Association Of Short-chain Fatty Acids-producing Bacterial Diet And Obesity

Background:Obesity can increase the risk of many chronic diseases.Previous studies suggest that dietary fiber must be metabolized by specific gut bacteria to produce short-chain fatty acids（SCFAs）,and a fiber-rich diet and its metabolites,SCFAs,can improve obesity.On the other hand,diet can also affect the diversity and functional composition of gut bacteria.Therefore,we hypothesized that diet could reduce the risk of obesity prevalence in part by affecting specific gut bacteria and its metabolites,SCFAs.To verify the above hypothesis,we propose to construct a dietary pattern:SCFAs-producing bacterial diet（SPBD）that can reflect the level of SCFAs-producing bacteria,and verify the ability of this dietary pattern to predict the relative abundance of SCFAs-producing bacteria.And to assess the associations between SPBD adherence and obesity in community-based cross-sectional study.Methods:This study was a community-based cross-sectional study using a multistage sampling in Huoshan County.The food frequency questionnaire was conducted,along with the collection of information on demographic characteristics and other lifestyle behaviors.Weight,height,hip and waist circumference were collected by physical examination.Stool specimens were collected and amplicon sequencing of the 16S ribosomal RNA（r RNA）gene was performed.Participants（n=392）who can provide qualified stool specimens were randomly divided into the construction set（n=270）and the validation set（n=122）in a ratio of 2:1.In the construction set,SPBD was derived based on reduced rank regression（RRR）and stepwise linear regression using 41 food or food groups as predictive variables,and the relative abundance of 10 SCFAs（propionic acid and butyric acid）-producing bacteria as response variables.In the validation set,the ability of SPBD-adherence score to predict the relative abundance of 10 propionic acid and butyric acid-producing bacteria was evaluated by multiple linear regression.In the total population（n=453）,we used multivariate logistic regression to estimate the odds ratio（OR）and 95%confidence interval（CI）for the associations of SPBD-adherence score with general obesity（body mass index≥28 kg/m²）and abdominal obesity（waist circumference:woman/man≥85/90 cm;waist to height ratio≥0.5;waist to hip ratio:woman/man≥0.85/0.90）.At the same time,we analyzed the associations of food or food groups in SPBD with general obesity and abdominal obesity.Results:In the construction set,there were 15 food or food groups included in the SPBD.Tea,soy beverages,soy products,mushrooms and algae,other vegetables and other aquatic products were positively associated with the relative abundance of SCFAs-producing bacteria.While pickled vegetables,red meat,shrimps,eggs,barbecued food,liquor,animal offal,sugar-sweetened beverages and condiments were negatively associated with the relative abundance of SCFAs-producing bacteria.In the validation set,after adjusting for potential confounding factors,the percentage changes（95%CI）of the relative abundance of SCFAs-producing bacteria in the lowest to highest quintile of SPBD-adherence score were 20.1%（95%CI:-15.6%～71.0%）and 96.9%（95%CI:39.1%～178.7%）,respectively,and the linear trend was statistically significant(P_trend<0.001),suggesting that SPBD-adherence score can better predict the abundance of SCFAs-producing bacteria.A total of 453 participants,with 79（17.44%）cases of general obesity and 148（32.67%）,266（58.72%）and 246（54.30%）cases of abdominal obesity based on waist circumference,waist to height ratio and waist to hip ratio,respectively.After adjusting for confounding factors,compared with the lowest tertile,participants in the highest tertile had a lower risk of general obesity(OR=0.47,95%CI:0.23-0.95,P_trend=0.017).The risk of abdominal obesity based on waist to height ratio and waist to hip ratio were reduced by 27%（OR=0.73,95%CI:0.58-0.92）and 25%（OR=0.75,95%CI:0.60-0.93）,respectively,for per 1 standard deviation increase in SPBD-adherence score.No association was observed between SPBD-adherence score and abdominal obesity based on waist circumference(OR=0.71,95%CI:0.41-1.25,P_trend=0.111).Among the15 SPBD food or food groups,the intake of soy products was significantly negatively associated with abdominal obesity based on waist circumference（OR=0.76,95%CI:0.59-0.98）and waist to height ratio（OR=0.73,95%CI:0.57-0.94）.While the intake of pickled vegetables was significantly positively associated with general obesity（OR=1.31,95%CI:1.03-1.67）and abdominal obesity based on waist to hip ratio（OR=1.61,95%CI:1.23-2.11）.No statistical association was observed between other food groups and obesity.Conclusion:Our study was the first to derive the dietary pattern SPBD associated with SCFAs-producing bacteria in the community population,and this dietary pattern could effectively predict the relative abundance of the SCFAs-producing bacteria.The high the adherence to SPBD,the lower the risk of obesity.Our findings suggest at the population level that diet could reduce the risk of obesity prevalence in part by affecting gut bacteria and its metabolites,SCFAs,which has certain mechanism significance.Following the SPBD is associated with reduced risk of obesity,which has certain public health significance.