PETRA LOUIS
Microbiology Group, Gut Health Theme, University of Aberdeen, Rowett Institute of Nutrition and Health,Greenburn Road Bucksburn, Aberdeen AB21 9SB, United Kingdom

Abstract

The human large intestine is colonised by a dense microbial community (microbiota) whose activities have a profound effect on human health. With the development of modern molecular tools a much better understanding of the composition of the microbiota has been gained in recent years. The microbiota can be modulated by diet, especially the type and level of certain dietary carbohydrates that serve as energy source for the microbes, and this modulation appears to depend on the composition of the individual microbiota present in each person. A brief overview will be given of the current knowledge in this field of research.

INTRODUCTION

The human body is colonised by a highly diverse microbial community (microbiota), resident mainly on the skin and intestinal tract. The microbial density is highest in the large intestine, as the conditions in this body compartment are particularly favourable for microbial growth: dietary constituents (mainly certain carbohydrates) that the human host cannot digest in the upper gut serve as a food source, the pH is in the neutral to slightly acidic range and the passage of digesta through the colon is relatively slow, allowing sufficient time for microbial growth before wash-out from the system. The microbiota consists mainly of anaerobic bacteria, as most of the oxygen entering the system is quickly consumed by facultative anaerobes, with Archaea, Eukaryotic microbes and viruses also present (1). The interaction between the microbiota and its host can be regarded as a symbiotic relationship in healthy people, as the host provides a habitat for the microbes, while the activities of the microbiota have mostly beneficial effects on the host. This includes the provision of short-chain fatty acids (SCFA; mainly acetate, propionate and butyrate) ...