Abstract
BackgroundObesity and related comorbidities are major health concerns among many US immigrant populations. Emerging evidence suggests a potential involvement of the gut microbiome. Here, we evaluated gut microbiome features and their associations with immigration, dietary intake, and obesity in 2640 individuals from a population-based study of US Hispanics/Latinos.ResultsThe fecal shotgun metagenomics data indicate that greater US exposure is associated with reduced ɑ-diversity, reduced functions of fiber degradation, and alterations in individual taxa, potentially related to a westernized diet. However, a majority of gut bacterial genera show paradoxical associations, being reduced with US exposure and increased with fiber intake, but increased with obesity. The observed paradoxical associations are not explained by host characteristics or variation in bacterial species but might be related to potential microbial co-occurrence, as seen by positive correlations among Roseburia, Prevotella, Dorea, and Coprococcus. In the conditional analysis with mutual adjustment, including all genera associated with both obesity and US exposure in the same model, the positive associations of Roseburia and Prevotella with obesity did not persist, suggesting that their positive associations with obesity might be due to their co-occurrence and correlations with obesity-related taxa, such as Dorea and Coprococcus.ConclusionsAmong US Hispanics/Latinos, US exposure is associated with unfavorable gut microbiome profiles for obesity risk, potentially related to westernized diet during acculturation. Microbial co-occurrence could be an important factor to consider in future studies relating individual gut microbiome taxa to environmental factors and host health and disease.
Highlights
Obesity and related comorbidities are major health concerns among many US immigrant populations
Principal-coordinates analysis (PCoA) of weighted UniFrac distances indicated that both host obesity and US exposure (US born and duration of US residence) significantly co-varied with the β-diversity of gut microbiome and explained moderate proportion of variance (PERMANOVA analysis by adonis function from vegan package, R2 = 0.9% and 1.8% respectively, both P < 0.001) (Additional file 1: Figure S1B)
While we found expected positive associations between bacterial genera (e.g., Roseburia and Prevotella which were associated with higher fiber intake) and xylanase, Dorea and Coprococcus which were positively associated with obesity were positively associated with xylanase (Fig. 4D)
Summary
Obesity and related comorbidities are major health concerns among many US immigrant populations. Emerging evidence suggests that immigration is associated with gut microbiome alterations, which might be related to changes in diet and other factors during the acculturation process [10, 11]. A recent study in immigrants from Thailand to the USA found that US immigration was associated with loss of gut microbiome diversity and reduced ratio of Prevotella to Bacteroides, and loss of gut microbiome diversity was associated with obesity [10]. These results suggested a potential involvement of gut microbiota alterations in immigration-related obesity [10]. The mechanisms underlying the unexpected association between gut Prevotella and human diseases are not fully understood [21,22,23]
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