Abstract MP68: Dietary Lignan and Cardio-metabolic Risk: Exploring the Role of the Gut Microbiome

Background and Study Purpose: The conversion of plant lignans to enterolignans for absorption is mediated through the gut microbiota. We explored the interconnections between the intake of dietary lignans, circulating concentrations of plasma enterolignans, the gut microbiome, and cardio-metabolic risk factors (LDL-cholesterol, HDL-cholesterol, & triglycerides). Design and method: The study was a repeated cross-sectional survey of up to 4 stool samples. Dietary lignan intake was assessed by two 7 day weighed records administered to coincide with fecal sample collection. DNA was extracted from 916 samples provided by 301 participants, and RNA was extracted from 369 samples from a subgroup of 96 participants. P<0.25 after false discovery rate correction was considered statistically significant. Results: A high ratio of plasma enterolactone to dietary lignan was significantly associated with the relative abundance of 35 species (24 enriched and 11 depleted species), including 8 Bacteroidetes and 13 Firmicutes species. Greater dietary lignan was only significantly associated with a lower plasma ratio of triglyceride to HDL when plasma enterolactone was high. The association between dietary lignans and ratio of TG to HDL was mainly mediated by plasma enterolactone level (mediation effect: 74.3%, P=0.002), which was partially captured by the weighted species score (mediation effect: 28.6%, P=0.02). We observed several significant interactions between dietary lignans and presence of species on ratio of TG to HDL, suggesting that the protective effect of dietary lignans on CVD risk factor depends on the presence/abundance of certain microbiota. The relative abundance of microbial pathways involved in I-isoleucine biosynthesis and glutaryl-coa degradation pathways were significantly greater in in participants with a higher level of plasma enterolactone. Conclusion: The health benefits of dietary lignans on lipid levels may be modified by the greater enrichment of biologically relevant microbiota species. FIGURE