Kanako Sugawara^1,, Ailing Hu¹, Takuji Yamaguchi¹, Masahiro Tabuchi¹, Yasushi Ikarashi¹, Hiroyuki Kobayashi¹

Bananas, rich in prebiotics, dietary fibre, oligosaccharides, vitamins and minerals, have positive effects on gut health. However, their impact on oral cavity-derived gut microbiota and the intestinal environment remains unclear. This study investigated changes of the gut microenvironment and oral cavity-derived gut microbiota populations induced by banana intake. Twenty-six healthy women were instructed to consume two bananas per day for 2 weeks. We measured urinary indoxyl sulfate levels (a general gut microenvironment index) and the proportion of oral microbiota species within the gut microbiota before and after the 2-week banana consumption period. Banana intake significantly reduced urinary indoxyl sulfate levels. Additionally, participants aged < 40 years showed decreased indole levels, while no significant change occurred in those aged ≥ 40 years. The total number of bacterial species decreased due to banana intake. However, oral microbiota and Porphyromonas spp. populations remained unchanged in all participants. Nevertheless, participants with a high urinary indoxyl sulfate levels before banana intake showed slightly reduced oral microbiota and Porphyromonas spp. prevalence after banana intake, along with significantly lower urinary indoxyl sulfate levels. Therefore, the decreases in urinary indoxyl sulfate and the prevalence of oral cavity-derived bacteria and Porphyromonas spp. indicates the regulatory activity of bananas on gut microbiota.

oral bacteria, gut microbiota, Porphyromonas spp, indoxyl sulfate, banana intake