From probiotic yoghurts to kombucha, gut health has become a booming industry, often fuelled by bold claims and shaky science. Yet behind the marketing, doctors are increasingly convinced that the trillions of microbes living in our digestive system, known as the gut microbiome, may influence far more than digestion.
A growing body of research suggests it could also play a role in how well we age BBC reported.
At St Mary’s Hospital in London, colorectal surgeon and microbiome researcher Professor James Kinross studies patients’ stool samples to map the bacteria living inside them. He believes these microbes are “deeply ingrained” in overall health and may affect frailty, recovery from illness and even longevity.
Not everyone agrees on how strong the evidence is, but few dispute that the gut is emerging as a key area of ageing research.
Clues have come from people who live exceptionally long lives. When Spain’s Maria Branyas Morera died in 2024 aged 117, scientists compared her gut bacteria with those of younger women. She had followed a Mediterranean-style diet, exercised daily, and eaten yoghurt three times a day.
Researchers believe the fermented dairy may have helped boost bacteria that reduce inflammation, a process linked to ageing.
Similar patterns have been found elsewhere. Studies of centenarians in China and Europe show their guts tend to contain a wide variety of microbes.
Dr Mary Ni Lochlainn, a geriatrician at King’s College London, compares this to a healthy garden: the more diverse the plants, the more resilient the ecosystem. By contrast, the microbiome usually becomes less varied with age, as beneficial species disappear.
Why does that matter? Loss of microbial diversity has been linked to frailty a reduced ability to recover from infections, falls or surgery, as well as chronic disease.
Older people who maintain richer gut bacteria into their 80s and 90s tend to stay healthier for longer.
So can people improve their “gut age”? The science is still developing, but diet appears to matter. Research suggests foods rich in fibre, polyphenols and healthy fats, such as vegetables, olive oil and oily fish, encourage beneficial bacteria. Ultra-processed foods and refined sugars, by contrast, can do the opposite.
Genetics and environment also play a role, and scientists caution against one-size-fits-all solutions.
Still, the message from the lab is clear: nurturing the microbes inside us may be one of the more promising frontiers in healthy ageing.
