Studies have demonstrated health benefits of caffeine consumption, including decrease in cardiovascular disease, diabetes, and liver diseases. The exact mechanisms are not known. Caffeine consumption may possibly modulate the gut microbiome and therefore affect health and disease risk. We examined the association between caffeine consumption and the composition and structure of the colonic-gut microbiota.
In this study, 34 participants underwent a screening colonoscopy and had endoscopically normal colons. We obtained a total of 97 snap-frozen colonic mucosa biopsies from various segments of colon from these individuals. Microbial DNA was extracted, and subsequently amplified for the 16S rRNA gene V4 region and sequenced using the Illumina MiSeq platform. We analyzed the sequencing data using the UPARSE and SILVA database for operational taxonomic unit (OTU) classification. Self-administered BLOCK Food Frequency Questionnaire was used to ascertain daily caffeine consumption. We compared the diversity and relative abundance of bacterial taxonomies by high (≥82.9 mg) vs. low (<82.9 mg) consumption of caffeine. False discover rate (FDR) P-values were reported and <0.05 indicated statistical significance.
The alpha diversity was the greatest in high caffeine consumers (Shannon index P < 0.0001). The beta diversity differed significantly between high vs. low caffeine drinkers (P = 0.0001). The composition of microbiomes did not differ at the phylum level based on caffeine consumption. At the genus level, high caffeine consumption was associated with increased relative abundance of Faecalibacterium (P < 0.0005) and Roseburia (P = 0.02), but decreased levels of Erysipelatoclostridium (P value <0.001) and an OTU belonging to the Lachnospiraceae family (Unc8895) (P < 0.0005). The observed association was seen regardless of age and dietary quality. Other bacteria commonly detected in gut microbiomes, including Odoribacter, Dialister, Fusicatenibactor, Alistipes, Blautia, and multiple members of Lachnospiraceae, were significantly more abundant (P < 0.05) in participants with higher caffeine consumption (Table 1).
Higher caffeine consumption was associated with increased richness and evenness of the mucosa-associated gut microbiota, and higher relative abundance of anti-inflammatory bacteria, such as Faecalibacterium and Roseburia and lower levels of potentially harmful Erysipelatoclostridium.