Gut microbiome testing

What it is

Gut microbiome testing sequences bacterial DNA from a stool sample. Two methods are sold interchangeably though they differ: 16S rRNA gene sequencing identifies which bacteria are present down to roughly the genus level, while shotgun metagenomics resolves species and strains and reads functional genes. Providers translate the result into diet, supplement and probiotic plans for gut health and longevity. The interpretive layer is where it thins out. There is no consensus definition of a healthy microbiome and no validated reference range to score a person against (Shanahan et al., Gastroenterology, 2021), and a 2024 international consensus held that microbiome analysis is not ready to guide clinical care outside specialist centers. The one place the evidence is strong, fecal transplantation for recurrent C. difficile, now served by the approved products Rebyota and Vowst, is not what longevity clinics sell.