Holobiome and Radicle Science launch 6,000-person gut-brain trial
Holobiome and Radicle Science have launched GUT-FEELINGS, a decentralised, randomised controlled trial they describe as the largest interventional mental wellness study in US history. Backed by a grant from the Advanced Research Projects Agency for Health (ARPA-H), the two-year initiative will enrol more than 6,000 participants across two waves and test 19 proprietary food-derived prebiotic formulations against placebo, targeting self-reported anxiety and related mental wellness outcomes. Initial results are expected in the second half of 2027.
The study runs for 16 weeks per wave and uses a 20-arm design, randomising participants who report feelings of anxiety to one of the 19 prebiotic arms or a placebo. Outcomes include validated anxiety measures alongside stress, mood, sleep, quality of life, and metabolic markers. The biological data collection is notably ambitious: the protocol encompasses ultra-deep fecal microbiome sequencing, metabolomics, blood proteomics, wearable sensor data, continuous glucose monitoring, and facial scanning, generating more than 24,000 fecal samples and 12,000 blood samples in aggregate.
The platforms behind the trial
The study is designed to feed directly into Holobiome's developing gut microbiome foundation model, Mercator, which the company is building to map microbiome states to health outcomes and guide prebiotic and probiotic development. Holobiome's platform centres on its Microbiome Vault, described as a collection of gut bacterial strains, and a proprietary database linking more than 120,000 human metagenomes to specific health conditions.
Radicle Science contributes its patented Reflexive Trials platform, which the company says automates the orchestration of complex multi-arm, multi-omic decentralised studies and routes resulting evidence back into research and development workflows. Radicle reports having conducted placebo-controlled research with nearly 100,000 Americans since 2021, providing a comparator dataset and operational infrastructure at national scale.
Philip Strandwitz, chief executive and co-founder of Holobiome, said the trial addresses a gap in the field: "The missing link is large-scale multimodal data from interventional studies, the kind this trial is designed to generate."
Market context and regulatory considerations
The gut-brain axis has attracted growing scientific and commercial attention over the past decade, with a number of academic spinouts and venture-backed biotechs pursuing microbiome-based therapeutic and wellness candidates. Most programmes to date have targeted gastrointestinal indications, where regulatory pathways are more established; mental health applications remain earlier-stage and face a higher evidentiary bar from regulators and payers alike.
GUT-FEELINGS sits at the intersection of consumer wellness and clinical research, a position that carries distinct regulatory nuances. Because the interventions are prebiotic food products rather than drug candidates, they fall outside conventional pharmaceutical development pathways. The ARPA-H funding places the study within the agency's EVIDENT initiative, which focuses on generating objective measures of mental health and wellbeing. That federal framing may strengthen any future regulatory or reimbursement case, but the company has not indicated plans to seek FDA approval for specific health claims at this stage.
The parallel 19-arm design is the study's most operationally distinctive feature. Rather than advancing a single candidate through sequential trials, both companies are betting that a high-throughput, evidence-first model can compress the innovation cycle and surface responder subpopulations early. How well the approach translates beyond wellness into regulated pharmaceutical development will depend on the quality and reproducibility of the multimodal data the study generates, and on independent peer review of the eventual findings.