Common sweeteners in foods and drinks may harm the growth of important gut bacteria, according to new research. That gut bacteria support digestive health.
Researchers at Cambridge Univ. grew 25 species of gut bacteria. The gut bacteria strains included helpful, harmful and neutral species. Then the bacteria were exposed to 39 common natural and artificial sweeteners.
About 75 percent of the sweeteners impacted at least one species of the bacteria’s ability to multiply. Some completely stopped the growth of bacteria linked to a healthy gut.
The researchers also looked at how common compounds, including common medications, caffeine, vanillin and more, interact with the sweeteners to impact the body. They saw more than 100 interactions when the sweeteners were with other compounds. In 34 of the interactions, the effects were worse. In 68, the combination weakened them. That shows that the impact of a sweetener can vary completely by how it’s consumed. The type of food it’s in, or what that food is eaten with, affects how it interacts with the gut.
The largest impact was seen when the sweetener isosteviol was combined with the antidepressant duloxetine. Duloxetine is used for depression, anxiety and chronic pain. When combined, they “strongly suppressed” two species of helpful bacteria that aid digestive health and metabolic regulation. More than 4.2 million Americans were prescribed duloxetine in 2023.
The combo changed the balance of a simulated microbiome. That allowed some bacteria to thrive while others dwindled. Experiments also found that the combo increased toxicity toward host cells and disrupted cells involved in inflammation and immune health.
“Our study suggests that artificial sweeteners don’t just pass through the body passively — they can interact with gut microbes, and these effects can be amplified or altered by other substances like medications,” said Professor Kiran Patil, the study’s senior author. “These findings can help guide new studies toward understanding how sweeteners might influence health in unexpected ways.”
It’s essential to note that these are lab results using just 25 strains of bacteria in a controlled environment. Researchers controlled the original concentration of bacteria. The human gut is much more complex and changeable.
This research is an important step as it uses human cells. Prof. Patin said, “Most of what we know about the potential impact of sweeteners on our health comes from animal research or from population studies. While these studies have indicated involvement of the microbiome in mediating the effect of sweeteners, it’s difficult to know how sweeteners act in the body — is it through direct interactions with our gut bacteria?”
Research in human bodies is needed to get a fuller picture of how sweeteners impact the body.
