Can your gut microbiome influence how long you live?
There are clear indications that a healthy, diverse gut microbiome is associated with living longer and more healthily, but whether that relationship can be reversed by deliberately changing your microbiome has not yet been proven. For now, dietary choices (such as less animal protein and more fibre) offer the most concrete starting point.
A diverse gut microbiome, populated by bacteria that produce anti-inflammatory compounds (such as short-chain fatty acids), is associated with healthier ageing in multiple studies conducted around the world. This pattern has been found consistently across different countries and age groups, but the research is observational: we do not yet know for certain whether a healthy microbiome causes people to live longer, or whether healthy people simply tend to have a healthier microbiome.
One analysis of more than 9,000 people revealed something striking: individuals who, at an advanced age (above 80 years), had an increasingly 'unique' gut microbiome were more likely to survive the following four years than peers whose microbiome still closely resembled that of younger adults. People who retained high levels of Bacteroides bacteria at an advanced age (a group that is abundant in younger adults) actually had a worse survival prognosis.
In people aged 105 and older, certain bacterial groups (such as Akkermansia and Bifidobacterium) were found more frequently than in younger older adults. This is an intriguing finding, but the study was small and observational. Whether these bacteria contribute to an exceptionally long life or are simply associated with it remains unknown.
Researchers describe three biological pathways through which the gut microbiome could theoretically influence lifespan: strengthening the gut wall, suppressing chronic low-grade inflammation (a well-known factor in ageing), and improving the functioning of the energy centres in your cells. These are biologically plausible mechanisms, but the direct evidence for them comes largely from animal and laboratory research, not from large studies in humans.
A high intake of animal protein is associated in observational studies with unfavourable changes in the gut microbiome and increased inflammation. Whether this also affects lifespan in the long term has not yet been proven. And the most practical point: there is currently insufficient evidence that the gut microbiome can be deliberately improved through probiotics, prebiotics, or faecal transplantation in a way that actually extends lifespan. The idea is appealing, but the necessary clinical evidence in humans is still lacking.
Based on observational studies (including a large cohort study of >9,000 people), mechanistic studies, and animal research. No large randomised intervention trials in humans are available for lifespan extension. Causal relationships have not yet been proven.