CHICAGO — In what could be the latest twist in the centuries-old quest for the fountain of youth, researchers announced they’ve found a way to reduce the signs of aging in older mice. And it involves the gut. 

In a new study, a fecal microbiota sample taken when eight mice were young and transplanted later to the same mice was associated with fewer cancers, less DNA damage, and longer telomere lengths. The treated mice also showed significantly greater bacterial diversity, reduced inflammation, and less liver damage compared to eight controls.

“None of the mice with the restored microbiome developed liver cancer by the end of the study, whereas liver cancer was found in 2 out of 8 aging controls,” said Qingjie Li, PhD, study investigator and associate professor in the Division of Gastroenterology and Hepatology at The University of Texas Medical Branch in Galveston. 

Li previewed these findings during a media briefing in advance of Digestive Disease Week (DDW) 2026. 

There is a need to find new, effective therapies for many age-related diseases, Li said. The US population older than age 65 is projected to grow to 88.5 million by 2050, double the number in 2010, which will increase the incidence of diseases such as liver cancer. 

Hepatocellular carcinoma (HCC), linked to alterations in gut bacteria, is the most rapidly increasing cancer in men and women, Li added. “The treatment options are limited, and it is difficult to catch early.” 

Looked at another way, he said, a healthy microbiome “has a broader influence on the body’s cancer defenses than previously understood. It means the microbiome is a target, which can be potentially acted on.” 

These preclinical findings hold great promise. “This could potentially open the door to microbiome-based strategies for healthy aging and cancer prevention approaches that could be safer and more accessible than many current therapies,” said Li. However, there is a caveat, he added. “This is animal research and cannot automatically be translated to people.”

Role of the Aging Microbiome?

A primary aim of the study was to determine if changes in the gut microbiome associated with aging are a by-product of getting older, or if the aging microbiome plays an active role in increasing risks, including liver cancer. 

The researchers collected fecal pellets from 4-month-old mice. The material was weighed, processed, and stored at -80 °C (-112 °F). Next, mice received an oral dose of equal amounts of their own youthful microbiome for 10 months, starting at 12 months of age, which is considered “middle age” for mice.

At the same time, control mice received sterilized fecal slurry with no active microbiota. At 22 months, investigators assessed liver function and any molecular changes. A third group of 3-month-old mice served as youthful controls. 

The transplanted mice showed significantly increased alpha diversity in their gut microbiota. For example, they demonstrated a 213-fold reduction in Ileibacterium and a 27-fold increase in Lachnospiraceae FCS020. This reflected a successful restoration of younger mouse microbiota, Li said.

In addition, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels , elevated with aging, were significantly reduced by the transplantation. This supports functional rejuvenation, he added.

The fecal microbiota transplant was also associated with decreased mononuclear cell infiltration in the liver, lower levels of inflammatory and fibrotic markers, including interleukin-6 and fibronectin, and improved mitochondrial function reflected in lower age-related oxygen consumption rates.

Genetic findings also support the influence of the gut microbiome on liver cancer. For example, the investigators examined liver tissue at the end of the study. They found that untreated older mice showed increased levels of MDM2 gene, which inhibits the p53 tumor suppression gene. Mice treated with their own younger microbiota and the 3-month-old younger control mice had lower MDM2. 

“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,” Li noted in a press release.

‘Interesting and Provocative’

“It is interesting that the microbiota transplant was associated with less cancer, but more interesting to me was the reduction in other features of aging, like telomere shortening, mitochondrial function, and DNA damage biomarkers,” said briefing moderator Loren Laine, MD, a gastroenterologist and professor of medicine at the Yale School of Medicine in New Haven, Connecticut. “That makes this abstract extremely interesting and provocative.” 

Laine asked why younger gut microbiota could have these widespread effects. 

“That's a good question, and we still don't fully understand it,” Li responded. He added that multiple genes and pathways are likely involved, and lowering inflammation and improving immune function probably play a role. 

In response to why the researchers chose autologous fecal transplants, Li said transplanting the mice’s own microbiota has important advantages. Autologous samples are more compatible with their own immune system, for example. 

On the other hand, some microbiome species might die off during long-term preservation, which would favor a donor transplantation strategy, he noted. 

Based on the findings, Laine asked if everyone should save their stool from childhood. “I’m not sure about that,” Li answered, but added he did recently preserve a sample of his own microbiota. 

Future research is warranted, he said. “We need to replicate these findings and understand exactly which components of the youthful microbiome are doing the work.” 

Li will present “Restoration of a youthful gut microbiome reduces liver aging and suppresses tumorigenesis in older mice” (Abstract 524), at 9:15 AM CDT, on May 2 at DDW 2026. The study was independently supported. Li and Laine reported no relevant financial relationships. 

Damian McNamara is a freelance contributor to Medscape Medical News. He worked full-time for Medscape and WebMD from 2018 to 2024. Damian has a BA in chemistry and an MA in science, health, and environmental reporting/journalism.