A recent study found that the composition of bacterial species that populate the human gut—the gut microbiota—evolves with age, particularly in the first years of life, and it differs among people from diverse geographic regions, potentially reflecting varying nutrition. Scientists sequenced the gut microbiomes (microbiota DNA) of healthy individuals of different ages from the Amazonas of Venezuela, the African nation of the Republic of Malawi, and metropolitan areas of the United States to determine whether differences could be discerned in the diversity of bacterial communities and in the metabolic and nutritional functionality of the genes they contained. Microbiome DNA was obtained from fecal samples donated by members of the study cohort, which included parents, children, siblings, and identical and fraternal twins. A broad spectrum of information was obtained from the analysis of the microbiome data. Of particular importance, microbiota bacterial diversity increased with age in all populations, and bacterial species composition evolved from an infant microbiota into an adult microbiota during the first 3 years of life. In addition, the repertory of microbiome genes involved in vitamin biosynthesis, carbohydrate metabolism, and other metabolic functions also changed with age and differed among the countries. There were greater differences in bacterial community composition among the children than among the adults, and there were significant differences in the types of bacteria represented by the microbiomes of the three geographically representative populations. The greatest differences among populations were seen between the United States and the other two countries, in terms of their bacterial capacities for metabolizing vitamins, carbohydrates, proteins, and other substances, which closely reflect dietary patterns in these countries. This study reveals significant differences in the gut microbiome among young children and adults and among cultures with different diets, underscoring the importance of considering microbiome contributions in studies and nutrition-related policies involving human development, nutrition, physiology, and the impact of westernization.
Yatsunenko T, Rey FE, Manary MJ, et al. Human gut microbiome viewed across age and geography. Nature 486: 222-227, 2012.