Faecal microbiota transplant (FMT)

Faecal microbiota transplant (FMT) is the transfer of processed stool from a healthy donor into the gastrointestinal tract of a recipient, with the aim of reconstituting a disrupted microbial community. Its only firmly established clinical indication is recurrent Clostridioides difficile infection (CDI), where it achieves cure rates exceeding 80–90 % and has superior efficacy to antibiotics alone, and it is now guideline-recommended for this purpose in most Western health systems. For all other indications — inflammatory bowel disease, metabolic syndrome, autism spectrum disorder, neurological conditions and ageing-related outcomes — the evidence base is investigational and results from randomised trials have been mixed, with some showing modest effects and others showing no benefit. Delivery methods include colonoscopy, nasogastric or nasoduodenal tube, enema and encapsulated freeze-dried preparations; donor screening is critical and complex, requiring testing for a broad panel of pathogens, and several serious adverse events including transmission of multi-drug-resistant organisms have been reported. The 'longevity' framing of FMT — informed by mouse studies showing life-extension after transfer from young donors — remains speculative in humans.