Overview
- A peer-reviewed study published February 26 in Communications Biology sent three identical, standardized fecal samples to each of seven direct-to-consumer companies and found widely divergent microbial profiles.
- The cross-company differences were about as large as those typically seen between samples from different people, indicating poor reproducibility across providers.
- At least one company delivered contradictory assessments on replicates, labeling two results as healthy and one as unhealthy, and companies varied in detecting taxa such as Clostridium.
- NIST created a homogenized human stool reference material used in the study and now sells it for calibration and quality control to help improve testing consistency.
- Authors attribute inconsistencies to differences in collection, processing, sequencing, analysis, and interpretation, warn consumers against making medical decisions based on these tests, and call for clear standards and stronger oversight.