Kristin Verbeke | KU Leuven (original) (raw)

Papers by Kristin Verbeke

Gastroenterology, 2013

G A A b st ra ct s and healthy individuals, using the terminal-restriction fragment length polymo... more G A A b st ra ct s and healthy individuals, using the terminal-restriction fragment length polymorphism (TRFLP) analysis. Results; Clostridium cluster IV and subcluster XIVa components were significantly decreased, whereas the Lactobacillales and Bifidobacterium populations significantly increased in the T2DM patients compared with the healthy individuals. However, after 12 weeks of TGD therapy, the ratio of the Bacteroides population to that of Firmicutes in the TGD groups significantly increased and was significantly higher compared with that in the placebo group. By dendrogram analysis, almost all (8 of 10) of the healthy individuals were classified into cluster III, whereas more than half (27 of 40) of the T2DM patients were classified into cluster I before the treatment. After the TGD treatment, the numbers of T2DM patients in clusters I and III decreased and increased, respectively, indicating that TGD improved the growth of the fecal bacterial communities in the T2DM patients. Conclusion; Therefore, the mechanism underlying the decrease in the blood glucose levels and inhibition of body weight gain in the T2DM patients may be the modulation of gut microbiota induced by TGD administration.

Nature Reviews Gastroenterology & Hepatology, 2019

Short-chain fatty acids (SCFAs), the main metabolites produced by bacterial fermentation of dieta... more Short-chain fatty acids (SCFAs), the main metabolites produced by bacterial fermentation of dietary fibre in the gastrointestinal tract, are speculated to have a key role in microbiota-gut-brain crosstalk. However, the pathways through which SCFAs might influence psychological functioning, including affective and cognitive processes and their neural basis, have not been fully elucidated. Furthermore, research directly exploring the role of SCFAs as potential mediators of the effects of microbiota-targeted interventions on affective and cognitive functioning is sparse, especially in humans. This Review summarizes existing knowledge on the potential of SCFAs to directly or indirectly mediate microbiota-gut-brain interactions. The effects of SCFAs on cellular systems and their interaction with gut-brain signalling pathways including immune, endocrine, neural and humoral routes are described. The effects of microbiota-targeted interventions such as prebiotics, probiotics and diet on psychological functioning and the putative mediating role of SCFA signalling will also be discussed, as well as the relationship between SCFAs and psychobiological processes. Finally , future directions to facilitate direct investigation of the effect of SCFAs on psychological functioning are outlined.

Gastroenterology, 2012

Background/Aims: Aspiration secondary to dysphagia is an important complication leading to increa... more Background/Aims: Aspiration secondary to dysphagia is an important complication leading to increased rates of morbidity and mortality. There is scarce evidence for the effects of different bolus temperatures in swallowing behaviour in dysphagic patients [Hamdy et al, Neurogastroenterol Motil 2003;Watando et al, J Am Geriatr Soc 2004]. Moreover, there is very limited evidence for the effects of temperature on automated and complex swallowing liquid boluses on swallowing behaviour, assessed by a novel reaction time task (Mistry et al, J Physiol 2007), in healthy participants. Methods: Nineteen healthy participants (9 male, 29.7±3 years old, mean ±SEM) swallowed an intra-pharyngeal catheter with built-in pressure transducers allowing the recording of changes in pressures signal in the hypopharynx. Subjects were cued to swallow by an electrical pulse to the hand 5 ml boluses of either cold (4°C), hot (45°C) or room temperature (21°C) water, while performing 10 normal-paced swallows, 10 fast-paced swallows and 10 challenged swallows within a predetermined timewindow. Each block of (total 30) swallows were repeated twice in a pseudo-randomised manner for all temperatures. Quantitative measurements of time to the predetermined pharyngeal pressure threshold and percentage of successful challenged swallows were collected and presented as mean±SEM. Data were analysed with non-parametric Wilcoxon's test in SPSS 14. Results: Normal-paced swallows: Swallowing latencies of cold water swallows (1390 ± 80 ms) were significantly reduced compared to hot water (1545 ± 87 ms) and room temperature (1593 ± 79 ms) water swallows (z=-2.91, p<0.01 and z=-3.42, p<0.01, respectively)(Figure 1). Fast swallows: No difference was observed between the three different bolus temperatures. Challenged swallows: Contrary to the normal-paced swallows, cold bolus challenged swallows were less accurately performed (29.5 ± 3%) compared to challenged swallows with room temperature boluses (38.9 ± 3%)(z=-2.0, p=0.04) and hot temperature boluses (38.2 ± 3%) (z=-2.28, p=0.02). Conclusion: Bolus temperature plays an important role in healthy swallowing behaviour and can alter swallowing performance. Cold temperature appears to alter swallowing behaviour differentially by shortening the latency of normal-paced automated swallows, while reducing successful rates in challenged swallowing tasks. The latter maybe a consequence of speedier handling of cold bolus in the oropharynx. Based on our results, further research is warranted for the use of different temperatures in dysphagic patients to explore therapeutic effects in reducing aspiration.

Frontiers in Nutrition

BackgroundIncorporation of wheat bran (WB) into food products increases intake of dietary fiber, ... more BackgroundIncorporation of wheat bran (WB) into food products increases intake of dietary fiber, which has been associated with improved mood and cognition and a lower risk for psychiatric disorders such as depression, with short-chain fatty acids (SCFAs) as candidate mediators of these effects. Modifying WB using extrusion cooking increases SCFA production in vitro relative to unmodified WB.ObjectiveThe aim of this study was to evaluate the effects of extruded WB on psychobiological functioning and the mediating role of SCFAs.MethodsIn a randomized, triple-blind, placebo-controlled trial, 69 healthy male participants consumed 55 g of breakfast cereal containing either extruded WB or placebo daily for 28 days. At pre- and post-intervention visits, the cortisol response to experimentally induced stress was measured as a primary outcome. In addition, serum SCFAs and brain-derived neurotrophic factors were quantified as potential mediators. Secondary psychobiological outcomes included ...

matched-pair analysis of 20 patients in groups A and B with respect to gender, age, weight, and G... more matched-pair analysis of 20 patients in groups A and B with respect to gender, age, weight, and GFR. Group A received 10 mg of prednisone per day [mean (SD), 14.8 (5.1) mg; n 10], whereas group B received 5 mg of prednisone per day. Despite the small sample size, the matched-pair analysis showed significantly higher Cys C concentrations in group A [mean (95% CI), 2.86 (1.75– 3.98) mg/L] than in group B [2.3 (1.48–3.14) mg/L; P 0.049]. BTP concentrations were not affected by steroids [1.58 (0.93–2.22) mg/L vs 1.79 (1.21–2.38) mg/L; P 0.1]. Our data show similar diagnostic performance for BTP, Cys C, and creatinine in RTx patients. In fact, when renal function decreased, BTP and Cys C detected a diminished GFR earlier and increased more prominently than creatinine. We found only 5 published studies using ROC analyses for evaluation of the diagnostic performance of BTP. BTP was superior to creatinine in 2 investigations in children (8, 14). In adults, at cutoff points of 70 and 80 mL m...

The American Journal of Clinical Nutrition, 2021

Background Wheat bran (WB) has been associated with improved gastrointestinal health and a reduce... more Background Wheat bran (WB) has been associated with improved gastrointestinal health and a reduced risk of metabolic disorders. Reducing the particle size of WB might increase its fermentability and facilitate cross-feeding between the gut bacteria and in this way produce health effects. Objectives We investigated the impact of WB with reduced particle size (WB RPS) on colonic fermentation and host health in normal-weight (NW) and obese (OB) participants compared with placebo (PL). Methods During 1 mo, 36 NW and 14 OB participants daily consumed 20 g WB RPS or PL (maltodextrin). Before and after the intervention, fasting serum and fecal SCFAs, fecal metabolite profiles, and microbiota composition were measured as fermentation parameters. Fecal output, fecal dry weight (%), fat excretion, transit, stool consistency, intestinal permeability, and serum total cholesterol, triglyceride, and C-reactive protein concentrations were measured as health parameters. The impact of WB RPS on the ...

Behavioral and Brain Sciences, 2019

Dietary fiber and prebiotics consistently modulate microbiota composition and function and hence ... more Dietary fiber and prebiotics consistently modulate microbiota composition and function and hence may constitute a powerful tool in microbiota-gut-brain axis research. However, this is largely ignored in Hooks et al.’s analysis, which highlights the limitations of probiotics in establishing microbiome-mediated effects on neurobehavioral functioning and neglects discussing the potential of prebiotics in warranting the microbiota's role in such effects.

Critical Reviews in Food Science and Nutrition, 2019

Consumption of wheat bran (WB) has been associated with improved gastrointestinal health and a re... more Consumption of wheat bran (WB) has been associated with improved gastrointestinal health and a reduced risk for colorectal cancer, cardiovascular diseases and metabolic disorders. These benefits are likely mediated by a combination of mechanisms, including colonic fermentation of the WB fibre, faecal bulking and the prevention of oxidative damage due to its antioxidant capacities. The relative importance of those mechanisms is not known and may differ for each health effect. WB has been modified by reducing particle size, heat treatment or modifying tissue composition to improve its technological properties and facilitate bread making processes. However, the impact of those modifications on human health has not been fully elucidated. Some modifications reinforce whereas others attenuate the health effects of coarse WB. This review summarises available WB modifications, the mechanisms by which WB induces health benefits, the impact of WB modifications thereon and the available evidence for these effects from in vitro and in vivo studies. gastrointestinal health and a decreased risk for the development of cardiovascular diseases (CVD), cancer and metabolic diseases (Stevenson et al. 2012). Modifications of the tissue composition and physical properties of bran can improve its technological properties but may also affect specific health effects. Reducing WB particle size improves the accessibility of nutrients within the bran (Rosa et al. 2013), such as phenolic antioxidants, whereas heat treatment inactivates several enzymes, thereby reducing its biochemical reactivity (Mosharraf, Kadivar, and Shahedi 2009). Despite the benefits associated with WB consumption, the use of WB also raises some concerns. Cereals can be contaminated with mycotoxins produced by a variety of fungi that colonise the crops during growing or storage. Depending on their concentrations, mycotoxins can induce adverse health effects in humans and animals. However, applying appropriate pre-and postharvest strategies can mitigate the risk for mycotoxin contamination (Cheli et al. 2017). Furthermore, WB also contains some anti-nutrients like phytates that form strong complexes with minerals and in this way, may hamper the absorption and reduce the bioavailability of the minerals. This review provides an overview of available modifications of WB, the putative mechanisms by which modified WB affects health and the available evidence on those health benefits from in vitro, animal and human studies. WHEAT BRAN: DEFINITION, STRUCTURE AND COMPOSITION WB refers to the outer layers of the wheat kernel, which surround the germ and the endosperm. It is composed of different histological tissue layers (Figure 1a, b). Starting from the outside of the wheat kernel, one observes the pericarp (epidermis, hypodermis, cross cells and tubular cells), the seed coat or testa, the nucellar epidermis and the aleurone layer, which is tightly bound to the seed coat (Delcour and Hoseney 2010). In the jargon of millers, the term bran is a collective name for all the above tissue layers together with some 4 residual starchy endosperm that remains attached to the aleurone layer after milling. From the botanical point of view, the aleurone layer and the residual starchy endosperm are not part of the bran. The pericarp is the outermost layer of the bran fraction and is made of three layers: epicarp, mesocarp and endocarp. It is composed of empty cells, mostly consisting of cell wall polysaccharides, such as branched heteroxylans and cellulose, with numerous cross-links between the polymer chains, formed by ferulic acid dimers (Brouns et al. 2012, Fincher and Stone 1986). The arabinoxylan in the pericarp layer has a highly branched structure (high arabinose to xylose ratio) and is therefore to large extent resistant to bacterial fermentation (Barron, Surget, and Rouau 2007). The aleurone layer, in contrast, is a monocellular layer located at the inner site of the bran that contains β-glucans, few proteins and high amounts of lowly substituted arabinoxylan and esterified ferulic acid monomers (Brouns et al. 2012). Due to the low arabinose to xylose ratio, the arabinoxylans in aleurone are easily degraded by the gut microbiota. Moreover, the aleurone layer is particularly rich in nutrients like the minerals iron, magnesium, zinc and calcium and almost all of the B-group vitamins. Coarse WB has a particle size between 1500 and 2000 µm with a wide particle size distribution. It is usually composed of 43-62% dietary fibre which mainly consists of arabinoxylan (AX) and to a lesser extent of beta-glucan, cellulose, fructan and lignin.

mSystems, 2018

This study is the first to determine the safety and tolerance in humans of a butyrate-producing C... more This study is the first to determine the safety and tolerance in humans of a butyrate-producing Clostridium cluster IV next-generation probiotic. Advances in gut microbiota research have triggered interest in developing colon butyrate producers as next-generation probiotics. Butyricicoccus pullicaecorum 25-3 T is one such potential probiotic, with demonstrated safety in vitro as well as in animal models. Here, we produced an encapsulated B. pullicaecorum formulation that largely preserved its viability over an 8-month storage period at 4°C. Administration of this formulation to healthy volunteers allowed us to establish the intervention as safe and well tolerated. The probiotic intervention did not cause disruptive alterations in the composition or metabolic activity of health-associated microbiota. The results presented pave the way for the exploration of the impact of the strain on microbiota alterations in a clinical setting.

$Research paper thumbnail of Fat binding capacity and modulation of the gut microbiota both determine the effect of wheat bran fractions on adiposity$

Scientific reports, Jan 17, 2017

The aim of this study was to determine the impact of different wheat bran fractions on the gut mi... more The aim of this study was to determine the impact of different wheat bran fractions on the gut microbiota and fat binding capacity to explain their differential effects on metabolic and inflammatory disorders induced by a western diet (WD) in mice. Wheat bran derived arabinoxylan oligosaccharides (AXOS), a crude fraction of wheat bran (WB), or the same wheat bran with reduced particle size (WBs) were added to the WD of mice for 8 weeks. AXOS shifted the gut microbiota composition, blunted Clostridium and Turicibacter genera and strongly promoted Bifidobacterium and Butyricicoccus genera, independently of changes in gut antimicrobial peptide expression. AXOS was the most efficient to reduce adiposity. Only WB fraction promoted fat excretion and differed from the other fractions by the capacity to increase the Akkermansia genus and to counteract gut interleukin 1 beta (IL1β) overexpression. Strikingly, WBs promoted steatosis and adipose tissue inflammation, despite its ability -like W...

Journal of Nutritional Science, 2014

Wheat bran extract (WBE) is a food-grade soluble fibre preparation that is highly enriched in ara... more Wheat bran extract (WBE) is a food-grade soluble fibre preparation that is highly enriched in arabinoxylan–oligosaccharides. In this placebo-controlled cross-over human intervention trial, tolerance to WBE as well as the effects of WBE on faecal parameters, including faecal output and bowel habits, were studied. After a 2-week run-in period, twenty healthy volunteers consumed WBE (15 g/d in the first week, 30 g/d in the second week), oligofructose (15 g/d in the first week, 30 g/d in the second week) and placebo (for 2 weeks) in a random order, with 2-week washout periods between each treatment period. Subjects collected a 72 h stool sample for analysis of faecal output, stool pH and stool moisture concentration. Additionally, the volunteers completed questionnaires scoring occurrence frequency and distress severity of eighteen gastrointestinal (GI) symptoms. An overall GI symptom measure was calculated to analyse the overall effect of WBE and oligofructose on GI symptoms. Intake of...

Gastroenterology, 2015

Background: Many studies have focused on the fecal microbiota however it is now widely accepted t... more Background: Many studies have focused on the fecal microbiota however it is now widely accepted that the gastrointestinal (GI) mucosa associated microbiota, rather than luminal content, is critically important in host-microbe interactions linked to health and disease. Mucosal biopsy is the most common sampling technique used to assess the mucosa associated microbiota. However, normal biopsy devices are designed to take samples for histologic assessment. Thus when biopsies are taken via working channels that are also used to aspirate luminal content it is highly likely that cross contamination occurs, that ultimately questions the validity of these samples. In view of this difficulty we have developed a novel device that allows targeted biopsies to be taken in any segment of the GI tract without cross contamination in an aseptic manner. Methods: Six patients undergoing upper GI endoscopy for iron deficiency were recruited with consent and ethical approval. In pilot experiments various prototypes of a sampling device were tested in vivo. Two final configurations of a sheath that covered miniature biopsy forceps were tested and compared with the normal single-use biopsy forceps (18 samples). Matched duodenal biopsy samples were collected from each patient, transferred individually into RNA later, and subject to gDNA extraction. Amplicon libraries spanning the V6-V8 region of the 16S rRNA gene were constructed, sequenced using the Illumina MiSeq platform, and analysed via the QIIME pipeline. Results: Microbial DNA, representing a diverse community, was observed in all duodenal samples obtained using the aseptic device, indicating this device is effective in sampling mucosa associated organisms present in the duodenum (Chao 1 estimated richness = 386, Good's coverage 99.8%). Assessment of the duodenal microbiota revealed a community dominated by the genera Streptococcus, Prevotella, Veillonella, Neisseria and Porphyromonas. There were substantial differences in the microbiota of samples obtained using the aseptic device and samples obtained with standard biopsy forceps. Only a low level of correlation (Pearson's r<0.6) between the matched biopsy pairs was seen across all bacterial phyla observed. Phylogenetic based (UniFrac) evaluation of beta-diversity revealed the aseptic samples clustered together and showed reduced inter-individual variability compared to those obtained with standard forceps. Conclusions: Sampling of duodenal biopsies with routine biopsy forceps resulted in greater microbial diversity as compared to samples acquired under aseptic conditions. This suggests cross contamination from other sites of the upper GI tract when utilising standard forceps. Based upon our data, aseptic techniques with a specific sampling device should be used to collect samples for studies that aim to define the mucosa associated microbiota.