In lab dishes, about three-quarters of 39 sweeteners changed the growth of at least one gut bacterium

What the research found

Study (laboratory bacteria, not a human trial). Sonja Blasche, Kiran Raosaheb Patil, and colleagues at the MRC Toxicology Unit, University of Cambridge, report in Molecular Systems Biology (2026; 22(9):1453; DOI 10.1038/s44320-026-00225-6). ScienceDaily ran it on 17 Oct 2026. They grew 25 gut bacterial species and exposed them to 39 low-calorie sweeteners. About three in four sweeteners changed the growth of at least one species, sometimes slowing or stopping it. Pairing sweeteners with caffeine, vanillin, advantame, or eight common pharmaceuticals produced more than 100 cases where the effect changed: 34 stronger, 68 weaker. Isosteviol plus the antidepressant duloxetine strongly slowed Roseburia intestinalis and Parabacteroides merdae, species tied to gut health and blood sugar regulation, and it lowered diversity in a 25-species community. The authors note more than 4.2 million U.S. patients were prescribed duloxetine in 2023. These are dishes and a model community, not people. Do not start, stop, or change a prescribed antidepressant because of this headline. Not medical advice. Not a substitute for a prescribed medicine. Off-label use is clinician-only.

Evidence level: Human study. A study in people, but an association isn't proof of cause.

Read the original at University of Cambridge / Molecular Systems Biology