Wild Rice and Brown Rice Reduce Liver and Serum Lipids in Wistar Rats fed Either a Total Western Diet or a High Fat Diet

OBJECTIVES: Non-alcoholic fatty liver disease (NAFLD) prevalence is increasing, and no pharmacological intervention exists to treat it. Here, we determined the effect of feeding wild rice and brown rice on liver lipids and the gut microbiome when fed two different high fat background diets meant to induce fatty liver. METHODS: In the HFD trial, male Wistar rats (n = 8 per group) were fed either a high fat diet (HF), or a HF containing either 20% wild rice (WR) or 20% brown rice (BR) for 8 weeks. Cecal contents, liver, and epididymal fat pads were harvested. Microbiome analysis of cecal contents was conducted by 16S sequencing. In the TWD trial, male Wistar rats (n = 12 per group) were fed the AIN-93G diet (Basal), the Total Western Diet (TWD; a high fat diet that mimics the average American diet), or the TWD containing 30% WR (WR) for 10 weeks, then liver and epididymal fat pads were harvested. RESULTS: In the HFD trial, both WR and BR significantly reduced total liver lipids compared to HF (p < 0.0001). However, epididymal fat pad weight was not reduced in either of the rice groups compared to HF (p > 0.05). Serum cholesterol was also reduced in WR compared to HF (p < 0.0188). In the TWD trial, the TWD elevated total liver lipids compared to Basal, but WR reduced liver lipids significantly (p < o.oo6) compared to TWD. WR did not lower epididymal fat pad weight (p > 0.1) compared to TWD. Additionally, p-AMPK/AMPK was increased in WR compared to TWD (p < 0.003). This shift in AMPK activation was not seen in the HFD trial (p > 0.05). In the HFD trial microbiome analysis, the beta-diversity measure of community dissimilarity indicated that WR had a significantly different microbial profile compared to the animals fed the HF diet (p < 0.003) while BR had an increased abundance of lactobacillus (p < 0.03) compared to animals fed the HF diet. CONCLUSIONS: Wild rice feeding reduced fatty liver, using two different high fat background diets, and altered the gut microbiome. Wild rice should be further explored as a dietary approach to prevent development of non-alcoholic fatty liver disease (NAFLD), and to investigate whether hepatic lipid reductions are mediated by changes in the gut microbiome. FUNDING SOURCES: The TWD trial was sponsored by the Whiteside Institute for Clinical Research and the HFD trial was sponsored by the Minnesota Cultivated Wild Rice Council.