Scientists Find Unexpected Gut Health Effects After Testing 39 Popular Sweeteners - Video

Artificial sweeteners may not be as biologically inactive as once believed. New laboratory research suggests that some commonly used sugar substitutes can directly interfere with beneficial gut bacteria, and their effects may become even stronger when combined with certain medications or food additives.

The findings, published in Molecular Systems Biology, highlight a potential interaction between sweeteners, the gut microbiome, and commonly prescribed drugs.

Researchers from the University of Cambridge tested 39 commercially used sweeteners on 25 species of gut bacteria grown in the laboratory. Around three-quarters of the sweeteners affected the growth of at least one bacterial species, with several slowing or completely stopping the growth of microbes associated with a healthy digestive system.

The most striking finding involved isosteviol, a sweetener used in the food industry, and duloxetine, an antidepressant prescribed for depression, anxiety, and chronic pain. Together, the two compounds sharply suppressed the growth of R. intestinalis and P. merdae—two bacterial species linked to digestive health, blood sugar regulation, and immune function.

To better reflect real-life conditions, researchers also created a simplified microbial community containing all 25 bacterial species. The isosteviol-duloxetine combination reduced microbial diversity and altered the balance of gut bacteria, while additional experiments suggested increased toxicity toward certain host cells and changes in inflammatory and immune responses.

Researchers identified more than 100 interactions in which a sweetener's effect changed when paired with other compounds such as caffeine, vanilla extract, food additives, or medications.

Despite the findings, scientists caution that the work was conducted entirely in laboratory models, not in humans. They emphasize that the results do not prove sweeteners cause health problems, as digestion, diet, genetics, and the existing gut microbiome may alter these effects in real life.

Future human studies are needed to determine whether these interactions influence health outside the laboratory.

REFERENCE: Sonja Blasche, Vinita Periwal, Nonantzin Beristain Covarrubias, Anna Lindell, Indra Roux, Stephan Kamrad, Simone Mozzachiodi, Rob Bradley, Hilal Ozgur, Bini Ramachandran, Vladimir Benes, Kiran Raosaheb Patil. Common xenobiotics modulate gut microbial responses to low‑calorie sweeteners in vitro. Molecular Systems Biology, 2026; DOI: 10.1038/s44320-026-00225-6