Growing numbers of people are turning to diet drinks and sugar-free foods containing non-nutritive sweeteners. These additives provide sweetness without calories, but scientists are increasingly investigating whether they may have hidden long-term health effects. New research in mice suggests that some of those effects could extend beyond a single generation.
The study, led by researchers at the Universidad de Chile and published in Frontiers in Nutrition, examined the sweeteners sucralose and stevia. Both are widely used in beverages, desserts and processed foods worldwide. Researchers investigated how these additives might affect metabolism, gut bacteria and gene activity in exposed animals and their descendants.
How the mouse study was designed
Researchers divided 47 male and female mice into three groups. One group received plain drinking water, while the other two were given water containing sucralose or stevia at doses similar to human dietary intake. The animals were then bred, and their offspring were followed across two generations.
Only the original adult mice consumed the sweeteners directly. Their first- and second-generation offspring received plain water. This design allowed researchers to examine whether biological effects could persist after exposure ended, potentially highlighting epigenetic influences.
Across all generations, the team conducted oral glucose tolerance tests, a standard method for assessing how efficiently the body handles sugar. They also collected fecal samples to examine the gut microbiome and measure short-chain fatty acids, key metabolites produced by gut bacteria that can influence gene regulation.
Changes in glucose regulation and gut bacteria
Sucralose and stevia did not affect metabolism in identical ways. In the first generation, only male descendants of sucralose-exposed mice showed signs of impaired glucose tolerance. This suggested changes in how their bodies processed sugar despite never consuming the sweetener themselves.
By the second generation, elevated fasting blood sugar appeared in male descendants of the sucralose group and female descendants of the stevia group. Although the animals did not develop diabetes, researchers identified these subtle changes as early markers that could indicate greater vulnerability to metabolic disease under additional stress, such as a high-fat diet.
The gut microbiomes of mice exposed to either sweetener became more diverse but produced fewer short-chain fatty acids. Lower levels of these fatty acids, which help regulate inflammation and gut health, were also detected in both subsequent generations. The pattern suggested that sweetener-induced changes in gut bacteria and their metabolites may persist beyond direct exposure.
Sucralose showed stronger, longer effects
Sucralose produced more pronounced and persistent changes than stevia. Mice originally given sucralose showed larger shifts in the composition of their gut bacteria, including increases in potentially harmful microbes and decreases in beneficial ones. These imbalances remained detectable two generations later.
Gene activity in the liver and intestines also changed. In sucralose-exposed lineages, genes associated with inflammation became more active, while those involved in metabolism and gut barrier function were suppressed. Stevia also altered gene expression, but its effects tended to be weaker and faded after the first generation.
According to the authors, these differences in gene expression are best viewed as early biological signals. The study did not identify outright disease but instead detected small changes in glucose regulation, immune responses and intestinal integrity. Over time, and when combined with other risk factors, such changes might contribute to metabolic problems.
What this means for human health
The researchers emphasize that their findings do not establish direct harm in humans. Mouse models allow researchers to tightly control diet and environment, while human biology and real-world eating patterns are considerably more complex. It remains unclear whether these multigenerational effects occur in people or at typical levels of consumption.
Nonetheless, the findings contribute to a broader scientific debate surrounding non-nutritive sweeteners. Other recent human and animal studies have associated certain sweeteners, including sucralose and some sugar alcohols, with changes in the gut microbiome, altered glucose responses and possible effects on appetite regulation.
Health authorities currently differ in their guidance. The World Health Organization has advised against using non-sugar sweeteners long term for weight control, citing limited evidence of sustained benefits and potential metabolic risks. Meanwhile, regulators including the U.S. Food and Drug Administration continue to consider several sweeteners safe when consumed within established intake limits.
Lead author Dr. Francisca Concha Celume said the aim is not to alarm consumers but to encourage further research and moderation. For now, experts suggest focusing on overall dietary quality, prioritizing whole foods and limiting both added sugars and heavy reliance on artificial or highly processed sweeteners where possible.
