Oat Bran Supplementation Improves Glucose Metabolism, Food Addiction, and Gut Microbiota in Rats With High-Fat Diet-Induced Obesity

Abstract

Oat bran (OB), a byproduct of the oat milling process, is a nutrient-dense cereal cultivated in cool, dry mountainous regions and is known for its potential health benefits. To explore its obesity-alleviating effects and the underlying mechanisms, we examined the influence of OB on glucose metabolism, appetite-regulating hormones, gut microbiota composition, and plasma metabolomics in high-fat diet (HFD)-induced obese rats. Our findings revealed that OB supplementation (30%) significantly reduced body weight gain and fat accumulation, improved dyslipidemia and glucose homeostasis, and increased levels of appetite-suppressing hormones, including glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), in HFD-induced rats. Furthermore, OB markedly reshaped the gut microbiota by enhancing microbial α-diversity, promoting the growth of beneficial bacteria such as Allobaculum, Blautia, and Lactobacillus while inhibiting the proliferation of Akkermansia and Ruminococcaceae UCG-005. These microbial changes were positively or negatively correlated with the leptin (LEP), insulin (INS), GLP-1, and PYY levels, suggesting a potential link between OB intake and metabolic regulation. In addition, OB exerted beneficial effects on the plasma metabolite levels, notably increasing octadecanoic acid, myristic acid, oleic acid, trimethylamine oxide, cholesterol, and l-carnitine while modulating the six key metabolic pathways related to fatty acid biosynthesis and cholesterol metabolism. Collectively, these results underscore the potential of OB as a functional food for obesity management and metabolic health improvement.