Myths, Facts and Science: Stevia under the Microscope

May 15, 2024

Steviosid Glycosid aus den Blättern der Steviapflanze

May 15, 2024

Stevia has been considered a popular alternative to sugar for years. Nevertheless, a certain skepticism remains. Time and again, reports emerge about possible side effects. But how much of this is actually scientifically proven? A sober look at the facts shows that the concerns are largely unfounded. The decisive factor for an objective assessment of possible risks is the dosage. Many of the effects discussed only occur in extremely high quantities, which are hardly ever reached in everyday life. Studies that suggest health risks are often based on unrealistic scenarios or animal experiments with overdoses. They are therefore not relevant for normal consumption.

What actually is Stevia?

Stevia, or more precisely Stevia rebaudiana, is a plant from South America whose leaves naturally have an intense sweetness. This is due to so-called steviol glycosides, in particular stevioside and rebaudioside A. Unlike synthetic sweeteners such as aspartame or sucralose, steviol glycosides are broken down into steviol in the body and processed further.

Health effects. A sugar substitute with advantages?

Stevia is often advertised as a healthier alternative to sugar, especially for diabetics or people who want to reduce their sugar intake. Indeed, studies show that Stevia itself does not affect blood sugar levels. This distinguishes it from some artificial sweeteners.

One controversial topic is the effect on the intestinal flora. Research suggests that all non-nutritive sweeteners, including stevia, can cause slight changes in the microbial composition of the gut. However, it is unclear whether these have long-term health consequences.

Are there any health risks?

One point that is repeatedly discussed is the potential impairment of fertility due to high doses of stevia. Some animal experiments suggest reduced fertility. However, these results are not consistent and cannot be transferred to normal consumption levels. The same applies to the discussion about mutagenic effects. Although there has been some speculation, the assessments of international scientists and regulatory authorities are clear. The European Food Safety Authority (EFSA) and the US FDA have classified Stevia as safe. The tolerable daily dose is 4 mg per kilogram of body weight. This amount is hardly reached in practice.

How reliable are the studies on stevia?

Many alarming headlines are based on observational studies that have methodological weaknesses. For example, a large-scale French study found a link between the consumption of artificial sweeteners, including stevia, and a slightly increased risk of cardiovascular disease. However, such studies only show correlations, not causal relationships. For example, higher sweetener consumption could also be associated with other factors, such as an overall less healthy lifestyle or less exercise. In addition, the proportion of affected individuals in the cohort studied was extremely low.

Animal studies suggesting fertility problems associated with stevia were carried out with unrealistically high doses. These quantities are far above what a human would consume. International assessments are clear here. Stevia is safe. Nevertheless, misleading reporting and a general skepticism about sweeteners repeatedly cause uncertainty.

The right dosage. How much is safe?

Stevia is usually added to food and drinks to taste. There is no fixed recommendation. Nevertheless, there are toxicological upper limits. The estimated maximum daily intake is about 8 mg per kilogram of body weight. For a person weighing 68 kg, this corresponds to around 540 mg per day. This is a value that is within the recommended upper limits and enables antioxidant and anti-inflammatory effects without causing toxic or fertility-impairing effects. Long-term studies with a daily intake of up to 1.5 g of stevia also show no health disadvantages.

The scientific evidence is clear

The scientific evidence clearly supports the safety of stevia as a sugar substitute. Those who consume it in moderate amounts need not be concerned about their intestinal flora or possible long-term effects. The importance of dosage is often underestimated. Many studies that identify possible risks work with quantities that bear no relation to realistic consumption. For example, the doses of stevia that led to fertility problems in animal experiments would correspond to the consumption of several hundred stevia sweetener tablets per day in humans.

A completely unrealistic scenario. The same applies to other foods. Even water can be toxic in extreme quantities. Even supposedly harmless substances such as salt or caffeine are harmful to health in high doses. Nevertheless, they are not under the same suspicion as Stevia. Anyone who is unsettled by alarmist headlines should therefore consider one thing. Scientific studies must always be considered in the context of their methodology and dosage. According to the current state of research, there is no reason for concern. Normal consumption of stevia is harmless to health.