High-Fat Diet Reduces the Formation of Butyrate, but Increases Succinate, Inflammation, Liver Fat and Cholesterol in Rats, while Dietary Fibre Counteracts These Effects

Greta Jakobsdottir,Göran Molin,Jie Xu,Margareta Nyman,Siv Ahrné

doi:10.1371/journal.pone.0080476

Abstract

IntroductionObesity is linked to type 2 diabetes and risk factors associated to the metabolic syndrome. Consumption of dietary fibres has been shown to have positive metabolic health effects, such as by increasing satiety, lowering blood glucose and cholesterol levels. These effects may be associated with short-chain fatty acids (SCFAs), particularly propionic and butyric acids, formed by microbial degradation of dietary fibres in colon, and by their capacity to reduce low-grade inflammation.ObjectiveTo investigate whether dietary fibres, giving rise to different SCFAs, would affect metabolic risk markers in low-fat and high-fat diets using a model with conventional rats for 2, 4 and 6 weeks.Material and MethodsConventional rats were administered low-fat or high-fat diets, for 2, 4 or 6 weeks, supplemented with fermentable dietary fibres, giving rise to different SCFA patterns (pectin – acetic acid; guar gum – propionic acid; or a mixture – butyric acid). At the end of each experimental period, liver fat, cholesterol and triglycerides, serum and caecal SCFAs, plasma cholesterol, and inflammatory cytokines were analysed. The caecal microbiota was analysed after 6 weeks.Results and DiscussionFermentable dietary fibre decreased weight gain, liver fat, cholesterol and triglyceride content, and changed the formation of SCFAs. The high-fat diet primarily reduced formation of SCFAs but, after a longer experimental period, the formation of propionic and acetic acids recovered. The concentration of succinic acid in the rats increased in high-fat diets with time, indicating harmful effect of high-fat consumption. The dietary fibre partly counteracted these harmful effects and reduced inflammation. Furthermore, the number of Bacteroides was higher with guar gum, while noticeably that of Akkermansia was highest with the fibre-free diet.

Highlights

Obesity is linked to type 2 diabetes and risk factors associated to the metabolic syndrome
The concentration of succinic acid in the rats increased in high-fat diets with time, indicating harmful effect of high-fat consumption
Dietary fibre plays an interesting role through short-chain fatty acids (SCFAs), propionic and butyric acids, formed by the colonic microbiota

Summary

Introduction

Obesity is linked to type 2 diabetes and risk factors associated to the metabolic syndrome. Consumption of dietary fibres has been shown to have positive metabolic health effects, such as by increasing satiety, lowering blood glucose and cholesterol levels. These effects may be associated with short-chain fatty acids (SCFAs), propionic and butyric acids, formed by microbial degradation of dietary fibres in colon, and by their capacity to reduce low-grade inflammation. Obesity/overweight is a serious health risk and related to many metabolic diseases, such as type 2 diabetes, insulin resistance and coronary heart disease, stroke and cancer [1,2] Another obesityassociated disease, increasing in prevalence, is non-alcoholic fatty liver disease (NAFLD) and its progressive form, non-alcoholic steatohepatitis. SCFAs per se have been shown to have many positive health effects, such as reducing pro-inflammatory state, increasing insulin sensitivity and improving satiety [7,13]

Methods

Results

Conclusion