| Currently,cardiovascular disease（CVD）is the leading cause of death among women worldwide.Contrary to the previously held belief that the incidence rate of CVD in women is significantly lower than that of men,the incidence rate and mortality of CVD in women are comparable to that of men and are even significantly higher than that of men after age 60.In addition to the quantity of dietary fat,the impact of dietary fat type on chronic diseases dominated by CVD cannot be overlooked.There are,however,few reports on population trials that investigate the effects of different fats on cardiometabolic profiles,and the vast majority of existing randomized controlled trials use supplements.Therefore,90 middle-aged and elderly women（aged 35 to 69）were chosen as subjects for this study.Through a 3-month randomized controlled double-blind feeding trial（RCT）,we investigated the effects of camellia seed oil（CSO）,olive oil（OO）,and soybean oil（SO）（as controls）on the cardiometabolic profiles（the primary outcome is weight;the secondary outcomes are the remaining cardiometabolic profiles except for weight）（serum fatty acid content as a compliance evaluation index）.Based on the multi-omics analysis,the effects of the three oils on gut microbiota,gut microbial metabolism,and serum lipidomics were investigated in a panoramic manner.The results of the multi-omics analysis were used to investigate the possible path of influence of three oils on the cardiometabolic profiles of middle-aged and elderly women.The main findings are as follows:（1）According to the results of the RCT,the weight of participants in all three groups decreased,but there was no significant difference between the groups.During the intervention period,the OO group had higher high-density lipoprotein cholesterol（HDL-C）（p=0.03）,and the CSO group had lower aspartate aminotransferase（AST）（p=0.02）.Compared to SO,OO and CSO have greater positive effects on certain indices of cardiometabolic profiles;however,the positive effects are heterogeneous.In addition,participants compliance was relatively high.The changing trend of serum oleic acid andα-linolenic acid was consistent with that of the intervention groups.（Chapter Ⅱ）（2）To explore the changes in gut microbiota in participants,fecal samples of participants in the RCT were detected.The results showed that the Simpson estimator in the CSO group decreased significantly（p=0.046）,and the change value of the Chao1 estimator was significantly lower than that in the SO group（p=0.046）.There was no significant difference in OTU level among the three groups.The relative content of Blautia in the CSO group was significantly increased（p=0.01）.The relative abundance of Atopobium（p=0.02）,Haemophilus（p<0.01）,and Saccharibacteria＿genera＿incertae＿sedis（p=0.04）between the OO group and CSO group was significantly different.The results of the correlation analysis showed that the relative abundance of Peptoniphilus was significantly negatively correlated with serum AST（r=-0.25）and PYRIDNUCSAL-PWY（r=-0.23）（pathways significantly different among groups）.The results showed that CSO significantly decreased the alpha diversity of gut microorganisms but increased the relative abundance of butyric acid-producing bacteria.Compared with the SO group,the CSO and OO groups may reduce the relative abundance of Peptoniphilus and synthesize NAD+through the PYRIDNUCSAL-PWY pathway.At the same time,as AST regulates the ratio of NAD+/NADH,they jointly affect the synthesis and homeostasis of NAD+and finally regulate myocardial function.（Chapter Ⅲ）（3）The fecal samples of the RCT participants were analyzed in order to investigate the changes in gut microbial metabolites and provide possible reasons for the results of the prior study.The results showed that,when compared with SO,the relative contents of indole and indoleacetaldehyde were up-regulated in OO and CSO,with OO being significantly up-regulated（p<0.01）.HDL-C was significantly correlated with indole（r=-0.25,p=0.02）and indoleacetaldehyde（r=-0.25,p=0.02）.2-Methoxybenzoic acid exhibited reverse regulation in the OO and CSO groups,where it was significantly correlated with Saccharibacteria＿genera＿incertae＿sedis.Saccharibacteria＿genera＿incertae＿sedis was significantly correlated with IL-8 and hs-CRP,respectively.The results of the KEGG enrichment analysis showed that the significantly different metabolites L-tryptophan,tryptamine,indoleacetic acid,and indoleacetaldehyde among the groups were all in the tryptophan metabolism pathway（p<0.01）.The results showed that,compared with SO,CSO and OO can positively affect the level of tryptophan metabolites in the gut,and OO may significantly increase the content of tryptophan metabolites through the tryptophan metabolism pathway,thus positively affecting the level of serum HDL-C.It is possible for CSO and OO to adjust the content of Saccharibacteria＿genera＿incertae＿sedis,affect the process of polyphenol metabolism to produce phenolic acid,and finally participate in the metabolism of IL-8 and hs-CRP.（Chapter Ⅳ）（4）The three oil samples and the serum samples of participants were analyzed to screen for differential lipid markers between the intervention groups.The results showed that 10different serum lipid markers were selected,including 6 triacylglycerols（TAG）,1phosphatidylethanolamine（PE）,and 3 phosphatidylcholines（PC）.The changing trend of serum 18:2 FA（TAG）in the three groups was consistent with the content of 18:2 FA（TAG）in the three oils.Serum a18:1/18:0（PC）was significantly higher in the OO group（p<0.05）and CSO group（p<0.05）than in the SO group.Serum C52:2/C53:9（TAG）was significantly correlated with AST（r=-0.363,p=0.048）and HDL-C（r=-0.519,p<0.01）,respectively,and had opposite regulatory trends in CSO and OO.The results showed that CSO and OO improved AST and HDL-C,respectively,which may be related to their different regulation modes of serum C52:2/C53:9（TAG）.（Chapter Ⅴ）（5）Based on the results of the randomized controlled feeding trial in Chapter Ⅱ,the multi-omics analysis in Chapters Ⅲ to Ⅴ was connected in series.The possible paths of three oils affecting cardiometabolic profiles in middle-aged and elderly women were explored.The results showed that the three oils may be involved in tryptophan metabolism by regulating Ezakiella(Coef.=-1.14*10-5,p=0.02),respectively regulating indole acetaldehyde（Coef.=1.67*103,p<0.01）and tryptamine（Coef.=1.64*103,p<0.01）,and finally affecting serum HDL-C levels（Coef.=0.29,p<0.01;Coef.=0.25,p=0.02）.The three oils affect Saccharibacteria＿genera＿incertae＿sedis（Coef.=6.92*10-5,p=0.03）,then regulate 7,12-Dioxolithocholic acid（Coef.=-1.02*103,p<0.01）,and finally regulate AST（Coef.=-2.63,p<0.01）.The three oils affect the d16:0/20:4（PE）in the serum through the C53:1/C54:8（TAG）,C56:2/C57:9（TAG）,and C54:1/C55:8（TAG）in the oil（Coef.=-7.14,p=0.01;Coef.=-13.04,p<0.01 and Coef.=-17.03,p<0.01）,and then finally,regulating the level of serum HDL-C（Coef.=-0.04,p=0.01）（There are significant mediating effects in all three paths,and the ratio of each mediating effect is 50%.）.According to the results in the preceding chapters,it can be inferred that,compared with SO and CSO,OO may increase the content of tryptophan metabolites through the tryptophan metabolism pathway by regulating Ezakiella,thus positively affecting the level of serum HDL-C;OO may affect the level of serum HDL-C by reducing serum d16:0/20:4（PE）,regulating the function of erythrocyte membrane transport protein,and affecting lipid metabolism.Compared with SO and OO,CSO may enhance the relative abundance of Saccharibacteria＿genera＿incertae＿sedis,regulating the content of secondary bile acid,and then positively affecting the level of serum AST.（Chapter Ⅵ）In conclusion,compared with SO,OO has a more positive impact on HDL-C,and CSO significantly reduces AST.OO may increase the content of tryptophan and its metabolites through the tryptophan metabolism pathway by affecting the level of Firmicutes,then positively affecting the level of serum HDL-C.OO may reduce the level of serum d16:0/20:4（PE）,regulating the function of erythrocyte membrane transport protein,and then affect the level of serum HDL-C.CSO may regulate the content of secondary bile acids in the gut by affecting Candidatus Saccharibacteria,and then ultimately affect the level of serum AST.The differential regulation of serum C52:2/C53:9（TAG）by CSO and OO may be related to their heterogeneous influence on cardiometabolic profiles. |
