Test by the team from Israel’s’ Ben-Gurion University of the Negev on artificial sweeteners contained in sports supplements found they may affect the balance of the gut microbial community.
“We, therefore, infer an effect of these artificial sweeteners on numerous molecular events that are at the core of intestinal microbial function, and by extension on the host metabolism,” the team writes in the International Journal of Molecular Sciences.
The findings are refuted by the International Sweeteners Association (ISA), which pointed to the study’s use of in vitro models that have ‘little biological relevance due to limitations from extrapolating tested concentrations in vitro to human exposure levels from the diet.’
“In fact, the concentrations shown to have some effect in the in-vitro setting would never be reached in the human intestine,” ISA’s spokesperson continues.
“In vitro testing conditions may cause reactions that would not be seen with real-life exposure conditions in humans, and thus, this study design cannot be predictive of what would happen in real-life use of a sweetener.”
The team began looking at Quorum Sensing (QS), a process that microorganisms use to communicate within their community and regulate group behaviours.
Using biosensor assays and protein characterisation methods, amongst other techniques, the team looked to identify aspartame, sucralose, and saccharin’s role in inhibiting the actions of the Gram-negative bacteria N-acyl homoserine lactone-based (AHL) communication system.
Whilst they found the sweeteners did not kill bacteria, further analysis revealed they bound to the ligand-binding pocket of proteins, possibly interfering with the proper housing of the native ligand and thus impeding protein folding.
“Along with the findings reported in the study, it is enticing to speculate that these artificial sweeteners could interfere with gut microbiota homeostasis, thus promoting the progression of digestive diseases,” the team writes.
“Studies indicate that IBD is associated with gut dysbiosis with a marked decrease in specific taxonomic groups including Firmicutes and Bacteroidetes.
“These gut residents are known to be involved in the regulation of the immune system, production of vitamins, facilitation of dietary substrates digestion, and repression of pathogens expansion.”
Again, ISA points to the study’s methodology, highlighting its design ignores the well understood pathways of low/no calorie sweeteners metabolism in the gut.
“Neither aspartame nor its metabolites ever reach the colon for direct interaction with the microbiota,” adds the spokesperson from the Brussels-based non-profit organisation.
“Sucralose is largely unabsorbed, but not digested in the gut, thus it is not a substrate for gut microbiota. Saccharin is rapidly absorbed and excreted unchanged in the urine.”
Revaluate sweetener use?
Artificial sweeteners are commonly used in many types of foods and beverages and are recommended for bodyweight reduction and persons living with type 2 diabetes mellitus and glucose intolerance.
Whilst regulatory agencies have approved the use of aspartame, saccharin, sucralose, acesulfame potassium (Ace-K), advantame, and neotame, there is still no consensus in the scientific community regarding the safety status of these artificial sweeteners.
Whilst randomised controlled trials (RCT) in humans suggest bodyweight benefits from the consumption of artificial sweeteners, there is still only limited data on other metabolic alterations, including altering gut microbiota in a manner that could enhance the metabolic diseases that they were intended to reduce.
“There is little accurate labelling of artificial sweeteners on products, which makes it difficult to know how much each product contains,” adds Professor Ariel Kushmaro, Head of the Laboratory of Environmental Biotechnology at Ben-Gurion University. “Our research should push the food industry to revaluate their use of artificial sweeteners."
Source: Int. J. Mol. Sci.
Published online: doi.org/10.3390/ijms22189863
“Inhibitory Effects of Artificial Sweeteners on Bacterial Quorum Sensing”
Authors: Victor Markus et al