The Regulatory Mechanism Of Lipid Metabolism In Plant Proteins Based On Improvement Of Intestinal Microorganism

Studies have shown that many plant proteins such as oat protein and soybean protein have the function of improving the regulation of lipid metabolism.While the animal proteins,particularly red meat proteins,are thought to be associated with lipid metabolic disorders.At present,the mechanism of the effect of plant proteins and animal proteins on health remains unclear.Recent studies have found that the interactions between intestinal flora and diet can regulate the host energy absorption and lipid metabolism.Therefore,the objective of this research is to evaluate how the plant proteins regulate cholesterol metabolism by modulating gut microbiota,and to explore the effect of plant proteins?rice protein,oat protein,soybean protein,pea protein?,white meat protein?chicken protein?and red meat proteins?pork protein,and beef protein?on the composition of intestinal flora in hamsters.This research provides a theoretical basis for the relationship among plant proteins,lipid metabolism and intestinal flora.The main research contents,results and conclusions were as follows:?1?The in vitro digestion of rice,oat,soybean,pea,chicken,pork,and beef proteins were carried out by using a two-step process of hydrolysis with pepsin and trypsin.The effect of different source of proteins on the characteristics of digestion and fermentation in vitro were studied.Results showed that the hydrolysis degree of white meat protein was significantly higher than that of red meat proteins?p<0.01?,and that of plant proteins were the lowest,indicating that animal proteins were more easily hydrolyzed.The fermentation liquor of soy protein has higher concentration of ammonia nitrogen?NH₃-N?and branched chain fatty acids?BCFA?,which makes it produce a higher concentration of microbial protein?MCP?;Although red meat proteins have high concentration of NH₃-N,it did not produce a higher concentration of MCP compared with that of soy protein.Both plant proteins and white meat protein reduced the value of pH,and a high concentration of short chain fatty acids?SCFA?was produced.It can be concluded that plant proteins and white meat protein have a good fermentation effect,reduce the pH value,increase of the concentration of SCFA,and increase of the produce of MCP were significantly better than that of the red meat proteins,which was better for intestinal health.?2?The dietary intervention in hamsters for five weeks,and the serum lipids,liver lipids,fecal lipids,the content of relevant metabolic enzymes,and gene expression were determined to evaluate the lipid-lowering effect of different source of proteins in hamsters.The results showed that plant proteins and white meat protein significantly reduced the level of serum cholesterol?p<0.05?,particularly the oat protein and soy protein,compared with that of red meat proteins.Pork protein and high-fat control group have no significant difference?p>0.05?for the function of reducing serum cholesterol.By determining the related metabolic enzymes and gene expression from serum,liver and fecal,it can be concluded the mechanism of the lipid-lowering effect of plant proteins were as follows:?1?The plant proteins can reduce the ratio of serum apolipoprotein B and apolipoprotein AI.?2?The plant proteins can decrease the content of liver 3-hydroxy-3-methyl glutaric acyl coenzyme A?HMG-CoA?reductase,and increase the content of 7 alpha hydroxylase.?3?The plant proteins can lower the expression of Fanny ester derivatives X receptor?FXR?and sterols control element binding protein 2?SREBP-2?.?4?The plant proteins can promote the excretion of fecal cholesterol.?3?16S rRNA high-throughput sequencing technology was employed to study the effect of different source of proteins on the composition of colon fecal microbiota and to clarify elucidate the lipid-lowering mechanism of plant proteins.The results showed that plant proteins increase the diversity of intestinal flora compared with red meat proteins,indicating that the intervention of different source of proteins lead to changes in the diversity of intestinal flora.At the phylum level,the plant proteins can reduce the number of Firmicutes,and increase the Bacteroidetes,and reduce the ratio of F/B to achieve the function of reducing the level of cholesterol;At the family level,the plant proteins can reduce the number of Erysipelotrichaceae and Eubacteriaceae,and increase the number of Bacteroidales_S24-7_group,Ruminococcaceae,Lachnospiraceae.In addition,ourresearchfoundthatErysipelotrichaceae,bacteroidales_s24-7_group,Eubacteriaceae,Ruminococcaceae,and Lachnospiraceae were closely related to the cholesterol metabolism of hamsters.?4?The mechanism of regulating lipid metabolism was analyzed by determining the intestinal flora metabolites,including BA,SCFA and TMAO.The results showed that plant proteins?except the pea protein?significantly increased the excretion of BA and SCFA compared with red meat proteins.The research also found that in addition to the rice protein,plant proteins reduced the content of TMAO in the serum of hamsters,among them,pea protein significantly reduced the content of TMAO?p<0.05?.But there was no significant difference between animal proteins and high-fat control group?p>0.05?.Combined with the results of the experiment of the lipid-lowering,it can be concluded that the lipid-lowering properties of plant proteins were associated with the increase the excretion of fecal BA and SCFA,and reduce the content of the serum of TMAO.In summary,plant proteins can improve the intestinal microecological environment.It can affect the host lipid metabolism by changing the composition and structure of intestinal flora,thus achieving the effect of lipid-lowering.