Stevia fact check: how safe is the sugar substitute?
Stevia is considered a natural sugar substitute and is often advertised as a healthy alternative. But what is it really good for? This text summarizes what we know about the origin, mode of action and possible risks of stevia and what role quality and dosage play.
Stevia has long been considered a popular alternative to sugar. Yet skepticism persists. Reports of potential side effects surface regularly. But how much of this is actually supported by science? A careful review of the evidence shows that most concerns are unfounded. The key factor in evaluating potential risks is dosage. Many of the reported effects only occur at extremely high levels of intake that are rarely, if ever, reached in everyday life. Studies suggesting health risks often rely on unrealistic scenarios or animal experiments using excessive doses. These findings are not relevant to normal human consumption.
What exactly is stevia?
Stevia, more specifically Stevia rebaudiana, is a plant native to South America whose leaves naturally contain intense sweetness. This is due to compounds called steviol glycosides, primarily stevioside and rebaudioside A. Unlike synthetic sweeteners such as aspartame or sucralose, steviol glycosides are metabolized in the body into steviol and then excreted.
Health effects: a better sugar alternative?
Stevia is often promoted as a healthier substitute for sugar, especially for individuals with diabetes or those looking to reduce their sugar intake. In fact, studies have shown that stevia does not affect blood glucose levels. This sets it apart from certain artificial sweeteners.
One debated topic is its impact on the gut microbiome. Research suggests that all non-nutritive sweeteners, including stevia, may cause mild changes in gut microbial composition. However, it remains unclear whether these changes have any long-term health consequences.
Are there any health risks?
A frequently discussed concern is the potential impact of high stevia intake on fertility. Some animal studies have shown reduced fertility, but the results are inconsistent and not applicable to normal human consumption. Similar uncertainty exists regarding mutagenic effects. While speculative claims have been made, international scientific and regulatory bodies have issued clear assessments. Both the European Food Safety Authority (EFSA) and the United States Food and Drug Administration (FDA) have classified stevia as safe. The acceptable daily intake is set at 4 milligrams per kilogram of body weight, a threshold that is rarely reached in practice.
How strong is the evidence on stevia?
Many alarming headlines are based on observational studies with notable methodological limitations. For example, a large French cohort study found a correlation between consumption of artificial sweeteners, including stevia, and a slightly increased risk of cardiovascular disease. However, such studies only show associations, not causation. Higher sweetener intake could also be linked to other factors such as an overall less healthy lifestyle or lower physical activity. Furthermore, the proportion of affected individuals in the study population was very small.
Animal studies reporting fertility issues used doses that are far beyond what humans would realistically consume. Regulatory evaluations are consistent on this point: stevia is considered safe. Nonetheless, confusing media coverage and general skepticism toward sweeteners continue to create uncertainty.
The right dosage: how much is considered safe?
Stevia is typically used according to personal taste, with no fixed recommended amount. However, toxicological limits do exist. EFSA has set the acceptable daily intake at 4 milligrams per kilogram of body weight, based on steviol equivalents. For an adult weighing 68 kilograms, this corresponds to about 270 milligrams of steviol per day. Depending on the specific steviol glycosides used, this is equivalent to roughly 500 to 600 milligrams of glycosides. Some studies involving much higher intakes, up to 1.5 grams per day over several weeks or months, have not reported adverse effects. However, these findings are limited and cannot be considered conclusive. In laboratory and animal studies, stevia has shown antioxidant and anti-inflammatory properties, but the relevance of these effects in humans remains uncertain.
What does current research say?
The available body of evidence supports the conclusion that stevia is safe for regular use in moderate amounts. Dosage is often underestimated when interpreting study outcomes. Many studies reporting risks use intake levels that are far above realistic consumption. For example, the doses that caused fertility issues in animals would equate to a human consuming several hundred stevia tablets per day.
This is clearly an unrealistic scenario. The same principle applies to many other substances. Even water can be toxic in extreme amounts. Everyday compounds like salt or caffeine are also harmful at excessive doses, yet they are not subjected to the same scrutiny as stevia. When interpreting alarming headlines, it is essential to consider the context of each study, particularly its methodology and dosage levels. Based on current scientific knowledge, there is no reason for concern. Typical stevia intake poses no known health risk.