Comparison between Organic and Inorganic Zinc Forms and Their Combinations with Various Dietary Fibers in Respect of the Effects on Electrolyte Concentrations and Mucosa in the Large Intestine of Pigs.

This study aimed to determine the effects of Zn sources, used with potato fiber (PF) or lignocellulose (LC), on electrolyte concentration and the mucus layer in the large intestine of pigs. The experiment involved 24 barrows with an initial body weight of 10.8 ± 0.82 kg, divided into four groups fed the following diets: LC and ZnSO4, LC and Zn glycinate (ZnGly), PF and ZnSO4, or PF and ZnGly. Fiber supplements provided 10 g crude fiber/kg diet, while Zn additives introduced 120 mg Zn/kg diet. After four weeks of feeding, the pigs were sacrificed and digesta and tissue samples were taken from the cecum and colon. PF increased the water content and decreased the phosphorus concentration in the large intestine in comparison with LC. PF also increased calcium, iron, and chloride concentrations in the descending colon. Mucus layer thickness and histological parameters of the large intestine were not affected. ZnGly diets increased MUC12 expression in the cecum as compared to the LC-ZnSO4 group. In the ascending colon, the PF-ZnGly diet increased MUC5AC expression, while both PF groups had greater MUC20 expression in comparison with the LC-ZnSO4 group. In the transverse colon, the LC-ZnGly group and both PF groups had higher MUC5AC expression in comparison with the LC-ZnSO4 group, and both ZnGly groups had higher MUC20 expression than ZnSO4 groups. PF and ZnGly increased MUC4 and MUC5AC expression in the descending colon. PF and ZnGly may exert a beneficial effect on colon health in pigs by upregulating the expression of the MUC5AC and MUC20 genes and are more effective than LC and ZnSO4.

Effect of feeding calcium gluconate embedded in a hydrogenated fat matrix on feed intake, gastrointestinal fermentation and morphology, intestinal brush border enzyme activity and blood metabolites in growing lambs.

Gluconate salts have been identified as a butyrate precursor when fed to non-ruminant species and may increase the butyrate concentration in the large intestine supporting gastrointestinal health and development. The objective of this study was to evaluate the dose response of hydrogenated fat-embedded calcium gluconate (HFCG) on performance and gastrointestinal tract (GIT) development in growing lambs. Thirty-two wether lambs were used in a randomized complete block design and assigned to 1 of 4 treatments differing in the inclusion of HFCG: 0.0% (CON), 0.075% (LOW), 0.30% (MED), and 0.60% of the diet (HIGH). Lambs were allocated into individual pens and fed ad libitum with feed delivered twice daily. Feed intake was recorded daily, and body weight (BW) was assessed at the beginning and the end of the 29-d period. Blood was sampled on day 21, prior to feeding and 6 h post-feeding to evaluate changes in ß-hydroxybutyrate, glucose, and insulin concentrations. Total fecal collection was conducted during days 25 to 28 to assess apparent total tract digestibility. On day 29, lambs were slaughtered, and the entire GIT was separated by region to enable sampling of tissue and digesta. Data were analyzed to assess linear, quadratic, and cubic effects of HFCG dose. Final BW, average daily gain, and dry matter intake decreased linearly (P ≤ 0.02) with increasing HFCG. Increasing inclusion of HFCG linearly decreased (P = 0.01) the thickness of the stratum corneum in ruminal papillae but did not affect other strata (P ≥ 0.34). Omasal digesta weight linearly decreased (P = 0.01) as the concentration of HFCG increased and abomasal digesta weight was cubically affected (P = 0.03) the increasing dose of HFCG. Short-chain fatty acid concentration in the cecum was cubically affected (P < 0.01) with increasing dose of HFCG where low dose had the greatest concentration. Moreover, increasing the dietary supply of HFCG linearly increased the proportion of acetate (P = 0.04) in the cecum and linearly decreased the proportion of propionate in the digesta of both the cecum (P < 0.01) and colon (P = 0.01). Colon crypt depth was quadratically (P = 0.03) affected with the increasing dose of HFCG, where lambs fed MED had greatest crypt depth. We conclude that feeding HFCG to growing lambs did not increase butyrate concentration in the large intestine and consequently does not increase the absorptive surface area of the whole tract, the size of the GIT, or the functionality of the intestine.

Gluconate salts have been reported to be metabolized by microbes in the gastrointestinal tract to yield butyrate. Butyrate has shown potential to enhance functionality of the gastrointestinal tract by increasing the absorptive surface area, enzyme activity, and the barrier function. This study evaluated the inclusion of four levels of hydrogenated fat-embedded Ca-gluconate (HFCG; 0.0%, 0.075%, 0.30%, and 0.60% of the diet) designed to increase the production of butyrate in the large intestine. Thirty-two wether lambs were fed for 28 d, slaughtered, and eviscerated to allow complete evaluation of the gastrointestinal tract and its contents. Growth and dry matter intake decreased linearly with increasing dose of HFCG. Dose of HFCG cubically affected short-chain fatty acid concentration in the cecum with increased concentrations at the 0.075% dose. Moreover, increasing dose of HFCG linearly increased the proportion of acetate and linearly decreased the proportion of propionate in the cecum without altering the proportion of butyrate. Thus, the supplementation of HFCG did not increase butyrate concentration in the large intestine and did not enhance gastrointestinal tract function.

Effect of konjac glucomannan on metabolites in the stomach, small intestine and large intestine of constipated mice and prediction of the KEGG pathway.

The occurrence of constipation involves the whole gastrointestinal tract. Konjac glucomannan (KGM) has been clinically proven to alleviate constipation, but its mechanism has not been fully understood. The present study aimed to investigate the excretion-promoting effect of KGM on constipated mice and the underlying molecular mechanism. In this study, the UHPLC-QE orbitrap/MS method was used to determine the metabolic phenotypes of total gastrointestinal segments (i.e., the stomach {St}, small intestine {S}, and large intestine {L}) in constipated mice treated with KGM. The results showed that KGM improved the fecal water content, body weight growth rate, and serum gastrointestinal regulation related peptide levels. The metabolomics results revealed the decreased levels of amino acids, cholines, deoxycholic acid, arachidonic acid, thiamine and the increased levels of indoxyl sulfate, histamine, linoelaidic acid etc. The KEGG pathway analysis indicated that the relaxation effect of KGM supplementation was most likely driven by modulating the expression levels of various key factors involved in biosynthesis of amino acid (i.e., phenylalanine, tyrosine and tryptophan), linoleic acid metabolism, biosynthesis of secondary metabolites, and arachidonic acid metabolism signalling pathways. The results indicated that KGM alleviates constipation by regulating potential metabolite markers and metabolic pathways in different gastrointestinal segments.

Effect of Vitamin D3 in Composition of Original Rectal Suppositories on Parameter of Protein Oxidative Modification in Large Intestine in Experimental Ulcerative Colitis.

The effect of vitamin D3 in the composition of original rectal suppositories on the content of products of oxidative modification of proteins in mucous membrane of the large intestine was studied in rats with experimental ulcerative colitis provoked by a two-stage administration of 3% oxazolone. The rectal suppositories with vitamin D3 (1500 IU) were administered every 12 h during 5 days. Condition of the rats was assessed according to disease activity index (DAI), while the content of oxidative modification products of proteins in the homogenate of the mucous membrane was assayed with extraction-spectrophotometric method in the lesion focus of large intestine. DAI increased during entire observation period of ulcerative colitis, which correlated with the level of products of spontaneous and induced oxidative modification of proteins in mucous membrane of the colon. The study examined the pharmaceutical and technological features of novel rectal suppositories of original composition weighing 300 mg, which are based on polyethylene glycol supplemented with aqueous solution of vitamin D3 (10%). The use of rectal suppositories with vitamin D3 reduced DAI and inhibited the oxidative modification of proteins.

Tadalafil versus linaclotide in gastrointestinal dysfunction and depressive behavior in constipation-predominant irritable bowel syndrome.

BACKGROUND: Intestinal GC-C/cGMP pathway may be involved in visceral hypersensitivity and fluid secretion in irritable bowel syndrome (IBS). The guanylcyclase C agonist linaclotide, approved for IBS- constipation, is contraindicated in children as it may cause severe diarrhea. In contrast, drugs increasing cGMP by inhibiting phosphodiesterase 5 (PDE-5) are well tolerated in children with pulmonary hypertension. Accordingly, we investigated whether beneficial effects of linaclotide in IBS might be shared by PDE-5inhibitor tadalafil without the severe diarrhea reported for linaclotide. Since depression is commonly comorbid with IBS and is implicated in its pathophysiology; and since tadalafil is absorbed systemically and crosses blood brain barrier, whereas linaclotide does not, impact of both drugs on behavioral changes in IBS was also investigated. METHODS: 72 rats were divided into 6groups (control naive, control tadalafil, control linaclotide, untreated IBS, IBS tadalafil, and IBS linaclotide-treated). IBS was induced by 0 to 4 °C intragastric saline for 14 days. RESULTS: Both drugs reduced visceral hypersensitivity and colonic C fos. Tadalafil, and to a greater extent, linaclotide increased colonic cGMP, fecal pellets (8.66 ± 4.6 (IBS),versus14.8 ± 3.3(tadalafil), 20 ± 1.2(linaclotide), fecal water content (29.8 ± 5.5 (IBS), versus 47.83 ± 12.6 (tadalafil), 63.58 ± 11.6 (linaclotide) and reduced intestinal transit time (% distance travelled: 29 ± 6.1(IBS), versus 40.58 + 7.5(tadalafil), 51.83 ± 8.3(linaclotide). Tadalafil, but not linaclotide, increased hippocampal cGMP, and improved behavioral tests scores compared to linaclotide (immobility time: 97.3 ± 12.5 s (IBS) versus 68 ± 12.8(tadalafil), 80 ± 17.06 (linaclotide). CONCLUSION: Systemic PDE-5 inhibitors might be alternatives to locally acting guanyl cyclase agonists in IBS, inducing less severe diarrhea and more beneficial effects on the associated behavioral changes.

Electrospun oral formulations for combined photo-chemotherapy of colon cancer.

In this work, we report new formulations for the combined photo-chemotherapy of colon cancer. Fibers were fabricated via coaxial-electrospinning with the intent of targeting delivery of the anti-cancer drug carmofur (CAR) and the photosensitizer rose bengal (RB) selectively to the colon site. The fibers comprised a hydroxypropyl methylcellulose (HPMC) core loaded with the active ingredients, and a pH-sensitive Eudragit L100-55 shell. The fibers were found to be homogeneous and cylindrical and have visible core-shell structures. X-ray diffraction and differential scanning calorimetry demonstrated that both CAR and RB were present in the fibers in the amorphous physical form. In vitro drug release studies showed that the fibers have the potential to selectively deliver drugs to the colon, with only 10-15 % release noted in the acidic conditions of the stomach but sustained release at pH 7.4. Cytotoxicity studies were undertaken on human dermal fibroblast (HDF) and colon cancer (Caco-2) cells, and the influence of light on cell death was also explored. The fibers loaded with CAR alone showed obvious toxicity to both cell lines, with and without the application of light. The RB-loaded fibers led to high viability (ca. 80% for both cell types) in the absence of light, but much greater toxicity was noted (30-50%) with light. The same trends were observed with the formulation containing both CAR and RB, but with lower viabilities. The RB and RB/CAR loaded systems show clear selectivity for cancerous over non-cancerous cells. Finally, mucoadhesion studies revealed there were strong adhesive forces between the rat colonic mucosa and the fibers after they had passed through an acidic environment. Such electrospun fibers thus could have potential in the development of oral therapies for colon cancer.

Response of gastrointestinal fermentative activity and colonic microbiota to protected sodium butyrate and protected sodium heptanoate in weaned piglets challenged with ETEC F4.

This study aimed to evaluate the potential of two new fat-protected butyrate or heptanoate salts to improve gut health and control post-weaning colibacillosis in weaning piglets challenged with enterotoxigenic Escherichia coli (ETEC) F4+, particularly focusing on their impact on intestinal microbiota and fermentative activity along the gastrointestinal tract (GIT). Seventy-two 21-d-old pigs were fed a plain diet (CTR) or supplemented with sodium butyrate (BUT) or sodium heptanoate (HPT), both at 0.3%. After a week of adaptation, animals were orally challenged at days 8 and 9 with 5.8 · 109 and 6.6 · 1010 cfu, respectively, and were euthanised on d 4 and d 8 post-inoculation (PI) (n = 8) to collect blood, digesta and tissue samples and characterise microbial groups, pathogen loads (qPCR), fermentation, ileal histomorphometry and immune markers. Colonic microbiota was analysed by 16S rRNA gene MiSeq sequencing. Supplementing both acid salts did not compensate clinical challenge effects nor performance impairments and neither histomorphometry nor serum biomarkers. Changes in the gastric fermentative activity were registered, BUT reducing lactic acid concentrations (day 8 PI), and with HPT fewer animals presenting detectable concentrations of propionic, butyric and valeric acids. At ileum BUT increased acetic acid concentration (day 8 PI), and both additives reduced short-chain fatty acids (SCFA) in the colon. Increases in enterobacteria and coliforms counts in ileal digesta (day 4 PI, p < 0.10) and mucosa scrapes (p < 0.05) were registered although E. coli F4 gene copies were unaffected. Regarding changes in the colonic microbiota (day 4 PI), Prevotellaceae and Prevotella were promoted with BUT supplementation whereas only minor groups were modified in HPT-treated animals. Summarising, although the pathogen loads or inflammatory mediators remained unresponsive, butyrate and heptanoate showed a significant impact on microbial fermentation along the whole GIT, being able to modify different bacterial groups at the colon. It could be hypothesised that these effects might be mediated by a carry-over effect of the changes observed in gastric fermentation, but possibly also to a better nutrient digestion in the foregut as a result of the reduced colonic SCFA concentrations.

High-Amylose Maize, Potato, and Butyrylated Starch Modulate Large Intestinal Fermentation, Microbial Composition, and Oncogenic miRNA Expression in Rats Fed A High-Protein Meat Diet.

High red meat intake is associated with the risk of colorectal cancer (CRC), whereas dietary fibers, such as resistant starch (RS) seemed to protect against CRC. The aim of this study was to determine whether high-amylose potato starch (HAPS), high-amylose maize starch (HAMS), and butyrylated high-amylose maize starch (HAMSB)-produced by an organocatalytic route-could oppose the negative effects of a high-protein meat diet (HPM), in terms of fermentation pattern, cecal microbial composition, and colonic biomarkers of CRC. Rats were fed a HPM diet or an HPM diet where 10% of the maize starch was substituted with either HAPS, HAMS, or HAMSB, for 4 weeks. Feces, cecum digesta, and colonic tissue were obtained for biochemical, microbial, gene expression (oncogenic microRNA), and immuno-histochemical (O6-methyl-2-deoxyguanosine (O6MeG) adduct) analysis. The HAMS and HAMSB diets shifted the fecal fermentation pattern from protein towards carbohydrate metabolism. The HAMSB diet also substantially increased fecal butyrate concentration and the pool, compared with the other diets. All three RS treatments altered the cecal microbial composition in a diet specific manner. HAPS and HAMSB showed CRC preventive effects, based on the reduced colonic oncogenic miR17-92 cluster miRNA expression, but there was no significant diet-induced differences in the colonic O6MeG adduct levels. Overall, HAMSB consumption showed the most potential for limiting the negative effects of a high-meat diet.

Protein Supplements and Their Relation with Nutrition, Microbiota Composition and Health: Is More Protein Always Better for Sportspeople?

Sports nutrition products are developed and targeted mainly for athletes to improve their nutrient intake, performance, and muscle growth. The fastest growing consumer groups for these products are recreational sportspeople and lifestyle users. Although athletes may have elevated physiological protein requirements and they may benefit from dietary supplements, the evidence regarding the role of dietary protein and supplements in the nutrition of recreational sportspeople and sedentary populations is somewhat complex and contradictory. In high-protein diets, more undigested protein-derived constituents end up in the large intestine compared to moderate or low-protein diets, and hence, more bacterial amino acid metabolism takes place in the colon, having both positive and negative systemic and metabolic effects on the host. The aim of the present review is to summarize the impact of the high-protein products and diets on nutrition and health, in sportspeople and in sedentary consumers. We are opening the debate about the current protein intake recommendations, with an emphasis on evidence-based effects on intestinal microbiota and personalized guidelines regarding protein and amino acid supplementation in sportspeople and lifestyle consumers.

Short communication: Effect of abomasal inorganic phosphorus infusion on phosphorus absorption in large intestine, milk production, and phosphorus excretion of dairy cattle.

The objective of the study was to evaluate the effect of inorganic phosphorus (Pi) infusion on P absorption in large intestine, milk production, and phosphorus excretion. Four ruminally and ileally cannulated crossbred cows were used in a 4 × 4 Latin square with 21-d periods. Cows were fed a total mixed ration containing 0.21% P, providing 50% of the cows' P requirement. Cobalt-EDTA was used as marker to measure large intestine digesta flow. On d 13 to 21 of each period, each cow was infused daily with 0, 20.1, 40.2, or 60.3 g of Pi into the abomasum and total collection was conducted on d 18 to 21. Ileal samples were collected every 9 h on d 18 to 21. Feed, digesta, and fecal samples were analyzed for total P and Pi using the molybdovanadate yellow method and blue method, respectively. All data were analyzed using PROC GLIMMIX in SAS 9.3 (SAS Institute Inc., Cary, NC) using contrasts to evaluate linear, quadratic, and cubic effects of Pi infusion dose. Dry matter intake, apparent dry matter digestibility, milk yield, and milk total P were unaffected by Pi infusion. Ileal flow and fecal excretion of total P and Pi increased linearly with increasing infused Pi. In the large intestine, net absorption of TP and Pi was increased linearly with increasing infused Pi. The magnitude of absorption from the large intestine was greater than reflected in current models, raising questions that could be evaluated with longer infusion periods or dietary alteration.

Prebiotic effects of resistant starch from purple yam (Dioscorea alata L.) on the tolerance and proliferation ability of Bifidobacterium adolescentis in vitro.

The in vitro prebiotic effects of resistant starch (RS), prepared by different treatments from purple yam, on Bifidobacterium adolescentis (bifidobacteria for short), were investigated. Tolerance tests indicated that bifidobacteria in PDS (prepared by debranching combined with autoclaving) and PDS.H (PDS further treated by double enzyme hydrolysis) media adapted better to simulated upper gastrointestinal conditions (at pH 1.5-3.0 and 0.3% and 1.0% bile acid) than those in GLU (glucose) and DAS (prepared by autoclaving) media. PDS.H, which had the highest digestion resistibility, exhibited significant effects on the OD600 nm value (1.544) and the pH value (4.21) when the carbohydrate concentration was 20 g L-1. Additionally, the exponential growth phase of bifidobacteria was 2 h in the PDS or PDS.H media, whereas it was 4 h in the GLU or DAS media. A higher content of short-chain fatty acids (SCFAs) was obtained in the PDS.H medium. Analysis of the structural features of RS and fermented RS indicated that PDS, especially PDS.H, had a rougher surface and higher crystallinity than DAS. Fermented RS in a simulated large bowel environment showed an eroded surface and decreased crystallinity. All of these findings suggest that RS with a rough surface and perfect crystalline structure could protect bifidobacteria from gastrointestinal conditions and enhance the proliferation of bifidobacteria.

The effect of Lactobacillus acidophilus and Lactobacillus casei on the in vitro bioaccessibility of flaxseed lignans (Linum usitatissimum L.).

Secoisolariciresinol (SECO) is present in flaxseeds as a glucoside, secoisolariciresinol diglucoside (SDG), which can be metabolized to enterodiol (ED) and enterolactone (EL) by the human intestinal microbiota. The aim of this study was to evaluate the effect of Lactobacillus casei and Lactobacillus acidophilus on the bioaccessibility of flaxseed lignans from a complete in vitro digestion of whole flaxseeds (WFs) and flaxseed flour (FF). Lignans are only detected in the large intestine. The bioaccessibility of SDG for FF digestion can be ordered as follows: control (without probiotics) > L. casei > L. acidophilus; and for WF digestion, only in the presence of L. casei SDG was detected. For SECO and EL, the presence of both probiotics had no effect on FF and WF digestion. However, in the digestion of WF both L. casei and L. acidophilus increased ED bioaccessibility in the first 12 h; but both probiotics had no significant effect on FF digestion.

Antibiotics-induced modulation of large intestinal microbiota altered aromatic amino acid profile and expression of neurotransmitters in the hypothalamus of piglets.

The evidence of gut microbiota-mediated modulation of brain function has been widely recognized from studies using germ-free rodents or animals with oral antibiotic-induced microbiota depletion. Since the large intestine harbors greater numbers and more diverse of microbes than in the small intestine, large intestinal microbiota may play a crucial role in the modulation of brain function. In this study, a large intestinal microbiota-targeted strategy was used to investigate the impact of large intestinal microbiota on brain function. Twelve piglets (12.08 ± 0.28 kg) fitted with a T-cannula at the distal ileum were fed a standard diet and randomly assigned to two groups (n = 6) for ileal infusion of either saline or antibiotics. After 25 days of infusion, ileal and fecal microbiota, serum amino acids and neurotransmitters, and hypothalamic transcriptomics were analyzed. While the antibiotic infusion did not change the proximal ileal microbial composition, it markedly altered the fecal microbial composition and increased aromatic amino acid (AAAs) metabolism (p < 0.05), suggesting the infusion specifically targeted large intestinal microbes. Concentrations of AAAs were likewise decreased in the blood and hypothalamus (p < 0.05) by antibiotic infusion. Antibiotic infusion further decreased concentrations of hypothalamic 5-hydroxytryptamine (5-HT) and dopamine, in line with AAAs being their precursors. An up-regulation in gene expressions of neurotransmitter transporters and synthetases was observed (q < 0.001). In conclusion, the distalileal-antibiotic infusion altered neurotransmitter expression in the porcine hypothalamus and this effect occurred simultaneously with changes in both the large intestinal microbiota, and AAAs in the large intestine, blood and hypothalamus. These findings indirectly indicate that large intestinal microbiota affects hypothalamic neurotransmitter expressions. Read the Editorial Highlight for this article on page 208.

Effects of fermented soybean meal on carbon and nitrogen metabolisms in large intestine of piglets.

Fermented soybean meal (FSM), which has lower anti-nutritional factors and higher active enzyme, probiotic and oligosaccharide contents than its unfermented form, has been reported to improve the feeding value of soybean meal, and hence, the growth performance of piglets. However, whether FSM can affect the bacterial and metabolites in the large intestine of piglets remains unknown. This study supplemented wet-FSM (WFSM) or dry-FSM (DFSM) (5% dry matter basis) in the diet of piglets and investigated its effects on carbon and nitrogen metabolism in the piglets' large intestines. A total of 75 41-day-old Duroc×Landrace×Yorkshire piglets with an initial BW of 13.14±0.22 kg were used in a 4-week feeding trial. Our results showed that the average daily gain of piglets in the WFSM and DFSM groups increased by 27.08% and 14.58% and that the feed conversion ratio improved by 18.18% and 7.27%, respectively, compared with the control group. Data from the prediction gene function of Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) based on 16S ribosomal RNA (rRNA) sequencing showed that carbohydrate metabolism function families in the WFSM and DFSM groups increased by 3.46% and 2.68% and that the amino acid metabolism function families decreased by 1.74% and 0.82%, respectively, compared with the control group. These results were consistent with those of other metabolism studies, which showed that dietary supplementation with WFSM and DFSM increased the level of carbohydrate-related metabolites (e.g. 4-aminobutanoate, 5-aminopentanoate, lactic acid, mannitol, threitol and ß-alanine) and decreased the levels of those related to protein catabolism (e.g. 1,3-diaminopropane, creatine, glycine and inosine). In conclusion, supplementation with the two forms of FSM improved growth performance, increased metabolites of carbohydrate and reduced metabolites of protein in the large intestine of piglets, and WFSM exhibited a stronger effect than DFSM.

Bioaccessibility of phenolic compounds following in vitro large intestine fermentation of nuts for human consumption.

A bioaccessibility study of polyphenols after in vitro simulated large intestine fermentation was carried out on edible nuts. Raw nuts were also analysed for total phenolic content and antioxidant potential, considering both bound and free phenolics. The highest phenolic content was found in walnuts, followed by pistachios extracts (596.9 and 410.1 mg gallic acid equivalents 100 g-1, respectively). Consistently, the total antioxidant capacity was highest in walnuts (3689.7 µM trolox equivalents 100 g-1) followed by peanuts and pistachios (3169.6 and 2990.1 µM trolox equivalents 100 g-1, respectively). Data showed high correlations between total phenolics and both antioxidant activities. The metabolomics-based phenolic profile depicted during in vitro fermentation showed a degradation of higher-molecular-weight phenolics over 48 hours of faecal fermentation, with a concurrent increase in low-molecular-weight compounds (hydroxybenzoic and hydroxycinnamic acids, alkylphenols, and tyrosols). Our findings indicate that nuts deliver polyphenols into the colon, with bioaccessibility values not negligible for alkylphenols, tyrosols and phenolic acids.

Association between the gut microbiota and mineral metabolism.

The aim of this review is to present the most recent scientific evidence of interactions between the intestinal microbiota and minerals, and the effect of this interaction on the health of the host. The Web of Science database from the years 2013-2017 on this topic was reviewed. Numerous in vitro studies have shown that iron significantly affects the intestinal microbiota. However, Bifidobacteriaceae are capable of binding iron in the large intestine, thereby limiting the formation of free radicals synthesized in the presence of iron, and thus reducing the risk of colorectal cancer. Animal studies have revealed that supplementation with probiotics, prebiotics and synbiotics has a significant effect on bone calcium, phosphate and bone metabolism. The dynamic interaction between microbiota and zinc was shown. Human studies have provided evidence of the influence of probiotic bacteria on parathormone, calcium and phosphate levels and thus on bone resorption. Recent studies have produced new information mainly on the impact of the intestinal bacteria on the metabolism of calcium and iron. From a scientific perspective, the most urgent fields that remain to be investigated are the identification of all human gut microbes and new therapies targeting the interaction between intestinal bacteria and minerals. © 2017 Society of Chemical Industry.

The green tea modulates large intestinal microbiome and exo/endogenous metabolome altered through chronic UVB-exposure.

The attenuating effects of green tea supplements (GTS) against the ultraviolet (UV) radiation induced skin damages are distinguished. However, the concomitant effects of GTS on the large intestinal microbiomes and associated metabolomes are largely unclear. Herein, we performed an integrated microbiome-metabolome analysis to uncover the esoteric links between gut microbiome and exo/endogenous metabolome maneuvered in the large intestine of UVB-exposed mice subjected to dietary GTS. In UVB-exposed mice groups (UVB), class Bacilli and order Bifidobacteriales were observed as discriminant taxa with decreased lysophospholipid levels compared to the unexposed mice groups subjected to normal diet (NOR). Conversely, in GTS fed UVB-exposed mice (U+GTS), the gut-microbiome diversity was greatly enhanced with enrichment in the classes, Clostridia and Erysipelotrichia, as well as genera, Allobaculum and Lachnoclostridium. Additionally, the gut endogenous metabolomes changed with an increase in amino acids, fatty acids, lipids, and bile acids contents coupled with a decrease in nucleobases and carbohydrate levels. The altered metabolomes exhibited high correlations with GTS enriched intestinal microflora. Intriguingly, the various conjugates of green tea catechins viz., sulfated, glucuronided, and methylated ones including their exogenous derivatives were detected from large intestinal contents and liver samples. Hence, we conjecture that the metabolic conversions for the molecular components in GTS strongly influenced the gut micro-environment in UVB-exposed mice groups, ergo modulate their gut-microbiome as well as exo/endogenous metabolomes.

Quantity and source of dietary protein influence metabolite production by gut microbiota and rectal mucosa gene expression: a randomized, parallel, double-blind trial in overweight humans.

Background: Although high-protein diets (HPDs) are frequently consumed for body-weight control, little is known about the consequences for gut microbiota composition and metabolic activity and for large intestine mucosal homeostasis. Moreover, the effects of HPDs according to the source of protein need to be considered in this context.Objective: The objective of this study was to evaluate the effects of the quantity and source of dietary protein on microbiota composition, bacterial metabolite production, and consequences for the large intestinal mucosa in humans.Design: A randomized, double-blind, parallel-design trial was conducted in 38 overweight individuals who received a 3-wk isocaloric supplementation with casein, soy protein, or maltodextrin as a control. Fecal and rectal biopsy-associated microbiota composition was analyzed by 16S ribosomal DNA sequencing. Fecal, urinary, and plasma metabolomes were assessed by 1H-nuclear magnetic resonance. Mucosal transcriptome in rectal biopsies was determined with the use of microarrays.Results: HPDs did not alter the microbiota composition, but induced a shift in bacterial metabolism toward amino acid degradation with different metabolite profiles according to the protein source. Correlation analysis identified new potential bacterial taxa involved in amino acid degradation. Fecal water cytotoxicity was not modified by HPDs, but was associated with a specific microbiota and bacterial metabolite profile. Casein and soy protein HPDs did not induce inflammation, but differentially modified the expression of genes playing key roles in homeostatic processes in rectal mucosa, such as cell cycle or cell death.Conclusions: This human intervention study shows that the quantity and source of dietary proteins act as regulators of gut microbiota metabolite production and host gene expression in the rectal mucosa, raising new questions on the impact of HPDs on the large intestine mucosa homeostasis. This trial was registered at clinicaltrials.gov as NCT02351297.

The microbial fermentation characteristics depend on both carbohydrate source and heat processing: a model experiment with ileo-cannulated pigs.

The effects of carbohydrate (CHO) source and processing (extrusion cooking) on large intestinal fermentation products were studied in ileo-cannulated pigs as a model for humans. Pigs were fed diets containing barley, pea or a mixture of potato starch:wheat bran (PSWB) either raw or extrusion cooked. Extrusion cooking reduced the amount of starch fermented in the large intestine by 52-96% depending on the CHO source and the total pool of butyrate in the distal small intestine + large intestine by on average 60% across diets. Overall, extrusion cooking caused a shift in the composition of short-chain fatty acids (SCFA) produced towards more acetate and less propionate and butyrate. The CHO source and processing highly affected the fermentation characteristics and extrusion cooking generally reduced large intestinal fermentation and resulted in a less desirable composition of the fermentation products. The latter outcome is non-conducive to a healthy large intestinal environment and its resulting metabolic health.

Effects of pectin on fermentation characteristics, carbohydrate utilization, and microbial community composition in the gastrointestinal tract of weaning pigs.

SCOPE: We aimed to investigate the effects of three different soluble pectins on the digestion of other consumed carbohydrates, and the consequent alterations of microbiota composition and SCFA levels in the intestine of pigs. METHODS AND RESULTS: Piglets were fed a low-methyl esterified pectin enriched diet (LMP), a high-methyl esterified pectin enriched diet (HMP), a hydrothermal treated soybean meal enriched diet (aSBM) or a control diet (CONT). LMP significantly decreased the ileal digestibility of starch resulting in more starch fermentation in the proximal colon. In the ileum, low-methyl esterified pectin present was more efficiently fermented by the microbiota than high-methyl esterified pectin present which was mainly fermented by the microbiota in the proximal colon. Treated soybean meal was mainly fermented in the proximal colon and shifted the fermentation of cereal dietary fiber to more distal parts, resulting in high SCFA levels in the mid colon. LMP, HMP, and aSBM decreased the relative abundance of the genus Lactobacillus and increased that of Prevotella in the colon. CONCLUSION: The LMP, HMP, and aSBM, differently affected the digestion processes compared to the control diet and shaped the colonic microbiota from a Lactobacillus-dominating flora to a Prevotella-dominating community, with potential health-promoting effects.