The study outlines the effects of the artificial sweeteners, saccharin, sucralose, and aspartame, on the gut bacteria Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) that could lead to gut wall damage and infection.
"Our study is the first to show that some of the sweeteners most commonly found in food and drink can make normal and 'healthy' gut bacteria become pathogenic,” explains Dr Havovi Chichger, Senior Lecturer in Biomedical Science at Anglia Ruskin University (ARU) and senior author of the paper.
These pathogenic changes include greater formation of biofilms and increased adhesion and invasion of bacteria into human gut cells.
"These changes could lead to our own gut bacteria invading and causing damage to our intestine, which can be linked to infection, sepsis and multiple-organ failure.”
The study’s conclusions drew a response from industry groups representing low/no calories sweetener makers, who challenged the findings, particularly the study type and applicability to real-life.
“The in-vitro study design limits the relevance of any findings to humans, as such studies cannot reproduce the whole, complex, interactive system that is present in humans or animals,” the International Sweeteners Association (ISA) says.
Real-life scenarios
“For example, in the current experiment, isolated bacteria were exposed for two consecutive days to high concentrations of low/no calorie sweeteners out of the human body.
“This study design ignores the well documented pathways of the different sweeteners’ metabolism in the gut and the time and amount of sweeteners that reach the gut microbiome.
“Therefore, these results cannot be predictive of what would happen in real-life use of low/no calorie sweeteners.”
The team used models of microbiota (E. coli NCTC10418 and E. faecalis ATCC19433) and the intestinal epithelium (Caco-2 cells), that were exposed to concentrations of saccharin, sucralose, and aspartame.
Their pathogenicity and changes in interactions with Caco-2 cells were measured using in vitro studies.
Findings show that sweeteners increased the ability of bacteria to form a biofilm. Bacteria growing in biofilms are less sensitive to antimicrobial resistance treatment and are more likely to secrete toxins and express disease-causing molecules.
The study found concentrations of all three artificial sweeteners equivalent to two cans of diet soft drink, could increase the adhesion of E. coli and E. faecalis to intestinal Caco-2 cells, and increase biofilm formation.
Additionally, all three sweeteners caused the pathogenic gut bacteria to invade Caco-2 cells found in the wall of the intestine, with the exception of saccharin which had no significant effect on E. coli invasion.
"There is a lot of concern about the consumption of artificial sweeteners, with some studies showing that sweeteners can affect the layer of bacteria which support the gut, known as the gut microbiota,” adds Dr Chichger.
"We know that overconsumption of sugar is a major factor in the development of conditions such as obesity and diabetes. Therefore, it is important that we increase our knowledge of sweeteners versus sugars in the diet to better understand the impact on our health."
Regulatory approval
In additional comment, ISA added that the scientific opinions of regulatory authorities worldwide have repeatedly confirmed the safety of all approved low/no calorie sweeteners.
“Before approving a low/no calorie sweeteners for use on the market, food safety authorities such as the Joint Expert Scientific Committee on Food Additives (JECFA) of the United Nations Food & Agriculture Organization (FAO) and of the World Health Organization (WHO), the European Food Safety Authority (EFSA) and the US Food and Drug Administration (FDA), thoroughly review all the available scientific evidence, including about any effect on the gut functioning.
“Current evidence show no adverse effect of low/no calorie sweeteners on gut microbiota.”
ISA, based in Brussels, Belgium added that diabetes and dental diseases remained major global health challenges, where low/no calorie sweeteners could be helpful in creating healthier food environments.
“Low/no calorie sweeteners provide a wide choice of sweet-tasting options with low or no calories, and thus can be a useful tool, when used in place of sugar and as part of a balanced diet, in helping reduce overall sugar and calorie intake, as well as in managing blood glucose levels.
“Low/no calorie sweeteners are also not fermentable by oral bacteria, which means that they do not contribute to tooth demineralisation, which is one of the reasons for tooth decay.”
Source: Int. J. Mol. Sci.
Published online: doi.org/10.3390/ijms22105228
“Artificial Sweeteners Negatively Regulate Pathogenic Characteristics of Two Model Gut Bacteria, E. coli and E. faecalis.”
Authors: Aparna Shil et al.