Gut health home-testing kit outcomes vary between kits and manufacturers

Results and health assessments from gut microbiome home-testing kits vary whether they are produced by the same or different manufacturers.

The findings on testing kits from seven providers, published in Communications Biology, highlight the need for caution when interpreting or acting on test results, according to the authors.

Direct-to-consumer gut microbiome testing kits provide information on an individual’s microbiome composition, and many use these results to generate health assessments. However, the accuracy of these tests remains uncertain and no study has systematically evaluated their performance until now.

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Stephanie Servetas, Scott Jackson, and colleagues compared the results obtained from 21 direct-to-consumer gut microbiome testing kits from seven anonymised companies. All of the kits analysed the same combined fecal sample from an individual donor.

Clostridium highly variable

The authors found that the abundance of specific gut bacterial species varied across testing kit results, with the genus Clostridium — which includes several human pathogens such as Clostridioides difficile, a cause of diarrhoea — among the most variable.

While the average abundance of Clostridium reported by the American Gut Project was just over 2.5%, one company in this study reported five times this abundance, and three others failed to detect it in one or more samples.

When evaluating the accuracy of health assessments, the authors found that one of the three identical samples analysed by kits from the same company was categorised as ‘unhealthy’, while the other two were categorised as ‘healthy’.

The authors propose that a lack of standardised sampling procedures, sample processing and analysis, and the metrics used by testing companies may contribute to these discrepancies. They suggest that standardising sampling protocols and testing methods could help improve the accuracy of direct-to-consumer microbiome testing.