Soy Protein Concentrate With Low and High Isoflavones Can Reverse Non-alcoholic Fatty Liver Disease Caused by Obesity and Alter Gut Microbial Composition

Objectives: To examine the effects of 10 weeks feeding of low and high isoflavones levels in soy protein concentrate after 8 weeks on casein (CAS) as control diet on protection against Non-Alcoholic Fatty Liver Disease (NAFLD) and determine alterations within the fecal gut microbiome in this obese rat model. Methods: Twenty-one, six-week-old male Zucker rats were fed were randomly assigned to casein diet (CAS), soy protein with low isoflavones (LIF), or soy protein with high isoflavones (HIF) for 10 weeks (n=7 rats/group). Rats were sacrificed and livers were samples taken for histopathological analysis. Fecal samples were collected for DNA extraction and microbial community composition was determined through amplicon sequencing of the V4 region of the 16S rRNA gene on an Illumina MiSeq. Microbial community data was analyzed via QIIME 2 using Amplicon Sequencing Variants (ASVs). The steatosis was semiquantitated as a score of 0 to 4 in each case based on relative degree of steatosis within hepatocytes: (0) no steatosis; (1) < 25%; (2) 25–50%; (3) >50–75% and (4) >75%. Results: The LIF and LHF-fed rats had significantly (p< 0.05) lower steatosis scores, microvascular score and liver weight compared to control (p< 0.05). There were no significant differences between LIF vs HIF for steatosis score. Similarly, beta diversity analysis of the gut microbial communities were significantly different (p< 0.05), between the controls and both LIF & HIF. There were no significant differences in beta diversity between LIF and HIF. Additionally, No significant differences in alpha diversity were observed between any of the groups. Differential abundance analysis via ANCOM-BC, found 122 significantly different ASVs between the control and LIF/HIF groups. Compared to the controls the LIF/HIF group, contained 21 enriched ASVs and 101 depleted ASVs. Conclusions: We found that soy protein concentrate regardless of isoflavones levels can reverse NAFLD caused by obesity and this protection was associated with alteration of gut microbial composition. Funding Sources: This project is supported by USDA grant 2020-67017-3084 to RH.