LONDON: Artificial and low-calorie sweeteners could influence the growth of certain gut bacteria, according to a new laboratory study, although researchers caution that the findings do not yet show the same effects occur in people.
Scientists at the University of Cambridge examined how 39 commercially used sweeteners affected 25 species of gut bacteria grown under laboratory conditions.
Published in the journal Molecular Systems Biology, the study found that about three-quarters of the sweeteners influenced the growth of at least one bacterial species. In some cases, they slowed or stopped the growth of bacteria associated with a healthy gut.
The researchers then looked at what happened when the sweeteners were combined with substances many people consume or take regularly, including caffeine, flavourings and several medicines.
More than 100 interactions were identified, with some combinations strengthening the sweeteners’ effects while others reduced them.
One of the strongest interactions involved the sweetener isosteviol and the antidepressant duloxetine. Together, they significantly suppressed two bacterial species believed to play an important role in digestive health.
The researchers also created a simplified laboratory model containing all 25 bacterial species to explore how the microbial community responded as a whole.
Further analysis suggested that some sweetener combinations increased toxicity towards certain cells and influenced cells involved in inflammation and immune responses.
Lead author Sonja Blasche of the university’s Medical Research Council Toxicology Unit said the findings challenged the common assumption that sweeteners were biologically inactive.
“Sweeteners are often marketed as metabolically neutral, but our study challenges this idea,” she said.
However, the researchers stressed that their work was conducted entirely in the laboratory. Human digestive systems are vastly more complex than laboratory cultures, meaning the findings cannot be assumed to translate directly to everyday diets or health outcomes.
More research involving people will be needed before scientists can determine whether consuming these sweeteners meaningfully alters the human gut microbiome or affects long-term health.
For now, the study offers another glimpse into the complex relationship between diet and the trillions of bacteria that live inside the digestive system – while underscoring how much remains to be understood.
