Effects of two kinds of marine algae polysaccharides and their oligosaccharides on lipid metabolism and gut microbiota in high-fat diet mice

Abnormal lipid metabolism is manifested in a variety of metabolic diseases. In recent years, studies have shown that the pathogenesis of these disorders is closely associated with the gut microbiota. Marine algae polysaccharides, such as sodium alginate and its oligosaccharides, can reduce blood lipids and improve lipid metabolism to reduce body weight. Polysaccharides are difficult to be absorbed by the human body due to their large molecular weight, which limits their application in the field of medicine and food. In this study, two kinds of marine algae polysaccharides and their oligosaccharides were used to investigate their effects on body weight, lipid metabolism, inflammatory factors, and intestinal health and microbiota in high-fat diet mice. The results showed that after feeding a high-fat diet, the mice's body weight and serum lipids were increased. The formation of fat droplets was observed in the liver cells. Small intestinal microvilli were destroyed and showed obvious accumulation of epithelial cells. After feeding mice with sodium alginate, agar, and its oligosaccharides, the level of body weight and the pathological damage of the liver and intestine were relieved. Gut microbiota analysis showed that two kinds of polysaccharides and their oligosaccharides could improve the composition of gut microbiota at the phylum and genus level, increase the abundance of <i>Lactobacillus</i> and <i>Akkermansia</i>, and reduce the abundance of opportunistic pathogenic bacteria. This study provides a direction for the prevention and treatment of lipid metabolic diseases and ideas for the development of marine functional food.IMPORTANCEAbnormal lipid metabolism is manifested in a variety of metabolic diseases. Marine algae polysaccharides, such as sodium alginate and its oligosaccharides, can reduce blood lipids and improve lipid metabolism to reduce body weight. Polysaccharides are difficult to absorb by the human body due to their large molecular weight, which limits their application in the field of medicine and food. After feeding mice with sodium alginate, agar, and its oligosaccharides, the level of body weight, serum lipids, inflammatory factors, and the pathological damage of liver and intestine were relieved. Gut microbiota analysis showed that two kinds of polysaccharides and their oligosaccharides could improve the composition of gut microbiota at the phylum and genus level, increase the abundance of <i>Lactobacillus</i> and <i>Ackermania</i>, and reduce the abundance of harmful bacteria. This study provides a direction for the prevention and treatment of lipid metabolic diseases and ideas for the development of marine functional food.