Abstract Body: Introduction

Plant-based diets have gained attention for their potential to improve cardiovascular health through various mechanisms, including the modulation of gut microbiota and metabolites. To investigate the impact of plant-based diets on cardiovascular disease (CVD) risk factors, we conducted the Study with Appetizing Plantfoods - Meat Eating Alternatives Trial (SWAP-MEAT) (NCT03718988). Participants were assigned to consume either plant-based meats or animal meats for two consecutive 8-week phases, swapping from either plant-to-animal or vice versa at the 8-week midpoint. We previously reported improvements in several CVD risk factors, including a decrease in trimethylamine N-oxide (TMAO) levels in both plant-based diet groups. We found a diet-order effect: participants assigned a plant-based diet for phase 1 did not see an increase in TMAO during their subsequent animal-meat phase, suggesting differential effects on microbiome composition and production of trimethylamine (TMA), a precursor of TMAO, based on the sequence of dietary interventions. Our objective was to determine if the intestinal environment, made up of metabolites, microbiota, and the enzymes they secrete, were altered between groups 1 and 2 after phase 1, mediating the order effect we observed in our original SWAP-MEAT study.

Methods
We investigated the expression of specific microbiome-encoded genes in relation to subsequent serum TMAO concentrations, as well as determined fecal metabolite differences that correspond to the different diets. We conducted 16S microbiome analysis, metabolomics analysis, and qRT-PCR analysis to measure the relative abundance of mRNA from genes involved in TMA production.

We tested Spearman’s correlations of TMA enzymes, metabolites, and microbes with TMAO across groups to evaluate changes in the intestinal environment in groups 1 and 2.

Results

We identified around 50 significant metabolites, and 12 significant microbiota genera correlated with TMAO. No significant correlation was found for the TMA ensues CntA, CutC, and GrdH with TMAO.

Conclusions

By identifying trends associated with both dietary patterns and TMA production, we aim to advance personalized patient care and develop targeted therapies for CVD prevention. Ultimately, this research advances microbiome-based approaches for cardiovascular disease prevention and informs future interventions targeting gut microbiota and metabolites.