Gut microbiota fermentation of prebiotics increases satietogenic and incretin gut peptide production with consequences for appetite sensation and glucose response after a meal

Prebiotic fibres dose-dependently increase satiety hormones and alter Bacteroidetes and Firmicutes in lean and obese JCR:LA-cp rats

There is a growing interest in modulating gut microbiota with diet in the context of obesity. The purpose of the present study was to evaluate the dose-dependent effects of prebiotics (inulin and oligofructose) on gut satiety hormones, energy expenditure, gastric emptying and gut microbiota. Male lean and obese JCR:LA-cp rats were randomised to either of the following: lean 0 % fibre (LC), lean 10 % fibre (LF), lean 20 % fibre (LHF), obese 0 % fibre (OC), obese 10 % fibre (OF) or obese 20 % fibre (OHF). Body composition, gastric emptying, energy expenditure, plasma satiety hormone concentrations and gut microbiota (using quantitative PCR) were measured. Caecal proglucagon and peptide YY mRNA levels were up-regulated 2-fold in the LF, OF and OHF groups and 3-fold in the LHF group. Ghrelin O-acyltransferase mRNA levels were higher in obese v. lean rats and decreased in the OHF group. Plasma ghrelin response was attenuated in the LHF group. Microbial species measured in the Bacteroidetes division decreased, whereas those in the Firmicutes increased in obese v. lean rats and improved with prebiotic intake. Bifidobacterium and Lactobacillus increased in the OHF v. OC group. Bacteroides and total bacteria negatively correlated with percentage of body fat and body weight. Enterobacteriaceae increased in conjunction with glucose area under the curve (AUC) and glucagon-like peptide-1 AUC. Bacteroides and total bacteria correlated positively with ghrelin AUC yet negatively with insulin AUC and energy intake (P < 0·05). Several of the mechanisms through which prebiotics act (food intake, satiety hormones and alterations in gut microbiota) are regulated in a dose-dependent manner. The combined effects of prebiotics may have therapeutic potential for obesity.

Gut microbiota: next frontier in understanding human health and development of biotherapeutics

The gut microbiota is a remarkable asset for human health. As a key element in the development and prevention of specific diseases, its study has yielded a new field of promising biotherapeutics. This review provides comprehensive and updated knowledge of the human gut microbiota, its implications in health and disease, and the potentials and limitations of its modification by currently available biotherapeutics to treat, prevent and/or restore human health, and future directions. Homeostasis of the gut microbiota maintains various functions which are vital to the maintenance of human health. Disruption of the intestinal ecosystem equilibrium (gut dysbiosis) is associated with a plethora of human diseases, including autoimmune and allergic diseases, colorectal cancer, metabolic diseases, and bacterial infections. Relevant underlying mechanisms by which specific intestinal bacteria populations might trigger the development of disease in susceptible hosts are being explored across the globe. Beneficial modulation of the gut microbiota using biotherapeutics, such as prebiotics, probiotics, and antibiotics, may favor health-promoting populations of bacteria and can be exploited in development of biotherapeutics. Other technologies, such as development of human gut models, bacterial screening, and delivery formulations eg, microencapsulated probiotics, may contribute significantly in the near future. Therefore, the human gut microbiota is a legitimate therapeutic target to treat and/or prevent various diseases. Development of a clear understanding of the technologies needed to exploit the gut microbiota is urgently required.

Effects of oligofructose on appetite profile, glucagon-like peptide 1 and peptide YY3-36 concentrations and energy intake

In rats, oligofructose has been shown to stimulate satiety hormone secretion, reduce energy intake and promote weight loss. The present study aimed to examine the effect of oligofructose supplementation on appetite profiles, satiety hormone concentrations and energy intake in human subjects. A total of thirty-one healthy subjects (ten men and twenty-one women) aged 28 (SEM 3) years with a BMI of 24·8 (SEM 0·3) kg/m(2) were included in a randomised double-blind, cross-over study. The subjects received 10 g oligofructose, 16 g oligofructose or 16 g placebo (maltodextrin) daily for 13 d, with a 2-week washout period between treatments. Appetite profile, active glucagon-like peptide 1 (GLP-1) and peptide YY3-36 (PYY) concentrations and energy intake were assessed on days 0 and 13 of the treatment period. Time × treatment interaction revealed a trend of reduction in energy intake over days 0-13 by oligofructose (P = 0·068). Energy intake was significantly reduced (11 %) over time on day 13 compared with day 0 with 16 g/d oligofructose (2801 (SEM 301) v. 3217 (SEM 320) kJ, P < 0·05). Moreover, energy intake was significantly lower with 16 g/d oligofructose compared with 10 g/d oligofructose on day 13 (2801 (SEM 301) v. 3177 (SEM 276) kJ, P < 0·05). Area under the curve (AUC) for GLP-1 on day 13 was significantly higher with 16 g/d oligofructose compared with 10 g/d oligofructose (45 (SEM 4) v. 41 (SEM 3) pmol/l × h, P < 0·05). In the morning until lunch, AUC(0-230 min) for PYY on day 13 was significantly higher with 16 g/d oligofructose compared with 10 g/d oligofructose and placebo (409 (SEM 35) v. 222 (SEM 19) and 211 (SEM 20) pg/ml × h, P < 0·01). In conclusion, 16 g/d and not 10 g/d oligofructose may be an effective dose to reduce energy intake, possibly supported by higher GLP-1 and PYY concentrations.

Gut microbiota and the pathogenesis of insulin resistance

Several reviews recently explored how the gut microbiota was able to control host energy metabolism, and thereby the development of adiposity. In this review, we focused on the state of the art that supports a link between the gut microbiota composition and activity, and the management of glycemia associated with overweight and diabetes. Several microbial-derived compounds are related to disturbances of glucose homeostasis including the gram-negative-derived lipopolysaccharides. Some nutrients with prebiotic properties, which escape the digestion in the upper part of the gut, modify the composition of the gut microbiota in favor of bacteria that could play a beneficial role on glucose homeostasis, namely by modulating the endocrine function of the gut, and by reinforcing the gut barrier. Adequate intervention studies in diabetic patients are required to assess the relevance of those experimental data for human health.

Effects of NUTRIOSE® dietary fiber supplementation on body weight, body composition, energy intake, and hunger in overweight men

The objective of the present study was to determine the effectiveness of a soluble dietary fiber, NUTRIOSE(®), on body weight, body composition, energy intake and hunger in overweight Chinese men. The volunteers were randomized in double-blind fashion to 250 ml fruit juice supplemented with NUTRIOSE(®) (Test, n = 60) or a maltodextrin (Control, n = 60) at a dosage of 17 g twice daily for 12 weeks. Body weight, body composition were performed at 0, 4, 8 and 12 weeks while daily energy intake and hunger were assessed every 3 days. Test subjects had reductions in body weight (1.5 kg, P < 0.001), body mass index (0.5 kg/m(2), P < 0.001) and body fat percentage (0.3%, P < 0.001) versus Controls. NUTRIOSE(®) supplementation resulted in a lower daily energy intake (3,079 kJ/day, P < 0.001) with group differences noted as early as 3 days. Test subjects reported less hunger across the study period versus Controls (P < 0.01). NUTRIOSE(®) supplementation for 12 weeks results in body composition improvements and reduces body weight, energy intake and hunger in overweight men.

Dietary proteins as determinants of metabolic and physiologic functions of the gastrointestinal tract

Dietary proteins elicit a wide range of nutritional and biological functions. Beyond their nutritional role as the source of amino acids for protein synthesis, they are instrumental in the regulation of food intake, glucose and lipid metabolism, blood pressure, bone metabolism and immune function. The interaction of dietary proteins and their products of digestion with the regulatory functions of the gastrointestinal (GI) tract plays a dominant role in determining the physiological properties of proteins. The site of interaction is widespread, from the oral cavity to the colon. The characteristics of proteins that influence their interaction with the GI tract in a source-dependent manner include their physico-chemical properties, their amino acid composition and sequence, their bioactive peptides, their digestion kinetics and also the non-protein bioactive components conjugated with them. Within the GI tract, these products affect several regulatory functions by interacting with receptors releasing hormones, affecting stomach emptying and GI transport and absorption, transmitting neural signals to the brain, and modifying the microflora. This review discusses the interaction of dietary proteins during digestion and absorption with the physiological and metabolic functions of the GI tract, and illustrates the importance of this interaction in the regulation of amino acid, glucose, lipid metabolism, and food intake.

Rye kernel breakfast increases satiety in the afternoon - an effect of food structure

Background

The structure of whole grain cereals is maintained to varying degrees during processing and preparation of foods. Food structure can influence metabolism, including perceived hunger and satiety. A diet that enhances satiety per calorie may help to prevent excessive calorie intake. The objective of this work was to compare subjective appetite ratings after consumption of intact and milled rye kernels.

Methods

Two studies were performed using a randomized, cross-over design. Ratings for appetite (hunger, satiety and desire to eat) were registered during an 8-h period after consumption of whole and milled rye kernels prepared as breads (study 1, n = 24) and porridges (study 2, n = 20). Sifted wheat bread was used as reference in both study parts and the products were eaten in iso-caloric portions with standardized additional breakfast foods. Breads and porridges were analyzed to determine whether structure (whole vs. milled kernels) effected dietary fibre content and composition after preparation of the products. Statistical evaluation of the appetite ratings after intake of the different breakfasts was done by paired t-tests for morning and afternoon ratings separately, with subjects as random effect and type of breakfast and time points as fixed effects.

Results

All rye breakfasts resulted in higher satiety ratings in the morning and afternoon compared with the iso-caloric reference breakfast with sifted wheat bread. Rye bread with milled or whole kernels affected appetite equally, so no effect of structure was observed. In contrast, after consumption of the rye kernel breakfast, satiety was increased and hunger suppressed in the afternoon compared with the milled rye kernel porridge breakfast. This effect could be related to structural differences alone, because the products were equal in nutritional content including dietary fibre content and composition.

Conclusions

The study demonstrates that small changes in diet composition such as cereal grain structure have the potential to effect feelings of hunger and satiety.

Trial registration

This trial was registered at clinicaltrials.gov as NCT01042418.

Dietary fiber is associated with circulating concentrations of C-reactive protein in breast cancer survivors: the HEAL study

Inflammation is a suspected risk factor for breast cancer and its subsequent prognosis. The extent to which dietary and lifestyle factors might influence inflammation is important to examine. Specifically, dietary fiber may reduce systemic inflammation, but this relationship has not been examined among breast cancer survivors. We examined associations between dietary fiber and serum concentrations of C-reactive protein (CRP) and serum amyloid A (SAA), among 698 female breast cancer survivors from the Health, Eating, Activity, and Lifestyle (HEAL) Study. Data are from interviews and clinical visits conducted 24-months post-study enrollment. Multivariate-adjusted linear regression estimated associations of total, soluble, and insoluble fiber with serum concentrations of CRP and SAA. Logistic regression estimated the odds of elevated CRP (defined as >3.0 mg/l) across tertiles of dietary fiber intake. Mean total dietary fiber intake was 13.9 ± 6.4 g/day. Mean CRP and SAA were 3.32 ± 3.66 and 7.73 ± 10.23 mg/l, respectively. We observed a multivariate-adjusted inverse association between total dietary fiber intake and CRP concentrations (β, -0.029; 95% CI, -0.049, -0.008). Results for insoluble fiber were similar (β, -0.039; 95% CI, -0.064, -0.013). Among survivors who consumed >15.5 g/day of insoluble dietary fiber, a 49% reduction in the likelihood of having elevated CRP concentrations (OR, 0.51; 95% CI, 0.27, 0.95) was observed compared to those who consumed <5.4 g/day (P = 0.053). Our results suggest that diets high in fiber may benefit breast cancer survivors via reductions in systemic inflammation; elevated inflammation may be prognostic for reduced survival.

Childhood overweight after establishment of the gut microbiota: the role of delivery mode, pre-pregnancy weight and early administration of antibiotics

OBJECTIVE

To investigate whether delivery mode (vaginal versus by caesarean section), maternal pre-pregnancy body mass index (BMI) and early exposure to antibiotics (<6 months of age) influence child's risk of overweight at age 7 years, hence supporting the hypotheses that environmental factors influencing the establishment and diversity of the gut microbiota are associated with later risk of overweight.

DESIGN

Longitudinal, prospective study with measure of exposures in infancy and follow-up at age 7 years.

METHODS

A total of 28 354 mother-child dyads from the Danish National Birth Cohort, with information on maternal pre-pregnancy BMI, delivery mode and antibiotic administration in infancy, were assessed. Logistic regression analyses were performed with childhood height and weight at the 7-year follow-up as outcome measures.

RESULTS

Delivery mode was not significantly associated with childhood overweight (odds ratio (OR):1.18, 95% confidence interval (CI): 0.95-1.47). Antibiotics during the first 6 months of life led to increased risk of overweight among children of normal weight mothers (OR: 1.54, 95% CI: 1.09-2.17) and a decreased risk of overweight among children of overweight mothers (OR: 0.54, 95% CI: 0.30-0.98). The same tendency was observed among children of obese mothers (OR: 0.85, 95% CI: 0.41-1.76).

CONCLUSION

The present cohort study revealed that a combination of early exposures, including delivery mode, maternal pre-pregnancy BMI and antibiotics in infancy, influences the risk of overweight in later childhood. This effect may potentially be explained by an impact on establishment and diversity of the microbiota.

Probiotics as an emerging therapeutic strategy to treat NAFLD: focus on molecular and biochemical mechanisms

Nonalcoholic fatty liver disease (NAFLD) is currently the most common liver disease worldwide, both in adults and in children. NAFLD is characterized by aberrant lipid storage in hepatocytes (hepatic steatosis) and inflammatory progression to nonalcoholic steatohepatitis. Evidences so far suggest that intrahepatic lipid accumulation does not always derive from obesity. Gut microbiota has been considered as a regulator of energy homeostasis and ectopic fat deposition, suggesting its implications in metabolic diseases. Probiotics are live microbial that alter the enteric microflora and have beneficial effects on human health. Although the molecular mechanisms of probiotics have not been completely elucidated yet, many of their effects have proved to be beneficial in NAFLD, including the modulation of the intestinal microbiota, an antibacterial substance production, an improved epithelial barrier function and a reduced intestinal inflammation. Given the close anatomical and functional correlation between the bowel and the liver, and the immunoregulatory effects elicited by probiotics, the aim of this review is to summarize today's knowledge about probiotics in NAFLD, focusing in particular on their molecular and biochemical mechanisms, as well as highlighting their efficacy as an emerging therapeutic strategy to treat this condition.

The gut microbiome as therapeutic target

Obesity, type-2 diabetes and low-grade inflammation are becoming worldwide epidemics. In this regard, the literature provides a novel concept that we call "MicrObesity" (Microbes and Obesity), which is devoted to deciphering the specific role of dysbiosis and its impact on host metabolism and energy storage. In the present review, we discuss novel findings that may partly explain how the microbial community participates in the development of the fat mass development, insulin resistance and low-grade inflammation that characterise obesity. In recent years, numerous mechanisms have been proposed and several proteins identified. Amongst the key players involved in the control of fat mass development, Fasting induced adipose factor, AMP-activated protein kinase, G-protein coupled receptor 41 and G-protein coupled receptor 43 have been linked to gut microbiota. In addition, the discovery that low-grade inflammation might be directly linked to the gut microbiota through metabolic endotoxaemia (elevated plasma lipopolysaccharide levels) has led to the identification of novel mechanisms involved in the control of the gut barrier. Amongst these, the impacts of glucagon-like peptide-2, the endocannabinoid system and specific bacteria (e.g., Bifidobacterium spp.) have been investigated. Moreover, the advent of probiotic and prebiotic treatments appears to be a promising "pharmaco-nutritional" approach to reversing the host metabolic alterations linked to the dysbiosis observed in obesity. Although novel powerful molecular system biology approaches have offered great insight into this "small world within", more studies are needed to unravel how specific changes in the gut microbial community might affect or counteract the development of obesity and related disorders.

Impact of microbial transformation of food on health - from fermented foods to fermentation in the gastro-intestinal tract

Fermentation of food components by microbes occurs both during certain food production processes and in the gastro-intestinal tract. In these processes specific compounds are produced that originate from either biotransformation reactions or biosynthesis, and that can affect the health of the consumer. In this review, we summarize recent advances highlighting the potential to improve the nutritional status of a fermented food by rational choice of food-fermenting microbes. The vast numbers of microbes residing in the human gut, the gut microbiota, also give rise to a broad array of health-active molecules. Diet and functional foods are important modulators of the gut microbiota activity that can be applied to improve host health. A truly multidisciplinary approach is required to increase our understanding of the molecular mechanisms underlying health beneficial effects that arise from the interaction of diet, microbes and the human body.

Quantification of butyryl CoA:acetate CoA-transferase genes reveals different butyrate production capacity in individuals according to diet and age

The gastrointestinal microbiota produces short-chain fatty acids, especially butyrate, which affect colonic health, immune function and epigenetic regulation. To assess the effects of nutrition and aging on the production of butyrate, the butyryl-CoA:acetate CoA-transferase gene and population shifts of Clostridium clusters lV and XlVa, the main butyrate producers, were analysed. Faecal samples of young healthy omnivores (24 ± 2.5 years), vegetarians (26 ± 5 years) and elderly (86 ± 8 years) omnivores were evaluated. Diet and lifestyle were assessed in questionnaire-based interviews. The elderly had significantly fewer copies of the butyryl-CoA:acetate CoA-transferase gene than young omnivores (P=0.014), while vegetarians showed the highest number of copies (P=0.048). The thermal denaturation of the butyryl-CoA:acetate CoA-transferase gene variant melting curve related to Roseburia/Eubacterium rectale spp. was significantly more variable in the vegetarians than in the elderly. The Clostridium cluster XIVa was more abundant in vegetarians (P=0.049) and in omnivores (P<0.01) than in the elderly group. Gastrointestinal microbiota of the elderly is characterized by decreased butyrate production capacity, reflecting increased risk of degenerative diseases. These results suggest that the butyryl-CoA:acetate CoA-transferase gene is a valuable marker for gastrointestinal microbiota function.

Prebiotic effects: metabolic and health benefits

The different compartments of the gastrointestinal tract are inhabited by populations of micro-organisms. By far the most important predominant populations are in the colon where a true symbiosis with the host exists that is a key for well-being and health. For such a microbiota, 'normobiosis' characterises a composition of the gut 'ecosystem' in which micro-organisms with potential health benefits predominate in number over potentially harmful ones, in contrast to 'dysbiosis', in which one or a few potentially harmful micro-organisms are dominant, thus creating a disease-prone situation. The present document has been written by a group of both academic and industry experts (in the ILSI Europe Prebiotic Expert Group and Prebiotic Task Force, respectively). It does not aim to propose a new definition of a prebiotic nor to identify which food products are classified as prebiotic but rather to validate and expand the original idea of the prebiotic concept (that can be translated in 'prebiotic effects'), defined as: 'The selective stimulation of growth and/or activity(ies) of one or a limited number of microbial genus(era)/species in the gut microbiota that confer(s) health benefits to the host.' Thanks to the methodological and fundamental research of microbiologists, immense progress has very recently been made in our understanding of the gut microbiota. A large number of human intervention studies have been performed that have demonstrated that dietary consumption of certain food products can result in statistically significant changes in the composition of the gut microbiota in line with the prebiotic concept. Thus the prebiotic effect is now a well-established scientific fact. The more data are accumulating, the more it will be recognised that such changes in the microbiota's composition, especially increase in bifidobacteria, can be regarded as a marker of intestinal health. The review is divided in chapters that cover the major areas of nutrition research where a prebiotic effect has tentatively been investigated for potential health benefits. The prebiotic effect has been shown to associate with modulation of biomarkers and activity(ies) of the immune system. Confirming the studies in adults, it has been demonstrated that, in infant nutrition, the prebiotic effect includes a significant change of gut microbiota composition, especially an increase of faecal concentrations of bifidobacteria. This concomitantly improves stool quality (pH, SCFA, frequency and consistency), reduces the risk of gastroenteritis and infections, improves general well-being and reduces the incidence of allergic symptoms such as atopic eczema. Changes in the gut microbiota composition are classically considered as one of the many factors involved in the pathogenesis of either inflammatory bowel disease or irritable bowel syndrome. The use of particular food products with a prebiotic effect has thus been tested in clinical trials with the objective to improve the clinical activity and well-being of patients with such disorders. Promising beneficial effects have been demonstrated in some preliminary studies, including changes in gut microbiota composition (especially increase in bifidobacteria concentration). Often associated with toxic load and/or miscellaneous risk factors, colon cancer is another pathology for which a possible role of gut microbiota composition has been hypothesised. Numerous experimental studies have reported reduction in incidence of tumours and cancers after feeding specific food products with a prebiotic effect. Some of these studies (including one human trial) have also reported that, in such conditions, gut microbiota composition was modified (especially due to increased concentration of bifidobacteria). Dietary intake of particular food products with a prebiotic effect has been shown, especially in adolescents, but also tentatively in postmenopausal women, to increase Ca absorption as well as bone Ca accretion and bone mineral density. Recent data, both from experimental models and from human studies, support the beneficial effects of particular food products with prebiotic properties on energy homaeostasis, satiety regulation and body weight gain. Together, with data in obese animals and patients, these studies support the hypothesis that gut microbiota composition (especially the number of bifidobacteria) may contribute to modulate metabolic processes associated with syndrome X, especially obesity and diabetes type 2. It is plausible, even though not exclusive, that these effects are linked to the microbiota-induced changes and it is feasible to conclude that their mechanisms fit into the prebiotic effect. However, the role of such changes in these health benefits remains to be definitively proven. As a result of the research activity that followed the publication of the prebiotic concept 15 years ago, it has become clear that products that cause a selective modification in the gut microbiota's composition and/or activity(ies) and thus strengthens normobiosis could either induce beneficial physiological effects in the colon and also in extra-intestinal compartments or contribute towards reducing the risk of dysbiosis and associated intestinal and systemic pathologies.

Gut microbiota and obesity

Intestinal epithelium, mucosal immune system, and bacterial flora represent a morpho-functional system on dynamic balance responsible for the intestinal metabolic and trophic functions, and the regulation of mucosal and systemic host's immunity. Obesity is a pathological condition affecting a growing number of people especially in the Western countries resulting from the failure of the organism's energetic balance based on the perfect equality of income, waste, and storage. Recent evidences explain the mechanisms for the microbial regulation of the host's metabolism both in health and disease. In particular, animal studies have explained how quali-/quantitative changes in microflora composition are able to affect the absorption of the nutrients and the energy distribution. Antibiotics, prebiotics, probiotics, and symbiotics are the instruments utilized in the current clinical practice to modulate the intestinal bacterial flora in man both in health and pathologic conditions with promising preliminary results on prevention and therapy of obesity and related metabolic diseases.

Obesity, diabetes, and gut microbiota: the hygiene hypothesis expanded?

The connection between gut microbiota and energy homeostasis and inflammation and its role in the pathogenesis of obesity-related disorders are increasingly recognized. Animals models of obesity connect an altered microbiota composition to the development of obesity, insulin resistance, and diabetes in the host through several mechanisms: increased energy harvest from the diet, altered fatty acid metabolism and composition in adipose tissue and liver, modulation of gut peptide YY and glucagon-like peptide (GLP)-1 secretion, activation of the lipopolysaccharide toll-like receptor-4 axis, and modulation of intestinal barrier integrity by GLP-2. Instrumental for gut microbiota manipulation is the understanding of mechanisms regulating gut microbiota composition. Several factors shape the gut microflora during infancy: mode of delivery, type of infant feeding, hospitalization, and prematurity. Furthermore, the key importance of antibiotic use and dietary nutrient composition are increasingly recognized. The role of the Western diet in promoting an obesogenic gut microbiota is being confirmation in subjects. Following encouraging results in animals, several short-term randomized controlled trials showed the benefit of prebiotics and probiotics on insulin sensitivity, inflammatory markers, postprandial incretins, and glucose tolerance. Future research is needed to unravel the hormonal, immunomodulatory, and metabolic mechanisms underlying microbe-microbe and microbiota-host interactions and the specific genes that determine the health benefit derived from probiotics. While awaiting further randomized trials assessing long-term safety and benefits on clinical end points, a healthy lifestyle--including breast lactation, appropriate antibiotic use, and the avoidance of excessive dietary fat intake--may ensure a friendly gut microbiota and positively affect prevention and treatment of metabolic disorders.

Antiobesity effects of Bifidobacterium breve strain B-3 supplementation in a mouse model with high-fat diet-induced obesity

The aim of the present study was to evaluate the anti-obesity activity of a probiotic bifidobacterial strain in a mouse model with obesity induced by a high-fat diet. The mice were fed a high-fat diet supplemented with Bifidobacterium breve B-3 at 10(8) or 10(9) CFU/d for 8 weeks. B. breve B-3 supplementation dose-dependently suppressed the accumulation of body weight and epididymal fat, and improved the serum levels of total cholesterol, fasting glucose and insulin. The bifidobacterial counts in the caecal contents and feces were significantly increased with the B. breve B-3 administration. The expression of genes related to fat metabolism and insulin sensitivity in the gut and epididymal fat tissue was up-regulated by this administration. These results suggest that the use of B. breve B-3 would be effective in reducing the risk of obesity.

Free fatty acid receptors: emerging targets for treatment of diabetes and its complications

Fatty acids (FAs) are important as metabolic substrates and as structural components of biological membranes. However, they also function as signalling molecules. Recently, a series of G protein-coupled receptors (GPRs) for FAs has been described and characterized. These receptors have differing specificities for FAs of differing chain length and degree of saturation, for FA derivatives such as oleoylethanolamide, and for oxidized FAs. They are a critical component of the body's nutrient sensing apparatus, and small molecule agonists and antagonists of these receptors show considerable promise in the management of diabetes and its complications. Agonists of the long-chain free fatty acid receptors FFAR1 and GPR119 act as insulin secretagogues, both directly and by increasing incretins. Although, drugs acting at short-chain FFA receptors (FFAR2 and FFAR3) have not yet been developed, they are attractive targets as they regulate nutrient balance through effects in the intestine and adipose tissue. These include regulation of the secretion of cholecystokinin, peptide YY and leptin. Finally, GPR132 is a receptor for oxidized FAs, which may be a sensor of lipid overload and oxidative stress, and which is involved in atherosclerosis. Regulation of its signalling pathways with drugs may decrease the macrovascular risk experienced by diabetic patients. In summary, FA receptors are emerging drug targets that are involved in the regulation of nutrient status and carbohydrate tolerance, and modulators of these receptors may well figure prominently in the next generation of antidiabetic drugs.

Functional intestinal microbiome, new frontiers in prebiotic design

In this review we focus on the revision of the prebiotic concept in the context of the new metagenomic era. Functional metagenomic data provided by the Human Microbiome Project are revolutionizing the view of the symbiotic relationship between the intestinal microbiota and the human host. A deeper knowledge of the mechanisms that govern the dynamic interplay between diet, intestinal microbiota and host nutrition opens the way to better information on the prebiotic structure-function relationships, tailoring prebiotic formula into specific health attributes. On the other hand, functional genomic studies of the sourdough microbial communities allow to scan the environmental variability to identify novel metabolic traits for the biosynthesis of new potential prebiotic molecules. The integration of the functional analyses provided by the massive sequencing of bacterial genomes and metagenomes will allow the rational production of a desired prebiotic molecule with specific functional properties.