Restoration of the integrity of rat caeco-colonic mucosa by resistant starch, but not by fructo-oligosaccharides, in dextran sulfate sodium-induced experimental colitis

Effects of hindgut acidosis on production, metabolism, and inflammatory biomarkers in feed-restricted lactating dairy cows

Study objectives were to evaluate the effects of hindgut acidosis (HGA) on production, metabolism, and inflammation in feed-restricted (FR) dairy cows. Twelve rumen-cannulated cows were enrolled in a study with 3 experimental periods (P). During P1 (5 d), baseline data were collected. During P2 (2 d), all cows were FR to 40% of their baseline feed intake. During P3 (4 d), cows remained FR and were assigned to 1 of 2 abomasal infusion treatments: (1) control (FR-CON; 6 L of H₂O/d; n = 6) or (2) starch (FR-ST; 4 kg of corn starch + 6 L of H₂O/d; n = 6). Respective treatments were partitioned into 4 equal doses (1 kg of corn starch/infusion) and were abomasally infused daily at 0000, 0600, 1200, and 1800 h. All 3 P were analyzed independently and the effects of treatment, time, and treatment × time were assessed using PROC MIXED, and P1 and P2 data were analyzed using the treatments cows were destined to be assigned to during P3. Hallmark production and metabolic responses to feed restriction were observed in both treatments, including decreased milk yield (39%) and energy-corrected milk (32%), circulating glucose (12%), insulin (71%), and increased circulating nonesterified fatty acids (3.2-fold) throughout both P2 and P3, relative to P1. However, despite a marked reduction in fecal pH (0.96 units), the aforementioned metrics were unaltered by HGA. During P3, starch infusions increased circulating β-hydroxybutyrate, with the most pronounced increase occurring on d 2 (81% relative to FR-CON). Further, feed restriction decreased blood urea nitrogen during P2 (17% relative to P1) in both treatments, and this was exacerbated by starch infusions during P3 (31% decrease relative to FR-CON). In contrast to our hypothesis, neither feed restriction nor HGA increased circulating acute-phase proteins (serum amyloid A and lipopolysaccharide binding protein) relative to P1 or FR-CON, respectively. Thus, despite marked reductions in fecal pH, prior feed restriction did not appear to increase the susceptibility to HGA.

Microbial-Derived Tryptophan Catabolites, Kidney Disease and Gut Inflammation

Uremic metabolites, molecules either produced by the host or from the microbiota population existing in the gastrointestinal tract that gets excreted by the kidneys into urine, have significant effects on both health and disease. Tryptophan-derived catabolites are an important group of bacteria-produced metabolites with an extensive contribution to intestinal health and, eventually, chronic kidney disease (CKD) progression. The end-metabolite, indoxyl sulfate, is a key contributor to the exacerbation of CKD via the induction of an inflammatory state and oxidative stress affecting various organ systems. Contrastingly, other tryptophan catabolites positively contribute to maintaining intestinal homeostasis and preventing intestinal inflammation—activities signaled through nuclear receptors in particular—the aryl hydrocarbon receptor (AhR) and the pregnane X receptor (PXR). This review discusses the origins of these catabolites, their effect on organ systems, and how these can be manipulated therapeutically in the future as a strategy to treat CKD progression and gut inflammation management. Furthermore, the use of biotics (prebiotics, probiotics, synbiotics) as a means to increase the presence of beneficial short-chain fatty acids (SCFAs) to achieve intestinal homeostasis is discussed.

Control of lymphocyte functions by gut microbiota-derived short-chain fatty acids

A mounting body of evidence indicates that dietary fiber (DF) metabolites produced by commensal bacteria play essential roles in balancing the immune system. DF, considered nonessential nutrients in the past, is now considered to be necessary to maintain adequate levels of immunity and suppress inflammatory and allergic responses. Short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, are the major DF metabolites and mostly produced by specialized commensal bacteria that are capable of breaking down DF into simpler saccharides and further metabolizing the saccharides into SCFAs. SCFAs act on many cell types to regulate a number of important biological processes, including host metabolism, intestinal functions, and immunity system. This review specifically highlights the regulatory functions of DF and SCFAs in the immune system with a focus on major innate and adaptive lymphocytes. Current information regarding how SCFAs regulate innate lymphoid cells, T helper cells, cytotoxic T cells, and B cells and how these functions impact immunity, inflammation, and allergic responses are discussed.

The Facilitators and Barriers of Adopting Amylase-Rich Flour to Enhance Complementary Foods in the Kersa District Community of Eastern Ethiopia

Achieving the optimal transition to a family diet over the first two years of life has remained a challenge in Ethiopia. The use of amylase-rich flour (ARF) can improve complementary foods. However, utilisation requires an effective delivery strategy for upskilling the community to use ARF. The aim of this study was to explore facilitators and barriers of cascading ARF skills to improve complementary foods. The study was conducted in Gale Mirga kebele of Kersa district in Eastern Ethiopia in 2016. The study utilised exploratory qualitative research that used participatory action. Focus group discussions (FGDs) were conducted with the Health Development Army (HDA) leaders, religious leaders, and observation of participatory complementary food demonstrations. Cultural acceptability and the presence of HDA structure that supports skill development were identified as key facilitators to ARF use. On the other hand, the potential barriers to expanding ARF skill were lack of sustainability of external skill support for HDA leaders, perceived time constraints, unsuitable demonstration settings, cooking method, and large group size. The indigenous community's knowledge of germination has not been used to improve complementary foods. The universal use of ARF requires integration into the Health Extension Programme (HEP) with support and supervision for HDA leaders.

Deficiency of Dietary Fiber Modulates Gut Microbiota Composition, Neutrophil Recruitment and Worsens Experimental Colitis

Ulcerative colitis is an inflammatory disease of the colon that is associated with colonic neutrophil accumulation. Recent evidence indicates that diet alters the composition of the gut microbiota and influences host–pathogen interactions. Specifically, bacterial fermentation of dietary fiber produces metabolites called short-chain fatty acids (SCFAs), which have been shown to protect against various inflammatory diseases. However, the effect of fiber deficiency on the key initial steps of inflammation, such as leukocyte–endothelial cell interactions, is unknown. Moreover, the impact of fiber deficiency on neutrophil recruitment under basal conditions and during inflammation in vivo is unknown. Herein, we hypothesized that a fiber-deficient diet promotes an inflammatory state in the colon at baseline and predisposes the host to more severe colitis pathology. Mice fed a no-fiber diet for 14 days showed significant changes in the gut microbiota and exhibited increased neutrophil-endothelial interactions in the colonic microvasculature. Although mice fed a no-fiber diet alone did not have observable colitis-associated symptoms, these animals were highly susceptible to low dose (0.5%) dextran sodium sulphate (DSS)-induced model of colitis. Supplementation of the most abundant SCFA, acetate, prevented no-fiber diet-mediated enrichment of colonic neutrophils and colitis pathology. Therefore, dietary fiber, possibly through the actions of acetate, plays an important role in regulating neutrophil recruitment and host protection against inflammatory colonic damage in an experimental model of colitis.

The effects of resistant starches on inflammatory bowel disease in preclinical and clinical settings: a systematic review and meta-analysis

Background

Inflammatory bowel disease (IBD) is a debilitating chronic disease with limited treatment options. Resistant starches may represent a novel treatment for IBD. However, its efficacy and safety remain unclear. Our objective was to perform a systematic review to summarize the preclinical and clinical effects of resistant starch, which may help guide future studies.

Methods

Medline, EMBASE, and the Cochrane Central Register were searched. Included studies investigated the use of resistant starch therapy in in vivo animal models of IBD or human patients with IBD. Articles were screened, and data extracted, independently and in duplicate. The primary outcomes were clinical remission (clinical) and bowel mucosal damage (preclinical).

Results

21 preclinical (n = 989 animals) and seven clinical (n = 164 patients) studies met eligibility. Preclinically, resistant starch was associated with a significant reduction in bowel mucosal damage compared to placebo (standardized mean difference − 1.83, 95% CI − 2.45 to − 1.20). Clinically, five studies reported data on clinical remission but clinical and methodological heterogeneity precluded pooling. In all five, a positive effect was seen in patients who consumed resistant starch supplemented diets. The majority of studies in both the preclinical and clinical settings were at a high or unclear risk of bias due to poor methodological reporting.

Conclusions

Our review demonstrates that resistant starch is associated with reduced histology damage in animal studies, and improvements in clinical remission in IBD patients. These results need to be tempered by the risk of bias of included studies. Rigorously designed preclinical and clinical studies are warranted.

Trial registration

The review protocols were registered on PROSPERO (preclinical: CRD42019130896; clinical: CRD42019129513).

Oligosaccharides in goats' milk-based infant formula and their prebiotic and anti-infection properties

Human milk contains an abundant supply and diverse array of oligosaccharides that are known to impart significant health benefits to the nursing infant including establishment and maintenance of a healthy gut microflora, immune development and protection against gastrointestinal infections. When breastfeeding is not possible or insufficient, infant formulas are commonly used as an alternative. However, limited information is available about the presence of naturally occurring oligosaccharides in these infant formulas and their likely health benefits. The present study examined the presence of naturally occurring oligosaccharides in commercial goats' milk-based stage 1 and stage 2 infant formulas and their prebiotic and anti-infection properties. LC/MS was used to detect and quantify oligosaccharides and their prebiotic potential was assessed by their ability, at concentrations present in reconstituted ready-to-use infant formula, to promote the growth of Bifidobacterium animalis subsp. lactis BB12, B. longum BB536, Lactobacillus acidophilus 4461 and L. casei 2607 in vitro. For anti-infection properties, the ability of goat milk oligosaccharides to prevent the adhesion of Escherichia coli NCTC 10418 and a Salmonella typhimurium isolate to Caco-2 cells was investigated. The results showed the presence of fourteen quantifiable oligosaccharides in stage 1 and stage 2 goats' milk-based infant formula. This was similar to the number of oligosaccharides detected in the fresh goats' milk. Of these, five were structurally similar to those found in human milk. These oligosaccharides were shown to significantly enhance the growth of bifidobacteria and lactobacilli and reduce the adhesion of E. coli NCTC 10418 and S. typhimurium to Caco-2 cells. Together, these results suggest that oligosaccharides naturally present in goats' milk-based infant formula exhibit strong prebiotic and anti-pathogen adhesion properties and may confer gut health benefits to infants.

Polysaccharides: bowel health and gut microbiota

Polysaccharides that contain many sugar monomers include starch and non-starch polysaccharides (NSPs) together with resistant starch (RS). Dietary polysaccharides are well known to have a wide range of biological benefits for bowel health. Gut microbiota and their fermentative products, short chain fatty acids (SCFA), which have recently been highlighted as metabolic regulators, are thought to mediate the function of dietary complex carbohydrates and bowel health. We discuss the influence of various polysaccharides on human bowel health and the mechanisms underlying these effects. We also describe their biological effects on intestinal health and the mechanisms underlying their activity; the polysaccharides were divided into three categories: dietary, microbial, and host-derived polysaccharides. Physiological impacts of non-starch polysaccharides (NSPs) and resistant starch (RS), both of which pass through the small intestine nearly intact and can be fermented by gut microbiota in the large intestine, are similar to each other. They exert a wide range of beneficial effects including anti-inflammation, gut epithelial barrier protection, and immune modulation through both microbiota-dependent and -independent mechanisms. Bacterial polysaccharides usually found in the cell wall generally act as immune modulators, and host-derived polysaccharides not only protect host cells from pathogenic microbial neighbors but also affect overall intestinal health via interactions with gut microbes. Considering these observations, further studies on polysaccharides will be important for bowel health.

Role of inulin as prebiotics on inflammatory bowel disease

The present review is focused on the prebiotic impact of inulin on the management of the gastrointestinal disorder. Prebiotics can be described as "non-digestible food ingredient stimulating the growth of a certain number of bacteria in the colon, which can improve the host health". In 2004 this definition was modernized to include other areas that may benefit from selective targeting of particular microorganisms: "selectively fermented ingredients that alter the configuration and activity in the gastrointestinal microbiota that confer positive effect". The positive impact of prebiotics in experimental colitis and human inflammatory bowel disease (IBD) has already been established. Prebiotics shows a positive effect in the prevention of IBD by modulating the trophic functions of the flora. Inulin enhances the growth of indigenous lactobacilli and/or bifidobacteria by inducing colonic production of short chain fatty acids (SCFA's) and these properties are related to decreased mucosal lesion scores and diminished mucosal inflammation. Inulin shows a positive approach to retain microbial populations and to support epithelial barrier function by their prebiotic effect which helps in the host defense against invasion and pathogens translocation (endogenous and/or exogenous) and in the inhibition of gastrointestinal diseases and this impact should be verified in further clinical studies. In the present review, we discussed the positive effect of prebiotics in rat IBD models and in human subjects along with their potential protective mechanisms. Preclinical and clinical data revealed that the gut mucosal barrier would be improved by the use of prebiotics in IBD.

An integrated look at the effect of structure on nutrient bioavailability in plant foods

The true bioavailability of a nutrient being intrinsically coupled to the specific food matrix in which it occurs remains poorly considered in nutrition science. During digestion, the food matrix and, in particular, the structure of food modulate the extent and kinetics to which nutrients and bioactive compounds make themselves available for absorption. In this perspective, we describe an integrated look at the effect of structure on nutrient bioavailability in plant foods. Based on this integrated look, cell wall integrity and the particle size of the plant material during its transit in the small intestine determine the bioavailability of plant nutrients; in turn, cell wall integrity and particle size are determined by the level of oral processing and, accordingly, what subsequently escapes digestion in the upper intestine and is utilized by colon microbiota. Ultimately, the effect on nutrient digestion is linked to food structure through each step of digestion. A consideration of the structure rather than just the composition of foods opens up possibilities for the design of healthier foods. © 2018 Society of Chemical Industry.

The Impact of Fructo-Oligosaccharides on Gut Permeability and Inflammatory Responses in the Cecal Mucosa Quite Differs between Rats Fed Semi-Purified and Non-Purified Diets

The effects of fructo-oligosaccharides (FOS) on gut-barrier function are still controversial in human and animal studies. Diet conditions would be a major factor for the controversy in animal studies. We fed rats a semi-purified (SP) or a non-purified diet (NP) with or without FOS (60 g/kg diet) for 9 (experiment 1) or 10 d (experiment 2). We assessed microbial fermentation, gut permeability, and inflammatory responses in the cecum (experiment 1), and mucus layer in the cecum, intestinal transit time and microbiota composition (experiment 2). FOS supplementation induced a very acidic fermentation due to the accumulation of lactate and succinate in SP, while short-chain fatty acids were major products in NP. Gut permeability estimated by urinary chromium-EDTA excretion, bacterial translocation into mesenteric lymph nodes, myeloperoxidase activity, and expressions of the inflammatory cytokine genes in the cecal mucosa were greater in SP+FOS than in SP, but these alterations were not observed between NP and NP+FOS (experiment 1). FOS supplementation destroyed the mucus layer on the epithelial surface in SP, but not in NP. Intestinal transit time was 3-fold longer in SP+FOS than in SP, but this was not the case between NP and NP+FOS. Lower species richness of cecal microbiota was manifest solely in SP+FOS (experiment 2). These factors suggest that impact of FOS on gut permeability and inflammatory responses in the cecal mucosa quite differs between SP and NP. Increased gut permeability in SP+FOS could be evoked by the disruption of the mucus layer due to stasis of the very acidic luminal contents.

Anti-inflammatory effects of newly synthesized α-galacto-oligosaccharides on dextran sulfate sodium-induced colitis in C57BL/6J mice

α-Galacto-oligosaccharides have been reported to have beneficial health effects. The purpose of this study was to investigate the preventive effects of a newly synthesized α-galacto-oligosaccharide mixture (α-GOSg), as well as raffinose family oligosaccharides (RFOs), on dextran sulfate sodium (DSS)-induced colitis in mice. When administered in drinking water at 0.5% for 15 days, both α-GOSg and RFOs significantly decreased fecal hemoglobin content, partially prevented colon length shortening, reduced the severity of colon inflammation, and attenuated DSS-induced upregulation of cyclooxygenase-2. In addition, the activation of the inflammatory regulator nuclear factor-kappa B was slightly inhibited by α-GOSg. The results showed that the newly synthesized α-GOSg preparation has similar anti-inflammatory activities as RFOs in this colitis model. The anti-inflammatory activity of α-GOSg in humans remains to be investigated.

Inflammatory bowel disease and immunonutrition: novel therapeutic approaches through modulation of diet and the gut microbiome

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract, thought to at least in part reflect an aberrant immune response to gut bacteria. IBD is increasing in incidence, particularly in populations that have recently immigrated to western countries. This suggests that environmental factors are involved in its pathogenesis. We hypothesize that the increase in IBD rates might reflect the consumption of an unhealthy Western diet, containing excess calories and lacking in key nutritional factors, such as fibre and vitamin D. Several recent studies have determined that dietary factors can dramatically influence the activation of immune cells and the mediators they release through a process called immunonutrition. Moreover, dietary changes can profoundly affect the balance of beneficial versus pathogenic bacteria in the gut. This microbial imbalance can alter levels of microbiota-derived metabolites that in turn can influence innate and adaptive intestinal immune responses. If the diet-gut microbiome disease axis does indeed underpin much of the 'western' influence on the onset and progression of IBD, then tremendous opportunity exists for therapeutic changes in lifestyle, to modulate the gut microbiome and to correct immune imbalances in individuals with IBD. This review highlights four such therapeutic strategies - probiotics, prebiotics, vitamin D and caloric restriction - that have the potential to improve and add to current IBD treatment regimens.

Prebiotic Supplementation Following Ileocecal Resection in a Murine Model is Associated With a Loss of Microbial Diversity and Increased Inflammation

BACKGROUND

Individuals with Crohn's disease frequently require ileocecal resection (ICR), and inflammation often recurs in the neoterminal ileum following surgery. Fructooligosaccharide (FOS) is a fermentable prebiotic that stimulates the growth of bifidobacteria and may promote anti-inflammatory activity. The aim of this study was to determine if supplementation of a postICR diet with FOS in a mouse model would be effective in stimulating the growth of bifidobacteria and reducing systemic and local inflammation.

METHODS

ICR was performed in IL10-/- mice (129S1/SvlmJ) with colitis. Following surgery, nonICR control and ICR mice were fed a chow diet ± 10% FOS for 28 days. Serum, colon, and terminal ileum (TI) were analyzed for cytokine expression by MesoScale discovery platform. DNA extracted from stool was analyzed using 16s rRNA sequencing and qPCR. Expression of occludin and ZO1 was assessed using qPCR. Short-chain fatty acid (SCFA) concentrations were assessed using gas chromatography.

RESULTS

ICR led to increased systemic inflammation (P < 0.05) and a significant decline in fecal microbial diversity (P < 0.05). Mice on the FOS diet had a greater reduction in microbial diversity and also had worsened inflammation as evidenced by increased serum IL-6 (P < 0.05) and colonic IFNγ and TNFα (P < 0.05). Expression of occludin and ZO1 were significantly reduced in FOS-supplemented mice. There was a correlation between loss of diversity and the bifidogenic effectiveness of FOS (r = -0.61, P < 0.05).

CONCLUSIONS

FOS-supplementation of a postICR diet resulted in a decrease in fecal bacterial diversity, reduction in barrier function, and increased gut inflammation.

Shared mechanisms among probiotic taxa: implications for general probiotic claims

Strain-specificity of probiotic effects has been a cornerstone principle of probiotic science for decades. Certainly, some important mechanisms are present in only a few probiotic strains. But scientific advances now reveal commonalities among members of certain taxonomic groups of probiotic microbes. Some clinical benefits likely derive from these shared mechanisms, suggesting that sub-species-specific, species-specific or genus-specific probiotic effects exist. Human trials are necessary to confirm specific health benefits. However, a strain that has not been tested in human efficacy trials may meet the minimum definition of the term 'probiotic' if it is a member of a well-studied probiotic species expressing underlying core mechanisms and it is delivered at an effective dose.

Effect of resistant starch on the intestinal health of old dogs: fermentation products and histological features of the intestinal mucosa

The effects of resistant starch (RS) intake on nutrient digestibility, microbial fermentation products, faecal IgA, faecal pH, and histological features of the intestinal mucosa of old dogs were evaluated. The same formulation was extruded in two different conditions: one to obtain elevated starch cooking degree with low RS content (0.21%) and the other lower starch cooking with high RS content (1.46%). Eight geriatric Beagles (11.5 ± 0.38 years old) were fed each diet for 61 days in a crossover design. Food intake, nutrient digestibility, fermentation products, faecal pH, and faecal IgA were examined via variance analysis. Histological results of intestinal biopsies were assessed via Wilcoxon test for paired data. The morphometric characteristics of large intestine crypts were evaluated via paired t tests (p < .05). Protein, fat, and energy digestibilities were higher for the low-RS diet (p < .05). Dogs receiving the high-RS diet had lower faecal pH and higher values for propionate, butyrate, total volatile fatty acids, and lactate (p < .05). No differences between diets were found in the histological parameters of the gut mucosa, and only a tendency for deeper crypts in the descending colon was observed for dogs fed the high-RS diet (p = .083). The intake of a corn-based kibble diet manufactured with coarse ground raw material and low starch gelatinization to obtain 1.4% of RS affected microbial fermentation products and faecal pH and tended to increase crypt depth in the descending colon of old dogs.

Dietary Fermentable Fiber Reduces Intestinal Barrier Defects and Inflammation in Colitic Mice

BACKGROUND

Dietary fiber (DF) and its fermentation metabolites play an important role in establishing and maintaining intestinal health.

OBJECTIVE

This study investigated the effects of fermentable DF, guar gum (GG), and partially hydrolyzed GG (PHGG) on the epithelial tight junction (TJ) barrier and inflammation in a murine model of dextran sodium sulfate (DSS)-induced colitis.

METHODS

In Expt. 1, male, 7-wk-old BALB/c mice weighing ∼21 g were fed diets with 0%, 5%, and 10% GG for 12 d and administered distilled water with 2% DSS for 7 d beginning 5 d after the start of feeding. In Expt. 2, mice were provided diets with or without 10% PHGG and GG for 13 d and administered distilled water with 2% DSS for 8 d from 5 d after the start of feeding. In Expt. 3, mice were provided diets with or without 10% PHGG and GG for 14 d without DSS administration. Colitis score, colon TJ proteins, and fecal SCFA concentrations were analyzed.

RESULTS

In Expts. 1 and 2, the clinical score in the DSS group was ∼100% greater than that in the DSS+10% GG and PHGG groups on days 12 and 13 (P < 0.01). The DSS+10% GG and PHGG groups showed ∼110%, 60%, 120%, and 110% greater (P < 0.05) expression of occludin and claudin 3, 4, and 7, respectively, in the colon than did the DSS group. The DSS+10% GG and PHGG groups had greater total fecal SCFA concentrations (25.1 and 12.0 mmol/L) than did the DSS group (3.3 mmol/L) on day 9 (P < 0.01). TJ protein expression did not differ between groups in Expt. 3.

CONCLUSION

These findings suggest that microbial metabolites of PHGG and GG, and possibly SCFAs, reduce intestinal barrier defects and inflammation in colitic mice.

Moderately Fermentable Potato Fiber Attenuates Signs and Inflammation Associated with Experimental Colitis in Mice

BACKGROUND

Dietary fiber intake leading to short-chain fatty acid (SCFA) production could be a strategy to combat intermittent bouts of inflammation during ulcerative colitis.

OBJECTIVE

Our objective was to evaluate dietary potato fiber (PF) in attenuating inflammation using a dextran sodium sulfate (DSS)-induced colitis mouse model. We hypothesized that PF would show anti-inflammatory effects compared with cellulose due in part to SCFA production.

METHODS

Male C57Bl/6J mice were fed diets containing either 8% cellulose or 14.5% PF for a 22-d feeding study. Starting on study day 14, mice were provided either distilled water (control) or 2% (wt:vol) DSS in drinking water for 5 d (cellulose+control, n = 17; PF+control, n = 16; cellulose+DSS, n = 17; and PF+DSS, n = 16). Body weights and food and water intakes were collected daily from day 14 through day 22. Distal colon tissue was analyzed for histologic outcomes and changes in gene expression, and cecal contents were analyzed for SCFA concentrations. Data were analyzed by ANOVA, with repeated measures applied where necessary.

RESULTS

At day 5 post-DSS induction, cellulose+DSS mice exhibited a 2% reduction (P < 0.05) in body weight compared with PF+DSS and PF+ and cellulose+control mice. PF+DSS mice had greater (P < 0.05) cecal butyrate concentrations [24.5 μmol/g dry matter (DM)] than did cellulose+DSS mice (4.93 μmol/g DM). Mice fed PF+DSS had lower (P < 0.05) infiltration of leukocytes in the distal colon than did mice fed cellulose+DSS (mean histology scores of 1.22 and 2.30, respectively). Furthermore, mice fed cellulose+DSS exhibited 1.42, 11.5, 8.48, and 35.5 times greater (P < 0.05) colon mRNA expression of tumor necrosis factor α (Tnfa) and interleukin (Il) 1b, Il6, and Il17a, respectively, and 7.10 times greater (P < 0.05) expression of C-X-C motif ligand 1 (Cxc1) compared with mice fed PF+DSS.

CONCLUSIONS

These results suggest that PF fed to mice before and during DSS colitis attenuates inflammation, potentially through SCFA production; however, future studies are needed to understand the role of dietary fiber intake and immune activation.

Preventive rather than therapeutic treatment with high fiber diet attenuates clinical and inflammatory markers of acute and chronic DSS-induced colitis in mice

PURPOSE

Inflammatory bowel diseases (IBDs) are chronic inflammatory disorders with important impact on global health. Prebiotic and probiotic strategies are thought to be useful in the context of experimental IBD. Here, we compared the effects of preventive versus therapeutic treatment with a high fiber diet (prebiotic) in combination or not with Bifidobacterium longum (probiotic) in a murine model of chronic colitis.

METHODS

Colitis was induced by adding dextran sulfate sodium (DSS) to drinking water for 6 days (acute colitis) or for 5 cycles of DSS (chronic colitis).

RESULTS

Administration of the high fiber diet protected from acute colitis. Protection was optimal when diet was started 20 days prior to DSS. A 5-day pretreatment with acetate, a short-chain fatty acid, provided partial protection against acute colitis. In chronic colitis, pretreatment with the high fiber diet attenuated clinical and inflammatory parameters of disease. However, when the treatment with the high fiber diet started after disease had been established, overall protection was minimal. Similarly, delayed treatment with acetate or B. longum did not provide any protection even when the probiotic was associated with the high fiber diet.

CONCLUSION

Preventive use of a high fiber diet or acetate clearly protects mice against acute and chronic damage induced by DSS in mice. However, protection is lost when therapies are initiated after disease has been established. These results suggest that any therapy aimed at modifying the gut environment (e.g., prebiotic or probiotic strategies) should be given early in the course of disease.

Resistant starch in food: a review

The nutritional property of starch is related to its rate and extent of digestion and absorption in the small intestine. For nutritional purposes, starch is classified as rapidly available, slowly available and resistant starch (RS). The exact underlying mechanism of relative resistance of starch granules is complicated because those factors are often interconnected. The content of RS in food is highly influenced by food preparation manner and processing techniques. Physical or chemical treatments also alter the level of RS in a food. Commercial preparations of RS are now available and can be added to foods as an ingredient for lowering the calorific value and improving textural and organoleptic characteristics along with increasing the amount of dietary fiber. RS has assumed great importance owing to its unique functional properties and health benefits. The beneficial effects of RS include glycemic control and control of fasting plasma triglyceride and cholesterol levels and absorption of minerals. This review attempts to analyze the information published, especially in the recent past, on classification, structure, properties, applications and health benefits of RS.

The role of dietary fibre in inflammatory bowel disease

The aetiology of inflammatory bowel diseases (IBD), which are primarily Crohn's disease and ulcerative colitis, still remains unclear, while the incidence of IBD is constantly increasing, especially in the industrialised countries. Among genetic, environmental, and immunological factors, changes in the composition of the intestinal microflora and diet are indicated as very important in initiating and sustaining inflammation in patients with IBD. Above all nutrients dietary fibre is an especially important component of diet in the context of IBD. A potentially protective effect of high-fibre diet on intestinal disorders was described as early as in 1973. Several trials performed in animal models of IBD and human studies have reported that supplementation of some types of dietary fibre can prolong remission and reduce lesions of the intestinal mucosa during the course of the disease. This paper presents the current state of knowledge on the effects of dietary fibre in IBD.

Fructooligosaccharides exert intestinal anti-inflammatory activity in the CD4+ CD62L+ T cell transfer model of colitis in C57BL/6J mice

PURPOSE

Fructooligosaccharides (FOS) are used as functional foods due to their prebiotic effects. Intestinal anti-inflammatory activity has been established in most, but not all, studies in animal models of colitis, using mainly chemically induced inflammation. Our goal was to test the effect of FOS (degree of polymerization 2-8) in the chronic, lymphocyte-driven CD4+ CD62L+ T cell transfer model of colitis.

METHODS

Colitis was induced by transfer of CD4+ CD62L+ T cells to C57BL/6J Rag1(-/-) mice. FOS (75 mg day(-1)) was administered by gavage as a post-treatment. Three groups were established: non-colitic (NC), colitic control (C, CD4+ CD62L+ transferred mice treated with vehicle) and colitic+FOS (C+FOS, similar but treated with FOS). Mice were killed after 13 days.

RESULTS

Treatment of mice with FOS ameliorated colitis, as evidenced by an increase in body weight, a lesser myeloperoxidase and alkaline phosphatase activities, a lower secretion of proinflammatory cytokines by mesenteric lymph node cells ex vivo (IFN-γ, IL-17, and TNF-α), and a higher colonic expression of occludin (C+FOS vs. C, p < 0.05). Increased relative abundance of lactic acid bacteria was observed in FOS-treated mice (p < 0.05).

CONCLUSIONS

FOS exert intestinal anti-inflammatory activity in T lymphocyte-dependent colitis, suggesting it may be useful in the management of inflammatory bowel disease in appropriate conditions.

Beneficial Effects of Probiotics, Prebiotics, Synbiotics, and Psychobiotics in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a group of diseases characterized by inflammation of the small and large intestine and primarily includes ulcerative colitis and Crohn's disease. Although the etiology of IBD is not fully understood, it is believed to result from the interaction of genetic, immunological, and environmental factors, including gut microbiota. Recent studies have shown a correlation between changes in the composition of the intestinal microbiota and IBD. Moreover, it has been suggested that probiotics and prebiotics influence the balance of beneficial and detrimental bacterial species, and thereby determine homeostasis versus inflammatory conditions. In this review, we focus on recent advances in the understanding of the role of prebiotics, probiotics, and synbiotics in functions of the gastrointestinal tract and the induction and maintenance of IBD remission. We also discuss the role of psychobiotics, which constitute a novel class of psychotropic agents that affect the central nervous system by influencing gut microbiota.

Intake of indigestible carbohydrates influences IgA response and polymeric Ig receptor expression in the rat submandibular gland

Secretory IgA in the saliva is essential for protection from mucosally transmitted pathogens and maintaining homeostasis at mucosal surfaces of the oral cavity. Expression of submandibular gland polymeric Ig receptor (pIgR) is essential for IgA secretion. In the present study, we investigated the influence of indigestible carbohydrates on IgA production in the salivary gland and saliva. Five-week-old rats were fed a fibre-free diet (control), or a diet with 5 % (w/w) fructo-oligosaccharide (FOS) or a combination of 2·5 % (w/w) polydextrose (PDX) and 2·5 % (w/w) lactitol for 21-d. IgA concentrations in the caecal digesta, submandibular gland tissue, and saliva in the FOS and PDX+lactitol diet groups were significantly higher than those in the control group (P< 0·05). The increase in IgA in the submandibular gland tissue was confirmed using immunohistochemical analysis. However, the IgA concentrations of serum did not differ between the FOS or PDX+lactitol groups and the control group (P= 0·5). In the FOS and PDX+lactitol groups, thepIgRmRNA (pIgR/β-actin) expression level in the submandibular gland tissue was significantly higher than that in the control group (P< 0·05). The present study suggests that indigestible carbohydrates play an important role in the increase in IgA concentrations in the submandibular gland tissue, saliva, and caecal digesta.

Diet in the pathogenesis and treatment of inflammatory bowel diseases

Some of the most common symptoms of the inflammatory bowel diseases (IBD, which include ulcerative colitis and Crohn's disease) are abdominal pain, diarrhea, and weight loss. It is therefore not surprising that clinicians and patients have wondered whether dietary patterns influence the onset or course of IBD. The question of what to eat is among the most commonly asked by patients, and among the most difficult to answer for clinicians. There are substantial variations in dietary behaviors of patients and recommendations for them, although clinicians do not routinely endorse specific diets for patients with IBD. Dietary clinical trials have been limited by their inability to include a placebo control, contamination of study groups, and inclusion of patients receiving medical therapies. Additional challenges include accuracy of information on dietary intake, complex interactions between foods consumed, and differences in food metabolism among individuals. We review the roles of diet in the etiology and management of IBD based on plausible mechanisms and clinical evidence. Researchers have learned much about the effects of diet on the mucosal immune system, epithelial function, and the intestinal microbiome; these findings could have significant practical implications. Controlled studies of patients receiving enteral nutrition and observations made from patients on exclusion diets have shown that components of whole foods can have deleterious effects for patients with IBD. Additionally, studies in animal models suggested that certain nutrients can reduce intestinal inflammation. In the future, engineered diets that restrict deleterious components but supplement beneficial nutrients could be used to modify the luminal intestinal environment of patients with IBD; these might be used alone or in combination with immunosuppressive agents, or as salvage therapy for patients who do not respond or lose responsiveness to medical therapies. Stricter diets might be required to induce remission, and more sustainable exclusion diets could be used to maintain long-term remission.

Mucosal healing in inflammatory bowel diseases: is there a place for nutritional supplementation?

Advanced mucosal healing (MH) after intestinal mucosal inflammation coincides with sustained clinical remission and reduced rates of hospitalization and surgical resection, explaining why MH is increasingly considered as a full therapeutic goal and as an endpoint for clinical trials. Intestinal MH is a complex phenomenon viewed as a succession of steps necessary to restore tissue structure and function. These steps include epithelial cell migration and proliferation, cell differentiation, restoration of epithelial barrier functions, and modulation of cell apoptosis. Few clinical studies have evaluated the needs for specific macronutrients and micronutrients and their effects on intestinal MH, most data having been obtained from animal and cell studies. These data suggest that supplementation with specific amino acids including arginine, glutamine, glutamate, threonine, methionine, serine, proline, and the amino acid-derived compounds, polyamines can favorably influence MH. Short-chain fatty acids, which are produced by the microbiota from undigested polysaccharides and protein-derived amino acids, also exert beneficial effects on the process of intestinal MH in experimental models. Regarding supplementation with lipids, although the effects of ω-3 and ω-6 fatty acids remain controversial, endogenous prostaglandin synthesis seems to be necessary for MH. Finally, among micronutrients, several vitamin and mineral deficiencies with different frequencies have been observed in patients with inflammatory bowel diseases and supplementation with some of them (vitamin A, vitamin D3, vitamin C, and zinc) are presumed to favor MH. Future work, including clinical studies, should evaluate the efficiency of supplementation with combination of dietary compounds as adjuvant nutritional intervention for MH of the inflamed intestinal mucosa.

Cooked navy and black bean diets improve biomarkers of colon health and reduce inflammation during colitis

Common beans contain non-digestible fermentable components (SCFA precursors) and phenolic compounds (phenolic acids, flavonoids and anthocyanins) with demonstrated antioxidant and anti-inflammatory potential. The objective of the present study was to assess the in vivo effect of cooked whole-bean flours, with differing phenolic compound levels and profiles, in a mouse model of acute colitis. C57BL/6 mice were fed a 20 % navy bean or black bean flour-containing diet or an isoenergetic basal diet (BD) for 2 weeks before the induction of experimental colitis via 7 d dextran sodium sulphate (DSS, 2 % (w/v) in the drinking-water) exposure. Compared with the BD, both bean diets increased caecal SCFA and faecal phenolic compound concentrations (P< 0·05), which coincided with both beneficial and adverse effects on colonic and systemic inflammation. On the one hand, bean diets reduced mRNA expression of colonic inflammatory cytokines (IL-6, IL-9, IFN-γ and IL-17A) and increased anti-inflammatory IL-10 (P< 0·05), while systemically reduced circulating cytokines (IL-1β, TNFα, IFNγ, and IL-17A, P< 0·05) and DSS-induced oxidative stress. On the other hand, bean diets enhanced DSS-induced colonic damage as indicated by an increased histological injury score and apoptosis (cleaved caspase-3 and FasL mRNA expression) (P< 0·05). In conclusion, bean-containing diets exerted both beneficial and adverse effects during experimental colitis by reducing inflammatory biomarkers both locally and systemically while aggravating colonic mucosal damage. Further research is required to understand the mechanisms through which beans exert their effects on colonic inflammation and the impact on colitis severity in human subjects.

Probiotics, prebiotics, synbiotics in prevention and treatment of inflammatory bowel diseases

Probiotics, prebiotics, and synbiotics are functional components able to exert positive effects on human health. Numerous medical conditions lack effective and safe approaches for prevention or treatment, thus usage of probiotics, prebiotics, and synbiotics is an alternative. Further, the benefit related to the consumption of these compounds is associated with lower morbidity of chronic diseases and reduced health-care costs. Various types of mediums to deliver probiotics/synbiotics to the human GIT are used. Although capsules and tablets are frequently applied as delivery systems for probiotics, the major challenge of the commercial sector is to market new functional foods containing probiotics and/or prebiotics. Discovering of new probiotic/synbiotic functional foods is connected to the interest of the food industry to revitalize continuously through introduction of products with improved nutritional value and pleasant taste, but also with health benefit for the consumers. The review provides insights and new perspectives in respect to usage of functional components and foods in prevention and treatment of inflammatory bowel diseases (IBD) that are highly correlated with the modern lifestyle. The therapeutic and safety properties of probiotics and prebiotics, their role in pathogenesis of IBD, potential to prevent and treat these diseases as well as postulated mechanisms of action will be discussed, highlighting the main areas in which further research is an emergence.

Resistant starch induces catabolic but suppresses immune and cell division pathways and changes the microbiome in the proximal colon of male pigs

Consumption of resistant starch (RS) has been associated with various intestinal health benefits, but knowledge of its effects on global gene expression in the colon is limited. The main objective of the current study was to identify genes affected by RS in the proximal colon to infer which biologic pathways were modulated. Ten 17-wk-old male pigs, fitted with a cannula in the proximal colon for repeated collection of tissue biopsy samples and luminal content, were fed a digestible starch (DS) diet or a diet high in RS (34%) for 2 consecutive periods of 14 d in a crossover design. Analysis of the colonic transcriptome profiles revealed that, upon RS feeding, oxidative metabolic pathways, such as the tricarboxylic acid cycle and β-oxidation, were induced, whereas many immune response pathways, including adaptive and innate immune system, as well as cell division were suppressed. The nuclear receptor peroxisome proliferator-activated receptor γ was identified as a potential key upstream regulator. RS significantly (P < 0.05) increased the relative abundance of several butyrate-producing microbial groups, including the butyrate producers Faecalibacterium prausnitzii and Megasphaera elsdenii, and reduced the abundance of potentially pathogenic members of the genus Leptospira and the phylum Proteobacteria. Concentrations in carotid plasma of the 3 main short-chain fatty acids acetate, propionate, and butyrate were significantly higher with RS consumption compared with DS consumption. Overall, this study provides novel insights on effects of RS in proximal colon and contributes to our understanding of a healthy diet.

Pathobiology and potential therapeutic value of intestinal short-chain fatty acids in gut inflammation and obesity

BACKGROUND

The lumen of the gastrointestinal tract contains many substances produced from the breakdown of foodstuffs, from salivary, esophageal, intestinal, hepatic, and pancreatic secretions, and from sloughed cells present in the gastrointestinal lumen. Although these substances were traditionally regarded as waste products, there is increasing realization that many can be biologically active, either as signalling compounds or as nutrients. For example, proteins are broken down into amino acids, which are then sensed by nutrient receptors. The gut microbiome, which is at highest abundance in the ileocecum, has powerful metabolic activity, digesting and breaking down unabsorbed carbohydrates, proteins, and other ingested nutrients into phenols, amines, volatile organic compounds, methane, carbon dioxide, hydrogen, and hydrogen sulfide into volatile fatty acids, also called short-chain fatty acids (SCFAs).

CONCLUSION

These latter substances are the topic of this review. In this review, we will briefly discuss recent advances in the understanding SCFA production, signalling, and absorption, followed by a detailed description and discussion of trials of SCFAs, probiotics, and prebiotics in the treatment of gastrointestinal disease, in particular ulcerative colitis (UC), pouchitis, short bowel syndrome, and obesity.

The new prophylactic strategy for colon cancer in inflammatory bowel disease by modulating microbiota

It is well understood that intestinal microbiota play an important role in the pathogenesis of inflammatory bowel disease (IBD). In addition, IBD patients are well known to have a higher risk of developing colon cancer due to chronic inflammation. Recent evidence suggests that manipulation of microbiota improves the clinical outcome of patients with IBD and may reduce onset of colon cancer without obvious toxicity. This review summarizes the current experimental and clinical knowledge about the role of intestinal microbiota in IBD and colon cancer, and the nutraceutical therapy for colon cancer.

The interplay between fiber and the intestinal microbiome in the inflammatory response

Fiber intake is critical for optimal health. This review covers the anti-inflammatory roles of fibers using results from human epidemiological observations, clinical trials, and animal studies. Fiber has body weight-related anti-inflammatory activity. With its lower energy density, a diet high in fiber has been linked to lower body weight, alleviating obesity-induced chronic inflammation evidenced by reduced amounts of inflammatory markers in human and animal studies. Body weight-unrelated anti-inflammatory activity of fiber has also been extensively studied in animal models in which the type and amount of fiber intake can be closely monitored. Fermentable fructose-, glucose-, and galactose-based fibers as well as mixed fibers have shown systemic and local intestinal anti-inflammatory activities when plasma inflammatory markers and tissue inflammation were examined. Similar anti-inflammatory activities have also been demonstrated in some human studies that controlled total fiber intake. The anti-inflammatory activities of synbiotics (probiotics plus fiber) were reviewed as well, but there was no convincing evidence indicating higher efficacy of synbiotics compared with that of fiber alone. Adverse effects have not been observed with the amount of fiber intake or supplementation used in studies, although patients with Crohn's disease may be more sensitive to inulin intake. Several possible mechanisms that may mediate the body weight-unrelated anti-inflammatory activity of fibers are discussed based on the in vitro and in vivo evidence. Fermentable fibers are known to affect the intestinal microbiome. The immunomodulatory role of the intestinal microbiome and/or microbial metabolites could contribute to the systemic and local anti-inflammatory activities of fibers.

The delay in the development of experimental colitis from isomaltosyloligosaccharides in rats is dependent on the degree of polymerization

Background

Isomaltosyloligosaccharides (IMO) and dextran (Dex) are hardly digestible in the small intestine and thus influence the luminal environment and affect the maintenance of health. There is wide variation in the degree of polymerization (DP) in Dex and IMO (short-sized IMO, S-IMO; long-sized IMO, L-IMO), and the physiological influence of these compounds may be dependent on their DP.

Methodology/Principal Findings

Five-week-old male Wistar rats were given a semi-purified diet with or without 30 g/kg diet of the S-IMO (DP = 3.3), L-IMO (DP = 8.4), or Dex (DP = 1230) for two weeks. Dextran sulfate sodium (DSS) was administered to the rats for one week to induce experimental colitis. We evaluated the clinical symptoms during the DSS treatment period by scoring the body weight loss, stool consistency, and rectal bleeding. The development of colitis induced by DSS was delayed in the rats fed S-IMO and Dex diets. The DSS treatment promoted an accumulation of neutrophils in the colonic mucosa in the rats fed the control, S-IMO, and L-IMO diets, as assessed by a measurement of myeloperoxidase (MPO) activity. In contrast, no increase in MPO activity was observed in the Dex-diet-fed rats even with DSS treatment. Immune cell populations in peripheral blood were also modified by the DP of ingested saccharides. Dietary S-IMO increased the concentration of n-butyric acid in the cecal contents and the levels of glucagon-like peptide-2 in the colonic mucosa.

Conclusion/Significance

Our study provided evidence that the physiological effects of α-glucosaccharides on colitis depend on their DP, linkage type, and digestibility.

Changes in bowel microbiota induced by feeding weanlings resistant starch stimulate transcriptomic and physiological responses

The ability to predictably engineer the composition of bowel microbial communities (microbiota) using dietary components is important because of the reported associations of altered microbiota composition with medical conditions. In a synecological study, weanling conventional Sprague-Dawley rats (21 days old) were fed a basal diet (BD) or a diet supplemented with resistant starch (RS) at 5%, 2.5%, or 1.25% for 28 days. Pyrosequencing of 16S rRNA genes and temporal temperature gradient electrophoresis (TTGE) profiles in the colonic digesta showed that rats fed RS had altered microbiota compositions due to blooms of Bacteroidetes and Actinobacteria. The altered microbiota was associated with changes in colonic short-chain fatty acid (SCFA) concentrations, colonic-tissue gene expression (Gsta2 and Ela1), and host physiology (serum metabolite profiles and colonic goblet cell numbers). Comparisons between germ-free and conventional rats showed that transcriptional and serum metabolite differences were mediated by the microbiota and were not the direct result of diet composition. Altered transcriptomic and physiological responses may reflect the young host's attempts to maintain homeostasis as a consequence of exposure to a new collection of bacteria and their associated biochemistry.

Inulin and fructo-oligosaccharides have divergent effects on colitis and commensal microbiota in HLA-B27 transgenic rats

Modulation of intestinal microbiota by non-digestible carbohydrates may reduce inflammation in inflammatory bowel disease (IBD). The aim of the present study was to assess the effects of inulin and fructo-oligosaccharides (FOS) on intestinal microbiota and colitis in HLA-B27 transgenic rats, a well-validated rodent model for IBD. In this study, 4-week-old rats were fed 8 g/kg body weight inulin or FOS for 12 weeks, or not. Faeces were collected at 4 and 16 weeks of age; and caecal samples were collected at necropsy. The effects of inulin and FOS on chronic intestinal inflammation were assessed using a gross gut score, histology score and levels of mucosal IL-1β. Intestinal microbiota were characterised by quantitative PCR and denaturing gradient gel electrophoresis. Colitis was significantly reduced in all FOS-fed rats compared to the control diet, whereas inulin decreased chronic intestinal inflammation in only half the number of animals. Quantitative analysis of caecal microbiota demonstrated that inulin increased the numbers of total bacteria and the Bacteroides-Prevotella-Porphyromonas group, FOS increased bifidobacteria, and both fructans decreased Clostridium cluster XI. In the faecal samples, both inulin and FOS decreased total bacteria, Bacteroides-Prevotella-Porphyromonas group, and Clostridium clusters XI and XIVa. FOS increased Bifidobacterium spp., and mediated a decrease of gene copies of Enterobacteriaceae and Clostridium difficile toxin B in faeces. SCFA concentrations in the faecal and caecal samples were unaffected by the diets. In conclusion, FOS increased the abundance of Bifidobacterium spp., whereas both fructans reduced Clostridium cluster XI and C. difficile toxin gene expression, correlating with a reduction of chronic intestinal inflammation.

Soluble fibers and resistant starch ameliorate disease activity in interleukin-10-deficient mice with inflammatory bowel disease

Our goal in this study was to determine the potential for dietary fibers to prevent gut inflammation in IL-10-deficient (IL-10(-/-)) mice. C57BL/6J wild-type (WT) mice (n = 90) and IL-10(-/-) mice (n = 185) were assigned to a control diet or diets supplemented with PROMITOR soluble corn fiber (SCF), STA-LITE III polydextrose (PDX), Biogum (BG), Pullulan (PI-20), PROMITOR resistant starch-75 (RS-75), SCF&BG, RS-75&BG, and inulin (4 g fiber/100 g diet). On d 47, spleen, mesenteric lymph nodes (MLN), duodenum, jejunum, ileum, and colon were macroscopically and histologically evaluated. The spleen and Peyer's patches (PP) were collected for isolating mononuclear cells and measuring the percentages of regulatory T cells (Treg) and cytokines produced by CD4(+) T cells (i.e. IFNγ and IL-10). Dietary supplementation with RS-75, SCF, RS-75&BG, and inulin ameliorated disease activity on d 47. Dietary RS-75 and inulin supplementation decreased ileal and colonic inflammatory lesions. RS-75, SCF, and inulin decreased IFNγ production by effector CD4(+) T cells from PP and RS-75 increased the IL-10-expressing cells in spleen of WT mice. Dietary SCF, PDX, BG, PI-20, and RS-75 upregulated colonic PPARγ expression in WT mice and SCF upregulated Supressor of cytokine signaling 3 in IL-10(-/-) mice. These data suggest that soluble fibers and resistant starch influence Treg cells, IFNγ, and colonic PPARγ expression to suppress gut inflammation.

African americans may have to consume more than 12 grams a day of resistant starch to lower their risk for type 2 diabetes

African Americans have a high prevalence rate of type 2 diabetes mellitus (DM). High-maize 260 (National Starch and Chemical Co., Bridgewater, NJ, USA) resistant starch (RS) is a promising food ingredient to reduce risk factors for type 2 DM. A 14-week, double-blind, crossover design study was conducted with African American male (n = 8) and female (n = 7) subjects at risk for type 2 DM. All subjects consumed bread containing 12 g of added RS or control bread (no added RS) for 6 weeks, separated by a 2-week washout period. There were no significant differences in the subjects' fasting plasma glucose levels due to the consumption of the RS bread versus the control bread. Fructosamine levels were significantly lower after consumption of both RS and control bread than at baseline. However, we found no significant difference in fructosamine levels due to treatment effects, i.e., RS bread intake versus the control bread. There were no significant differences in insulin or C-reactive protein levels due to treatment, gender, or sequence effects. Mean homeostasis model assessment of insulin resistance decreased to normal values (>2.5) at the end of the 14-week study, although there were no significant treatment effects. The results of this study suggest that African Americans may need to consume more than 12 g/day of RS to lower their risk for type 2 DM.

Effects of fructo-oligosaccharide on DSS-induced colitis differ in mice fed nonpurified and purified diets

We investigated whether feeding a purified compared with nonpurified diet supplemented with or without fructo-oligosaccharide (FOS; 50 g/kg diet) altered the response of C57BL/6 mice to DSS-induced diarrhea. In Expt. 1, we examined disease severity in mice receiving DSS (2% in drinking water) for 5 d. In Expt. 2, we measured cecal organic acid concentrations and fecal water-holding capacity (WHC). In Expts. 3 and 4, we tested whether polycarbophil calcium (PC), a water-absorbing polymer, altered fecal WHC and disease severity. FOS exacerbated diarrhea and weight loss in mice fed the purified diet and reduced fecal bleeding in mice fed the nonpurified diet (P < 0.05). Without DSS administration, cecal acetate and butyrate concentrations were higher in mice fed the nonpurified diet than in mice fed the purified diet (P < 0.05). Fecal WHC was higher in mice fed the nonpurified diet than in mice fed the purified diet (P < 0.05). One day after starting DSS administration, cecal succinate concentrations were higher in mice fed the FOS-supplemented purified diet than in mice fed the other 3 diets, whereas SCFA concentrations were higher in mice fed the nonpurified diet than in mice fed the purified diet (P < 0.05). PC supplementation increased fecal WHC and prevented FOS exacerbation of diarrhea in mice fed the purified diet (P < 0.05). We conclude that the effects of FOS on DSS-induced diarrhea differ in mice fed the purified and nonpurified diets. The protective effect of nonpurified diet was associated with increased production of organic acids and WHC in the intestinal contents.

Resistant starches types 2 and 4 have differential effects on the composition of the fecal microbiota in human subjects

BACKGROUND

To systematically develop dietary strategies based on resistant starch (RS) that modulate the human gut microbiome, detailed in vivo studies that evaluate the effects of different forms of RS on the community structure and population dynamics of the gut microbiota are necessary. The aim of the present study was to gain a community wide perspective of the effects of RS types 2 (RS2) and 4 (RS4) on the fecal microbiota in human individuals.

METHODS AND FINDINGS

Ten human subjects consumed crackers for three weeks each containing either RS2, RS4, or native starch in a double-blind, crossover design. Multiplex sequencing of 16S rRNA tags revealed that both types of RS induced several significant compositional alterations in the fecal microbial populations, with differential effects on community structure. RS4 but not RS2 induced phylum-level changes, significantly increasing Actinobacteria and Bacteroidetes while decreasing Firmicutes. At the species level, the changes evoked by RS4 were increases in Bifidobacterium adolescentis and Parabacteroides distasonis, while RS2 significantly raised the proportions of Ruminococcus bromii and Eubacterium rectale when compared to RS4. The population shifts caused by RS4 were numerically substantial for several taxa, leading for example, to a ten-fold increase in bifidobacteria in three of the subjects, enriching them to 18-30% of the fecal microbial community. The responses to RS and their magnitudes varied between individuals, and they were reversible and tightly associated with the consumption of RS.

CONCLUSION

Our results demonstrate that RS2 and RS4 show functional differences in their effect on human fecal microbiota composition, indicating that the chemical structure of RS determines its accessibility by groups of colonic bacteria. The findings imply that specific bacterial populations could be selectively targeted by well designed functional carbohydrates, but the inter-subject variations in the response to RS indicates that such strategies might benefit from more personalized approaches.

From the gut to the peripheral tissues: the multiple effects of butyrate

Butyrate is a natural substance present in biological liquids and tissues. The present paper aims to give an update on the biological role of butyrate in mammals, when it is naturally produced by the gastrointestinal microbiota or orally ingested as a feed additive. Recent data concerning butyrate production delivery as well as absorption by the colonocytes are reported. Butyrate cannot be detected in the peripheral blood, which indicates fast metabolism in the gut wall and/or in the liver. In physiological conditions, the increase in performance in animals could be explained by the increased nutrient digestibility, the stimulation of the digestive enzyme secretions, a modification of intestinal luminal microbiota and an improvement of the epithelial integrity and defence systems. In the digestive tract, butyrate can act directly (upper gastrointestinal tract or hindgut) or indirectly (small intestine) on tissue development and repair. Direct trophic effects have been demonstrated mainly by cell proliferation studies, indicating a faster renewal of necrotic areas. Indirect actions of butyrate are believed to involve the hormono-neuro-immuno system. Butyrate has also been implicated in down-regulation of bacteria virulence, both by direct effects on virulence gene expression and by acting on cell proliferation of the host cells. In animal production, butyrate is a helpful feed additive, especially when ingested soon after birth, as it enhances performance and controls gut health disorders caused by bacterial pathogens. Such effects could be considered for new applications in human nutrition.