Differences in the gut microbiomes of distinct ethnicities within the same geographic area are linked to host metabolic health

Background: The human gut microbiota exhibits marked variation around the world, which has been attributed to dietary intake and other environmental factors. However, the degree to which ethnicity-associated differences in gut microbial community structure and function are maintained following immigration or in the context of metabolic disease is poorly understood. Results: We conducted a multi-omic study of 46 lean and obese East Asian (EA) and White (W) participants living in the San Francisco Bay Area. 16S rRNA gene sequencing revealed significant differences between ethnic groups in bacterial richness and community structure. W individuals were enriched for the mucin-degrading Akkermansia muciniphila. EA participants had increased levels of multiple Bacteroidetes species, fermentative pathways detected by metagenomics, and the short-chain fatty acid end products acetate, propionate, and isobutyrate. Differences in the gut microbiota between the EA and W groups could not be explained by reported dietary intake, were more pronounced for lean individuals, and were associated with current geographical location. Microbiome transplantations into germ-free mice confirmed that the differences in the gut microbiota of the EA and W individuals we analyzed are indeed independent of diet and that they differentially impact host body weight and adiposity in genetically identical mouse recipients. Conclusions: The reported findings emphasize the utility of studying diverse ethnic groups within a defined geographical location and provide a starting point for dissecting the mechanisms contributing to the complex interactions between the gut microbiome and ethnicity-associated lifestyle, demographic, metabolic, and genetic factors.