A study found that simply changing the gut microbiome environment can alter ovarian function and fertility.
Researchers at the University of Southern California (USC) said that when they transplanted the gut microbiome of older female mice into young mice, both ovarian function and reproductive success improved. The findings were published on Mar. 3 in the international journal Nature Aging.
The gut microbiome refers to the community of microorganisms living in the gut. Recently, more studies have shown that these microbes are linked not only to digestion but also to mental health, metabolism, cardiovascular disease, and other aspects of overall health. This time, it was confirmed that the effect can extend to ovarian and reproductive function. In particular, ovarian aging is known to be associated not only with the likelihood of pregnancy but also with an increased risk of osteoporosis, cardiovascular disease, and dementia.
The researchers administered antibiotics to young female mice to eliminate their existing gut microbiome, then transplanted fecal microbiota from other mice to rebuild the gut environment. Fecal microbiota transplantation is, literally, a method of transferring microbes in stool to alter the composition of bacteria in the gut. In this study, the researchers used feces from young female mice and from older female mice whose reproductive function had nearly ended.
The researchers expected that microbes from older mice would harm the ovaries of young mice. But the results were the opposite. In young mice that received microbes from older mice, ovarian cell gene expression patterns became closer to those of even younger individuals, and inflammation, a representative marker of tissue aging, decreased. In other words, changing the gut microbiome made the ovaries of young mice healthier and closer to a younger state.
Actual reproductive outcomes were better as well. Some mice that received microbes from young mice did not bear offspring even after mating with males, but all mice that received microbes from older mice bore offspring.
Bérénice Benayoun, a USC professor, said, "This suggests that there is bidirectional communication between the ovaries and the gut microbiome, and that this mode of communication changes across the lifespan."
The researchers pointed to the "estrobolome" as the background. The estrobolome is a gut microbial network involved in estrogen metabolism, and estrogen is a hormone that affects female (female animal) reproductive function, bone health, and cardiovascular health. The team believes that as the ovaries age and become less sensitive to signals from the estrobolome, gut microbes may compensate by sending stronger related signals, and when those microbes enter young ovaries, they boost reproductive capacity.
However, the researchers noted, "These are results from experiments in mice, and further research is needed to see whether the same effects appear in humans," while adding, "A precise approach to modulating the gut microbiome shows the potential to become a new therapeutic strategy for ovarian aging, infertility, and healthy aging."
References
Nature Aging (2026), DOI: https://doi.org/10.1038/s43587-026-01069-3