Negative effects of artificial sweeteners may pass on to next generation, study suggests
In mice, consumption of sucralose and stevia altered gut microbiome composition, reduced beneficial short-chain fatty acids, and changed gene expression related to inflammation and metabolism, with some effects persisting across generations. Sucralose produced more pronounced and lasting metabolic and microbiome disruptions than stevia. These findings suggest potential transgenerational metabolic impacts of artificial sweeteners.
Health organizations are starting to raise concerns about the potential long-term impacts of artificial sweeteners, which taste sweet but—unlike sugar—contain no calories, suggesting they could interfere with energy metabolism and increase the eventual risk of diabetes or cardiovascular disease.
Now a new study in mice indicates that the popular sweeteners sucralose and stevia have negative effects on the gut microbiome and gene expression, potentially compromising metabolic health, which can be transmitted between generations.
The scientists found that different sweeteners produced different effects, which changed over time.

In the first generation, only the male offspring of sucralose-consuming mice showed signs of impaired glucose tolerance, but by the second generation, elevated fasting blood sugar was detected in male descendants of sucralose-consuming mice and female descendants of stevia-consuming mice.

Both groups of mice that ate sweeteners had more diverse fecal microbiomes but lower concentrations of short-chain fatty acids, suggesting the bacteria were producing fewer beneficial metabolites; both succeeding generations also had lower concentrations of short-chain fatty acids.

Sucralose-consuming mice were more seriously and more persistently affected by changes to the fecal microbiome, with more pathogenic species and fewer beneficial species of bacteria in their feces.

Similarly, sucralose appears to kick-start the expression of genes linked to inflammation and dampen the expression of genes linked to metabolism for two generations after consumption. Stevia also impacts gene expression, but its effects are smaller and are not passed on for more than one generation.

Artificial and Natural Non-Nutritive Sweeteners Drive Divergent Gut and Genetic Responses Across Generations, Frontiers in Nutrition (2026). DOI: 10.3389/fnut.2026.1694149

Women's immune systems show bigger age-related changes than men's

Immunological aging exhibits distinct sex-specific patterns, with women showing more pronounced age-related changes, including increased inflammatory immune cells, potentially explaining higher autoimmune disease prevalence and postmenopausal inflammatory pathologies. In men, immune aging changes are less extensive but include increased pre-leukemia blood cells, correlating with higher blood cancer rates in older men. These findings highlight the importance of considering biological sex in precision medicine for aging and immune health.
Statistics show clear differences in the population's immune system according to sex: men are more susceptible to infections and cancers, while women have stronger immune responses, which translate, for example, into better responses to vaccines. Even so, with a more reactive immune system, the probability of the body attacking itself also increases, causing 80% of autoimmune disease development to occur in women.
In this context, understanding the aging of the immune system is key since, with age, the composition of immune cells changes and their protective functions deteriorate, causing a greater susceptibility to diseases.
A new study published this week in Nature Aging demonstrated, for the first time, that immunological aging follows different dynamics between men and women, identifying the cells and genes responsible for the process, and providing a molecular explanation for the differences that previously were only observed globally in the population.
The results reveal that women present more pronounced changes in the immune system with age, with an increase in inflammatory immune cells. This finding could help explain why autoimmune diseases are mainly developed by women, especially at advanced ages, as well as the worsening of certain inflammatory pathologies after menopause.
On the other hand, the changes associated with immune system aging observed in men are globally less extensive, but an increase in certain blood cells presenting pre-leukemia alterations was observed, a fact that could explain why some blood cancers are more frequent in older men.
Finding these patterns was possible thanks to the analysis of blood samples from nearly 1,000 people of different ages covering the entire adult life, combined with a technology capable of analyzing each cell individually, called single-cell RNA sequencing. In total, the researchers analyzed the activity of 20,000 genes in more than one million blood cells, which allowed them to identify how the immune system changes over the years and detect clear differences between sexes.

Maria Sopena-Rios et al, Single-cell analysis of the human immune system reveals sex-specific dynamics of immunosenescence, Nature Aging (2026). DOI: 10.1038/s43587-026-01099-x