Prebiotic effects: metabolic and health benefits. Br J Nutr. 2010;104 Suppl 2:S1-S63. [PMID: 20920376 DOI: 10.1017/s0007114510003363]

Gastrointestinal microbiota and some children diseases: a review

The bacterial colonization is defined immediately after birth, through direct contact with maternal microbiota and may be influenced during lactation. There is emerging evidence indicating that quantitative and qualitative changes on gut microbiota contribute to alterations in the mucosal activation of immune system leading to intra- or extra-intestinal diseases. A balance between pathogenic and beneficial microbiota throughout childhood and adolescence is important to gastrointestinal health, including protection against pathogens, inhibition of pathogens, nutrient processing (synthesis of vitamin K), stimulation of angiogenesis, and regulation of host fat storage. Probiotics can promote an intentional modulation of intestinal microbiota favoring the health of the host. This paper is a review about modulation of intestinal microbiota on prevention and adjuvant treatment of pediatric gastrointestinal diseases.

Yacon (Smallanthus sonchifolius)-derived fructooligosaccharides improves the immune parameters in the mouse

Owing to its high contents of fructooligosaccharides (FOSs), the yacon (Smallanthus sonchifolius) root is used in traditional Andean medicine as a substitute for cane sugar in diabetes and for obesity prevention. This study was designed to test the hypothesis that regular consumption of yacon works to improve the immune system. BALB/c mice were fed with the AIN-93 diet supplemented with 5% commercial FOS or either 3% or 5% yacon FOS for 30 consecutive days. Animals in the control group were fed with nonsupplemented ration. Food intake; weight gain; serum levels of IgA, IgM, and IgG; levels of fecal IgA, production of nitric oxide by peritoneal macrophages, frequencies of T and B lymphocytes in the spleen and peripheral blood, T-cell proliferation, and cytokine production were evaluated in all groups. No significant differences were observed in food intake and weight gain when the experimental and control groups were compared. Also, serum levels of IgA, IgM, and IgG; nitric oxide production in peritoneal macrophages; frequencies of T and B lymphocytes in the spleen and peripheral blood; T-cell proliferation; and production of interleukin (IL)-4, interferon-γ, IL-10, and tumor necrosis factor α did not differ in the different groups. The intake of FOS, however, led to a significant reduction of the proinflammatory cytokine IL-1β in macrophage cultures and elevation of the levels of fecal IgA. Together, these results indicate that the daily consumption of yacon does not exert negative effects on the immune system, helps to preserve an anti-inflammatory state in phagocytic cells, and improves mucosal immunity, possibly preventing the risks associated with autoimmune and metabolic diseases.

The effect of selected synbiotics on microbial composition and short-chain fatty acid production in a model system of the human colon

BACKGROUND

Prebiotics, probiotics and synbiotics can be used to modulate both the composition and activity of the gut microbiota and thereby potentially affecting host health beneficially. The aim of this study was to investigate the effects of eight synbiotic combinations on the composition and activity of human fecal microbiota using a four-stage semicontinuous model system of the human colon.

METHODS AND FINDINGS

Carbohydrates were selected by their ability to enhance growth of the probiotic bacteria Lactobacillus acidophilus NCFM (NCFM) and Bifidobacterium animalis subsp. lactis Bl-04 (Bl-04) under laboratory conditions. The most effective carbohydrates for each probiotic were further investigated, using the colonic model, for the ability to support growth of the probiotic bacteria, influence the composition of the microbiota and stimulate formation of short-chain fatty acids (SCFA).The following combinations were studied: NCFM with isomaltulose, cellobiose, raffinose and an oat β-glucan hydrolysate (OBGH) and Bl-04 with melibiose, xylobiose, raffinose and maltotriose. All carbohydrates showed capable of increasing levels of NCFM and Bl-04 during fermentations in the colonic model by 10(3)-10(4) fold and 10-10(2) fold, respectively. Also the synbiotic combinations decreased the modified ratio of Bacteroidetes/Firmicutes (calculated using qPCR results for Bacteroides-Prevotella-Porphyromonas group, Clostridium perfringens cluster I, Clostridium coccoides - Eubacterium rectale group and Clostridial cluster XIV) as well as significantly increasing SCFA levels, especially acetic and butyric acid, by three to eight fold, as compared to the controls. The decreases in the modified ratio of Bacteroidetes/Firmicutes were found to be correlated to increases in acetic and butyric acid (p=0.04 and p=0.03, respectively).

CONCLUSIONS

The results of this study show that all synbiotic combinations investigated are able to shift the predominant bacteria and the production of SCFA of fecal microbiota in a model system of the human colon, thereby potentially being able to manipulate the microbiota in a way connected to human health.

Host responses to the human microbiome

The human gut is home to vast numbers of bacteria (gut microbiota), which outnumber the cells in the human body by an order of magnitude. The gut microbiota has coevolved with humans and can be considered an organ of similar size as the liver, containing more than 1,000 cell types (bacterial species) and encoding 150-fold more genes than are present in the human genome. Accordingly, the gut microbiota may have profound effects on various host responses, either directly or indirectly, by modifying food components or endogenously produced molecules into signaling molecules. Recent findings suggest that an altered gut microbial composition is associated with inflammatory bowel disease and obesity, indicating that the gut microbiota should be considered a contributing factor in several common diseases.

The role of the gut microbiota in nutrition and health

The microbial communities that colonize different regions of the human gut influence many aspects of health. In the healthy state, they contribute nutrients and energy to the host via the fermentation of nondigestible dietary components in the large intestine, and a balance is maintained with the host's metabolism and immune system. Negative consequences, however, can include acting as sources of inflammation and infection, involvement in gastrointestinal diseases, and possible contributions to diabetes mellitus and obesity. Major progress has been made in defining some of the dominant members of the microbial community in the healthy large intestine, and in identifying their roles in gut metabolism. Furthermore, it has become clear that diet can have a major influence on microbial community composition both in the short and long term, which should open up new possibilities for health manipulation via diet. Achieving better definition of those dominant commensal bacteria, community profiles and system characteristics that produce stable gut communities beneficial to health is important. The extent of interindividual variation in microbiota composition within the population has also become apparent, and probably influences individual responses to drug administration and dietary manipulation. This Review considers the complex interplay between the gut microbiota, diet and health.

Transcriptional analysis of prebiotic uptake and catabolism by Lactobacillus acidophilus NCFM

The human gastrointestinal tract can be positively modulated by dietary supplementation of probiotic bacteria in combination with prebiotic carbohydrates. Here differential transcriptomics and functional genomics were used to identify genes in Lactobacillus acidophilus NCFM involved in the uptake and catabolism of 11 potential prebiotic compounds consisting of α- and β- linked galactosides and glucosides. These oligosaccharides induced genes encoding phosphoenolpyruvate-dependent sugar phosphotransferase systems (PTS), galactoside pentose hexuronide (GPH) permease, and ATP-binding cassette (ABC) transporters. PTS systems were upregulated primarily by di- and tri-saccharides such as cellobiose, isomaltose, isomaltulose, panose and gentiobiose, while ABC transporters were upregulated by raffinose, Polydextrose, and stachyose. A single GPH transporter was induced by lactitol and galactooligosaccharides (GOS). The various transporters were associated with a number of glycoside hydrolases from families 1, 2, 4, 13, 32, 36, 42, and 65, involved in the catabolism of various α- and β-linked glucosides and galactosides. Further subfamily specialization was also observed for different PTS-associated GH1 6-phospho-β-glucosidases implicated in the catabolism of gentiobiose and cellobiose. These findings highlight the broad oligosaccharide metabolic repertoire of L. acidophilus NCFM and establish a platform for selection and screening of both probiotic bacteria and prebiotic compounds that may positively influence the gastrointestinal microbiota.

Metabolomics reveals drastic compositional changes during overwintering of Jerusalem artichoke (Helianthus tuberosus L.) tubers

Metabolic changes were investigated in overwintering Jerusalem artichoke (Helianthus tuberosus L.) tubers using proton nuclear magnetic resonance ((1)H NMR) metabolomics. Three varieties were studied; as a result of overwintering, the amount of inulin was found to decrease in Jerusalem artichoke tubers. This was mainly due to its conversion to sucrose and, at the same time, formation of inulin with a lower degree of polymerization. Major effects on the concentration of citric acid, malic acid, γ-aminobutyric acid (GABA), and adenosine were also found. Intriguingly, malic acid concentration increased and citric acid concentration decreased. These changes, together with an increase in sucrose and GABA concentrations, were ascribed to mobilization of nutrients prior to sprouting, suggesting that malic acid and GABA serve as carbon and nitrogen sources during sprouting of Jerusalem artichokes.

Up-regulating the human intestinal microbiome using whole plant foods, polyphenols, and/or fiber

Whole plant foods, including fruit, vegetables, and whole grain cereals, protect against chronic human diseases such as heart disease and cancer, with fiber and polyphenols thought to contribute significantly. These bioactive food components interact with the gut microbiota, with gut bacteria modifying polyphenol bioavailability and activity, and with fiber, constituting the main energy source for colonic fermentation. This paper discusses the consequences of increasing the consumption of whole plant foods on the gut microbiota and subsequent implications for human health. In humans, whole grain cereals can modify fecal bacterial profiles, increasing relative numbers of bifidobacteria and lactobacilli. Polyphenol-rich chocolate and certain fruits have also been shown to increase fecal bifidobacteria. The recent FLAVURS study provides novel information on the impact of high fruit and vegetable diets on the gut microbiota. Increasing whole plant food consumption appears to up-regulate beneficial commensal bacteria and may contribute toward the health effects of these foods.

The role of whole grains in body weight regulation

Whole grain (WG)-rich diets are purported to have a variety of health benefits, including a favorable role in body weight regulation. Current dietary recommendations advocate substituting WG for refined grains (RG), because many of the beneficial bioactive components intrinsic to WG are lost during the refining process. Epidemiological studies consistently demonstrate that higher intakes of WG, but not RG, are associated with lower BMI and/or reduced risk of obesity. However, recent clinical trials have failed to support a role for WG in promoting weight loss or maintenance. Though the biochemical and structural characteristics of WG have been shown to modulate appetite, nutrient availability, and energy utilization, the capacity of WG foods to elicit these effects varies with the type and amount of grain consumed as well as the nature of its consumption. As such, WG foods differentially affect physiologic factors influencing body weight with the common practice of processing and reconstituting WG ingredients during food production likely mitigating the capacity for WG to benefit body weight regulation.

Alterations of the gut microbiota in high-fat diet mice is strongly linked to oxidative stress

Alterations of the gut microbiota induced by diet exert a strong influence on the development of metabolic syndrome. In this study, we prove the hypothesis that the long-term high-fat diet (HFD) may influence gut microbiota directly and/or indirectly by changing the redox state. Lipoic acid (LA), as a universal antioxidant, was used to improve the redox state. Reactive oxygen species (ROS), total antioxidant capacity (T-AOC), and malondialdehyde (MDA) were analyzed to profile oxidative stress states. PCR-denaturing gradient gel electrophoresis (DGGE) was used to describe gut flora structures, while plate count was employed for the quantitative analysis of Escherichia coli, lactobacilli, and enterococcus. The influence of redox state on the vitality of gut-derived bacteria was measured in vitro. ROS and MDA, which significantly decreased in LA mice compared with HFD mice, showed a strong positive association with E. coli and enterococcus (P < 0.05) and a negative association with lactobacilli (P < 0.05). Increased T-AOC in LA mice showed a high positive association with lactobacilli (P < 0.05) and a negative correlation with E. coli and enterococcus. These correlations implied that the dietary effects on the gut microbiota were conferred, at least in part, through an effect on oxidative stress. This study provides evidence that modulation of the redox state by an antioxidant has the potential to improve gut microbiota, which has relevance for metabolic health.

Bacterial flora as a cause or treatment of chronic diarrhea

Intestinal microflora can be considered an organ of the body. It has several functions in the human gut, mostly metabolic and immunologic, and constantly interacts with the intestinal mucosa in a delicate equilibrium. Chronic diarrhea is associated with an alteration of gut microbiota when a pathogen invades the gut and also in several conditions associated with intestinal mucosal damage or bowel dysfunction, as in inflammatory bowel disease, irritable bowel syndrome, or small bowel bacterial overgrowth. This article discusses the basis of gut microbiota modulation. Evidence for the efficacy of gut microbiota modulation in chronic conditions is also discussed.

Prebiotic effect of soluble fibres from modern and old durum-type wheat varieties on Lactobacillus and Bifidobacterium strains

BACKGROUND

Wheat grains are a rich source of dietary fibres, particularly in the western human diet. Many of the health effects attributed to dietary fibres are believed to be related to their microbial fermentation in the gut. This study evaluated the ability of two potentially probiotic strains, Lactobacillus plantarum L12 and Bifidobacterium pseudocatenulatum B7003, to ferment soluble dietary fibres (SDFs) from modern and ancient durum-type wheat grains.

RESULTS

Fibre microbial utilisation was highly variable and dependent on the strain. SDFs from the varieties Svevo and Solex supported the growth of L. plantarum L12 the best, whereas those from the varieties Anco Marzio, Solex and Kamut(®) Khorasan were good carbohydrate substrates for B. pseudocatenulatum B7003. The highest prebiotic activity scores (describing the extent to which prebiotics support selective growth of probiotics) for B7003 were obtained with SDFs from the varieties Solex (0.57), Kamut(®) Khorasan (0.56) and Iride (0.55), whereas for L12 the highest scores were achieved with the varieties Orobel (0.63), Kamut(®) Khorasan (0.56) and Solex (0.53).

CONCLUSION

The present study has identified some SDFs from durum-type wheat grains as suitable prebiotic substrates for the selective proliferation of B. pseudocatenulatum B7003 and L. plantarum L12 in vitro. The results provide the basis for the potential utilisation of wheat-based prebiotics as a component of synbiotic formulations.

The health benefits of dietary fiber: beyond the usual suspects of type 2 diabetes mellitus, cardiovascular disease and colon cancer

Dietary fiber (DF) is deemed to be a key component in healthy eating. DF is not a static collection of undigestible plant materials that pass untouched or unencumbered through the gastrointestinal (GI) tract; instead, DFs are a vast array of complex saccharide-based molecules that can bind potential nutrients and nutrient precursors to prevent their absorption. Some DFs are fermentable, and the GI tract catabolism leads to the generation of various bioactive materials, such as short-chain fatty acids (SCFAs), that can markedly augment the GI tract biomass and change the composition of the GI tract flora. The health benefits of DFs include the prevention and mitigation of type 2 diabetes mellitus, cardiovascular disease and colon cancer. By modulating food ingestion, digestion, absorption and metabolism, DFs reduce the risk of hyperlipidemia, hypercholesterolemia and hyperglycemia. Emerging research has begun to investigate the role of DFs in immunomodulation. If substantiated, DFs could facilitate many biologic processes, including infection prevention and the improvement of mood and memory. This review describes the accepted physiologic functions of DFs and explores their new potential immune-based actions.

Fermentable carbohydrate restriction reduces luminal bifidobacteria and gastrointestinal symptoms in patients with irritable bowel syndrome

Preliminary studies indicate that dietary restriction of fermentable short-chain carbohydrates improves symptoms in irritable bowel syndrome (IBS). Prebiotic fructo-oligosaccharides and galacto-oligosaccharides stimulate colonic bifidobacteria. However, the effect of restricting fermentable short-chain carbohydrates on the gastrointestinal (GI) microbiota has never been examined. This randomized controlled trial aimed to investigate the effects of fermentable carbohydrate restriction on luminal microbiota, SCFA, and GI symptoms in patients with IBS. Patients with IBS were randomized to the intervention diet or habitual diet for 4 wk. The incidence and severity of symptoms and stool output were recorded for 7 d at baseline and follow-up. A stool sample was collected and analyzed for bacterial groups using fluorescent in situ hybridization. Of 41 patients randomized, 6 were withdrawn. At follow-up, there was lower intake of total short-chain fermentable carbohydrates in the intervention group compared with controls (P = 0.001). The total luminal bacteria at follow-up did not differ between groups; however, there were lower concentrations (P < 0.001) and proportions (P < 0.001) of bifidobacteria in the intervention group compared with controls when adjusted for baseline. In the intention-to-treat analysis, more patients in the intervention group reported adequate control of symptoms (13/19, 68%) compared with controls (5/22, 23%; P = 0.005). This randomized controlled trial demonstrated a reduction in concentration and proportion of luminal bifidobacteria after 4 wk of fermentable carbohydrate restriction. Although the intervention was effective in managing IBS symptoms, the implications of its effect on the GI microbiota are still to be determined.

The role of prebiotics and probiotics in prevention and treatment of childhood infectious diseases

Infant formulae and food products marketed for children have been increasingly supplemented with probiotics and/or prebiotics. A vast number of studies have accounted for the transit of probiotic use from alternative to more evidence-based medicine. Data support the use of certain probiotics for the adjunct treatment of acute viral gastroenteritis, and for prevention of gastrointestinal diseases. Further roles of prebiotics and probiotics are seen in the prevention of overall infectious diseases and respiratory infections. Data from well-conducted randomized-controlled trials support the therapeutic role for probiotics toward necrotizing enterocolitis in preterm infants. However, it is difficult to translate heterogeneous-based study results, which are mainly due to varying genera, strains, doses, study settings and measured outcomes, into evidence-based recommendations. This article focuses on the evidence of clinical benefits of prebiotics, probiotics and synbiotics toward prevention and treatment of pediatric infectious diseases.

Impact of a resistant dextrin on intestinal ecology: how altering the digestive ecosystem with NUTRIOSE®, a soluble fibre with prebiotic properties, may be beneficial for health

OBJECTIVES

The prebiotic potential of NUTRIOSE®--a sugar-free, digestion-resistant dextrin--was evaluated in two randomized, placebo-controlled trials that included 48 and 40 healthy volunteers, respectively.

METHODS

In study 1, the effect on colonic bacteria of NUTRIOSE® 10, 15 or 20 g/day administered for 14 days was examined; in study 2, gut microbial changes in response to NUTRIOSE® 8 g/day for 14 days were monitored using real-time polymerase chain reaction analysis.

RESULTS

NUTRIOSE® increased proliferation of Bacteroides and inhibited Clostridum perfringens in both studies, increased β-glucosidase activity (at 10 and 15 g/day) and decreased colonic pH (at 20 g/day). The increase in short-chain fatty acid production with NUTRIOSE® consumption was not statistically significant. There were no indications of gastrointestinal intolerance at any dose.

CONCLUSIONS

According to commonly accepted definitions, NUTRIOSE® is a prebiotic soluble fibre that provides a beneficial effect on colonic ecology while preserving digestive comfort.

Simultaneous determination of uronates found in polysaccharides from natural products by HPLC with fluorometric detection

A sensitive high-performance liquid chromatographic (HPLC) method for the determination of uronates isolated from polysaccharides found in natural products such as glycosaminoglycans and alginate is described. Preparation of iduronate, guluronate, and mannuronate as analytical standards for high performance liquid chromatography was achieved by depolymerization of dermatan sulfate and alginate in 2.5 mol L(-1) trifluoroacetic acid at 100°C for 6h. Structures of resulting products (iduronate, guluronate, and mannuronate) were characterized by 600 MHz (1)H NMR. Five uronates (glucuronate, iduronate, mannuronate, guluronate, and galacturonate) were separated on a Dionex CarboPac PA1 column using an isocratic elution with 8 mmol L(-1) acetate buffer (pH 4.84) and were monitored by fluorescence detection using 1.5% 2-cyanoacetamide as a post-column fluorogenic reagent. As little as 50 pmol of each uronate could be detected with excitation at 331 nm and emission at 383 nm.

Involvement of gut microbiota in the development of low-grade inflammation and type 2 diabetes associated with obesity

Obesity is associated with metabolic alterations related to glucose homeostasis and cardiovascular risk factors. These metabolic alterations are associated with low-grade inflammation that contributes to the onset of these diseases. We and others have provided evidence that gut microbiota participates in whole-body metabolism by affecting energy balance, glucose metabolism, and low-grade inflammation associated with obesity and related metabolic disorders. Recently, we defined gut microbiota-derived lipopolysaccharide (LPS) (and metabolic endotoxemia) as a factor involved in the onset and progression of inflammation and metabolic diseases. In this review, we discuss mechanisms involved in the development of metabolic endotoxemia such as the gut permeability. We also discuss our latest discoveries demonstrating a link between the gut microbiota, endocannabinoid system tone, leptin resistance, gut peptides (glucagon-like peptide-1 and -2), and metabolic features. Finally, we will introduce the role of the gut microbiota in specific dietary treatments (prebiotics and probiotics) and surgical interventions (gastric bypass).

Effect of alginate supplementation on weight loss in obese subjects completing a 12-wk energy-restricted diet: a randomized controlled trial

BACKGROUND

Acute studies with alginate-based preloads suggested that these strong gelling fibers may induce increased feelings of satiety and reduce energy intakes. However, the long-term efficacy and safety of alginate supplementation on body weight regulation are lacking.

OBJECTIVE

The primary aim of the study was to investigate the effects in subjects of alginate supplementation in conjunction with energy restriction (-300 kcal/d) on loss of body weight and fat and, second, on metabolic risk markers in comparison with in a placebo group.

DESIGN

In a parallel, double-blind, placebo-controlled study, we randomly assigned 96 obese subjects to either an energy-restricted diet plus a placebo preload supplement or an energy-restricted diet plus an alginate-based preload supplement (15 g fiber). The preload was administered as a beverage 3 times/d before main meals for a period of 12 wk.

RESULTS

No differences in loss of body weight and fat between groups were shown in the intension-to-treat (ITT) analysis (P > 0.1). However, in the completer analysis (n = 80), we showed a greater weight loss with alginate (6.78 ± 3.67 kg) than with the placebo (5.04 ± 3.40 kg) (P = 0.03), which was mainly attributed to a reduction in the percentage of body fat (P = 0.03). In the ITT analysis, a larger decrease in systolic and diastolic blood pressure was shown in the placebo group than in the alginate group (P < 0.05). Plasma concentrations of glucose, insulin, C-reactive protein, and ghrelin, HOMA-IR, and lipid metabolism did not differ between treatment groups in the ITT analysis (P > 0.1).

CONCLUSION

These results suggest that alginate supplementation as an adjunct to energy restriction may improve weight loss in obese subjects who complete a 12-wk dietary intervention.

Metabolic diseases and pro- and prebiotics: Mechanistic insights

Metabolic diseases, such as obesity and type 2 diabetes, are world-wide health problems. The prevalence of metabolic diseases is associated with dynamic changes in dietary macronutrient intake during the past decades. Based on national statistics and from a public health viewpoint, traditional approaches, such as diet and physical activity, have been unsuccessful in decreasing the prevalence of metabolic diseases. Since the approaches strongly rely on individual’s behavior and motivation, novel science-based strategies should be considered for prevention and therapy for the diseases. Metabolism and immune system are linked. Both overnutrition and infection result in inflammation through nutrient and pathogen sensing systems which recognize compounds with structural similarities. Dietary macronutrients (fats and sugars) can induce inflammation through activation of an innate immune receptor, Toll-like receptor 4 (TLR4). Long-term intake of diets high in fats and meats appear to induce chronic systemic low-grade inflammation, endotoxicity, and metabolic diseases. Recent investigations support the idea of the involvement of intestinal bacteria in host metabolism and preventative and therapeutic potentials of probiotic and prebiotic interventions for metabolic diseases. Specific intestinal bacteria seem to serve as lipopolysaccharide (LPS) sources through LPS and/or bacterial translocation into the circulation due to a vulnerable microbial barrier and increased intestinal permeability and to play a role in systemic inflammation and progression of metabolic diseases. This review focuses on mechanistic links between metabolic diseases (mainly obesity and type 2 diabetes), chronic systemic low-grade inflammation, intestinal environment, and nutrition and prospective views of probiotic and prebiotic interventions for the diseases.

Polyphenol-rich extract of pomegranate peel alleviates tissue inflammation and hypercholesterolaemia in high-fat diet-induced obese mice: potential implication of the gut microbiota

Pomegranate extracts have been used for centuries in traditional medicine to confer health benefits in a number of inflammatory diseases, microbial infections and cancer. Peel fruit are rich in polyphenols that exhibit antioxidant and anti-inflammatory capacities in vitro. Recent studies strongly suggest that the gut microbiota is an environmental factor to be taken into account when assessing the risk factors related to obesity. The aim of the present study was to test the prebiotic potency of a pomegranate peel extract (PPE) rich in polyphenols in a nutritional model of obesity associated with hypercholesterolaemia and inflammatory disorders. Balb/c mice were fed either a control diet or a high-fat (HF) diet with or without PPE (6 mg/d per mouse) over a period of 4 weeks. Interestingly, PPE supplementation increased caecal content weight and caecal pool of bifidobacteria. It did not significantly modify body weight gain, glycaemia, glucose tolerance and inflammatory markers measured in the serum. However, it reduced the serum level of cholesterol (total and LDL) induced by HF feeding. Furthermore, it counteracted the HF-induced expression of inflammatory markers both in the colon and the visceral adipose tissue. Together, these findings support that pomegranate constitutes a promising food in the control of atherogenic and inflammatory disorders associated with diet-induced obesity. Knowing the poor bioavailability of pomegranate polyphenols, its bifidogenic effect observed after PPE consumption suggests the involvement of the gut microbiota in the management of host metabolism by polyphenolic compounds present in pomegranate.

Effects of tea combined with high-protein meal replacement shakes on anthropometric measurements, lipid profiles, cellular biochemistry, neurochemistry, and microbial metabolism: a prospective observational study

OBJECTIVE

The purpose of this study was to report preliminary data on the effects of tea and high-protein meal replacement shakes on weight loss, waist-to-hip ratios, and lipid profiles in healthy subjects. Secondary analyses of urine samples assessed pre-post changes in cellular biochemistry, neurochemistry, and microbial metabolism.

METHODS

This study used a pre-post intervention design without a control group. Thirty healthy subjects (20-60 years of age; 23 women and 7 men) participated in a 28-day diet intervention program consisting of a cleansing day and 6 restricted diet days per week. On cleansing days, the subjects drank 4 oz of tea 4 times per day with a recommendation to drink at least 64 oz of filtered water. On the restricted diet days, the subjects drank 2 high-protein meal replacement shakes, consumed one 400- to 600-cal (1674.3-2511.5 joules) meal consisting of low-glycemic index foods, and drank at least 64 oz of filtered water.

RESULTS

Multiple paired t tests detected reductions in weight (6.4 lb), waist (1.9 in), and hip (1.1 in) measurements and in total cholesterol (13.3 mg/dL) and low-density lipoprotein cholesterol (11.4 mg/dL) (P < .05). Multiple paired t tests detected significant increases in energy metabolism from carbohydrates and amino acids and concomitant increases in oxidative stress (P < .05).

CONCLUSION

The data support the concept that a low-glycemic load diet intervention incorporating tea and high-protein meal replacement shakes may cause weight loss and improve lipid profiles. The significant physiologic changes from the urine samples did not reflect meaningful metabolic effects.

Intestinal microbiota, pathophysiology and translation to probiotic use in patients with irritable bowel syndrome

Probiotic agents have received growing attention in recent years as an alternative therapeutic tool in the management of irritable bowel syndrome. In this article, we will discuss the rationale that support this indication, including the role of intestinal microbiota in gastrointestinal function in both human and animal models, potential links between an impaired microbiota imbalance and the psycho-immunopathophysiology of irritable bowel syndrome, and the results of the available clinical trials to date.

Coffee, colon function and colorectal cancer

For several years the physiological effects of coffee have been focused on its caffeine content, disregarding the hundreds of bioactive coffee components, such as polyphenols, melanoidins, carbohydrates, diterpenes, etc. These compounds may exert their protection against colorectal cancer (CRC), the third most common cancer worldwide. However, the amount and type of compounds ingested with the beverage may be highly different depending on the variety of coffee used, the roasting degree, the type of brewing method as well as the serving size. In this frame, this paper reviews the mechanisms by which coffee may influence the risk of CRC development focusing on espresso and filtered coffee, as well as on the components that totally or partially reach the colon i.e. polyphenols and dietary fiber, including melanoidins. In particular the effects of coffee on some colon conditions whose deregulation may lead to cancer, namely microbiota composition and lumen reducing environment, were considered. Taken together the discussed studies indicated that, due to their in vivo metabolism and composition, both coffee chlorogenic acids and dietary fiber, including melanoidins, may reduce CRC risk, increasing colon motility and antioxidant status. Further studies should finally assess whether the coffee benefits for colon are driven through a prebiotic effect.

Galacto-oligosaccharides have prebiotic activity in a dynamic in vitro colon model using a (13)C-labeling technique

Galacto-oligosaccharides (GOS) are considered to be prebiotic, although the contribution of specific members of the microbiota to GOS fermentation and the exact microbial metabolites that are produced upon GOS fermentation are largely unknown. We aimed to determine this using uniformly (13)C-labeled GOS. The normal (control) medium and unlabeled or (13)C-labeled GOS was added to a dynamic, validated, in vitro model of the large-intestine containing an adult-type microbiota. Liquid-chromatography MS was used to measure the incorporation of (13)C label into metabolites. 16S-rRNA stable isotope probing coupled to a phylogenetic micro-array was used to determine label incorporation in microbial biomass. The primary members within the complex microbiota that were directly involved in GOS fermentation were shown to be Bifidobacterium longum, B. bifidum, B. catenulatum, Lactobacillus gasseri, and L. salivarius, in line with the prebiotic effect of GOS, although some other species incorporated (13)C label also. GOS fermentation led to an increase in acetate (+49%) and lactate (+23%) compared with the control. Total organic acid production was 8.50 and 7.52 mmol/g of carbohydrate fed for the GOS and control experiments, respectively. At the same time, the cumulative production of putrefactive metabolites (branched-chain fatty acids and ammonia) was reduced by 55%. Cross-feeding of metabolites from primary GOS fermenters to other members of the microbiota was observed. Our findings support a prebiotic role for GOS and its potential to act as a synbiotic in combination with certain probiotic strains.

Unraveling how probiotic yogurt works

No matter what the advertisements are, or are not, allowed to say, it would be good to know if probiotic yogurt, in addition to its nutritional value, has a beneficial effect on the gut. In this issue, McNulty, Gordon and their colleagues describe a parallel series of human and animal studies designed to uncover the effects of probiotic yogurt on the gut microbiota. The intake of yogurt supplemented with five bacterial species, including the probiotic Bifidobacterium animalis, did not appreciably alter the composition of the human or mouse gut microbiota, but it did induce transcriptional and metabolic changes that reflected host bacterial responses to the arrival of the new species. This elegant study provides a strategy to delineate the precise effects exerted by probiotic foods on the human gut.

Effects of fructooligosaccharide-inulin on Salmonella-killing and inflammatory gene expression in chicken macrophages

Salmonella Enteritidis (SE) is one of the leading causes of food-borne salmonellosis, and macrophages play an essential role in eliminating this pathogen. Among the interventions to improve Salmonella clearance in chickens are the use of prebiotics and direct fed microbials (DFM) in animal feed as they have immunomodulatory effects. Therefore, we tested the influence of a prebiotic fructooligosaccharide (FOS)-inulin on the ability of the chicken macrophage HD11 cell line to phagocytose and kill SE, and express selected inflammatory cytokines and chemokines in an in vitro model. There were significantly fewer viable intracellular SE in HD11 cells treated with FOS-inulin than the untreated cells. However, SE phagocytosis, nitric oxide expression or production were not influenced by the prebiotic treatment. Among the inflammatory markers tested, IL-1β expression was significantly lower in HD11 cells treated with FOS-inulin. These results suggest that FOS-inulin has the ability to modulate the innate immune system as shown by the enhanced killing of SE and decreased inflammasome activation.

The potential role of prebiotic fibre for treatment and management of non-alcoholic fatty liver disease and associated obesity and insulin resistance

Non-alcoholic fatty liver disease (NAFLD) and the more severe non-alcoholic steatohepatitis (NASH) represent a spectrum of diseases involving hepatic fat accumulation and histological features essentially identical to alcoholic liver disease; however, they occur in the absence of excessive alcohol intake. They typically arise in conjunction with one or more features of the metabolic syndrome. Lifestyle mediated weight loss remains the primary mode of therapy for NAFLD and NASH, but this is often ineffective and adjunctive medical and surgical treatments are presently lacking. Prebiotic fibres are a group of non-digestible carbohydrates that modulate the human microbiota in a manner that is advantageous to host health. Rodent studies suggest that dietary supplementation with prebiotic fibres positively impacts NAFLD by modifying the gut microbiota, reducing body fat, and improving glucoregulation. Future research should focus on placebo-controlled, human, clinical trials using histological endpoints to address the effects of prebiotics on NAFLD and NASH. The aim of this review is to summarize current knowledge about prebiotics as an emerging therapeutic target for NAFLD.

Composition of the early intestinal microbiota: knowledge, knowledge gaps and the use of high-throughput sequencing to address these gaps

The colonization, development and maturation of the newborn gastrointestinal tract that begins immediately at birth and continues for two years, is modulated by numerous factors including mode of delivery, feeding regime, maternal diet/weight, probiotic and prebiotic use and antibiotic exposure pre-, peri- and post-natally. While in the past, culture-based approaches were used to assess the impact of these factors on the gut microbiota, these have now largely been replaced by culture-independent DNA-based approaches and most recently, high-throughput sequencing-based forms thereof. The aim of this review is to summarize recent research into the modulatory factors that impact on the acquisition and development of the infant gut microbiota, to outline the knowledge recently gained through the use of culture-independent techniques and, in particular, highlight advances in high-throughput sequencing and how these technologies have, and will continue to, fill gaps in our knowledge with respect to the human intestinal microbiota.

Dysbiosis of Gut Microbiota (DOGMA)--a novel theory for the development of Polycystic Ovarian Syndrome

Polycystic Ovarian Syndrome (PCOS) is the most common cause for menstrual disturbance and impaired ovulation, effecting one in twenty women of reproductive age. As the majority of women with PCOS are either overweight or obese, a dietary or adipose tissue related trigger for the development of the syndrome is quite possible. It has now well established that PCOS is characterised by a chronic state of inflammation and insulin resistance, but the precise underlying triggers for these two key biochemical disturbances is presently unknown. In this paper we present support for a microbiological hypothesis for the development of PCOS. This novel paradigm in PCOS aetiology suggests that disturbances in bowel bacterial flora ("Dysbiosis of Gut Microbiota") brought about by a poor diet creates an increase in gut mucosal permeability, with a resultant increase in the passage of lipopolysaccaride (LPS) from Gram negative colonic bacteria into the systemic circulation. The resultant activation of the immune system interferes with insulin receptor function, driving up serum insulin levels, which in turn increases the ovaries production of androgens and interferes with normal follicle development. Thus, the Dysbiosis of Gut Microbiota (DOGMA) theory of PCOS can account for all three components of the syndrome-anovulation/menstrual irregularity, hyper-androgenism (acne, hirsutism) and the development of multiple small ovarian cysts.

Influence of a high-fat diet on gut microbiota, intestinal permeability and metabolic endotoxaemia

Lipopolysaccharide (LPS) may play an important role in chronic diseases through the activation of inflammatory responses. The type of diet consumed is of major concern for the prevention and treatment of these diseases. Evidence from animal and human studies has shown that LPS can diffuse from the gut to the circulatory system in response to the intake of high amounts of fat. The method by which LPS move into the circulatory system is either through direct diffusion due to intestinal paracellular permeability or through absorption by enterocytes during chylomicron secretion. Considering the impact of metabolic diseases on public health and the association between these diseases and the levels of LPS in the circulatory system, this review will mainly discuss the current knowledge about high-fat diets and subclinical inflammation. It will also describe the new evidence that correlates gut microbiota, intestinal permeability and alkaline phosphatase activity with increased blood LPS levels and the biological effects of this increase, such as insulin resistance. Although the majority of the studies published so far have assessed the effects of dietary fat, additional studies are necessary to deepen the understanding of how the amount, the quality and the structure of the fat may affect endotoxaemia. The potential of food combinations to reduce the negative effects of fat intake should also be considered in future studies. In these studies, the effects of flavonoids, prebiotics and probiotics on endotoxaemia should be investigated. Thus, it is essential to identify dietetic strategies capable of minimising endotoxaemia and its postprandial inflammatory effects.

Effect of fructooligosaccharide metabolism on chicken colonization by an extra-intestinal pathogenic Escherichia coli strain

Extra-intestinal pathogenic Escherichia coli (ExPEC) strains cause many diseases in humans and animals. While remaining asymptomatic, they can colonize the intestine for subsequent extra-intestinal infection and dissemination in the environment. We have previously identified the fos locus, a gene cluster within a pathogenicity island of the avian ExPEC strain BEN2908, involved in the metabolism of short-chain fructooligosaccharides (scFOS). It is assumed that these sugars are metabolized by the probiotic bacteria of the microbiota present in the intestine, leading to a decrease in the pathogenic bacterial population. However, we have previously shown that scFOS metabolism helps BEN2908 to colonize the intestine, its reservoir. As the fos locus is located on a pathogenicity island, one aim of this study was to investigate a possible role of this locus in the virulence of the strain for chicken. We thus analysed fos gene expression in extracts of target organs of avian colibacillosis and performed a virulence assay in chickens. Moreover, in order to understand the involvement of the fos locus in intestinal colonization, we monitored the expression of fos genes and their implication in the growth ability of the strain in intestinal extracts of chicken. We also performed intestinal colonization assays in axenic and Specific Pathogen-Free (SPF) chickens. We demonstrated that the fos locus is not involved in the virulence of BEN2908 for chickens and is strongly involved in axenic chicken cecal colonization both in vitro and in vivo. However, even if the presence of a microbiota does not inhibit the growth advantage of BEN2908 in ceca in vitro, overall, growth of the strain is not favoured in the ceca of SPF chickens. These findings indicate that scFOS metabolism by an ExPEC strain can contribute to its fitness in ceca but this benefit is fully dependent on the bacteria present in the microbiota.

Supplementation with galacto-oligosaccharides increases the percentage of NK cells and reduces colitis severity in Smad3-deficient mice

The gut microbiota plays an essential role in intestinal immunity. Prebiotics, including galacto-oligosaccharides (GOS), are fermentable fibers that beneficially affect the host by stimulating the growth of specific microbial populations. We investigated the effect of GOS on colitis development and on immune variables in Smad3-deficient mice treated with the pathogen Helicobacter hepaticus. Mice were supplemented daily with 5000 mg GOS/kg body weight 2 wk prior to infection and 4 wk postinfection, a time period during which colitis severity peaks in this model. Mice (n = 4-8/treatment at each time) were killed preinfection (0 d) and at 3, 7, and 28 d postinfection to evaluate immune variables in the spleen and in mesenteric lymph nodes (MsLN) by flow cytometry. Colon and cecum samples were collected for histopathologic analysis. Fecal pellets (n = 8-9/treatment) were collected prior to infection to measure relative changes in Bifidobacterium ssp. and Lactobacillum ssp. by real-time PCR. GOS significantly reduced colitis severity in response to H. hepaticus (P < 0.0001). This was associated with a significant increase in the percentage of NK cells in the spleen (P < 0.001) and in MsLN (P < 0.001) at 3 d postinfection and a 1.5-fold increase in fecal Bifidobacterium ssp. (P = 0.003). GOS stimulated NK expression of CCR9, a chemokine receptor involved in lymphocyte trafficking to the gut preinfection (0 d) in the blood (P = 0.02), spleen (P = 0.033), and MsLN (P = 0.017). In addition, GOS stimulated colonic IL-15 production 3 d postinfection (P < 0.001). These data suggest that GOS reduces colitis by modulating the function and trafficking of NK cells and may provide a novel therapeutic strategy for individuals with inflammatory bowel disease.

A simple and accurate method for determining wheat grain fructan content and average degree of polymerization

An improved method for the measurement of fructans in wheat grains is presented. A mild acid treatment is used for fructan hydrolysis, followed by analysis of the released glucose and fructose with high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Not only the amount of fructose set free from fructans but also the released glucose can be quantified accurately, allowing determination of the average degree of polymerization of fructans (DP(av)). Application of the mild acid treatment to different grain samples demonstrated that a correction should be made for the presence of sucrose and raffinose, but not for stachyose or higher raffinose oligosaccharides. The fructan content and DP(av) of spelt flour, wheat flour, and whole wheat flour were 0.6%, 1.2%, and 1.8% of the total weight and 4, 5, and 6, respectively. Validation experiments demonstrate that the proposed quantification method is accurate and repeatable and that also the DP(av) determination is precise.

Effect of killed whole yeast cell prebiotic supplementation on broiler performance and intestinal immune cell parameters

Two experiments were conducted to study the effect of CitriStim, a commercial killed whole yeast cell prebiotic, on broiler performance, regulatory T cells, CD4(+) and CD8(+) percentages, and IL-10 and IL-1 mRNA contents of the spleen and cecal tonsils. No immune challenges were imposed in either of the 2 experiments. One-day-old broiler chicks were fed a corn- and soybean meal-based diet supplemented with 0, 0.1, or 0.2% CitriStim (ADM, Decatur, IL) for 35 d. At 21 (P = 0.03) and 35 d (P = 0.02) of age, CitriStim supplementation at 0.2% increased regulatory T cell percentage in the cecal tonsil compared with that of the 0% CitriStim-supplemented group. At 21 (P = 0.08) and 35 d (P = 0.01) of age, CitriStim supplementation at 0.2% increased IL-10 mRNA content of the cecal tonsil compared with that of the 0% CitriStim-supplemented group. At 21 (P = 0.13) and 35 d (P < 0.01) of age, CitriStim supplementation at 0.2% decreased IL-1 mRNA content compared with that of the 0% CitriStim supplemented group. CitriStim supplementation did not (P > 0.05) alter the IL-10 and IL-1 mRNA contents in the spleen. CitriStim supplementation did not (P > 0.05) alter the CD4(+) and CD8(+) cell percentages in the spleen and cecal tonsil at 21 and 35 d of the experiment. CitriStim supplementation increased regulatory T cell percentage and IL-10 mRNA content and decreased IL-1 mRNA content in the cecal tonsil to produce a net antiinflammatory milieu. The immunomodulatory effect of CitriStim supplementation was a local effect rather than a systemic effect.

Composition and roles of intestinal microbiota in children

OBJECTIVE

To provide an update of the advantages of new-generation molecular diagnostics to study the diversity of intestinal microflora and to evaluate its alteration in human diseases.

METHODS

We review recent advances in understanding the complex ecosystem of gut microbiota based on a dynamic and mutual interaction with the host.

RESULTS

In vaginal delivery, the contact with the mother's vaginal and intestinal flora is an important source of Lactobacillus, Prevotella and other Bifidobacterium. On the opposite, in cesarean delivery, direct contact of the mouth of the newborn with vaginal and intestinal microbiota is replaced by exogenous non-maternally derived bacteria colonizing the infants' intestine producing a less diverse flora. The original microbiome settings evolve during the growth converging to three main clusters defined "enterotypes" in the adult age.

CONCLUSIONS

The key role in human health could depend on the balance between beneficial and harmful microbial species populating the gut, therefore the intestinal microflora can been considered as a potential biomarker and/or therapeutic target in intestinal and extra-intestinal diseases.