Effects Of Energy Supply Ratios Of Fat And Carbohydrate In Diet On Fat Metabolism And Intestinal Microbiota In Rats

Fat and carbohydrate are important energy supplies.In recent years,with the improvement of living standards,people are gradually increasing the intake of fat or carbohydrate from the diet,due to excessive intake of fat or carbohydrate such as starch for long-tirm,somebody may become over-weight or obesity,and suffer from other chronic diseases.On the other hand carbohydrate such as cellulose has a good therapeutic effect on obesity-related chronic diseases.Therefore,in this study,the rat model was used to study the effects of different energy supply ratio of fat and carbohydrate on body fat metabolism and intestinal microbiota on the basis of the same effective energy(metabolic energy).The results showed as follows:1.Under the same conditions of effective energy(metabolic energy)intake,it can ensure the consistency of cellulose in the diet,and the different ratios of fat and corn starch can affect the fat metabolism and intestinal microbiota of rat.According to the different energy supply ratios of fat and carbohydrate in diets,which were divided into four groups: group HF(high fat diet;fat and carbohydrate ratio was 41%: 44%),group MF(Midum fat diet;fat and carbohydrate ratio was 31%: 54%),group LF(Low fat diet;fat and carbohydrate ratio was 21%: 64%)and CON group(control diet).The results showed that there was no difference in the body weight of rats fed with different ratio of fat and carbohydrate diets in the condition of ensuring the effective energy(metabolic energy)consistency,which explained that calorie restriction was effective on weighte control.Compared with the control group,the group HF significantly increased the blood glucose and liver fat,and the group LF significantly increased the blood lipid level.The group HF and MF diets up-regulated the relative expression of SREBP1 gene in rat liver,SREBP1 played a key role in the regulation of fatty acid synthesis and mediated liver fat production.Moreover,group HF diet resulted in the decrease of intestinal villi height and the digestion and absorption of nutrients.The three groups of diets resulted in the increase of intestinal fatty acid content in the rats and change of the abundance of intestinal microbiota at the level of Phylum.The main results showed that the abundance of Firmicutes was decreased,while the relative abundance of Bacteroidetes was increased.2.The effects of different proportions of cellulose,oil and corn starch on the fatmetabolism and intestinal microbiota of rats were studied under the condition of the same effective energy(metabolic energy).According to the different energy supply ratio in diets,which were divided into four groups: group HFf(high fat and high fiber diet,the energy supply ratio of fat and carbohydrate was 40%:45%),group MFf(medium fat and medium fiber diet,the energy supply ratio of fat and carbohydrate was 30%:55%)and group LFf(low fat and low fiber diet,the energy supply ratio of fat and carbohydrate was 20%:65%)and CONf group(control diet).The results showed that the weight of rats in the group HFf and MFf was significantly lower than that of LFf group and control group,which indicated that the addition of high fiber in high fat diet had effect on weight loss under energy restriction.The blood glucose and blood lipids of the group HFf,MFf and LFf compared with the control group no significant difference.The group HFf increased remarkably in the level of liver fat.The three groups of diet upregulated the relative expression of the liver fat metabolism related gene HMG-CoA,and HMG-Co A as the rate-limiting enzyme in the synthesis of cholesterol in liver cells played an important role.Liver biopsy study found no effect on rat liver steatosis.However,in the group HFf,MFf and LFf resulted in decreased ileum villus height and crypt depth,and inhibition of nutrient uptake.Te group HFf and MFf group diets reduced the short-chain fatty acid,acetic acid,propionic acid and butyric acid content of cecal.The effect of the group HFf,MFf and LFf diets on the cecal microbiota were mainly manifested at the level of the Phylum: the decreased in the relative abundance of the Firmicutes bacteria and the increased of the Bacteroidetes.The relative abundance of intestinal Lactobacillus in the group HFf and MFf decreased.However,the relative abundance of Lactobacillus-murinus and Ruminococcus-bromii L2-63 was increased in the group LFf,which indicated that the proportion of fat and cellulose in the diet could improve of the intestinal microbiota.In summary,on the basis of ensuring same effective energy(metabolic energy),the addition of different cellulose in different proportions of fat and carbohydrate diet could reduce the increase of body weight,blood glucose and blood lipids of rats induced by high fat diet.However,regardless of the content of cellulose in the diet,it could lead to liver fat metabolism disorders and variation of intestinal microbiota by ensuring iso-energetic(metabolic energy)intake.This is helpful for people having a more clear understanding to eat too much fat and carbohydrate for effect of the body atthe metabolic level,but also has a positive guiding significance for people to control weight and blood lipids.