Effect of galactooligosaccharides on calcium absorption and preventing bone loss in ovariectomized rats

Prebiotics improve osteoporosis indicators in a preclinical model: systematic review with meta-analysis

CONTEXT

Studies using experimental models have demonstrated that prebiotics are involved in antiosteoporotic mechanisms.

OBJECTIVE

This study was conducted to determine the impact of supplementation with prebiotics in the basal diet of ovariectomized rats with induced osteoporosis as a preclinical model.

METHODS

A comprehensive systematic search was carried out in the electronic databases PubMed, Science Direct, Web of Science, Scielo, and Google through March 2022 for studies that investigated the impact of prebiotics on bone mineral density (BMD), bone mineral content (BMC), and bone biomechanics.

RESULTS

The search returned 844 complete articles, abstracts, or book chapters. After detailed screening, 8 studies met the inclusion criteria. Rats (n = 206), were randomly divided between control and treatment groups. Weighted mean differences (WMDs) with the 95%CIs were used to estimate the combined effect size. Compared with the control group, dietary intake of prebiotics significantly increased bone density in the BMD subgroups, with WMDs as follows: 0.03 g/cm3, 95%CI, 0.01-0.05, P < 0.00001, n = 46; and 0.00 g/cm2, 95%CI, 0.00-0.02, P < 0.00001, n = 81; total BMD: WMD, 0.01, 95%CI, 0.01-0.02, P < 0.00001, n = 127; bone content in BMC: WMD, 0.02 g, 95%CI, 0.00-0.04, P = 0.05, n = 107; and the 3-point-bend test: WMD, 15.20 N, 95%CI, 5.92-24.47, P = 0.00001, n = 120.

CONCLUSION

Prebiotics improve indicators of osteoporosis, BMD, BMC, and bone biomechanics in ovariectomized rats. More studies are needed to increase the level of evidence.

SYSTEMIC REVIEW REGISTRATION

Systematic Review Protocol for Animal Intervention Studies.

Effects of High-Fructose Corn Syrup on Bone Health and Gastrointestinal Microbiota in Growing Male Mice

Here, we explored the correlation between gut microbiota and bone health and the effects of high-fructose corn syrup (HFCS) on both. Sixteen 3-week-old male C57BL/6J mice were randomly divided into two groups and given purified water (control group) or 30% HFCS in water (HFCS group) for 16 weeks. The effects of HFCS were assessed via enzyme-linked immunosorbent assays, histopathological assays of colon and bone, and 16S rDNA sequence analysis of gut microbiota. The serum of HFCS group mice had lower levels of bone alkaline phosphatase (BALP), bone Gla protein (BGP), insulin-like growth factor 1 (IGF-1), and testosterone, and higher levels of type I collagen carboxyl-terminal telopeptide (ICTP) and tartrate-resistant acid phosphatase (TRAP) than that of the control group. HFCS caused trabecular bone damage by decreasing trabecular number and thickness and increasing trabecular separation. The HFCS group colons were shorter than the control group colons. The HFCS-fed mice showed mild, localized shedding of epithelial cells in the mucosal layer, focal lymphocytic infiltration of the lamina propria, mild submucosal edema, and loosely arranged connective tissue. The HFCS group displayed lower abundance and altered composition of gut microbiota. The abundance of Defluviitaleaceae UCG-011, Erysipelatoclostridium, Ruminococcaceae UCG-009, Lactobacillus, Blautia, and Parasutterella increased, positively correlating with BALP, BGP, IGF-1, and testosterone levels, and negatively correlating with ICTP and TRAP levels. Our study revealed a potential diet-gut microbiota-bone health axis.

Colonic expression of calcium transporter TRPV6 is regulated by dietary sodium butyrate

Dietary fibers have been shown to increase the intestinal absorption of calcium (Ca²⁺) and magnesium (Mg²⁺). However, the mechanisms that explain the enhanced electrolyte absorption remain unknown. Therefore, this study aims to investigate the short-term and long-term effects of 5% (w/w) sodium butyrate (Na-butyrate), an important end-metabolite of bacterial fermentation of dietary fibers, on Ca²⁺ and Mg²⁺ homeostasis in mice. Serum Ca²⁺ levels were only significantly increased in mice treated with Na-butyrate for 1 day. This was associated with a twofold increase in the mRNA expression levels of Trpv6 in the proximal and distal colon. Contrary, Na-butyrate did not affect serum Mg²⁺ concentrations at either of the intervention periods. However, we observed a reduction in urinary Mg²⁺ excretion, although not significantly, after 1 day of treatment. A significant reduction of 2.5-fold in urinary Mg²⁺ excretion was observed after 14 days of treatment. Indeed, 14-day Na-butyrate supplementation increased colonic Trpm7 expression by 1.2-fold compared to control mice. In conclusion, short-term Na-butyrate supplementation increases serum Ca²⁺ levels in mice. This was associated with increased mRNA expression levels of Trpv6 in the colon, suggesting that Na-butyrate regulates the expression of genes involved in active intestinal Ca²⁺ absorption.

Interactions of the microbiome with pharmacological and non-pharmacological approaches for the management of ageing-related musculoskeletal diseases

Despite major progress in the understanding of the pathophysiology and therapeutic options for common ageing-related musculoskeletal conditions (i.e. osteoporosis and associated fractures, sarcopenia and osteoarthritis), there is still a considerable proportion of patients who respond sub optimally to available treatments or experience adverse effects. Emerging microbiome research suggests that perturbations in microbial composition, functional and metabolic capacity (i.e. dysbiosis) are associated with intestinal and extra-intestinal disorders including musculoskeletal diseases. Besides its contributions to disease pathogenesis, the role of the microbiome is further extended to shaping individuals' responses to disease therapeutics (i.e. pharmacomicrobiomics). In this review, we focus on the reciprocal interactions between the microbiome and therapeutics for osteoporosis, sarcopenia and osteoarthritis. Specifically, we identify the effects of therapeutics on microbiome's configurations, functions and metabolic output, intestinal integrity and immune function, but also the effects of the microbiome on the metabolism of these therapeutics, which in turn, may influence their bioavailability, efficacy and side-effect profile contributing to variable treatment responses in clinical practice. We further discuss emerging strategies for microbiota manipulation as preventive or therapeutic (alone or complementary to available treatments) approaches for improving outcomes of musculoskeletal health and disease.

Use of Calcium Isotopic Tracers To Determine Factors That Perturb Calcium Metabolism

Calcium plays an important role in maintaining bone health. Ensuring adequate calcium intake throughout life is essential for reaching greater peak bone mass in young adulthood and lowering osteoporotic fracture risk when aging. Calcium homeostasis involves a complex interaction between three organ systems: intestine, kidney, and bone. Metabolic balance plus kinetic studies using calcium isotopic tracers can estimate calcium metabolism parameters and pinpoint how organs and processes are perturbed by internal and external modifiers. Both modifiable factors (e.g., vitamin D supplementations and dietary bioactives) and non-modifiable factors (e.g., age, sex, and race) influence calcium utilization. Current evidence suggests that prebiotic fibers may offer an alternative approach to enhance calcium absorption through altering gut microbiota to ultimately improve bone health.

Changes in the Gut Microbiome after Galacto-Oligosaccharide Administration in Loperamide-Induced Constipation

Unbalanced dietary habits and the consumption of high protein and instant foods cause an increase in constipation. Here, we evaluated the effects of galacto-oligosaccharide (GOS) on a rat model of loperamide-induced constipation by measuring various biological markers and cecal microbiota. The fecal water content and intestinal transit ratio significantly increased in the GOS-administered (GL and GH) groups than in the control group (p < 0.05, p < 0.01, and p < 0.001, respectively). The length of intestinal mucosa (p < 0.05 and p < 0.01, respectively) and area of crypt cells were (p < 0.01, both) significantly increased in the GOS-administered groups compared to the control group. The distribution of interstitial cells of Cajal, which is related to the intestinal movement, showed a significant increase in GOS-administered groups than in the control group (p < 0.01, both). The relative abundance of lactic acid bacteria (LAB), especially Lactobacillus and Lactococcus, significantly increased in the GL group than in the control group. Furthermore, there was a positive correlation between short chain fatty acids (SCFAs) and the gut microbiota in the GL groups. These results demonstrated that GOS administration effectively alleviates constipation by increasing LAB proliferation in the intestinal microbiota and SCFA production.

Prebiotic Carbohydrates for Therapeutics

The food industry is constantly shifting focus based on prebiotics as health-promoting substrates rather than just food supplements. A prebiotic is "a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon host well-being and health." Prebiotics exert a plethora of health-promoting effects, which has lead to the establishment of multimillion food and pharma industries. The following are the health benefits attributed to prebiotics: mineral absorption, better immune response, increased resistance to bacterial infection, improved lipid metabolism, possible protection against cancer, relief from poor digestion of lactose, and reduction in the risk of diseases such as intestinal disease, non-insulin-dependent diabetes, obesity and allergy. Numerous studies in both animals and humans have demonstrated the health benefits of prebiotics.

Immune boosting functional foods and their mechanisms: A critical evaluation of probiotics and prebiotics

Comprehensive studies conducted on the link between the gut microbiome and immunity in recent decades have correspondingly led to ever increasing interests in functional foods, especially probiotics and prebiotics. Probiotics and prebiotics play crucial roles in managing the intestinal microbiota in order to improve host health, even though their influence on other body sites are being investigated. Different colonic bacteria metabolize dietary prebiotics to produce beneficial metabolites, especially short chain fatty acids (SCFAs) that improve luminal contents and intestinal performance, while positively affecting overall host physiology. Thus, this review provides a general perspective of the immune system, the gut immune system and its microbiota. The review also evaluates functional foods with critical but comprehensive perspectives into probiotics and prebiotics, their immune boosting and mechanisms of action. It is recommended that further mechanistic and translational studies are conducted to promote health, social life and also empower poverty-stricken communities.

Probiotics and prebiotics in intestinal health and disease: from biology to the clinic

Probiotics and prebiotics are microbiota-management tools for improving host health. They target gastrointestinal effects via the gut, although direct application to other sites such as the oral cavity, vaginal tract and skin is being explored. Here, we describe gut-derived effects in humans. In the past decade, research on the gut microbiome has rapidly accumulated and has been accompanied by increased interest in probiotics and prebiotics as a means to modulate the gut microbiota. Given the importance of these approaches for public health, it is timely to reiterate factual and supporting information on their clinical application and use. In this Review, we discuss scientific evidence on probiotics and prebiotics, including mechanistic insights into health effects. Strains of Lactobacillus, Bifidobacterium and Saccharomyces have a long history of safe and effective use as probiotics, but Roseburia spp., Akkermansia spp., Propionibacterium spp. and Faecalibacterium spp. show promise for the future. For prebiotics, glucans and fructans are well proven, and evidence is building on the prebiotic effects of other substances (for example, oligomers of mannose, glucose, xylose, pectin, starches, human milk and polyphenols).

The gut-bone axis: how bacterial metabolites bridge the distance

The gut microbiome is a key regulator of bone health that affects postnatal skeletal development and skeletal involution. Alterations in microbiota composition and host responses to the microbiota contribute to pathological bone loss, while changes in microbiota composition that prevent, or reverse, bone loss may be achieved by nutritional supplements with prebiotics and probiotics. One mechanism whereby microbes influence organs of the body is through the production of metabolites that diffuse from the gut into the systemic circulation. Recently, short-chain fatty acids (SCFAs), which are generated by fermentation of complex carbohydrates, have emerged as key regulatory metabolites produced by the gut microbiota. This Review will focus on the effects of SCFAs on the musculoskeletal system and discuss the mechanisms whereby SCFAs regulate bone cells.

Effects of vitamin D2-fortified shiitake mushroom on bioavailability and bone structure

Bioavailability and bone loss inhibitory effects of vitamin D₂ derived from UV-irradiated shiitake mushroom were determined in vivo. The effect of the absence of ovaries on the bioavailability of vitamin D₂ and bone structure was also investigated. Sham operated (sham) and ovariectomized (OVX) rats were divided in 3 groups according to their diets, i.e. control: only vitamin D-deficient diets; UV(X): vitamin D-deficient diets with non-irradiated mushroom powder; UV(O): vitamin D-deficient diets with irradiated mushroom powder. The obtained results showed that vitamin D₂ from shiitake mushroom was able to increase bone mineral density and trabecular bone structure of femur bone as well as its bioavailability. The absence of estrogen induced adverse effects not only on bioavailability of vitamin D₂ but also on trabecular bone. In conclusion, vitamin D₂-fortified shiitake mushroom might help postmenopausal women increase vitamin D₂ bioavailability and retard trabecular bone loss. Abbreviations: OVX: ovariectomized; 25(OH)D: 25-hydroxyvitamin D; 1,25(OH)2D: 1,25-dihydroxyvitamin D; BMD: bone mineral density; micro-CT: micro computed tomography; RSM: response surface methodology; RP-HPLC: Reverse phase-high performance liquid chromatography; MS/MS: tandem mass spectrometry; E2: estradiol; NTx: N-terminal telopeptide of type I collagen; BV/TV: bone volume/total volume; BS/BV: bone surface/bone volume; Tb.Th: trabecular thickness; Tb.Sp: trabecular separation.

Biological Activities of Lactose-Based Prebiotics and Symbiosis with Probiotics on Controlling Osteoporosis, Blood-Lipid and Glucose Levels

Lactose-based prebiotics are synthesized by enzymatic- or microbial- biotransformation of lactose and have unique functional values. In this comprehensive review article, the biochemical mechanisms of controlling osteoporosis, blood-lipid, and glucose levels by lactose-based prebiotics and symbiosis with probiotics are reported along with the results of clinical investigations. Interaction between lactose-based prebiotics and probiotics reduces osteoporosis by (a) transforming insoluble inorganic salts to soluble and increasing their absorption to gut wall; (b) maintaining and protecting mineral absorption surface in the intestine; (c) increasing the expression of calcium-binding proteins in the gut wall; (d) remodeling osteoclasts and osteoblasts formation; (e) releasing bone modulating factors; and (f) degrading mineral complexing phytic acid. Lactose-based prebiotics with probiotics control lipid level in the bloodstream and tissue by (a) suppressing the expressions of lipogenic- genes and enzymes; (b) oxidizing fatty acids in muscle, liver, and adipose tissue; (c) binding cholesterol with cell membrane of probiotics and subsequent assimilation by probiotics; (d) enzymatic-transformations of bile acids; and (e) converting cholesterol to coprostanol and its defecation. Symbiosis of lactose-based prebiotics with probiotics affect plasma glucose level by (a) increasing the synthesis of gut hormones plasma peptide-YY, glucagon-like peptide-1 and glucagon-like peptide-2 from entero-endocrine L-cells; (b) altering glucose assimilation and metabolism; (c) suppressing systematic inflammation; (d) reducing oxidative stress; and (e) producing amino acids. Clinical investigations show that lactose-based prebiotic galacto-oligosaccharide improves mineral absorption and reduces hyperlipidemia. Another lactose-based prebiotic, lactulose, improves mineral absorption, and reduces hyperlipidemia and hyperglycemia. It is expected that this review article will be of benefit to food technologists and medical practitioners.

From Osteoimmunology to Osteomicrobiology: How the Microbiota and the Immune System Regulate Bone

Osteomicrobiology refers to the role of microbiota in bone health and the mechanisms by which the microbiota regulates post-natal skeletal development, bone aging, and pathologic bone loss. Here, we review recent reports linking gut microbiota to changes in bone phenotype. A pro-inflammatory cytokine milieu drives bone resorption in conditions such as sex steroid hormone deficiency. The response of the immune system to activation by the microbiome results in increased circulating osteoclastogenic cytokines in a T cell-dependent mechanism. Additionally, gut microbiota affect bone homeostasis through nutrient absorption, mediation of the IGF-1 pathway, and short chain fatty acid and metabolic products. Manipulation of microbiota through prebiotics or probiotics reduces inflammatory cytokine production, leading to changes in bone density. One mechanism of probiotic action is through upregulating tight junction proteins, increasing the strength of the gut epithelial layer, and leading to less antigen presentation and less activation of intestinal immune cells. Thus, prebiotics or probiotics may represent a future therapeutic avenue for ameliorating the risk of postmenopausal bone loss in humans.

Epithelial Barrier Function in Gut-Bone Signaling

The intestinal epithelial barrier plays an essential role in maintaining host homeostasis. The barrier regulates nutrient absorption as well as prevents the invasion of pathogenic bacteria in the host. It is composed of epithelial cells, tight junctions, and a mucus layer. Several factors, such as cytokines, diet, and diseases, can affect this barrier. These factors have been shown to increase intestinal permeability, inflammation, and translocation of pathogenic bacteria. In addition, dysregulation of the epithelial barrier can result in inflammatory diseases such as inflammatory bowel disease. Our lab and others have also shown that barrier disruption can have systemic effects including bone loss. In this chapter, we will discuss the current literature to understand the link between intestinal barrier and bone. We will discuss how inflammation, aging, dysbiosis, and metabolic diseases can affect intestinal barrier-bone link. In addition, we will highlight the current suggested mechanism between intestinal barrier and bone.

Bone Remodeling and the Microbiome

Exposed surfaces of mammals are colonized with 100 trillion indigenous bacteria, fungi, and viruses, creating a diverse ecosystem known as the microbiome. The gastrointestinal tract harbors the greatest numbers of these microorganisms, which regulate human nutrition, metabolism, and immune system function. Moreover, the intestinal microbiota contains pro- and anti-inflammatory products that modulate immune responses and may play a role in maintaining gut barrier function. Therefore, the community composition of the microbiota has profound effects on the immune status of the host and impacts the development and/or progression of inflammatory diseases. Accordingly, numerous studies have shown differences in the microbiota of patients with and without a given inflammatory condition. There is now strong evidence that the gut microbiome regulates bone homeostasis in health and disease, and that prebiotic and probiotics protect against bone loss. Herein, the evidence supporting the role of the microbiota and the effects of prebiotic and probiotics will be reviewed.

Prebiotics, Bone and Mineral Metabolism

Increasing interest in functional foods has driven discovery in the area of bioactive compounds. Prebiotics are non-digestible carbohydrate compounds that, when consumed, elicit health benefits and aid in the prevention and treatment of chronic diseases. While prebiotics have been shown to improve a number of chronic, inflammatory conditions, growing evidence exists for prebiotic effects on calcium metabolism and bone health. These novel dietary fibers have been shown to increase calcium absorption in the lower intestines of both preclinical and human models. Rodent models have also been imperative for understanding prebiotic effects on bone mineral density and measures of skeletal strength. Although fewer data are available for humans, bone-related prebiotic effects exist across the lifecycle, suggesting benefits for attainment of peak bone mass during adolescence and minimized bone resorption among postmenopausal women. These effects are thought to occur through prebiotic-microbe interactions in the large intestine. Current prebiotic mechanisms for improved mineral absorption and skeletal health include alterations in gut microbiota composition, production of short-chain fatty acids, altered intestinal pH, biomarker modification, and immune system regulation. While the majority of available data support improved mineral bioavailability, emerging evidence suggests alternate microbial roles and the presence of an intricate gut-bone signaling axis. Overall, the current scientific literature supports prebiotic consumption as a cost-effective and sustainable approach for improved skeletal health and/or fracture prevention. The goal of this review is to discuss both foundational and recent research in the area of prebiotics, mineral metabolism, and bone health.

Intestinal microbiota: a potential target for the treatment of postmenopausal osteoporosis

Postmenopausal osteoporosis (PMO) is a prevalent metabolic bone disease characterized by bone loss and structural destruction, which increases the risk of fracture in postmenopausal women. Owing to the high morbidity and serious complications of PMO, many efforts have been devoted to its prophylaxis and treatment. The intestinal microbiota is the complex community of microorganisms colonizing the gastrointestinal tract. Probiotics, which are dietary or medical supplements consisting of beneficial intestinal bacteria, work in concert with endogenous intestinal microorganisms to maintain host health. Recent studies have revealed that bone loss in PMO is closely related to host immunity, which is influenced by the intestinal microbiota. The curative effects of probiotics on metabolic bone diseases have also been demonstrated. The effects of the intestinal microbiota on bone metabolism suggest a promising target for PMO management. This review seeks to summarize the critical effects of the intestinal microbiota and probiotics on PMO, with a focus on the molecular mechanisms underlying the pathogenic relationship between bacteria and host, and to define the possible treatment options.

Association Between Gut Microbiota and Bone Health: Potential Mechanisms and Prospective

CONTEXT

It has been well established that the human gut microbiome plays a critical role in the regulation of important biological processes and the mechanisms underlying numerous complex diseases. Although researchers have only recently begun to study the relationship between the gut microbiota and bone metabolism, early efforts have provided increased evidence to suggest an important association.

EVIDENCE ACQUISITION

In this study, we attempt to comprehensively summarize the relationship between the gut microbiota and bone metabolism by detailing the regulatory effects of the microbiome on various biological processes, including nutrient absorption and the intestinal mucosal barrier, immune system functionality, the gut-brain axis, and excretion of functional byproducts. In this review, we incorporate evidence from various types of studies, including observational, in vitro and in vivo animal experiments, as well as small efficacy clinic trails.

EVIDENCE SYNTHESIS

We review the various potential mechanisms of influence for the gut microbiota on the regulation of bone metabolism and discuss the importance of further examining the potential effects of the gut microbiota on the risk of osteoporosis in humans. Furthermore, we outline some useful tools/approaches for metagenomics research and present some prominent examples of metagenomics association studies in humans.

CONCLUSION

Current research efforts, although limited, clearly indicate that the gut microbiota may be implicated in bone metabolism, and therefore, further exploration of this relationship is a promising area of focus in bone health and osteoporosis research. Although most existing studies investigate this relationship using animal models, human studies are both needed and on the horizon.

Safety evaluation of galacto-oligosaccharides

Galacto-oligosaccharides (GOS) have been added to infant formulas and conventional foods as prebiotics all over the world. The present study was conducted to assess the subchronic toxicity of a GOS syrup (VITAGOS™) when administered orally by gavage daily at 0, 1020, 2041, and 4082 mg GOS syrup/kg/day to male and female Sprague-Dawley rats to deliver doses of 0, 500, 1000, and 2000 mg GOS/kg/day for 90 days. Throughout the entire treatment period, no abnormal clinical signs or mortalities were observed. Similarly, no test article-related toxicologically adverse findings were seen in body weight, feed consumption, ophthalmological findings, hematology, coagulation, clinical chemistry, urinalysis, organ weights, and gross pathology or histopathology. Significant increases in the cecum weight of males and females treated with 2000 mg GOS/kg/day were associated with mucosal hypertrophy/hyperplasia; no changes in the cecum were noted at lower doses. The organ weight and histopathological changes noted in the cecum are consistent with findings in rats administered other poorly digestible and fermentable substances; thus, this is considered to be an adaptive rather than toxic response. The No-Observed-Adverse-Effect-Levels for VITAGOS™ is 4082 mg GOS syrup/kg body weight/day or 2000 mg GOS/kg body weight/day.

Gut microbiota-bone axis

The gut microbiota (GM) is an important regulator of body homeostasis, including intestinal and extra-intestinal effects. This review focuses on the GM-bone axis, which we define as the effect of the gut-associated microbial community or the molecules they synthesize, on bone health. While research in this field is limited, findings from preclinical studies support that gut microbes positively impact bone mineral density and strength parameters. Moreover, administration of beneficial bacteria (probiotics) in preclinical models has demonstrated higher bone mineralization and greater bone strength. The preferential bacterial genus that has shown these beneficial effects in bone is Lactobacillus and thus lactobacilli are among the best candidates for future clinical intervention trials. However, their effectiveness is dependent on stage of development, as early life constitutes an important time for impacting bone health, perhaps via modulation of the GM. In addition, sex-specific difference also impacts the efficacy of the probiotics. Although auspicious, many questions regarding the GM-bone axis require consideration of potential mechanisms; sex-specific efficacy; effective dose of probiotics; and timing and duration of treatment.

Safety evaluation of α-galacto-oligosaccharides for use in infant formulas investigated in neonatal piglets

Galacto-oligosaccharide (GOS), comprising galactoses with a glucose or sucrose, is a family of nondigestible oligosaccharides. The present study evaluates the safety of an α-GOS product (P-GOS® P) in a neonatal piglet model for 3 weeks. Three days after birth, neonatal piglets were divided into control and treated groups and provided with swine milk replacers in the absence and presence of 8 mg/mL—of the α-GOS product, respectively. An increase in the weight of the large intestines in treated males was noted, which is a common finding in studies of animals fed nondigestible oligosaccharides. There were no α-GOS product-related adverse effects in the piglets in terms of clinical signs, body weights, feed consumption, clinical chemistry, hematology, organ weights, or histopathology. The study demonstrated that formula supplemented with 8 mg/mL of P-GOS P is safe and well tolerated in neonatal piglets and supports the safe use of P-GOS P in infant formulas.

Effects of Proton Pump Inhibitor Administration and Intake of a Combination of Yogurt and Galactooligosaccharides on Bone and Mineral Metabolism in Rats

The aim of this study was to investigate the effects of proton pump inhibitor (PPI), the most potent acid-suppressing drug, administration and intake of a combination of yogurt and galactooligosaccharides (YG) on bone and mineral metabolism in adult rats. Twelve-week-old male Wistar rats were divided into three groups: a control group fed the control diet with vehicle administration, a PPI group fed the control diet with PPI administration and a YG + PPI group fed the YG diet with PPI administration. All of the groups received their respective experimental diets and daily subcutaneous injection of the vehicle or PPI for 12 weeks. The PPI group showed significantly lower bone mineral density (BMD) of the femur and the lumbar vertebrae and serum fibroblast growth factor 23 (FGF23) and significantly higher phosphorus absorption and serum 1,25-dihydroxyvitamin D (1,25(OH)2D) than the control group, although PPI did not affect calcium absorption. The PPI + YG group showed significantly higher BMD and serum FGF23 and significantly lower phosphorus absorption and serum 1,25(OH)2D than the PPI group. Furthermore, the PPI + YG group showed higher calcium absorption than the control group. These results suggest that although PPI administration did not affect calcium absorption, it adversely affected BMD and influenced phosphorus metabolism in adult rats. Furthermore, the YG diet beneficially affected BMD and attenuated the effects of PPI administration on phosphorus metabolism.

Distant Site Effects of Ingested Prebiotics

The gut microbiome is being more widely recognized for its association with positive health outcomes, including those distant to the gastrointestinal system. This has given the ability to maintain and restore microbial homeostasis a new significance. Prebiotic compounds are appealing for this purpose as they are generally food-grade substances only degraded by microbes, such as bifidobacteria and lactobacilli, from which beneficial short-chain fatty acids are produced. Saccharides such as inulin and other fructo-oligosaccharides, galactooligosaccharides, and polydextrose have been widely used to improve gastrointestinal outcomes, but they appear to also influence distant sites. This review examined the effects of prebiotics on bone strength, neural and cognitive processes, immune functioning, skin, and serum lipid profile. The mode of action is in part affected by intestinal permeability and by fermentation products reaching target cells. As the types of prebiotics available diversify, so too will our understanding of the range of microbes able to degrade them, and the extent to which body sites can be impacted by their consumption.

Reclassification of Eubacterium desmolans as Butyricicoccus desmolans comb. nov., and description of Butyricicoccus faecihominis sp. nov., a butyrate-producing bacterium from human faeces

A Gram-positive-staining, coccoid-shaped, non-motile, asporogenous, obligately anaerobic and butyrate-producing bacterium was recovered from a healthy human's faeces. The organism was isolated by the enrichment culture technique using yeast extract-casein hydrolysate-fatty acids broth supplemented with 0.5 % mucin. Phylogenetic analysis of 16S rRNA gene sequences demonstrated that the novel strain should be classified as a member of the Eubacterium desmolans-related cluster in the family Ruminococcaceae. Furthermore, this analysis demonstrated that the type strains of Butyricicoccus pullicaecorum (95.6 %) and Eubacterium desmolans (94.7 %) were the closest phylogenetic neighbours to strain YIT 12789T. However, DNA‒DNA reassociation values with these closest strains were less than 20 %. On the basis of the phenotypic, genotypic and chemotaxonomic features, the novel coccoid-shaped bacterium should be designated as a representative of a novel species of the genus Butyricicoccus, for which the name Butyricicoccus faecihominis sp. nov. is proposed. The type strain is YIT 12789T (=JCM 31056T=DSM 100989T). It is also proposed that Eubacterium desmolans be reclassified in the genus Butyricicoccus as Butyricicoccus desmolans comb. nov.

Early-Life Events, Including Mode of Delivery and Type of Feeding, Siblings and Gender, Shape the Developing Gut Microbiota

Colonization of the infant gut is believed to be critically important for a healthy growth as it influences gut maturation, metabolic, immune and brain development in early life. Understanding factors that influence this process is important, since an altered colonization has been associated with a higher risk of diseases later in life. Fecal samples were collected from 108 healthy neonates in the first half year of life. The composition and functionality of the microbiota was characterized by measuring 33 different bacterial taxa by qPCR/RT qPCR, and 8 bacterial metabolites. Information regarding gender, place and mode of birth, presence of siblings or pets; feeding pattern and antibiotic use was collected by using questionnaires. Regression analysis techniques were used to study associations between microbiota parameters and confounding factors over time. Bacterial DNA was detected in most meconium samples, suggesting bacterial exposure occurs in utero. After birth, colonization by species of Bifidobacterium, Lactobacillus and Bacteroides was influenced by mode of delivery, type of feeding and presence of siblings, with differences found at species level and over time. Interestingly, infant-type bifidobacterial species such as B. breve or B. longum subsp infantis were confirmed as early colonizers apparently independent of the factors studied here, while B. animalis subsp. lactis presence was found to be dependent solely on the type of feeding, indicating that it might not be a common infant gut inhabitant. One interesting and rather unexpected confounding factor was gender. This study contributes to our understanding of the composition of the microbiota in early life and the succession process and the evolution of the microbial community as a function of time and events occurring during the first 6 months of life. Our results provide new insights that could be taken into consideration when selecting nutritional supplementation strategies to support the developing infant gut microbiome.

Prebiotic and Probiotic Regulation of Bone Health: Role of the Intestine and its Microbiome

Recent advances in our understanding of how the intestinal microbiome contributes to health and disease have generated great interest in developing strategies for modulating the abundance of microbes and/or their activity to improve overall human health and prevent pathologies such as osteoporosis. Bone is an organ that the gut has long been known to regulate through absorption of calcium, the key bone mineral. However, it is clear that modulation of the gut and its microbiome can affect bone density and strength in a variety of animal models (zebrafish, rodents, chicken) and humans. This is demonstrated in studies ablating the microbiome through antibiotic treatment or using germ-free mouse conditions as well as in studies modulating the microbiome activity and composition through prebiotic and/or probiotic treatment. This review will discuss recent developments in this new and exciting area.

Gut Function-Enhancing Properties and Metabolic Effects of Dietary Indigestible Sugars in Rodents and Rabbits

Indigestible sugars (iS) have received particular interest in food and nutrition research due to their prebiotic properties and other health benefits in humans and animals. The main aim of this review article is to summarize the current knowledge regarding digestive and health-enhancing properties of iS such as sugar alcohols, oligosacharides, and polysaccharides, in rodents and rabbits. Besides ameliorating gut health, iS ingestion also elicits laxative effects and stimulate intestinal permeability and fluid secretions, thereby shortening digesta transit time and increasing stool mass and quality. In rodents and rabbits, as hindgut fermenters, consumption of iS leads to an improved nutrient digestibility, too. Cecal fermentation of iS reduces luminal pH and extends wall tissue facilitating absorption of key dietary minerals across hindgut. The microbial fermentation of iS also enhances excessive blood nitrogen (N) flowing into the cecum to be used as N source for bacterial growth, enhancing N retention in cecotrophic animals. This review also highlights the impact of iS on improving lipid metabolism, mainly by lowering cholesterol and triglycerides levels in the blood. The paper serves as an index of the current knowledge of iS effects in rodents and rabbits and also identifies gaps of knowledge that need to be addressed by future research.

Enhancement by Lactosucrose of the Calcium Absorption from the Intestine in Growing Rats

The effects of dietary lactosucrose on calcium absorption from the intestine and calcium accumulation in bones were investigated in growing female rats. The apparent calcium-45 ((45)Ca) absorption, residual (45)Ca ratio in the body, and (45)Ca accumulation in the femur and tibia of lactosucrose-supplemented rats were significantly higher than in control rats 24 h after the administration of a (45)CaCl(2) solution.

Ingestion of Raffinose Promotes Calcium Absorption in the Large Intestine of Rats

We examined the effects of feeding raffinose on intestinal calcium absorption in ovariectomized rats by two separate experiments. In experiment 1, female Sprague-Dawley rats (6 wk old) were divided into two groups: sham operation and ovariectomy, and fed diets with or without raffinose (30 g/kg diet) for 4 wk. In experiment 2, ovariectomized rats with cecocolonectomy or transsection and reanastomosis (sham) were divided into two groups as in experiment 1 and fed the same diets for 3 wk. In experiment 1, calcium absorption was lower in the ovariectomized rats than in the sham rats but calcium absorption in rats fed the raffinose diet was higher than that in rats fed the raffinose-free diet. In experiment 2, increased calcium absorption in the raffinose group was abolished by cecocolonectomy. The impaired absorption in ovariectomized rats was restored by feeding raffinose. The large intestine is involved in the beneficial effects of raffinose.

Fusicatenibacter saccharivorans gen. nov., sp. nov., isolated from human faeces

Three Gram-stain-positive, obligately anaerobic, non-motile, non-spore-forming, spindle-shaped bacterial strains (HT03-11(T), KO-38 and TT-111), isolated from human faeces were characterized by phenotypic and molecular taxonomic methods. Comparative 16S rRNA gene sequencing showed that the strains were highly related to each other genetically (displaying >99 % sequence similarity) and represented a previously unknown subline within the Blautia coccoides rRNA group of organisms (cluster XIVa). The closest phylogenetic neighbours of strain HT03-11(T) were Clostridium bolteae WAL 16351(T) (93.7 % 16S rRNA gene sequence similarity) and Clostridium saccharolyticum WM1(T) (93.7 % similarity). All isolates produced lactic acid, formic acid, acetic acid and succinic acid as fermentation end products from glucose. Their chemotaxonomic properties included lysine as the cell wall diamino acid and C16 : 0, C18 : 1ω7c DMA and C16 : 0 DMA as the major fatty acids. The G+C contents of the genomic DNA were 46.9-47.2 mol% (HPLC). Several phenotypic and chemotaxonomic characteristics could be readily used to differentiate the isolates from phylogenetically related clostridia. Therefore, strains HT03-11(T), KO-38 and TT-111 represent a novel species in a new genus of the family Lachnospiraceae, for which the name Fusicatenibacter saccharivorans gen. nov., sp. nov. is proposed. The type strain of the type species is HT03-11(T) ( = YIT 12554(T) = JCM 18507(T) = DSM 26062(T)).

Galacto-oligosaccharides increase calcium absorption and gut bifidobacteria in young girls: a double-blind cross-over trial

Adolescence is a time for rapid growth that represents an opportunity to influence peak bone mass. Prebiotic agents, such as galacto-oligosaccharides (GOS), increase Ca absorption in animal models and postmenopausal women. The objectives of the present study were to investigate the dose-response relationship of GOS supplementation on Ca absorption during growth and to assess changes in colonic microbiota to better understand the mechanism by which GOS is acting. A total of thirty-one healthy adolescent girls aged 10-13 years consumed smoothie drinks twice daily with 0, 2·5 or 5 g GOS for three 3-week periods in a random order. Fractional Ca absorption was determined from urinary Ca excretion over 48 h at the end of each 3-week period using a dual stable isotope method. Faecal microbiota and bifidobacteria were assessed by PCR-denaturing gradient gel electrophoresis and quantitative PCR. Fractional Ca absorption after the 48 h treatment with control, 5 and 10 g GOS/d was 0·393 (SD 0·092), 0·444 (SD 0·086) and 0·419 (SD 0·099), respectively. Significant improvements in Ca absorption were seen with both low and high doses of GOS compared with the control (P,0·02), but itwas not a dose-response relationship. The increase in absorption was greatest in the urine collected after 24 h, which is consistent with lower gut absorption. Faecal bifidobacteria increased (control 10·89 (SD 13·86), 5 g GOS 22·80 (SD 15·74) and 10 g GOS 11·54 (SD 14·20)) with the GOS treatment (P,0·03). The results suggest that daily consumption of 5 g GOS increases Ca absorption, which may be mediated by the gut microbiota, specifically bifidobacteria.

Biotechnological approaches for the production of prebiotics and their potential applications

Worldwide interest in prebiotics have been increasing extensively both as food ingredients and pharmacological supplements, since they have beneficial properties for human health. Prebiotics not only stimulate the growth of healthy bacteria such as bifidobacteria and lactobacilli in the gut but also increase the resistance towards pathogens. In addition to this, they also act as dietary fiber, an energy source for intestinal cells after converting to short-chain fatty acids, a stimulator of immune systems, sugar replacer etc. Moreover, due to heat resistant properties, they are able to maintain their intact form during the baking process and allow them to be incorporated into every day food products. Thus, they can be interesting and useful ingredients in the development of novel functional foods. This review provides comprehensive information about the different biotechnological techniques employed in the production of prebiotics and their potential applications in different areas.

Síntese de galacto-oligossacarídeos a partir de lactose usando β-galactosidase comercial de Kluyveromyces lactis

O objetivo deste trabalho foi estudar a influência de parâmetros reacionais na obtenção via enzimática de galacto-oligossacarídeos (GOS), utilizando-se a enzima comercial β-galactosidase de Kluyveromyces lactis (Lactozym® 3000 L), tendo como substrato a lactose. Foi proposto um planejamento experimental 2³, verificando a influência da temperatura (30 a 40 °C), da concentração de lactose (200 a 400 mg.mL-1) e da concentração de enzima (5 a 10 U.mL-1) no desempenho da reação enzimática. Os ensaios foram conduzidos a 180 rpm e pH 7,0 (tampão fosfato de sódio 0,1 M). A enzima Lactozym® 3000 L apresentou atividade de transgalactosilação, tendo sido atingido rendimento do processo igual a 41,9% e concentração de GOS de 167,5 mg.mL-1 no sistema reacional composto por 400 mg.mL-1 de lactose e 5 U.mL-1 de enzima a 30 °C em 14 h de reação. Nessa condição, a conversão de lactose foi de 65,0%. Maior concentração de lactose foi favorável ao mecanismo de transgalactosilação, enquanto que, em menores concentrações, o mecanismo hidrolítico predominou.

Characterization of Phascolarctobacterium succinatutens sp. nov., an asaccharolytic, succinate-utilizing bacterium isolated from human feces

Isolation, cultivation, and characterization of the intestinal microorganisms are important for understanding the comprehensive physiology of the human gastrointestinal (GI) tract microbiota. Here, we isolated two novel bacterial strains, YIT 12067(T) and YIT 12068, from the feces of healthy human adults. Phylogenetic analysis indicated that they belonged to the same species and were most closely related to Phascolarctobacterium faecium ACM 3679(T), with 91.4% to 91.5% 16S rRNA gene sequence similarities, respectively. Substrate availability tests revealed that the isolates used only succinate; they did not ferment any other short-chain fatty acids or carbohydrates tested. When these strains were cocultured with the xylan-utilizing and succinate-producing bacterium Paraprevotella xylaniphila YIT 11841(T), in medium supplemented with xylan but not succinate, their cell numbers became 2 to 3 orders of magnitude higher than those of the monoculture; succinate became undetectable, and propionate was formed. Database analysis revealed that over 200 uncultured bacterial clones from the feces of humans and other mammals showed high sequence identity (>98.7%) to YIT 12067(T). Real-time PCR analysis also revealed that YIT 12067(T)-like bacteria were present in 21% of human fecal samples, at an average level of 3.34 × 10(8) cells/g feces. These results indicate that YIT 12067(T)-like bacteria are distributed broadly in the GI tract as subdominant members that may adapt to the intestinal environment by specializing to utilize the succinate generated by other bacterial species. The phylogenetic and physiological properties of YIT 12067(T) and YIT 12068 suggest that these strains represent a novel species, which we have designated Phascolarctobacterium succinatutens sp. nov.

Galactooligosaccharides improve mineral absorption and bone properties in growing rats through gut fermentation

Galactooligosaccharides (GOS), prebiotic nondigestible oligosaccharides derived from lactose, have the potential for improving mineral balance and bone properties. This study examined the dose-response effect of GOS supplementation on calcium and magnesium absorption, mineral retention, bone properties, and gut microbiota in growing rats. Seventy-five 4-week-old male Sprague-Dawley rats were randomized into one of five treatment groups (n = 15/group) and fed a diet containing 0, 2, 4, 6, or 8% GOS by weight for 8 weeks. Dietary GOS significantly decreased cecal pH and increased cecal wall weight and content weight in a dose-dependent manner (p < 0.0001). Fingerprint patterns of the 16S rRNA gene PCR-DGGE from fecal DNA indicated the variance of bacterial community structure, which was primarily explained by GOS treatments (p = 0.0001). Quantitative PCR of the samples revealed an increase in the relative proportion of bifidobacteria with GOS (p = 0.0001). Net calcium absorption was increased in a dose-response manner (p < 0.01) with GOS supplementation. Dietary GOS also increased (p < 0.02) net magnesium absorption, femur ⁴⁵Ca uptake, calcium and magnesium retention, and femur and tibia breaking strength. Distal femur total and trabecular volumetric bone mineral density (vBMD) and area and proximal tibia vBMD increased (p < 0.02) with GOS supplementation. Trabecular-rich bones, that is, those that rapidly turn over, were most benefited. Regression modeling showed that GOS benefited calcium and magnesium utilization and vBMD through decreased cecal pH, increased cecal wall and content weight, and increased proportion of bifidobacteria.

A ingestão de prébioticos previne a malabsorção de ferro e anemia induzidas pela gastrectomia?: Estudo experimental em ratos

RACIONAL: Ratos gastrectomizados desenvolvem anemia, e a ingestão de galactooligossacarídeo (GOS) e a polidextrose (PDX) aumenta a absorção de ferro e promove a recuperação da anemia em ratos com deficiência de ferro. OBJETIVO: Avaliar se GOS e PDX estimulam a absorção de ferro em ratos gastrectomizados e normais. MÉTODOS: Os ratos foram laparotomizadas (controle falso-operado) e parcialmente gastrectomizados (Billroth II) em grupos de 20 animais. Os animais de ambos os tratamentos foram posteriormente submetidos à dieta controle (AIN-93M) ou a mesma dieta suplementada com GOS e PDX (25 g/kg de dieta cada) durante oito semanas e divididos em quatro subgrupos: sham-operados e gastrectomizados sem GOS e PDX, sham-operados e gastrectomizados com GOS e PDX. Dois animais morreram durante o experimento. Todos os ratos gastrectomizados receberam uma injeção intramuscular de vitamina B-12 a cada duas semanas. Hematócrito (HCT) e concentração de hemoglobina (HGB) foram dosados no início e nos dias 30 e 56 dias após o início da alimentação. No último dia do estudo, o sangue total foi coletado para determinação da concentração de ferro sérico. RESULTADOS: Na dieta com GOS e PDX a excreção de ferro nas fezes foi significativamente menor do que no grupo sem prebióticos. Absorção aparente de ferro e ferro sérico foram maiores nos grupos alimentados com GOS e PDX (ambos grupos: sham operados e gastrectomizados) do que nos grupos não alimentados com GOS e PDX. O HCT e HGB foram significativamente menores nos ratos gastrectomizados que no grupo controle, entretanto, a suplementação com GOS e PDX melhorou os níveis de HGB neste grupo. CONCLUSÃO: A associação de GOS e PDX aumenta a absorção de ferro em ratos shamoperados e gastrectomizados e ainda previne a anemia pós-gastrectomia.

Parasutterella secunda sp. nov., isolated from human faeces and proposal of Sutterellaceae fam. nov. in the order Burkholderiales

A novel, strictly anaerobic, non-spore-forming, Gram-reaction-negative coccobacillus bacterium, designated strain YIT 12071T, was isolated from human faeces. Biochemically, this strain was largely unreactive and asaccharolytic. Growth of this strain in peptone-yeast-extract broth was weak, producing no visible turbidity, and no short-chain fatty acids were detected as an end product of metabolism. Following 16S rRNA gene sequence analysis, strain YIT 12071T was found to be most closely related to Parasutterella excrementihominis (90 % sequence similarity) and phylogenetically distinct from other known genera belonging to the order Burkholderiales. Biochemical data supported the affiliation of this strain with the genus Parasutterella. Strain YIT 12071T, therefore, represents a novel species of the genus Parasutterella, for which the name Parasutterella secunda sp. nov. is proposed. The type strain is YIT 12071T (=DSM 22575T =JCM 16078T). On the basis of 16S rRNA gene sequence analysis, species of the genera Sutterella and Parasutterella form a distinct and deep evolutionary lineage of descent in the order Burkholderiales. This lineage could not be associated with any of the four known families of the order Burkholderiales. The distinct phylogenetic position and the unusual combination of chemotaxonomic characteristics shared by these genera, such as the predominant quinones and cellular fatty acid compositions, suggest that they constitute a novel family in the order Burkholderiales, for which the name Sutterellaceae fam. nov. is proposed to accommodate the genera Sutterella and Parasutterella.

Description of Christensenella minuta gen. nov., sp. nov., isolated from human faeces, which forms a distinct branch in the order Clostridiales, and proposal of Christensenellaceae fam. nov

A novel, strictly anaerobic, non-motile, non-spore-forming, Gram-negative, short, straight rod with tapered ends, designated YIT 12065(T), was isolated from human faeces. Strain YIT 12065(T) was saccharolytic and negative for catalase, oxidase and urease, hydrolysis of aesculin and gelatin, nitrate reduction and indole production. The end products of glucose fermentation were acetic acid and a small amount of butyric acid. The DNA G+C content was 51.3 mol%. The predominant fatty acids were iso-C(15:0), C(16:0) and C(14:0). Respiratory quinones were not detected. The cell wall contained glutamic acid, serine, alanine and ll-diaminopimelic acid. The whole-cell sugars were ribose, rhamnose, galactose and glucose. Phylogenetic analyses based on 16S rRNA gene sequences using three treeing algorithms revealed that the strain formed a novel family-level lineage within the phylum Firmicutes, class Clostridia, order Clostridiales. Caldicoprobacter oshimai JW/HY-331(T) was shown to be the closest named relative on the basis of 16S rRNA gene sequence similarity (86.9%), followed by Tindallia californiensis DSM 14871(T) (86.3%) and Clostridium ganghwense JCM 13193(T) (86.1%). Similar 16S rRNA gene sequences (98.6-96.7%) were found amongst faecal uncultured clones of human and dugong (Dugong dugon). They clustered with strain YIT 12065(T) in a distinct and deep evolutionary lineage of descent in the order Clostridiales. The distinct phylogenetic position supports the proposal of Christensenella gen. nov., with the type species Christensenella minuta sp. nov. (type strain YIT 12065(T) =DSM 22607(T) =JCM 16072(T)). A new family Christensenellaceae fam. nov. is also proposed.

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.

Slackia piriformis sp. nov. and Collinsella tanakaei sp. nov., new members of the family Coriobacteriaceae, isolated from human faeces

Three Gram-positive, strictly anaerobic, non-spore-forming, rod-shaped organisms (strains YIT 12062T, YIT 12063T and YIT 12064) were isolated from human faeces. Strain YIT 12062T was asaccharolytic and possessed a DNA G+C content of 58.3 mol%. Cells of strain YIT 12062T were negative for catalase, oxidase, urease, hydrolysis of aesculin and gelatin, nitrate reduction and indole production. Based on 16S rRNA gene sequence analysis, strain YIT 12062T was assigned to the genus Slackia (91.7–96.0 % sequence similarities to type strains of Slackia species). Biochemical data showed that the isolate was phenotypically distinct from all recognized species of the genus Slackia. Strain YIT 12062T therefore represents a novel species in the genus Slackia, for which the name Slackia piriformis sp. nov. is proposed. The type strain is YIT 12062T (=DSM 22477T=JCM 16070T). Following 16S rRNA gene sequence analysis, strains YIT 12063T and YIT 12064, which were isolated from different subjects, were shown to be most closely related to species of the genus Collinsella (93.8–95.1 % similarities to type strains). Although their phenotypic characteristics were very similar and they shared >99 % 16S rRNA gene sequence similarity and >97±1.8 % DNA–DNA relatedness, the two isolates could be discriminated by RAPD fingerprints. The DNA G+C contents of strains YIT 12063T and YIT 12064 were 60.8 and 61.0 mol%, respectively. They were saccharolytic in API test systems, positive for aesculin hydrolysis and negative for catalase, oxidase, urease, indole production, nitrate reduction and gelatin hydrolysis. The major end products of glucose fermentation of these strains were lactate, acetate and formate. Biochemical data supported the affiliation of strains YIT 12063T and YIT 12064 to the genus Collinsella and showed that they were phenotypically distinct from all recognized species of the genus Collinsella. Strains YIT 12063T and YIT 12064 therefore represent a novel species of the genus Collinsella, for which the name Collinsella tanakaei sp. nov. is proposed. The type strain is YIT 12063T (=DSM 22478T=JCM 16071T).

Bacteroides clarus sp. nov., Bacteroides fluxus sp. nov. and Bacteroides oleiciplenus sp. nov., isolated from human faeces

Three Gram-stain-negative, obligately anaerobic, non-spore-forming, rod-shaped bacteria (strains YIT 12056T, YIT 12057T and YIT 12058T) were isolated from human faeces. These strains were characterized by phylogenetic analyses based on 16S rRNA gene sequence and phenotypic tests. 16S rRNA gene sequence analyses revealed that strains YIT 12056T, YIT 12057T and YIT 12058T were most closely related to the type strains of Bacteroides gallinarum, Bacteroides uniformis and Bacteroides intestinalis with approximate similarity values of 96.6, 95.0 and 96.7 %, respectively. The DNA G+C contents of the novel strains were 45.3 (YIT 12056T), 45.2 (YIT 12057T) and 43.6 mol% (YIT 12058T) and the major respiratory quinones of all three isolates were menaquinones MK-10 and MK-11. These properties were typical for members of the genus Bacteroides. The results of the other phenotypic analyses also supported the affiliation of these strains to the genus Bacteroides. The 16S rRNA gene sequence analysis, analysis of the major cellular fatty acids and other biochemical tests enabled the genotypic and phenotypic differentiation of the three new strains. Based on these data, three novel species, Bacteroides clarus sp. nov., Bacteroides fluxus sp. nov. and Bacteroides oleiciplenus sp. nov. are proposed. The type strains of B. clarus, B. fluxus and B. oleiciplenus are YIT 12056T (=JCM 16067T=DSM 22519T), YIT 12057T (=JCM 16101T=DSM 22534T) and YIT 12058T (=JCM 16102T=DSM 22535T), respectively.

Alistipes indistinctus sp. nov. and Odoribacter laneus sp. nov., common members of the human intestinal microbiota isolated from faeces

Two anaerobic, non-spore-forming, non-motile, Gram-negative-staining bacteria, strains YIT 12060T and YIT 12061T, were isolated from human faeces. Cells of strain YIT 12060T were coccoid to rod-shaped with round ends, positive for catalase, negative for indole and oxidase production, produced succinic and acetic acids as end products of glucose metabolism in peptone/yeast extract/glucose medium and had a DNA G+C content of 55.2 mol%. The main respiratory quinones were MK-10 (40 %) and MK-11 (57 %). Fatty acid analysis demonstrated the presence of a high concentration of iso-C15 : 0 (56 %). Following 16S rRNA gene sequence analysis, this strain was found to be most closely related to species of the genus Alistipes, with 90.9–92.6 % gene sequence similarities to type strains of this species. Phylogenetic analysis and biochemical data supported the affiliation of strain YIT 12060T to the genus Alistipes of the family ‘Rikenellaceae’. Strain YIT 12060T therefore represents a novel species of the genus Alistipes for which the name Alistipes indistinctus sp. nov. is proposed; the type strain is YIT 12060T (=DSM 22520T=JCM 16068T). Cells of the other isolate, strain YIT 12061T, were pleomorphic rods that were asaccharolytic, catalase- and oxidase-negative, positive for gelatin hydrolysis and indole production, produced small amounts of succinic, acetic and iso-valeric acids as end products of metabolism in peptone/yeast extract medium and had a DNA G+C content of approximately 42.4 mol%. On the basis of 16S rRNA gene sequence similarity values, this strain was shown to belong to the family ‘Porphyromonadaceae’ and related to the type strains of Odoribacter splanchnicus (89.6 %) and Odoribacter denticanis (86.2 %); similarity values with strains of recognized species within the family ‘Porphyromonadaceae’ were less than 84 %. Biochemical data supported the affiliation of strain YIT 12061T to the genus Odoribacter. Strain YIT 12061T therefore represents a novel species for which the name Odoribacter laneus sp. nov. is proposed; the type strain is YIT 12061T (=DSM 22474T=JCM 16069T).