Inflammatory dietary potential and gut microbiota in older adults with overweight or obesity and metabolic syndrome.

INTRODUCTION

Understanding how inflammatory dietary potential modulates the gut microbiota diversity, composition, and function remains a topic of ongoing debate. The present study aims to assess the longitudinal relationship between inflammatory dietary potential and gut microbiota characteristics in older adults with overweight/obesity and metabolic syndrome.

METHODS

This longitudinal sub-study and secondary analyses nested under the context of the PREvención con Dieta Mediterránea-Plus (PREDIMED-Plus) randomized clinical trial included 648 participants (mean age 65 ± 5 years, 47 % women). Inflammatory dietary potential was based on energy-adjusted dietary inflammatory index (E-DII) score, assessed using a validated 143-item food frequency questionnaire. Gut microbiota was characterized using 16S rRNA sequencing and 518 identified faecal metabolites were analysed through liquid chromatography-tandem mass spectrometry. The relationship between E-DII score (exposure) and gut microbiota alpha and beta diversity and composition, in terms of microbial genera, and faecal metabolites (outcome) with available data at two timepoints (baseline and 1-year thereafter), and longitudinally, was subsequently analysed.

RESULTS

Anti-inflammatory dietary potential as measured by lower E-DII score, either as continuous or categorical, demonstrated significant associations with increased alpha diversity indices (i.e., Chao1, Inverse Simpson and Shannon; all P < 0.05), and distinct beta diversity profiles at baseline (R2 = 0.004; PERMANOVA P = 0.047) and after 1-year (R2 = 0.006; PERMANOVA P = 0.003). Furthermore, anti-inflammatory E-DII score was associated with 24 microbial genera, 4 faecal metabolites, and 1 metabolomic network (all FDR < 0.05). Pro-inflammatory E-DII score was also associated with 1 microbial genera and 2 faecal metabolites (all FDR < 0.05). Results remained significant when evaluating changes in E-DII over time with changes in alpha diversity indices and metabolomic network.

CONCLUSION

Anti-inflammatory dietary potential of diet may enhance gut microbiota diversity and potentially modulate its composition in older adults with metabolic syndrome.