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Gut health gains scientific spotlight amid ageing research
Scientists are investigating whether the trillions of microbes in the human gut influence how well-or poorly-people age, as new studies suggest a possible connection between gut diversity and longevity.
The microbiome's potential impact on ageing
Dr. James Kinross, a colorectal surgeon and microbiome researcher at Imperial College London, describes himself as a "microbiome evangelist," arguing that gut bacteria may play a pivotal role in determining lifespan and physical resilience in later years. While some experts caution that the field remains understudied, emerging research points to a link between gut health and ageing outcomes.
Lessons from centenarians
Maria Branyas Morera, the world's oldest person until her death in 2024 at age 117, became a case study for researchers. Scientists analyzing her stool, blood, and saliva samples found her gut microbiome contained unusually high levels of beneficial bacteria, which may have helped reduce inflammation. Dr. Manel Esteller, a geneticist at the University of Barcelona, noted that her cells appeared biologically younger than her chronological age.
A 2022 study in Nature examined stool samples from 18 centenarians in southeastern China, revealing a far greater diversity of gut bacteria compared to younger adults. Dr. Mary Ni Lochlainn, a geriatric medicine specialist at King's College London, likens a healthy gut to a thriving garden-one rich in variety rather than barren.
Gut diversity and frailty in old age
Research indicates that gut microbiome diversity tends to decline with age, but those who maintain robust bacterial populations into their 80s and 90s often enjoy longer, healthier lives. Kinross highlights a correlation between gut bacteria and frailty, suggesting that a balanced microbiome may help older adults recover more quickly from illness or injury.
A personal case study
After submitting a stool sample for analysis, a journalist in his 60s received mixed results: his gut microbiome was deemed "broadly healthy" but showed signs of age-related decline. Kinross compared the sample to a study of 62 Italians, concluding that the journalist's gut resembled that of a man five years older. The findings prompted reflections on decades of irregular eating habits, urban pollution, and stress.
Kinross reassured the journalist that his gut still had "the machinery for healthy ageing," though dietary changes would be necessary to optimize it. Esteller echoed this optimism, citing evidence that diet influences both lifespan and healthspan-the period of life free from chronic illness. He recommended foods rich in polyphenols (like olive oil) and omega-3 fatty acids (found in bluefish), while advising against refined sugars and ultra-processed foods.
Can diet reverse ageing?
Faecal transplant studies in mice have provided compelling evidence of causation. In a 2020 experiment, young mice that received gut bacteria from older mice began exhibiting signs of accelerated ageing, including memory decline and depressive-like behavior. Ni Lochlainn acknowledges the "chicken or egg" dilemma-whether a diverse gut drives healthy ageing or vice versa-but such studies suggest the microbiome may directly influence biological age.
Practical challenges
Following a tailored diet plan, the journalist incorporated kefir, kombucha, flaxseeds, and probiotics into his routine. While the regimen proved satiating, maintaining it amid a hectic schedule proved difficult. Kinross warned that meaningful changes require consistency, as sporadic adjustments yield minimal benefits.
Experts emphasize that diet is only one factor in ageing. Esteller estimates it accounts for roughly a third of outcomes, with genetics and lifestyle (exercise, smoking avoidance) contributing the rest. Prof. Kamila Hawthorne of the Royal College of GPs cautioned against overstating the microbiome's role, noting that "good health is not determined by any single factor."
Future research and unanswered questions
Kinross stressed that microbiome research across diverse populations remains in its early stages. Individual variability means personalized approaches may be necessary. For now, the journalist's experiment serves as a reminder: while the science is evolving, nurturing gut health could be a step toward healthier ageing.
"We know that centenarians... have more diverse microbiomes. There's something about those people who are kind of superior beings, in a way. They've managed to keep their diversity."
Dr. Mary Ni Lochlainn, King's College London
