not at all, is the most beneficial approach for long-term health. The ultra-processed nature of commercial stevia is a critical consideration for those seeking to reduce UPFs in their diet. For further information on ultra-processed foods, consult the Food Standards Agency website.
