Scientists restored young gut bacteria in aging mice and saw signs of rejuvenation along with complete protection from liver cancer.
Returning the gut microbiome to a more youthful state could help slow aging and lower the risk of liver cancer, according to research entitled “Restoration of a youthful gut microbiome reduces liver aging and suppresses tumorigenesis in older mice” presented at Digestive Disease Week (DDW) 2026.
Liver cancer is among the fastest-growing cancers worldwide, and the new findings suggest that age-related changes in gut bacteria may play a more important role in its development than previously recognized.
To investigate, researchers collected fecal samples from eight young mice and stored them for later use. As the mice aged, the scientists reintroduced each animal’s own preserved microbiome through a procedure known as fecal microbiota transplantation (FMT). Another eight mice served as controls and received a sterilized fecal slurry instead. A separate group of young mice provided baseline measurements for comparison.
Restored Gut Bacteria Reduced Cancer Risk
The differences between the groups were striking.
By the end of the study, none of the mice that received their youthful microbiome developed liver cancer. In contrast, liver cancer was detected in 2 of the 8 aging mice in the control group.
The treated mice also experienced lower levels of inflammation and showed less liver damage than untreated animals.
“We’re learning from this work that the aging microbiome actively contributes to liver dysfunction and cancer risk rather than simply reflecting the aging process,” said Qingjie Li, PhD, associate professor in the Division of Gastroenterology and Hepatology at The University of Texas Medical Branch, and lead researcher on the study. “The microbiome has a broader influence on the body’s cancer defenses than previously understood.”
Key Liver Cancer Gene Changed by Treatment
After completing the in vivo study, the research team performed a detailed examination of liver tissue samples.
Their analysis revealed differences involving MDM2, a gene already associated with liver cancer. MDM2 protein levels were low in young mice, elevated in untreated older mice, and reduced in older mice that received the microbiome treatment. This pattern made the treated animals resemble younger mice more closely at the molecular level.
“Restoring a more youthful microbiome can reverse several core features of aging at both the molecular and functional level, including inflammation, fibrosis, mitochondrial decline, telomere attrition, and DNA damage,” Dr. Li said.
From Heart Research to Liver Aging
The study originated from earlier research examining the heart. In that work, scientists found that altering the microbiome could improve cardiac function.
When the team later analyzed tissue samples from those experiments, they observed an even stronger effect in the liver. That unexpected finding led them to investigate the connection between the microbiome, aging, and liver disease in greater depth.
To reduce the risk of immune reactions and infection, the researchers used each mouse’s own preserved microbiome rather than bacteria from a donor. They also said this approach provides a cleaner proof-of-concept for future studies involving people.
Human Studies Still Needed
Dr. Li stressed that the findings come from animal research and should not be applied directly to humans.
However, he said he hopes the results will pave the way for first-in-human clinical trials in the near future, helping researchers determine whether restoring a youthful microbiome could one day become a strategy for combating aging-related liver disease and cancer.
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