PT  - JOURNAL ARTICLE
AU  - Asnicar, Francesco
AU  - Leeming, Emily R
AU  - Dimidi, Eirini
AU  - Mazidi, Mohsen
AU  - Franks, Paul W
AU  - Al Khatib, Haya
AU  - Valdes, Ana M
AU  - Davies, Richard
AU  - Bakker, Elco
AU  - Francis, Lucy
AU  - Chan, Andrew
AU  - Gibson, Rachel
AU  - Hadjigeorgiou, George
AU  - Wolf, Jonathan
AU  - Spector, Timothy D
AU  - Segata, Nicola
AU  - Berry, Sarah E
TI  - Blue poo: impact of gut transit time on the gut microbiome using a novel marker
AID  - 10.1136/gutjnl-2020-323877
DP  - 2021 Sep 01
TA  - Gut
PG  - 1665--1674
VI  - 70
IP  - 9
4099  - http://gut.bmj.com/content/70/9/1665.short
4100  - http://gut.bmj.com/content/70/9/1665.full
SO  - Gut2021 Sep 01; 70
AB  - Background and aims Gut transit time is a key modulator of host–microbiome interactions, yet this is often overlooked, partly because reliable methods are typically expensive or burdensome. The aim of this single-arm, single-blinded intervention study is to assess (1) the relationship between gut transit time and the human gut microbiome, and (2) the utility of the ‘blue dye’ method as an inexpensive and scalable technique to measure transit time.Methods We assessed interactions between the taxonomic and functional potential profiles of the gut microbiome (profiled via shotgun metagenomic sequencing), gut transit time (measured via the blue dye method), cardiometabolic health and diet in 863 healthy individuals from the PREDICT 1 study.Results We found that gut microbiome taxonomic composition can accurately discriminate between gut transit time classes (0.82 area under the receiver operating characteristic curve) and longer gut transit time is linked with specific microbial species such as Akkermansia muciniphila, Bacteroides spp and Alistipes spp (false discovery rate-adjusted p values <0.01). The blue dye measure of gut transit time had the strongest association with the gut microbiome over typical transit time proxies such as stool consistency and frequency.Conclusions Gut transit time, measured via the blue dye method, is a more informative marker of gut microbiome function than traditional measures of stool consistency and frequency. The blue dye method can be applied in large-scale epidemiological studies to advance diet-microbiome-health research. Clinical trial registry website https://clinicaltrials.gov/ct2/show/NCT03479866 and trial number NCT03479866.Data are available upon reasonable request. Metagenomes are deposited in EBI ENA under accession number PRJEB39223. The non-metagenomic data used for analysis in this study are held by the Department of Twin Research at King’s College London and access can be requested from https://twinsuk.ac.uk/resources-for-researchers/access-our-data/ to allow for anonymisation and compliance with GDPR standards.