Effect of prebiotic oligosaccharides on bowel habit and the gut microbiota in children with functional constipation (Inside study): study protocol for a randomised, placebo-controlled, multi-centre trial

BACKGROUND

Functional constipation (FC) in children is a common gastrointestinal disorder with a worldwide-pooled prevalence of 9.5%. Complaints include infrequent bowel movements, painful defecation due to hard and/or large stools, faecal incontinence, and abdominal pain. Prebiotic oligosaccharides have been shown to relieve constipation symptoms in young adults and elderly. However, sufficient evidence is lacking linking additional prebiotic intake to improve symptoms in children with FC. We hypothesise that prebiotic oligosaccharides are able to relieve symptoms of constipation in young children as well.

METHODS

In the present randomised, double-blind, placebo-controlled, multi-centre study, we will study the effects of two prebiotic oligosaccharides in comparison to placebo on constipation symptoms in children of 1-5 years (12 to 72 months) of age diagnosed with FC according to the Rome IV criteria for functional gastrointestinal disorders. The primary outcome measure will be change in stool consistency. Secondary outcomes include stool frequency and stool consistency in a number of cases (%). Tertiary outcomes include among others painful defecation, use of rescue medication, and quality of life. In addition, the impact on gut microbiome outcomes such as faecal microbiota composition and metabolites will be investigated. Participants start with a run-in period, after which they will receive supplements delivered in tins with scoops for 8 weeks, containing one of the two prebiotic oligosaccharides or placebo, followed by a 4-week wash-out period.

DISCUSSION

This randomised double-blind, placebo-controlled multi-centre study will investigate the effectiveness of prebiotic oligosaccharides in children aged 1-5 years with FC.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04282551. Registered on 24 February 2020.

What are Normal Defecation Patterns in Healthy Children up to Four Years of Age? A Systematic Review and Meta-Analysis

OBJECTIVE

To summarize available data on defecation frequency and stool consistency of healthy children up to age 4 in order to estimate normal references values.

STUDY DESIGN

Systematic review including cross-sectional, observational, and interventional studies published in English, that reported on defecation frequency and/or stool consistency in healthy children 0-4 years old.

RESULTS

Seventy-five studies were included with 16 393 children and 40 033 measurements of defecation frequency and/or stool consistency. Based on visual inspection of defecation frequency data, a differentiation was made between two age categories: young infants (0-14 weeks old) and young children (15 weeks-4 years old). Young infants had a mean defecation frequency of 21.8 per week (95 % CI, 3.9-35.2) compared with 10.9 (CI, 5.7-16.7) in young children (P < .001). Among young infants, human milk-fed (HMF) infants had the highest mean defecation frequency per week (23.2 [CI, 8.8-38.1]), followed by formula-fed (FF) infants (13.7 [CI 5.4-23.9]), and mixed-fed (MF) infants (20.7 [CI, 7.0-30.2]). Hard stools were infrequently reported in young infants (1.5%) compared with young children (10.5%), and a reduction in the frequency of soft/watery stools was observed with higher age (27.0% in young infants compared with 6.2% in young children). HMF young infants had softer stools compared with FF young infants.

CONCLUSIONS

Young infants (0-14 weeks old) have softer and more frequent stools compared with young children (15 weeks-4 years old).

The Modified Bristol Stool Form Scale: A Reliable and Valid Tool to Score Stool Consistency in Dutch (Non)Toilet-trained Toddlers

OBJECTIVE

The aim of the study was to assess whether the modified Bristol Stool Form Scale (m-BSFS) is reliable, valid and user-friendly to use by parents, grandparents, and day childcare employees to evaluate stool consistency in toilet and nontoilet-trained toddlers in the Netherlands.

STUDY DESIGN

Translation to Dutch and validity of the m-BSFS (scoring 32 general stool pictures) for 1 to 3 year old toddlers (n = 89) was evaluated by parents, grandparents, and day childcare employees. A subgroup of participants scored an additional 7 pictures of stools in a diaper to validate the m-BSFS for non-toilet-trained toddlers (n = 16). To determine inter-rater reliability, 2-way random effects single-rater intraclass correlation coefficient (ICC)consistency was used. Intra-rater reliability was measured by Cohen kappa (κ) by rating the same pictures in random order twice, with at least 1 week between the first and second scoring.

RESULTS

Inter- and intra-rater reliability of the m-BSFS were above recommended minimal standards of 0.61 for the 32 general stool pictures as well as for the 7 pictures of stools in a diaper. ICCconsistency for the general stool pictures of the first and second ratings were 0.71 (n = 89) and 0.79 (n = 77), respectively, with a κ of 0.71 (n = 77). ICCconsistency for the stools in diaper pictures of the first and second ratings were 0.93 (n = 16) and 0.93 (n = 15), respectively, with a κ of 0.77 (n = 15).

CONCLUSIONS

The m-BSFS is reliable, valid and user-friendly to use by Dutch-speaking parents, grandparents, and day childcare workers to evaluate stool consistency in both toilet- and nontoilet-trained toddlers in the Netherlands.

The effect of fiber and prebiotics on children's gastrointestinal disorders and microbiome

The bacteria received upon birth are the start of colonization of the approximately 10¹⁴ bacteria that are present in the mature human gastrointestinal tract, better known as the microbiota. The gut microbiota is implicated in gastrointestinal health, nutrient metabolism and benefits such as prevention of infection. Dietary fiber, including prebiotics, escape digestion in the small intestine and reach the colon intact, where they are partially or completely fermented by the gut microbiota. Areas covered: The possible interactions between dietary fiber, prebiotics and microbiota are discussed as well as how this relates to functional gastrointestinal disorders. During the first years of life the microbiota have not yet reached a stable state and is sensitive to disturbance by environmental factors. An imbalance in the microbiota early in life is found to be associated with several functional gastrointestinal disorders such as colic, functional abdominal pain, irritable bowel syndrome and constipation. Expert commentary: A better understanding of how gut microbial changes in early-life can impact gastrointestinal health might lead to new treatments or disease prevention. Nutritional strategies with fiber or prebiotics may support health due to modification of colonic microbiota composition and metabolic activity, for example by growth stimulation of Bifidobacterium and Lactobacillus.

Characterizing microbiota-independent effects of oligosaccharides on intestinal epithelial cells: insight into the role of structure and size : Structure-activity relationships of non-digestible oligosaccharides

PURPOSE

The direct effects of galacto-oligosaccharides (GOS), including Vivinal® GOS syrup (VGOS) and purified Vivinal® GOS (PGOS), on the epithelial integrity and corresponding interleukin-8 (IL-8/CXCL8) release were examined in a Caco-2 cell model for intestinal barrier dysfunction. To investigate structure-activity relationships, the effects of individual DP fractions of VGOS were evaluated. Moreover, the obtained results with GOS were compared with Caco-2 monolayers incubated with fructo-oligosaccharides (FOS) and inulin.

METHODS

Caco-2 monolayers were pretreated (24 h) with or without specific oligosaccharides or DP fractions of VGOS (DP2 to DP6) before being exposed for 12 or 24 h to the fungal toxin deoxynivalenol (DON). Transepithelial electrical resistance and lucifer yellow permeability were measured to investigate barrier integrity. A calcium switch assay was used to study the reassembly of tight junction proteins. Release of CXCL8, a typical marker for inflammation, was quantified by ELISA.

RESULTS

In comparison with PGOS, FOS and inulin, VGOS showed the most pronounced protective effect on the DON-induced impairment of the monolayer integrity, acceleration of the tight junction reassembly and the subsequent CXCL8 release. DP2 and DP3 in concentrations occurring in VGOS prevented the DON-induced epithelial barrier disruption, which could be related to their high prevalence in VGOS. However, no effects of the separate DP GOS fractions were observed on CXCL8 release.

CONCLUSIONS

This comparative study demonstrates the direct, microbiota-independent effects of oligosaccharides on the intestinal barrier function and shows the differences between individual galacto- and fructo-oligosaccharides. This microbiota-independent effect of oligosaccharides depends on the oligosaccharide structure, DP length and concentration.

Oligosaccharides in Urine, Blood, and Feces of Piglets Fed Milk Replacer Containing Galacto-oligosaccharides

Human milk oligosaccharides (HMOs) are absorbed into the blood (about 1% of the HMO intake) and subsequently excreted in urine, where they may protect the infant from pathogen infection. As dietary galacto-oligosaccharides (GOS) have partial structural similarities with HMOs, this study investigated the presence of GOS and oligosaccharides originating from milk replacer in blood serum, urine, and cecal and fecal samples of piglets, as a model for human infants. Using liquid chromatography-mass spectrometry and capillary electrophoresis with fluorescence detection, oligosaccharides originating from piglet diet including 3'-sialyllactose and specific GOS ranging from degree of polymerization 3 to 6 were detected in blood serum and in urine of piglets. In blood serum, GOS levels ranged from 16 to 23 μg/mL, representing about 0.1% of the GOS daily intake. In urine, approximately 0.85 g of GOS/g of creatinine was found. Cecum digesta and feces contained low amounts of oligosaccharides, suggesting an extensive GOS intestinal fermentation in piglets.

Galacto-oligosaccharides Protect the Intestinal Barrier by Maintaining the Tight Junction Network and Modulating the Inflammatory Responses after a Challenge with the Mycotoxin Deoxynivalenol in Human Caco-2 Cell Monolayers and B6C3F1 Mice

BACKGROUND

The integrity of the epithelial layer in the gastrointestinal tract protects organisms from exposure to luminal antigens, which are considered the primary cause of chronic intestinal inflammation and allergic responses. The common wheat-associated fungal toxin deoxynivalenol acts as a specific disruptor of the intestinal tight junction network and hence might contribute to the pathogenesis of inflammatory bowel diseases.

OBJECTIVE

The aim of the current study was to assess whether defined galacto-oligosaccharides (GOSs) can prevent deoxynivalenol-induced epithelial dysfunction.

METHODS

Human epithelial intestinal Caco-2 cells, pretreated with different concentrations of GOSs (0.5%, 1%, and 2%) for 24 h, were stimulated with 4.2-μM deoxynivalenol (24 h), and 6/7-wk-old male B6C3F1 mice were fed a diet supplemented with 1% GOSs for 2 wk before being orally exposed to deoxynivalenol (25 mg/kg body weight, 6 h). Barrier integrity was determined by measuring transepithelial electrical resistance (TEER) and intestinal permeability to marker molecules. A calcium switch assay was conducted to study the assembly of epithelial tight junction proteins. Alterations in tight junction and cytokine expression were assessed by quantitative reverse transcriptase-polymerase chain reaction, Western blot analysis, or ELISA, and their localization was visualized by immunofluorescence microscopy. Sections of the proximal and distal small intestine were stained with hematoxylin/eosin for histomorphometric analysis.

RESULTS

The in vitro data showed that medium supplemented with 2% GOSs improved tight junction assembly reaching an acceleration of 85% after 6 h (P < 0.05). In turn, GOSs prevented the deoxynivalenol-induced loss of epithelial barrier function as measured by TEER (114% of control), and paracellular flux of Lucifer yellow (82.7% of prechallenge values, P < 0.05). Moreover, GOSs stabilized the expression and cellular distribution of claudin3 and suppressed by >50% the deoxynivalenol-induced synthesis and release of interleukin-8 [IL8/chemokine CXC motif ligand (CXCL8)] (P < 0.05). In mice, GOSs prevented the deoxynivalenol-induced mRNA overexpression of claudin3 (P = 0.022) and CXCL8 homolog keratinocyte hemoattractant (Kc) (Cxcl1) (P = 0.06) as well as the deoxynivalenol-induced morphologic defects.

CONCLUSIONS

The results demonstrate that GOSs stimulate the tight junction assembly and in turn mitigate the deleterious effects of deoxynivalenol on the intestinal barrier of Caco-2 cells and on villus architecture of B6C3F1 mice.

Functional role and mechanisms of sialyllactose and other sialylated milk oligosaccharides

Human milk is a rich source of oligosaccharides. Acidic oligosaccharides, such as sialyllactose (SL), contain sialic acid (SA) residues. In human milk, approximately 73% of SA is bound to oligosaccharides, whereas only 3% is present in free form. Oligosaccharides are highly resistant to hydrolysis in the gastrointestinal tract. Only a small portion of the available oligosaccharides in breast milk is absorbed in the neonatal small intestine. SL and sialylated oligosaccharides are thought to have significant health benefits for the neonate, because of their roles in supporting resistance to pathogens, gut maturation, immune function, and cognitive development. The need for SA to allow proper development during the neonatal period is thought to exceed the endogenous synthesis. Therefore, these structures are important nutrients for the neonate. Based on the potential benefits, SL and sialylated oligosaccharides may be interesting components for application in infant nutrition. Once the hurdle of limited availability of these oligosaccharides has been overcome, their functionality can be explored in more detail, and supplementation of infant formula may become feasible.

Impact of galacto-oligosaccharides on the gut microbiota composition and metabolic activity upon antibiotic treatment during in vitro fermentation

Prebiotics are considered to have potential to reduce disturbances in the gut microbiota induced by antibiotics. Results in literature are, however, not consistent. The current in vitro study conducted in a fermentation screening platform allowed to unambiguously compare the impact of galacto-oligosaccharides (GOS) on adult gut microbiota composition and activity upon treatment with four antibiotics at two doses. The changes in relative abundance of bacteria upon antibiotic treatment and the growth of Bifidobacterium and Lactobacillus upon GOS addition were antibiotic and dose dependent. This conclusion explains discrepancies in literature and indicates that particular combinations of GOS antibiotic should be studied. The combination GOS-Amoxicillin was especially of interest as, after decrease in Bifidobacterium levels, a recovery of mainly Bifidobacterium longum was observed and could be correlated with specific degradation patterns of GOS. Next to different degradation profiles of individual GOS, an accumulation of monosaccharides and intermediate organic acids was observed in antibiotic-treated microbiota as compared to nontreated microbiota. This showed that although GOS were utilized and beneficial bacteria could grow in 3 of 4 antibiotics tested, the metabolic activity of an antibiotic-treated microbiota was still disturbed as compared to the nontreated microbiota.

Selective carbohydrate utilization by lactobacilli and bifidobacteria

AIM

To evaluate the ability of specific carbohydrates, including commercially available products, to support the growth of representatives of two well-known groups of gut commensals, namely lactobacilli and bifidobacteria.

METHODS AND RESULTS

Sixty-eight bacterial strains, representing 29 human-derived lactobacilli and 39 bifidobacteria (both human- and animal-derived), were tested for their ability to metabolize 10 different carbohydrates. Analysis of growth and metabolic activity was performed using a combination of diagnostic parameters, such as final OD600 , final pH, fermentation end products and growth rate.

CONCLUSIONS

The data assembled in this study provide significant complementary and comparative information on the growth-promoting properties of a range of carbohydrates, while also investigating interspecies differences between lactobacilli and/or bifidobacteria with regard to their carbohydrate utilization abilities. Galacto-oligosaccharides (GOS) and lactulose were shown to support the most favourable growth characteristics, whereas relatively poor growth of lactobacilli and bifidobacteria was observed on inulin, maltodextrin and polydextrose. GOS/inulin (9 : 1) and fructo-oligosaccharides (FOS)/inulin mixtures supported mostly similar growth abilities to those obtained for GOS and FOS, respectively. Microbial consumption of GOS, as determined by high-performance anion-exchange chromatography with pulsed amperometric detection, was evident for both lactobacilli and bifidobacteria.

SIGNIFICANCE AND IMPACT OF THE STUDY

These results may allow for the rational prediction of lactobacilli and/or bifidobacteria to be used in conjunction with prebiotics, such as GOS, as synbiotics.

High-throughput analysis of the impact of antibiotics on the human intestinal microbiota composition

Antibiotic treatments can lead to a disruption of the human microbiota. In this in-vitro study, the impact of antibiotics on adult intestinal microbiota was monitored in a new high-throughput approach: a fermentation screening-platform was coupled with a phylogenetic microarray analysis (Intestinal-chip). Fecal inoculum from healthy adults was exposed in a fermentation screening-platform to seven widely-used antibiotics during 24h in-vitro fermentation and the microbiota composition was subsequently determined with the Intestinal-chip. Phylogenetic microarray analysis was first verified to be reliable with respect to variations in the total number of bacteria and presence of dead (or inactive) cells. Intestinal-chip analysis was then used to identify and compare shifts in the intestinal microbial composition after exposure to low and high dose (1μgml(-1) and 10μgml(-1)) antibiotics. Observed shifts on family, genus and species level were both antibiotic and dose dependent. Stronger changes in microbiota composition were observed with higher doses. Shifts mainly concerned the bacterial groups Bacteroides, Bifidobacterium, Clostridium, Enterobacteriaceae, and Lactobacillus. Within bacterial groups, specific antibiotics were shown to differentially impact related species. The combination of the in-vitro fermentation screening platform with the phylogenetic microarray read-outs has shown to be reliable to simultaneously analyze the effects of several antibiotics on intestinal microbiota.

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

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

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

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

Inactivity and weight loss: effective criteria to identify frailty

The effectiveness was examined of inactivity and weight loss as criteria to identify a frail subgroup within independently living elderly persons participating in the SENECA study (Survey in Europe on Nutrition and the Elderly, a Concerted Action). Eight-hundred-forty-nine participants (aged 75 to 80) from nine countries were classified in four subgroups: 1) inactive elderly (lowest tertile activity score: n = 204); 2) weight losing elderly (lowest quintile: * 6.3% weight loss over 4-5 years: n = 108); 3) both inactive and weight losing (n = 54); 4) neither inactive nor weight losing: reference (n = 483). Differences in health, physical functioning and nutritional characteristics between groups 1, 2 and 3 respectively, and the reference group were evaluated. Compared to the weight-stable, active reference group, both inactive, weight losing (group 3) and inactive subjects (group 1) reported significantly more chronic diseases (2.2 and 1.8 vs. 1.1), disabilities (81 and 80 vs. 43%), use of medications (both 2.3 vs. 1.1) and care services (26 and 21 vs. 6%), and a lower self-rated health (2.8 and 3.1 vs. 3.8), relative health (1.9 and 2.1 vs. 2.6), and physical performance score (17 and 18 vs. 22). In addition, inadequate micronutrient intake and biochemical deficiencies were more prevalent. Weight-losing elderly were not significantly different from the reference group with respect to these characteristics. Therefore, physical inactivity alone or in combination with weight loss seems to be a practical and inexpensive screening criterion for identifying a subgroup of elderly with less favourable health and nutritional characteristics and poorer physical functioning among non-institutionalised elderly.