Sweeteners are widely used
Sweeteners bind to the taste receptors on our tongue and can thus create the perception of "sweet." They are often several hundred times sweeter than table sugar, yet have few or no calories.
Accordingly, sweeteners are widespread in our everyday lives. They are found in numerous diet products or foods labeled "sugar-free," and can be found in soft drinks, candy, chewing gum, and even toothpaste.
Which sweeteners are permitted in the EU?
There are currently 12 sweeteners approved in the EU (1):
- Acesulfame K (E 950)
- Aspartame (E 951)
- Cyclamate (E 952)
- Saccharin (E 954)
- Sucralose (E955)
- Thaumatin (E957)
- Neohesperidin DC (E 959)
- Steviol glycosides from Stevia (E960a)
- enzymatically produced steviol glycosides (E960c)
- Neotame (E961)
- Aspartame acesulfame salt (E 962)
For each of these substances, there is a so-called ADI (Acceptable Daily Intake). This value describes the maximum daily intake that is considered safe for regular consumption.
However, the approved sweeteners are currently being re-evaluated by the European Food Safety Authority (EFSA) because the original approvals and ADI values were based on outdated study results.
Sweeteners vs. sugar substitutes
In addition to sweeteners, so-called sugar substitutes also belong to the group of artificial sweeteners. Chemically speaking, these are sugar alcohols. Well-known examples are erythritol, xylitol (birch sugar), sorbitol, mannitol, and isomalt.
With the exception of erythritol, sugar substitutes are not calorie-free. However, they have significantly fewer calories than sugar and are therefore also used to reduce calories. Unlike sweeteners, there are no ADI values for sugar substitutes. However, since they can have a laxative effect in larger quantities (more than 20 to 30 g per day), a corresponding warning is included on the packaging.
Numerous studies warn against sweeteners
The health effects of sweeteners and sugar substitutes have already been investigated in numerous studies. For sweeteners in particular, there is a variety of research findings indicating health risks. Disruption of the intestinal flora could be a central mechanism of these adverse effects.
Study: Sweeteners damage the human microbiome
In the following, we would like to present a study published in 2022 in the journal Cell that investigated the effects of 4 different commonly used sweeteners on the human microbiome (2).
Structure of the study
120 healthy adults between the ages of 26 and 35 were selected as subjects for the study. To prevent bias in the study results, a dietary questionnaire was used to ensure that only individuals who did not consume artificial sweeteners in their normal diet were included in the study.
The subjects were divided into six groups of 20 people each. Four groups consumed six commercially available sachets of aspartame, saccharin, sucralose, or stevia daily for 14 days. The sachets were consumed evenly throughout the day.
Since glucose was added to the sweetener sachets as a filler, a fifth group received the same amount of glucose (5 g) as was present in the sachets, while the sixth group took nothing.
The following amounts of sweeteners were consumed daily:
- Aspartame: 240 mg (equivalent to 8% of the ADI based on 60 kg body weight)
- Saccharin: 180 mg (20% of the ADI)
- Sucralose: 102 mg (34% of the ADI)
- Stevia: 180 mg (75% of the ADI)
The amounts of sweeteners consumed (except for Stevia) were significantly below the permitted ADI values.
To determine the effect of the sweeteners on blood sugar regulation, participants wore a continuous glucose monitor throughout the study. Glucose tolerance tests were also conducted on specific days. Stool and saliva samples were also analyzed multiple times before, during, and after the intake period to examine the microbiome.
Sweeteners influence the microbiome
All 4 sweeteners tested had an impact on the composition or metabolic activity of the microbiome, both in the gut and in the oral cavity.
The composition of bacterial species changed most significantly with sucralose and saccharin. The activity of various bacterial metabolic pathways was altered in a variety of ways by all sweeteners. There were no changes in the microbiome in the control groups, which consumed only glucose or nothing at all.
Disturbance of blood sugar regulation
The sweeteners consumed not only influenced the microbiome but also the results of multiple glucose tolerance tests. Participants who consumed sucralose or saccharin showed significantly increased blood sugar peaks compared to those in the other groups. In the week following the intake period, blood sugar regulation gradually returned to normal.
This suggests that sucralose and saccharin in particular could cause glucose intolerance and even insulin resistance when taken over a longer period of time, thus contributing to the development of type II diabetes.
Altered intestinal flora as a cause of glucose intolerance
In order to demonstrate the connection between the administered sweeteners, the altered intestinal flora and the resulting glucose intolerance, an experiment with germ-free mice was added to the study.
The scientists administered intestinal bacteria from the subjects' stool to the mice. The animals that received microorganisms from individuals with impaired blood sugar regulation also showed elevated blood sugar levels after a glucose tolerance test. In contrast, the mice that received microbes from individuals with normal blood sugar regulation were also able to regulate their blood sugar levels normally.
Conclusion: Sweeteners are harmful even below the ADI value
The presented study impressively demonstrates that sweeteners can have adverse effects on human health even at levels well below the currently valid ADI. Each of these substances interacts with the microbiome in different ways, and the potential long-term health effects are still largely unexplored. However, it is clear that artificial sweeteners are not a healthy substitute for table sugar and that their use, like the use of sugar, should be severely restricted.
Sources
1) Sweeteners: What are sweeteners and sugar substitutes? Consumer Advice Center [Internet]. January 10, 2024 [accessed on: January 31, 2024].
2) Suez J, Cohen Y, Valdés-Mas R, et al. Personalized microbiome-driven effects of non-nutritive sweeteners on human glucose tolerance. Cell. 2022;185(18):3307-3328.e19.