Analysis of healthy reference ranges for clinically relevant gut microbial indicators: Mykinso cohort study in Japan

Background Although several large cohort studies have focused on the human gut microbiome, large cohort study of the Japanese gut microbiome is scarce, especially that of healthy or non-diseased individuals. The purpose of this study was to establish a reference range for gut microbial indices by collecting Japanese real-world microbiome data from a Mykinso cohort. Methods We collected stool samples and original survey on lifestyle from 5,843 Japanese people through Mykinso gut microbiome testing service. From the obtained 16S rRNA sequence data derived from the stool sample, the ratio and distribution of each taxon were analyzed. The relationship between different epidemiological attributes and gut microbial indicators were statistically tested. Results The qualitative and quantitative indicators of these common gut microbiota were confirmed to be strongly correlated with age, sex, constipation/diarrhea, and history of lifestyle-related diseases. Therefore, we set up the healthy sub-cohort that controlled for these attribute factors, and defined a reference range from the distribution of gut microbial index in that population. Conclusions The gut microbiota of Japanese people had high beta diversity, and there was no single “typical” gut microbiota type. We believe that the reference range of the gut microbial index obtained in this study can be a new reference value for determining the balance and health of the gut microbiota of an individual. In the future, it is necessary to clarify the clinical validity of this reference value by comparing with the clinical disease cohort.