ABSTRACT

Coffee intake in moderate amounts is associated with health benefits; however, how habitual coffee intake relates to gut microbiota and gastrointestinal physiology remains poorly understood. Here, we investigated in 61 healthy adults whether habitual coffee intake – assessed through eight-day dietary records and via urinary coffee biomarkers – was associated with gut microbiota composition and measurements of gastrointestinal physiology obtained by a wireless motility capsule. Frequent coffee drinkers (>3 out of 8 days of coffee intake) showed higher microbial richness compared to rare drinkers (<3/8 days), while caffeine metabolites positively correlated with faecal bacterial load. Lawsonibacter spp., Slackia spp., and unclassified Eggerthellaceae were more abundant in frequent drinkers, with Lawsonibacter positively associated with coffee intake. Caffeine metabolites were positively associated with colonic contractions, while habitual coffee intake and caffeine metabolites negatively associated with small intestinal pH. Small intestinal pH was also significantly lower in frequent coffee drinkers, compared to rare coffee drinkers. Together, these findings provide integrated evidence linking habitual coffee intake, not only to gut microbiota, but also to direct measurements of gastrointestinal physiology, warranting further investigation.

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