Probiotic Bacteria and Their Effect on Human Health and Well-Being

A. Guarino, E. M. M. Quigley, W. A. Walker, A., Guarino, E.M.M., Quigley, W.A., Walker, Berthold Koletzko, Berthold, Koletzko

• Publisher: S. Karger
• Year: 2013
• Print ISBN: 9783318023244
• eBook ISBN: 9783318023251
• Topic: Medicine
• Subtopic: Gastroenterology & Hepatology

Our microflora is an individual personal feature, providing a distinct tag to individuals. However, our intestinal microbiome is strongly affected by genetic, nutritional, and other external factors, and evolves with age. An effect of different microbial patterns on health appears very likely as there seem to be specific changes of intestinal microflora associated with various diseases. Specific microbial tags may thus be used as biomarkers of disease: to diagnose it, to monitor its evolution, and eventually to predict its response to treatment. This scenario opens the opportunity for targeting intestinal microflora using probiotics, both for prevention and treatment of an increasing number of conditions. Probiotic therapy is applied either as an adjunct to other treatments or as primary therapy, and evidence of efficacy is accumulating in several conditions, affecting either the intestine or nonintestinal organs. This publication provides an update on probiotics directed at physicians, biologists, biotechnologists, and researchers working in the food industry and agriculture, as well as in the environmental and basic sciences.

Probiotics in the Prevention and Treatment of Diseases in Adults and Children

Guarino A, Quigley EMM, Walker WA (eds): Probiotic Bacteria and Their Effect on Human Health and Well-Being.
World Rev Nutr Diet. Basel, Karger, 2013, vol 107, pp 103-121 (DOI: 10.1159/000345750)

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Metabolic Syndrome and Obesity in Adults

Susan E. Power^a,b · Gerald F. Fitzgerald^a,b · Paul W. O’Toole^a,b · R. Paul Ross^b,c · Catherine Stanton^b,c · Eamonn M.M. Quigley^b,d · Eileen F. Murphy^e

^aDepartment of Microbiology, ^bAlimentary Pharmabiotic Centre, and ^dDepartment of Medicine, University College Cork, Cork, ^cTeagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, and ^eAlimentary Health Ltd., Cork, Ireland

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Abstract

The relatively recent discovery that changes in the composition and metabolic activity of the gut microbiota are associated with obesity and related disorders has led to an explosion of interest in this now distinct research field. In the following chapter, we discuss the current evidence related to how the modulation of gut microbial populations might have beneficial effects with respect to controlling obesity. A number of studies in both animals and humans have shown that the composition of the gut microbiota is significantly altered in obesity and diabetes. Strategies including specific functional foods, probiotics, and prebiotics have the potential to favorably influence host metabolism by targeting the gut microbiota. Indeed, probiotics appear to be a promising approach to alter the host metabolic alterations linked to the changes in the gut microbiota. However, the mechanisms by which probiotics may impact on the development of obesity and metabolic health remain unclear and require further investigation.

Copyright © 2013 S. Karger AG, Basel

The prevalence of obesity and its associated metabolic disorders has increased substantially over recent decades to a point where they have reached epidemic levels worldwide. As such, obesity is a major public health issue and is associated with an increased risk of cardiovascular disease (CVD), type 2 diabetes mellitus (T2D), atherosclerosis, nonalcoholic fatty liver disease (NAFLD), and certain cancers. Obesity is a complex condition that results from an imbalance between energy intake and expenditure and appears to be influenced by a combination of genetic, lifestyle, and environmental factors. In this chapter the current evidence linking gut microbiota with the development of obesity and obesity-related metabolic diseases and the effects of interventions and probiotics, in particular, on the management and prevention of obesity will be discussed.

Gut Microbiota and Obesity

Animal Studies

The availability of animal models and the advent of new molecular, culture-independent techniques have together greatly enhanced our ability to study the gut microbiota and its relationship to obesity. Mice, in particular, offer a suitable model for conducting such experiments as their gut microbiota, by virtue of a predominance of Firmicutes (60-80%) and Bacteroidetes (20-40%), exhibits an overall pattern that is similar to that of humans [1]. Furthermore, germ-free (GF) mice are particularly useful for understanding the role of the gut microbiota in health and disease and the mechanisms underlying microbiota-associated alterations in host physiology. A landmark study by Backhed et al. [2] found that GF mice were leaner than their conventional (CONV) counterparts, even though they consumed more food. In addition, colonization of GF mice with the gut microbiota harvested from CONV mice led to an increase in total body fat despite a decrease in food intake. GF mice have also been shown to be protected against obesity while consuming a Western-style high-fat diet [3, 4], but the source and type of fat and carbohydrate may be an important factor [4]. In fact, Fleissner et al. [4] observed that GF mice fed a high-fat diet lacking sucrose were no longer protected against the development of diet-induced obesity, illustrating the complexity of the interactions between diet, microbes, and host adiposity.

There is mounting evidence that it is not simply the presence, but also the relative proportions of the major microbial divisions, within the microbiota that is associated with obesity. The development of obesity is associated with an increase in the ratio of Firmicutes to Bacteroidetes in both diet-induced obese [5, 6] and genetically obese (ob/ob) mice [1, 7]. Furthermore, a recent study showed that feeding a high-fat diet determined the composition of the gut microbiota independent of obesity in mice [8]. In that study, Hildebrandt et al. [8] showed, using the resistin-like molecule-β knockout mice (which are resistant to diet-induced obesity), that the high-fat diet itself, and not the obese state, mainly accounted for the observed changes in the gut microbiota composition. Other work showed that switching from a low-fat to a high-fat diet resulted in a rapid and dramatic shift in the structure of the gut microbiota in mice in a single day [5]. Murphy et al. [9] investigated the effects of a high-fat diet and genetic obesity (the ob/ob mouse model) on the gut microbiota over time. While no significant changes in the proportions of the different microbial groups were observed in the control lean mice over the 8-week period, a progressive increase in Firmicutes in both the high-fat-fed and ob/ob mice was reported, but reaching statistical significance in the former case only. Moreover, Bacteroidetes proportions decreased overtime in all groups, but again reached statistical significance only in the ob/ob mice [9]. These studies suggest that microbial adaptation to diet over time, and perhaps with age, is an important variable in the complex relationship between the composition of the microbiota and obesity, and should be considered in future studies.

Human Studies

In man the relationship between the gut microbiota and obesity is somewhat more unclear. The first study examining the qualitative changes of the gut microbiota in 12 human obese individuals was published by Ley et al. [10] in 2006. In agreement with results from animal studies, the authors observed an increased ratio of Firmicutes to Bacteroidetes in obese individuals compared to matched lean individuals. Interestingly, after weight loss (following a fat-restricted or carbohydrate-restricted low-calorie diet), the ratio of Bacteroidetes to Firmicutes approached a lean-type profile after 52 weeks [10]. Comparison of the fecal microbiota of monozygotic and dizygotic twins who were either lean or obese also revealed that obesity was associated with a reduced representation of Bacteroidetes, reduced bacterial diversity, and increased proportions of Actinobacteria. Notably, no significant differences in the proportions of Firmicutes were apparent between lean and obese subjects [11]. Although a similar reduction of Bacteroidetes in obese subjects has been confirmed in another study [12], the concept that Bacteroidetes are reduced in obese subjects has been largely contradicted by other studies [13-16].

Duncan et al. [13] detected no differences in Bacteroidetes proportions between obese and nonobese individuals and no significant changes in the proportions of Bacteroidetes were detected in obese subjects following weight loss. Furthermore, Schwiertz et al. [14] reported a decrease in the ratio of Firmicutes to Bacteroidetes in obese human adults compared with lean controls. Similarly, Zhang et al. [15] reported that overweight individuals harbored more Bacteroidetes than normal-weight individuals. They showed that a subgroup of Bacteroidetes (Prevotellaceae) was significantly enriched in obese individuals. Moreover, surgical treatment for these morbidly obese subjects (gastric bypass) altered the gut microbiota toward an increase in γ-Proteobacteria (members of Enterobacteriaceae) and a proportional decrease in Firmicutes [15]. More recently, Zupancic et al. [16] found no association between the Bacteroidetes-Firmicutes ratio and any metabolic syndrome trait in an Old Order Amish sect. However, 22 bacterial species were found to be either positively or inversely correlated with obesity and metabolic syndrome traits, indicating that specific members of the gut microbiota may play a role in these metabolic derangements [16]. The conflicting results observed in these human studies emphasize the complexity of the relationship between gut microbiota and obesity. Further work is required to identify if obesogenic components of the gut microbiota exist. Moreover, the potential influence of confounding factors, such as diet, highlights the need for well-controlled large clinical trials to identify specific proximate microbiota-related biomarkers of risk for obesity and metabolic dysregulation.

Mechanisms Linking the Gut Microbiota to Obesity

Host Factors. The gut microbiota may be involved in the regulation of fat storage and composition. Fiaf (fasting-induced adipocyte factor) is involved in regulating fat storage by inhibiting lipoprotein lipase, while also promoting fatty acid release by inducing peroxisome proliferator-activated receptor coactivator [2]. It has been suggested that GF mice are resistant to obesity through a mechanism involving Fiaf in the intestine [2]. Indeed, GF Fiaf knockout (Fiaf-/-) mice gained significantly more weight than their GF wild-type littermates when fed a Western diet [3]. However, a more recent study found that while intestinal Fiaf mRN...

Table of contents

• Cover Page
• Front Matter
• Probiotics: Definition and Taxonomy 10 Years after the FAO/WHO Guidelines
• Intestinal Microbiota Composition in Children
• Intestinal Microbiota Composition in Adults
• The Intestinal Microbiota and Aging
• Shaping Intestinal Bacterial Community by TLR and NLR Signaling
• Importance of Early Microbial Colonization for Intestinal Immune Development
• Effects of the Intestinal Microbiota on Behavior and Brain Biochemistry
• Relationship between Bacterial Colonization of Human Digestive and Respiratory Tract
• Probiotics in the Prevention and Treatment of Inflammatory Bowel Diseases in Children
• Functional Gastrointestinal Disorders in Children
• Functional Gastrointestinal Disorders in Adults
• Metabolic Syndrome and Obesity in Children
• Metabolic Syndrome and Obesity in Adults
• Neonatal Necrotizing Enterocolitis
• Role of Probiotics in Allergies
• Probiotics in Respiratory Infections
• Are Probiotic Effects Dose-Related?
• Safety of Probiotics
• Age-Related Functional Feeding: A Novel Tool to Improve the Quality of Life
• Use of Microbes to Fight Microbes
• What Is the Future for Therapies Derived from the Microbiome (Pharmabiotics)?
• Author Index
• Subject Index