How artificial sweeteners can harm your gut

The study, published in the International Journal of Molecular Sciences, is the first to show the pathogenic effects of some of the most widely-used artificial sweeteners -- saccharin, sucralose, and aspartame -- on two types of gut bacteria, E. coli (Escherichia coli) and E. faecalis (Enterococcus faecalis). 

Previous studies have shown that artificial sweeteners can change the number and type of bacteria in the gut, but the new molecular research, led by academics from Anglia Ruskin University (ARU), has demonstrated that sweeteners can also make the bacteria pathogenic. It found that these pathogenic bacteria can attach themselves to, invade, and kill Caco-2 cells, which are epithelial cells that line the wall of the intestine. 

"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," said Havovi Chichger, from ARU's Biomedical Science. 

"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," Chichger added. 

It is known that bacteria such as E. faecalis which cross the intestinal wall can enter the bloodstream and congregate in the lymph nodes, liver, and spleen, causing a number of infections including septicaemia. 

This new study discovered that at a concentration equivalent to two cans of diet soft drink, all three artificial sweeteners significantly increased the adhesion of both E. coli and E. faecalis to intestinal Caco-2 cells, and differentially increased the formation of biofilms. 

Bacteria growing in biofilms are less sensitive to antimicrobial resistance treatment and are more likely to secrete toxins and express virulence factors, which are molecules that can cause disease. 

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, the researchers said.