Clinical/Narrative Review

Subject Category: Clinical/Narrative Review

Citation: Clinical and Translational Gastroenterology (2015) 6, e91; doi:10.1038/ctg.2015.16
Published online 18 June 2015

The Influence of the Gut Microbiome on Obesity, Metabolic Syndrome and Gastrointestinal Disease
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Parth J Parekh1, Luis A Balart1 and David A Johnson2

  1. 1Department of Internal Medicine, Division of Gastroenterology and Hepatology, Tulane University, New Orleans, Louisiana, USA
  2. 2Department of Internal Medicine, Division of Gastroenterology and Hepatology, Eastern Virginia Medical School, Norfolk, Virginia, USA

Correspondence: DA Johnson, MD, MACG, FASGE, Department of Internal Medicine, Division of Gastroenterology and Hepatology, Eastern Virginia Medical School, Norfolk, Virginia 23510, USA. E-mail: dajevms@aol.com

Received 29 December 2014; Accepted 13 April 2015

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Abstract

There is a fine balance in the mutual relationship between the intestinal microbiota and its mammalian host. It is thought that disruptions in this fine balance contribute/account for the pathogenesis of many diseases. Recently, the significance of the relationship between gut microbiota and its mammalian host in the pathogenesis of obesity and the metabolic syndrome has been demonstrated. Emerging data has linked intestinal dysbiosis to several gastrointestinal diseases including inflammatory bowel disease, irritable bowel syndrome, nonalcoholic fatty liver disease, and gastrointestinal malignancy. This article is intended to review the role of gut microbiota maintenance/alterations of gut microbiota as a significant factor as a significant factor discriminating between health and common diseases. Based on current available data, the role of microbial manipulation in disease management remains to be further defined and a focus for further clinical investigation.

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INTRODUCTION

The gastrointestinal tract is thought to house ~1014 microorganisms, which in its totality is comprised of ~1,000 distinct bacterial species.1 Recent advances in sequencing technologies have given researchers further insight into the symbiotic relationship between the intestinal microbiome and its mammalian host.2 The “normal” gut flora encompasses a wide variety of microbacteria that have a vital role in digestion, fermenting unused energy substrates, maintaining the immune system, and in the synthesis of vitamins and enzymes (such as vitamin K and biotin).3 The metabolic activity performed by the gut microflora equates to that of a virtual organ, which is why many refer to the gut microflora as the “forgotten organ”. Factors influencing this relationship such as the environment,4 diet,5, 6 and genetics7 alter its metabolic capabilities resulting in the pathogenesis of a variety of disease states. Here, we review the literature in microbiome studies, the emerging links between the microbiome and its effect on gastrointestinal health, and approaches to manipulate this symbiotic relationship to potentially improve overall gastrointestinal health.

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CONCLUSION

There is clear evidence that the gut microbiome has a profound effect on the balance between health and disease. As we begin to understand how alterations in microbiota impact the pathogenesis of many disease states so to brings the possibility of potential targeted therapy. Unfortunately, studies to date have failed to provide long-term data. In addition, there have been only a select few studies taking into account genetic predisposition towards disease, as phenotypic disease states may be a culmination of genetic and environmental factors. Lastly, given the vast depth of the microbial environment future studies should not only focus on individual subspecies but also their interactions with surrounding microbes. Optimal disease management therefore remains to be defined and remains a significant focus for further clinical investigation.

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Conflict of interest

Guarantor of the article: David A. Johnson, MD, MACG, FASGE, FACP.

Specific author contributions: Concept, initiation of study, and writing up of manuscript: Parth J. Parekh, and David A. Johnson; writing up of manuscript: Luis A. Balart.

Financial support: None.

Potential competing interests: None.

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