Lotus Seed Resistant Starch and Sodium Lactate Regulate Small Intestinal Microflora and Improve Metabolic Disorders in Hyperlipidemic Rats

The effects of lotus seed resistant starch type 3 (LRS3) as a prebiotic and its postbiotic metabolite sodium lactate (SL) on the regulation of small intestinal flora homeostasis and the improvement of metabolic disorders in high-fat diet (HFD)-induced hyperlipidemic rats were investigated. Thirty-six male SD rats were administered LRS3, SL, or a combination of LRS3 and SL for consecutive 4 weeks, referred to as HLRS, HSL and HLRSSL groups, respectively. The diversity and metabolomics of small intestinal flora were measured compared to HFD model group (HMC). We found that the abundance of Romboutsia and Blautia was significantly reduced in the HLRS group, while Psychrobacter and Moheibacter abundance was significantly increased in the HSL group. In the HLRSSL group, the abundance of Ruminococcus and Treponema were found to be increased. Untargeted metabolomics showed that LRS3 promoted the production of taurodeoxycholic acid, while SL promoted production of estradiol-17beta 3-sulfate. However, simultaneous ingestion of LRS3 and SL promoted carvacrol and estradiol-17beta 3-sulfate production. The different metabolites between groups and HMC group were found in steroid hormone biosynthesis, amino acids biosynthesis and metabolism, vitamin B6 metabolism, pentose and glucuronate interconversions, taurine and hypotaurine metabolism, which are closely related to lipid metabolism and the development of hyperlipidemia. Finally, by constructing the correlation among lipid indicators, microbiota and metabolites, it was discovered that LRS3 and SL synergies effectively promote Treponema-dependent production of carvacrol, which further regulates blood lipid levels by inhibiting the production of cholesterol synthesis-related enzymes.