The human microbiome—those trillions of microbes that occupy the gut and many other parts of the body—plays a complex and intricate role in inflammatory diseases. One intriguing clue about its role is that place matters—the microbiome looks very different from one part of the world to another. Emigration and globalization reduce that diversity, with implications for biological systems that we don’t yet fully understand. How does location alter the microbial environment? What happens to the microbiome when people move from regions with traditional plant-based diets to the meat-centric and highly processed diet that dominates the Western plate?