Bifidogenic and butyrogenic effects of young barely leaf extract in an in vitro human colonic microbiota model

Young barley leaf extract (YBL) contains beneficial substances such as fructans, minerals, and vitamins. The effects of YBL administration on the human colonic microbiota and its production of metabolites were evaluated using an in vitro model culture system. Fermentations were started by inoculating fecal samples from nine healthy subjects, with or without 1.5% YBL. Bacterial 16S rRNA sequencing results confirmed that YBL administration significantly increased the relative abundances of bacteria related to the genus Bifidobacterium (p = 0.001, paired t-test) and those of the genera Faecalibacterium, Roseburia, Unclassified Ruminococcaceae, and Lachnospira (p = 0.013, p = 0.019, p = 0.028, and p = 0.034, respectively, paired t-test). Increased abundances of the latter genera corresponded to increased butyrate production in human colonic microbiota models following fermentation with 1.5% YBL, when compared to fermentation without 1.5% YBL (p = 0.006, Dunnett's test). In addition, YBL administration significantly increased the production levels of amino acids such as lysine, glutamate, serine, threonine, alanine, isoleucine, leucine, valine, and phenylalanine. Therefore, our results showed the health-promoting bifidogenic and butyrogenic effects of YBL.