Impact of diet on gut microbiota in the globalized world

The human gut ‘‘metagenome’’ is a complex consortium of trillions of microbes, whose collective genomes contain at least 100 times as many genes as our own eukaryote genome. This essential ‘‘organ’’ provides the host with enhanced metabolic capabilities, protection against pathogens, education of the immune system, and modulation of gastrointestinal development. Historically, the microbial ecosystem of the digestive tract was specific for a geographic area, as much as the flora and fauna of an ecosystem are geographically distinct. A clear example of this richness and diversity is that currently in Africa, the microbial composition is very different from that described in the Western world. Globalization of the microbial population of our digestive tracts is due to industrialization and standardization of food chain products that homogenize the microorganisms we ingest. We describe how this relative homogeneity of the microbial composition of Europeans and North Americans could be related to globalization rather than a transcendent tendency of humans to select the same bacteria worldwide