Abstract 48: Plant-based Diet Index and Cardiometabolic Risk Markers: Exploring the Role of the Gut Microbiome

Abstract

Objectives: To investigate the association between a plant-based diet index and microbial composition and functionality, as well as the inter-relationships between plant-based diets, gut microbiome, and cardiometabolic risk markers. Design and method: Metagenomic profiling was performed on 916 fecal samples collected among 301 men who participated in the Men’s Lifestyle Validation Study. Using data from a food frequency questionnaire, a Plant-based Diet Index (PDI) was derived to assess the adherence to a plant-based diets. The associations between PDI adherence and the relative abundance of microbial species and pathways were evaluated using Multivariate Association with Linear Models (MaAsLin2). P values below 0.25 after false discovery rate correction following the Benjamini-Hochberg method were considered statistically significant. Results: After multivariate adjustment, the value of the PDI score was significantly and positively associated with the ratio of Firmicutes to Bacteroidetes (Spearman r=0.10, P=0.005). Specifically, the PDI was significantly associated with the relative abundance of 77 taxa (including 39 species) out of 506 filtered taxa and 15 pathways (out of 80 filtered features). In particular, a higher adherence to the PDI was significantly, positively, associated with of the relative abundance of Firmicutes and of pathways involving degradation of complex plant carbohydrates. It was also inversely associated with the relative abundance of Bacteroidetes and Proteobacteria, as well as pathways involved in the urea cycle and amino acid biosynthesis. We also found that 14 species significantly interacted with PDI in modulating plasma ratio of TG to HDL-C. The association of PDI with lower TG to HDL ratio was significantly strengthened in the presence of the species positively correlated with the PDI score, such as Ruminococcus lactaris , Haemophilus parainfluenzae, and Methanobrevibacter smithii or in the absence of the species inversely correlated with the PDI score, such as Paraprevotella spp. Conclusions: A greater adherence to a plant-based diet was associated with a microbial profile featured by higher abundance of species in Firmicutes and depletion of species in Bacteroidetes and Proteobacteria, and such a profile may further strengthen the favorable associations between plant-based diets and human cardiometabolic risk.