Effects of hazelnut soluble dietary fiber on lipid-lowering and gut microbiota in high-fat-diet-fed rats

Hazelnut is one of the most popular nuts in the world, rich in nutrients and various active substances. In this study, soluble dietary fiber (SDF) was extracted from hazelnut kernels, and its physicochemical properties and absorbability were explored. Hazelnut-SDF exhibited ideal water-holding, oil-holding and swelling capacity, and glucose, cholesterol and cholate absorbing ability. Scanning electron microscopy and fourier transform infrared spectroscopy showed that hazelnut-SDF had typical polysaccharide structure of functional groups. The main monosaccharides were identified as arabinose, rhamnose, xylose, ribose, glucuronic acid, mannose and glucose by gas chromatography–mass spectrometry. In high-fat diet rats, hazelnut-SDF could improve serum lipid parameters, inhibit lipid accumulation in liver and adipocytes, and regulate the expression level of liver lipid synthesis-related genes. It also could adjust intestinal short chain fatty acids, promote the composition and structure of intestinal microbiota, and significantly balance the abundance of Alloprevotella, Fusicatenibacter, Lactobacillus, Roseburia, Ruminococcaceae_UCG-005, Ruminococcaceae_UCG-014 and Clostridiales. The results concluded that oral administration of hazelnut-SDF could alleviate hyperlipidemia and obesity, and might serve as a potential functional food ingredient.