Can certain fungi or bacteria in your gut influence your cellular ageing?
Yes, certain gut bacteria and their metabolic by-products can accelerate cellular ageing, but most of the evidence still comes from cell and mouse studies; for concrete supplement recommendations the human evidence is still too thin.
Gut bacteria produce substances that can directly age your cells. A good example is phenylacetylglutamine (PAGln), a compound produced by gut bacteria that occurs at higher concentrations in older people. In cell and mouse studies, PAGln caused damage to mitochondria (the energy factories in your cells) and to DNA, after which the cells entered an aged, non-dividing state. Blocking the receptor to which PAGln attaches, or using agents that clear away such aged cells, suppressed this effect in mice. Whether this also applies to humans has not yet been established.
The relationship between your gut inhabitants and cellular ageing works in both directions. A disrupted gut microbiome (less diversity, more harmful bacteria) encourages aged cells to accumulate. Those aged cells in turn secrete a cocktail of inflammatory substances that further disrupt the gut microbiome. This self-reinforcing process has been linked to age-related conditions such as bone loss, muscle wasting and joint degeneration, but the causal evidence in humans is still incomplete.
In women after the menopause, an additional factor plays a role. Lower oestrogen levels are associated with less diversity in the gut microbiome and a less dense gut barrier, allowing low-grade inflammatory substances to enter the bloodstream more easily. This is thought to contribute to bone loss. Oestrogen therapy can partially reverse this, but age-related factors appear to play a larger role than the menopause alone.
Probiotics and prebiotics are discussed as a possible way to slow this process, but honestly there is still too little research to say whether they actually work. Which specific bacterial strains curb cellular ageing, and at what dose, is unknown. It is therefore too early to recommend supplements on the basis of this mechanism. A Mediterranean diet influences the gut microbiome in a favourable way, but here too the direct effect on cellular ageing has not yet been demonstrated.
Claims based on PMID 39794469 (PAGln, cell and mouse studies), 39148278 and 34960102 (dysbiosis-senescence interaction, SASP, probiotics), 39585466 (menopause and gut microbiome), 37834025 (musculoskeletal system), 29244059 (Mediterranean diet). Human causal evidence is largely absent; cell and animal studies predominate.