Effect Of Beef And Chicken Diet On Human Intestinal Microorganism And Metabolism

Meat plays an important role in culture and diet structure.Because it is rich in nutrients(protein,fat,vitamins,minerals),meat has a great contribution to human growth,development and evolution.Meat protein is an important source for human protein.In recent years,a lot of animal studies have focused on the effects of dietary protein on health with mice,pigs,and monkeys,but little has been done in humans.After dietary meat proteins undergoes digestion in the body,and undigested proteins will enter the large intestine and be fermented by intestinal microbes.Metabolites could affect host health.Few studies have been done on the effects of diet on human intestinal microorganism,and metabolites.In this study,45 healthy male volunteers were recruited and beef and chicken diets were given for 4 weeks and gut microbiota and metabolic products were analyzed.In addition,in vitro fermentation was done by incubating feces collected on day 0,14 days(beef meals),and 28 days(chicken meal)with beef protein and chicken protein,respectively.The composition of gut microbes was analyzed.Finally,we investigated the differences in metabolites and metabolic pathways of intestinal microbes after feeding beef and chicken.It provides a scientific basis for the regulation of diet and health.The main research contents and results are as follows:1.Study on the effects of beef and chicken diets on human fecal microbesForty-five healthy male volunteers with similar backgrounds and eating habits were recruited to eat beef meals for 14 days and then chicken meals for another 14 days.Fecal samples were collected before diet intervention,14 days and 28 days,and composition and structure changes of fecal microbes were analyzed using 16S rRNA.The results showed that the detected fecal microbes mainly included the phyla of Bacteroidetes,Firmicutes,Proteobacteria,Fusobacteria,and Verrucomicrobia,of which Bacteroidetes and Firmicutes accounted for 90%of the total abundance.Compared with the control group(0 h samples),the abundance of Proteobacteria in gut microorganisms of the beef group was significantly decreased(p<0.05),while there was no significant difference in chicken group(p>0.05).The abundances of Lachnospira,Lachnospiraceae NK4 A136 group and Ruminococcus2 increased significantly(p<0.05).2.Study on in vitro fermentation characteristics of beef and chicken proteinOn the basis of the findings in the first chapter,fecal samples were collected after intake of beef meals and chicken meals for 14 days,respectively,and then fecal microbes were incubated with meat proteins at 37℃ for certain time.A total of 48 cultivates were subjected to 16S rRNA sequencing to detect composition and structure of fecal microbes.The results showed that the abundance of Proteobacteria and Actinobacteria increased significantly after adding meat protein to fecal microbes.The Bacteroidetes in the chicken protein group was significantly decreased(p<0.05).Addition of chicken protein to the culture increased the abundances of Megasphaera Megamonas,and Escherichia-Shigella,but decreased the abundance of Prevotella 9,Parabacteroides,and Faecalibacterium(p<0.05),and increased the abundances of Sutterella and[Ruminococcus]torques group as well(p<0.05).Addition of beef protein increased the abundance of Actinobacteria and Proteobacteria(p<0.05),but decreased the abundance of Bacteroidetes.At the genus level,addition of beef protein decreased the abundances of Alistipes,Alloprevotella,Lachnoclostridium,Lachnospira,Lachnospiraceae NK4 A136 group,Roseburia,Ruminococcus 2,Eubacterium eligens group,[Eubacterium]rectale group and Subdoligranulum,but significantly increased the abundance of Phascolarctobacterium(p<0.05).In vitro fermentation experiments showed that the meat protein significantly changed the abundances of Proteobacteria,Actinobacteria and Bacteroidetes.3.Effects of beef and chicken on gut microbial metabolismUnder the action of gut microbiota,undigested dietary components were degraded into small metabolites,which may have a certain impact on the host health.In the beef group,many alcohols were identified,which involve biological synthesis,and vitamins(vitamin D3,and E)metabolism,and lipid metabolism.In the chicken group,aldehydes and alcohols were identified,with an increase in those involving amino acid metabolism,and a reduction in those involving of lipid metabolism.Under the mode of anion scan nucleotides,fatty acid,amides,and vitamins(B9,D3,C,E)were identified.Some are involved in sugar metabolism(galactose metabolism).The above results indicated that intake of beef and chicken significantly altered the gut microbiota composition and metabolites involving different pathways and further affect host health.