Safety and Efficacy of Stevia Sweetener
Overview of Stevia and Its Properties
Recent research has examined the safety and efficacy of the stevia sweetener by analyzing the properties of the stevia leaf. Stevia rebaudiana is a shrub native to Brazil and Argentina. The leaves of this plant contain steviol glycosides, which are the primary extracts used as sweeteners. However, these extracts are often not completely pure, leading to a bitter aftertaste in some products. As a result, efforts are ongoing to enhance the purification of these extracts.
Composition of Steviol Glycosides
There are various types of steviol glycosides, but they typically share a common structure based on steviols, which serve as the backbone of stevia sweetener molecules. Most sweeteners derived from steviol glycosides are permitted for global use, provided they are highly purified and adhere to specific safety standards.
Review on Stevia Sweetener
A comprehensive review conducted by Samuel and colleagues aims to inform health professionals and the public about the safety and efficacy of stevia sweeteners. This study was published in The Journal of Nutrition.
Metabolism of Steviol Glycosides
Digestive Process
Steviol glycosides are indigestible and are primarily processed by gut bacteria, particularly bacteroides. These bacteria break down the components for energy, which may account for the zero-calorie claim associated with these sweeteners. Additionally, steviols may be transported to the liver for metabolism before being excreted. The literature suggests that various types of steviol glycosides exhibit similar metabolic pathways.
Safety Profile of Steviol Glycosides
Purity and Animal Studies
Highly purified steviol glycosides are deemed safe for consumption. However, crude and impure extracts have been linked to fertility issues in animal studies. A two-year study involving rats indicated no cancer development across all tested doses of steviol glycosides. Nonetheless, the highest dose resulted in changes to kidney function, body weight, and survival rates.
Impact on Specific Populations
No adverse effects were noted in animal studies assessing the impact of high-purity steviol glycosides on pregnant women and children. Many studies included an acceptable daily intake (ADI) guideline for consumption. Furthermore, evidence suggests that steviol glycosides are not genotoxic, indicating they do not compromise genetic integrity.
Effects on Health Parameters
Research on human safety has shown that certain doses of stevia sweeteners do not adversely affect blood pressure or fasting blood glucose levels in both diabetic and healthy individuals. Despite the allergenic potential of related plant families, no significant evidence of allergenic reactions was found in steviol glycosides, although crude extracts have presented such instances.
Potential Benefits of Steviol Glycosides
Blood Glucose Management
Some studies suggest that steviol glycosides may aid in managing blood glucose levels, presenting a preferable alternative to regular sugars. Longer studies, spanning from several months to a year, have indicated neutral effects on health. Moreover, steviol glycosides appear non-cariogenic compared to sucrose, although further long-term studies are necessary to confirm these findings.
Need for Further Research
Current Consensus and Gaps in Knowledge
Organizations like the Academy of Nutrition and Dietetics, the American Diabetes Association (ADA), and the American Heart Association (AHA) generally support the use of stevia sweeteners within approved nutritional and dietary guidelines. However, there are still gaps in scientific and policy positions regarding stevia, which can influence how healthcare professionals advise the public on its use. Continued research and education are essential to address these uncertainties.
References
Samuel, P et al. Stevia Leaf to Stevia Sweetener: Exploring Its Science, Benefits, and Future Potential. The Journal of Nutrition. 2018;148(7):1186S-1205S. doi: https://doi.org/10.1093/jn/nxy102.