Japanese Diet Score Is Associated with Gut Microbiota Composition in Young Japanese Adults

The Japanese diet (JD) is accepted as a healthy dietary pattern, which has protective effects against cancer and cardiovascular diseases. However, it remains unclear whether there is any association between the JD and fecal microbiota composition. This cross-sectional study examined the relationship between JD scores and fecal microbiota in young Japanese adults, through the analysis of fecal microbiota using the terminal restriction fragment length polymorphism (T-RFLP) method. JD scores were calculated with regard to nine food groups (rice, miso soup, pickles, green and yellow vegetables, seaweeds, fish, green tea, meat, and coffee) based on a brief self-administered diet-history questionnaire. JD total scores were categorized as low (score 0-3) or high (score 4-8). The high-scoring JD group exhibited a significantly higher relative abundance of Bacteroides than the low JD group, whereas the low JD group exhibited a significantly higher relative abundance of Prevotella than the high JD group. With regard to food group intakes, a higher consumption of rice was associated with a significantly lower relative abundance of Prevotella, whereas a higher consumption of green tea was associated with a significantly higher relative abundance of Bifidobacterium. To the best of our knowledge, this is the first study demonstrating an association between JD score and fecal microbiota and may allow the prediction of changes in fecal microbiota due to changes in the JD.