A company called Human Biome S.A. has registered a clinical trial to test whether capsules made from donor stool can slow down how fast people age, as estimated by a blood test.1 The study, listed on the US trials registry ClinicalTrials.gov as NCT07912164, was first posted on November 3, 2026, and is not yet recruiting.1 That means there are no results. What the record does show is exactly what the researchers plan to measure, in whom and for how long.
What happened
The trial will test fecal microbiota transplantation, usually shortened to FMT. It means taking gut bacteria from a healthy donor’s stool and putting them into another person’s gut.2 Here the bacteria are delivered as swallowed capsules, which the registry calls HBI MBiotix Caps.1
The study is described as randomized, double-blind and placebo-controlled.1 In plain words: people are assigned by chance to get either the real capsules or a matching dummy pill (a placebo), and neither the participants nor the study staff know who got which. The sponsor plans to enroll an estimated 68 people.1 The start is listed for December 2026, with the main results expected by December 2027.1
The registry says the trial is for adults aged 45 to 80 with what it calls “metabolic neglect.”1 The conditions listed include aging, inflammation, metabolic syndrome (a cluster of problems such as high blood sugar and high blood pressure), cognitive health and longevity.1 The registry lists the phase as “not applicable,” a label often used for studies that are not structured as standard drug trials.1
What the trial will ask participants to do
According to the record, people in the study will:1
- go through a short preparation phase with targeted antibiotics and a standard bowel cleanse;
- take 2 starting doses of the capsules or the dummy pill, then 5 “booster” rounds roughly every 4 weeks;
- come in for regular check-ups with physical exams, blood draws and memory and thinking tests, and collect stool samples at home;
- keep a diary of side effects, when they took the product, stool collection and what they eat.
The thinking tests named in the record are the CANTAB computer-based test battery and the MoCA, a short pen-and-paper screen for memory and thinking problems.1
What the researchers will measure
The trial’s first question is whether the capsules slow the “biological pace of aging” as measured by DunedinPACE.1 DunedinPACE is an epigenetic clock: a blood test that reads chemical tags on DNA and turns them into an estimate of how fast a person’s body is aging. It is a lab measure, not a direct count of illness or years lived.
The second question is whether the capsules lower long-lasting, low-level inflammation, using blood markers including suPAR, IL-6 and hs-CRP.1 The researchers also say they want to see whether the gut bacteria improve metabolic health and thinking skills through the “gut-brain axis,” the links between the gut and the brain.1
The official main outcome is a “responder rate”: the percentage of people who show a “clinical and biological response,” checked at the start, at week 13 and at week 26.1 The registry summary given to Biohack does not spell out what counts as a response, so it is not yet clear how much change on the aging clock or inflammation markers a person would need to be counted.
What this does not show yet
A trial registration is a plan, not a finding. Nobody has taken the capsules in this study yet, so it says nothing about whether they change aging, inflammation, thinking or anything else.
Even if results come out positive, several limits are already visible in the design. About 68 people is a small group for a question as broad as aging.1 The main follow-up runs to 26 weeks, roughly six months.1 And the headline measure is an aging clock and blood markers, not whether people stay healthier or live longer. A change in a lab score does not by itself show a change in health later in life.
The preparation phase also matters. Participants get antibiotics and a bowel cleanse before the capsules.1 Because both groups go through it, a well-run comparison against the dummy pill should help separate the effect of the donor bacteria from the effect of the preparation itself.
Who is behind it
The registry names Human Biome S.A. as the sponsor.1 The record shown to Biohack does not list other funders, collaborating hospitals or lead investigators. When a company sponsors a test of a product it is developing, the results it reports are worth reading alongside independent analysis once they appear.
How it fits the field
FMT is not new. Its main established use is for a hard-to-treat gut infection, Clostridium difficile (C. diff), that keeps coming back after antibiotics. A 2024 review in the journal BIOCELL put the cure rate there at 87% to 90%.2 It is recognized as a treatment for recurrent C. diff infection.3 It has also been tried for other gut conditions such as inflammatory bowel disease and irritable bowel syndrome.2
Interest in using it against aging grew from animal studies. In 2017, researchers found that feeding middle-aged African turquoise killifish the gut contents of young fish extended their lifespan and delayed decline in behavior, according to the BIOCELL review.2
A 2022 mouse study from the Quadram Institute and the University of East Anglia in the UK, published in the journal Microbiome, swapped gut bacteria between young and old mice.4 The team used young mice of 3 months and older mice of 18 and 24 months.3 Bacteria from old mice weakened the lining of young mice’s guts and set off inflammation in their brains and eyes.4 Going the other way, bacteria from young mice reversed those changes in old mice.4 The study was funded by the Biotechnology and Biological Sciences Research Council, part of UK Research and Innovation.4
The researchers themselves urged caution. Their institute’s announcement said they warned against applying the results directly to humans until similar studies in elderly people could be done.4 Lead author Aimee Parker said:
We were excited to find that by changing the gut microbiota of elderly individuals, we could rescue indicators of age-associated decline commonly seen in degenerative conditions of the eye and brain.
In that quote, “elderly individuals” refers to the old mice in the study.4
The BIOCELL review, which summarized much of this animal work, concluded that the field “is still in its infancy” while also describing FMT as having great potential for healthy aging.2 It noted that results may depend on the recipient’s age, sex, genes and the gut bacteria they end up with after the transplant.2 One of the review’s authors lists an affiliation with a Chinese drug company, Zhejiang Charioteer Pharmaceutical.2
The idea behind the new trial follows the same thread. Gut bacteria change with age, losing variety around age 60 to 70, according to a summary by the French company Exden, and those shifts have been linked to a leakier gut and age-related inflammation, sometimes called “inflammaging.”3 The new trial lists inflammaging as one of its conditions.1
What to watch next
- Recruitment: the registry status should change from “not yet recruiting” once enrollment begins, planned for December 2026.1
- How “response” is defined: whether the sponsor publishes a detailed plan showing what change on the aging clock and inflammation markers counts as success.
- Safety: participants will log side effects in a diary, and the trial lists safety as a goal alongside effectiveness.1
- Results: main results are expected by December 2027.1 Whether they appear in a peer-reviewed journal, and how they compare between the capsule and dummy-pill groups, will matter more than any single headline number.
