Relationships between barley consumption and gut microbiome characteristics in a healthy Japanese population: a cross-sectional study

Objective: Barley contains abundant soluble β –glucan fibres, which have established health benefits. In addition, the health benefits conferred by the gut microbiota have attracted considerable interest. However, few studies have focused on the barley intake and microbiota of the Japanese population. In this study, we aimed to identify the relationship between the barley consumption and gut microbiota composition of the Japanese population. Research Methods & Procedures: A total of 236 participants were recruited in Japan, and 94 participants with no complication of diabetes, hypertension, and dyslipidemia were selected for the study. We analysed faecal samples from the participants, their medical check –up results, and responses to questionnaires about dietary habits. The participants were grouped according to their median barley intake. Then, we assessed the relative abundance of 50 microbial genera throughout the group and selected 20 that differed at P < 0.1 (Mann–Whitney U –test). We also analysed the networks and clustering of the 20 selected genera. Results: According to their relative abundance, Bifidobacterium, Anaerostipes, and Butyricicoccus were candidate characteristic microbiota of the group that consumed large amounts of barley (P < 0.05). Furthermore, network and cluster analyses revealed that barley directly correlated with Bifidobacterium and Butyricicoccus. Conclusions: Barley consumption generates changes in the intestinal microbiota of the Japanese population. We found that Bifidobacterium, Anaerostipes, and Butyricicoccus abundance was positively associated with barley consumption. This study showed that barley is important for gut microbiota and relates to Japanese traditional food like natto.