Characterization of gut microbiota composition and functions in patients with chronic alcohol overconsumption

Excessive alcohol intake can alter the gut microbiota, which may underlie thepathophysiology of alcohol-related diseases. We examined gut microbiota compositionand functions in patients with alcohol overconsumption for >10 years, compared to acontrol group of patients with a history of no or low alcohol intake. Faecal microbiotacomposition was assessed by 16S rRNA sequencing. Gut microbiota functions wereevaluated by quantification of short-chain fatty acids (SCFAs) and predictivemetagenome profiling (PICRUSt). Twenty-four patients, mean age 64.8 years (19males), with alcohol overconsumption, and eighteen control patients, mean age 58.2years (14 males) were included. The two groups were comparable regarding basicclinical variables. Nutritional assessment revealed lower total score on the screeningtool Mini Nutritional Assessment, lower muscle mass as assessed by handgripstrength, and lower plasma vitamin C levels in the alcohol overconsumption group.Bacteria from phylum Proteobacteria were found in higher relative abundance, whilebacteria from genus Faecalibacterium were found in lower relative abundance in thegroup of alcohol overconsumers. The group also had higher levels of the generaSutterella, Holdemania and Clostridium, and lower concentration and percentage ofbutyric acid. When applying PICRUSt to predict the metagenomic composition, wefound that genes related to invasion of epithelial cells were more common in the groupof alcohol overconsumers. We conclude that gut microbiota composition and functionsin patients with alcohol overconsumption differ from patients with low consumption ofalcohol, and seem to be skewed into a putative pro-inflammatory direction.