The role of short chain fatty acids in appetite regulation and energy homeostasis.

C S Byrne,G Frost,D J Morrison,E S Chambers

doi:10.1038/ijo.2015.84

Abstract

Over the last 20 years there has been an increasing interest in the influence of the gastrointestinal tract on appetite regulation. Much of the focus has been on the neuronal and hormonal relationship between the gastrointestinal tract and the brain. There is now mounting evidence that the colonic microbiota and their metabolic activity have a significant role in energy homeostasis. The supply of substrate to the colonic microbiota has a major impact on the microbial population and the metabolites they produce, particularly short chain fatty acids (SCFAs). SCFAs are produced when non-digestible carbohydrates, namely dietary fibres and resistant starch, undergo fermentation by the colonic microbiota. Both the consumption of fermentable carbohydrates and the administration of SCFAs have been reported to result in a wide range of health benefits including improvements in body composition, glucose homeostasis, blood lipid profiles and reduced body weight and colon cancer risk. However, published studies tend to report the effects that fermentable carbohydrates and SCFAs have on specific tissues and metabolic processes, and fail to explain how these local effects translate into systemic effects and the mitigation of disease risk. Moreover, studies tend to investigate SCFAs collectively and neglect to report the effects associated with individual SCFAs. Here, we bring together the recent evidence and suggest an overarching model for the effects of SCFAs on one of their beneficial aspects: appetite regulation and energy homeostasis.

Highlights

Obesity has become a global epidemic, with incidence rates of over 20% in the majority of western countries.[1]
The main short chain fatty acids (SCFAs) produced by bacterial fermentation are acetate, propionate and butyrate, and are present in the approximate molar ratio of 60:20:20.18 It has been demonstrated that the consumption of soluble fermentable carbohydrates (FCs) increases the caecel content of SCFAs in animal models.[19,20]
A significant body of evidence suggests that SCFAs have a beneficial role in appetite and energy homeostasis

Summary

INTRODUCTION

Obesity has become a global epidemic, with incidence rates of over 20% in the majority of western countries.[1]. Lowland gorillas derive ~ 57% of their metabolisable energy from SCFAs, compared with 1.2–10% in humans from the average western diet.[15,16,17] The main SCFAs produced by bacterial fermentation are acetate, propionate and butyrate, and are present in the approximate molar ratio of 60:20:20.18 It has been demonstrated that the consumption of soluble fermentable carbohydrates (FCs) increases the caecel content of SCFAs in animal models.[19,20] The rate, ratio and extent of SCFA production, is a complex interplay between FC type, microbiome diversity and activity, and gut transit time.[21,22,23,24,25]. We review recent findings in this field and propose an interconnected picture of how SCFAs may affect appetite regulation and energy homeostasis

MATERIALS AND METHODS

Findings

CONCLUSION