Presented by: Miguel A. Garcia-Salcido
Background: multiple mechanisms linking the diversity and composition of the gut microbiome with metabolic diseases have been described. Some of those mechanisms are: the theory of energy harvesting, the microbiota-gut-brain axis, microbiota-host interactions, metabolites produced by microbiota, changes in the gut epithelium permeability and low-grade chronic inflammation. One of the major determinants of the composition and diversity of gut microbiota is the diet, and it´ s determined by the food environment (physical, economic, socio-cultural and political). Some authors described how industrialized-western-lifestyles have generated urban and semi-urban food environments (characterized by high consumption of saturated fat, animal-origin protein and food additives; with low consumption of fiber and plant-based protein). Replacing traditional food environments.
Aim: to determine the relationship between food environments with the gut microbiome diversity, biochemical and anthropometric measures associated with metabolic diseases in the Mexican population.
Methods: we conducted an observational, descriptive, cross-sectional study, from the gut microbiome analysis of metagenomic data. In a population composed of 42 participants from urban and semi-urban (including amerindians) environments in Mexico City.
Results: our results demonstrate differences in the composition and diversity of the gut microbiome between urban and semi-urban environments. We observed that 68.5% of the participants were women and 31.43% men, with a mean age of 41.8 (±11.3) years. There were no statistically significant differences for age (p=0.560) or sex (p=0.413) in the analized groups. Concerning the most consumed meals and products, semi-urban participants showed higher daily consumption frequencies of ultra-processed cereals (p=0.023), soft drinks (p<0.0001) and corn-based traditional meals (p=0.018); than urban participants. In the structural metagenomic analysis, for the urban group, we observed that the most abundant phylum was Bacteroidetes, followed by Firmicutes, Proteobacterias and Actinobacterias. In contrast, for the semi-urban group; the most abundant phylum was Firmicutes, followed by Bacteroidetes, Proteobacterias and Actinobacterias. We observed statistically significant differences in relative abundances of Bacteroidetes (p<0.0001), Firmicutes (p=0.0003), Actinobacteria (p<0.0001) and Euryarchaeota (p=0.002); between the groups. The principal coordinates analysis showed two clusters, grouping according to the food environment origin. Also, we identified four participants located in the transition zone of the clusters. Regarding the alpha diversity, the P50 value for Shannon Index was 2.81 (RIC 3.01-2.55) for urban group and 2.71 (3.05-2.22) for semi-urban group (p=0.734). P. copri, A. putredinis and F. parusnitzii species showed higher relative abundances for semi-urban, compared with urban group.
Conclusions: the composition and diversity of the gut microbiome of people from urban food environments are different, with respect to those from semi-urban food environments. There are differences in beta diversity between these two communities. However, there aren’t statistically significant differences in alpha diversity indices between food environments or between biochemical or anthropometric alterations. It is necessary to conduct studies with larger sample sizes to observe differences in these indices and to be able to make inferences at the species and strain levels.