Green Tea Liquid Consumption Alters the Human Intestinal and Oral Microbiome

<jats:sec><jats:title>Scope</jats:title><jats:p>GTPs (green tea polyphenols) exert anti‐CRC (colorectal cancer) activity. The intestinal microbiota and intestinal colonization by bacteria of oral origin has been implicated in colorectal carcinogenesis. GT modulates the composition of mouse gut microbiota harmonious with anticancer activity. Therefore, the effect of green tea liquid (GTL) consumption on the gut and oral microbiome is investigated in healthy volunteers (<jats:italic>n</jats:italic> = 12).</jats:p></jats:sec><jats:sec><jats:title>Methods and results</jats:title><jats:p>16S sequencing and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) analysis of both fecal and saliva samples (collected before intervention, after 2 weeks of GTL (400 mL per day) and after a washout period of one week) in healthy volunteers show changes in microbial diversity and core microbiota and difference in clear classification (partial least squares‐discriminant analysis [PLS‐DA]). An irreversible, increased FIR:BAC (<jats:italic>Firmicutes</jats:italic> to <jats:italic>Bacteroidetes</jats:italic> ratio), elevated SCFA producing genera, and reduction of bacterial LPS synthesis in feces are discovered in response to GTL. GTL alters the salivary microbiota and reduces the functional pathways abundance relevance to carcinogenesis. Similar bacterial networks in fecal and salivary microbiota datasets comprising putative oral bacteria are found and GTL reduces the fecal levels of <jats:italic>Fusobacterium</jats:italic>. Interestingly, both <jats:italic>Lachnospiraceae</jats:italic> and B/E (<jats:italic>Bifidobacterium</jats:italic> to <jats:italic>Enterobacteriacea</jats:italic> ratio—markers of colonization resistance [CR]) are negatively associated with the presence of oral‐like bacterial networks in the feces.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>These results suggest that GTL consumption causes both oral and gut microbiome alterations.</jats:p></jats:sec>