Validation of a food frequency questionnaire to measure intakes of inulin and oligofructose

Dietary Fiber in Inflammatory Bowel Disease: Are We Ready to Change the Paradigm?

Accumulating evidence from pre-clinical and clinical studies demonstrate the benefit of dietary fibers for inflammatory bowel disease (IBD). However, the majority of patients avoid or limit their consumption to manage their symptoms during the active and remission phases, although limited research supports these long-term dietary habits. Although recent evidence-based dietary guidelines highlight the importance of promoting an adequate intake of dietary fiber in IBD patients, intervention trials have not yet clearly clarified the quality and quantity of dietary fiber that should be consumed to be equally tolerated by and provide benefit for patients with IBD. This narrative review describes dietary fibers and their characteristics, analyzes the real-word studies on the impact of dietary fiber consumption in IBD in different clinical settings, and concludes with potential future directions in fiber research, focusing on the real-world needs of characterizing the consumption of fiber-rich foods and promoting their adequate intake.

Guidelines for microbiome studies in renal physiology

Gut microbiome research has increased dramatically in the last decade, including in renal health and disease. The field is moving from experiments showing mere association to causation using both forward and reverse microbiome approaches, leveraging tools such as germ-free animals, treatment with antibiotics, and fecal microbiota transplantations. However, we are still seeing a gap between discovery and translation that needs to be addressed, so that patients can benefit from microbiome-based therapies. In this guideline paper, we discuss the key considerations that affect the gut microbiome of animals and clinical studies assessing renal function, many of which are often overlooked, resulting in false-positive results. For animal studies, these include suppliers, acclimatization, baseline microbiota and its normalization, littermates and cohort/cage effects, diet, sex differences, age, circadian differences, antibiotics and sweeteners, and models used. Clinical studies have some unique considerations, which include sampling, gut transit time, dietary records, medication, and renal phenotypes. We provide best-practice guidance on sampling, storage, DNA extraction, and methods for microbial DNA sequencing (both 16S rRNA and shotgun metagenome). Finally, we discuss follow-up analyses, including tools available, metrics, and their interpretation, and the key challenges ahead in the microbiome field. By standardizing study designs, methods, and reporting, we will accelerate the findings from discovery to translation and result in new microbiome-based therapies that may improve renal health.

Shotgun Metagenomic Sequencing Revealed the Prebiotic Potential of a Fruit Juice Drink with Fermentable Fibres in Healthy Humans

Fibre-based dietary interventions are at the forefront of gut microbiome modulation research, with a wealth of 16S rRNA information to demonstrate the prebiotic effects of isolated fibres. However, there is a distinct lack of data relating to the effect of a combination of soluble and insoluble fibres in a convenient-to-consume fruit juice food matrix on gut microbiota structure, diversity, and function. Here, we aimed to determine the impact of the MOJU Prebiotic Shot, an apple, lemon, ginger, and raspberry fruit juice drink blend containing chicory inulin, baobab, golden kiwi, and green banana powders, on gut microbiota structure and function. Healthy adults (n = 20) were included in a randomised, double-blind, placebo-controlled, cross-over study, receiving 60 mL MOJU Prebiotic Shot or placebo (without the fibre mix) for 3 weeks with a 3-week washout period between interventions. Shotgun metagenomics revealed significant between-group differences in alpha and beta diversity. In addition, the relative abundance of the phyla Actinobacteria and Desulfobacteria was significantly increased as a result of the prebiotic intervention. Nine species were observed to be differentially abundant (uncorrected p-value of <0.05) as a result of the prebiotic treatment. Of these, Bifidobacterium adolescentis and CAG-81 sp900066785 (Lachnospiraceae) were present at increased abundance relative to baseline. Additionally, KEGG analysis showed an increased abundance in pathways associated with arginine biosynthesis and phenylacetate degradation during the prebiotic treatment. Our results show the effects of the daily consumption of 60 mL MOJU Prebiotic Shot for 3 weeks and provide insight into the functional potential of B. adolescentis.

Current evidence for dietary therapies in irritable bowel syndrome

PURPOSE OF REVIEW

Diet appears to trigger symptoms in the majority of individuals with irritable bowel syndrome (IBS) and is associated with a reduced quality of life. There has been a recent focus on the role of dietary therapies to manage individuals with IBS. The aim of this review is to discuss the utility of traditional dietary advice (TDA), low-FODMAP diet (LFD) and gluten-free diet (GFD) in IBS.

RECENT FINDINGS

Several recent randomized controlled trials (RCTs) have been published demonstrating the efficacy of the LFD and GFD in IBS, with the evidence base for TDA being predominantly based on clinical experience, with emerging RCTs evaluating TDA. Only one RCT has been published to date comparing TDA, LFD and GFD head to head, with no difference noted between diets in terms of efficacy. However, TDA has been noted to be more patient-friendly and is commonly implemented as a first-line dietary therapy.

SUMMARY

Dietary therapies have been demonstrated to improve symptoms in patients with IBS. In view of insufficient evidence to recommend one diet over another currently, specialist dietetic input in conjunction with patient preference is required to determine implementation of dietary therapies. Novel methods of dietetic delivery are required in view of the lack of dietetic provision to deliver these therapies.

Constipation-Predominant Irritable Bowel Syndrome (IBS-C): Effects of Different Nutritional Patterns on Intestinal Dysbiosis and Symptoms

Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder characterized by abdominal pain associated with defecation or a change in bowel habits. The pathogenesis of IBS is not completely clear, but it is known to be multifactorial and complex. Endogenous and exogenous factors such as abnormal GI motility, low-grade inflammation, increased epithelial permeability and visceral hypersensitivity, but diet and psychosocial aspects are also recognized as important actors. Furthermore, the interaction between diet and gut microbiota has gained interest as a potential contributor to the pathophysiology of IBS. To date, there is no specific diet for IBS with constipation (IBS-C); however, many studies show that fiber intake, especially soluble fiber such as inulin, could have a positive effect on symptoms. This review aims to evaluate the effects of some nutritional components such as fibers but also functional foods, prebiotics, probiotics and symbiotics on symptoms and microbiota in IBS-C subjects.

Preparation, Structural Characterisation, and Bioactivities of Fructans: A Review

Polysaccharides are important components of higher plants and have attracted increasing attention due to their many nutraceutical benefits in humans. Fructans, heterogeneous fructose polymers that serve as storage carbohydrates in various plants, represent one of the most important types of natural polysaccharides. Fructans have various physiological and therapeutic effects, which are beneficial to health, and have the ability to prevent or treat various diseases, allowing their wide use in the food, nutraceutical, and pharmaceutical industries. This article reviews the occurrence, metabolism, preparation, characterisation, analysis, and bioactivity of fructans. Further, their molecular weight, monosaccharide composition, linkages, and structural determination are described. Taken together, this review provides a theoretical foundation for further research into the structure-function relationships of fructans, as well as valuable new information and directions for further research and application of fructans in functional foods.

Diet and irritable bowel syndrome: an update from a UK consensus meeting

There has been a renewed interest in the role of dietary therapies to manage irritable bowel syndrome (IBS), with diet high on the agenda for patients. Currently, interest has focussed on the use of traditional dietary advice (TDA), a gluten-free diet (GFD) and the low FODMAP diet (LFD). A consensus meeting was held to assess the role of these dietary therapies in IBS, in Sheffield, United Kingdom.Evidence for TDA is from case control studies and clinical experience. Randomised controlled trials (RCT) have demonstrated the benefit of soluble fibre in IBS. No studies have assessed TDA in comparison to a habitual or sham diet. There have been a number of RCTs demonstrating the efficacy of a GFD at short-term follow-up, with a lack of long-term outcomes. Whilst gluten may lead to symptom generation in IBS, other components of wheat may also play an important role, with recent interest in the role of fructans, wheat germ agglutinins, as well as alpha amylase trypsin inhibitors. There is good evidence for the use of a LFD at short-term follow-up, with emerging evidence demonstrating its efficacy at long-term follow-up. There is overlap between the LFD and GFD with IBS patients self-initiating gluten or wheat reduction as part of their LFD. Currently, there is a lack of evidence to suggest superiority of one diet over another, although TDA is more acceptable to patients.In view of this evidence, our consensus group recommends that dietary therapies for IBS should be offered by dietitians who first assess dietary triggers and then tailor the intervention according to patient choice. Given the lack of dietetic services, novel approaches such as employing group clinics and online webinars may maximise capacity and accessibility for patients. Further research is also required to assess the comparative efficacy of dietary therapies to other management strategies available to manage IBS.

Psyllium reduces inulin-induced colonic gas production in IBS: MRI and in vitro fermentation studies

OBJECTIVE

Health-promoting dietary fibre including inulin often triggers gastrointestinal symptoms in patients with IBS, limiting their intake. Our aim was to test if coadministering psyllium with inulin would reduce gas production.

DESIGN

A randomised, four-period, four-treatment, placebo-controlled, crossover trial in 19 patients with IBS. Subjects ingested a 500 mL test drink containing either inulin 20 g, psyllium 20 g, inulin 20 g+ psyllium 20 g or dextrose 20 g (placebo). Breath hydrogen was measured every 30 min with MRI scans hourly for 6 hours. Faecal samples from a subset of the patients with IBS were tested using an in vitro fermentation model. Primary endpoint was colonic gas assessed by MRI.

RESULTS

Colonic gas rose steadily from 0 to 6 hours, with inulin causing the greatest rise, median (IQR) AUC_{(0-360 min)} 3145 (848-6502) mL·min. This was significantly reduced with inulin and psyllium coadministration to 618 (62-2345) mL·min (p=0.02), not significantly different from placebo. Colonic volumes AUC_{(0-360 min)} were significantly larger than placebo for both inulin (p=0.002) and inulin and psyllium coadministration (p=0.005). Breath hydrogen rose significantly from 120 min after inulin but not psyllium; coadministration of psyllium with inulin delayed and reduced the maximum increase, AUC_{(0-360 min)} from 7230 (3255-17910) ppm·hour to 1035 (360-4320) ppm·hour, p=0.007.Fermentation in vitro produced more gas with inulin than psyllium. Combining psyllium with inulin did not reduce gas production.

CONCLUSIONS

Psyllium reduced inulin-related gas production in patients with IBS but does not directly inhibit fermentation. Whether coadministration with psyllium increases the tolerability of prebiotics in IBS warrants further study.

TRIAL REGISTRATION NUMBER

NCT03265002.

Best Practices for Probiotic Research in Athletic and Physically Active Populations: Guidance for Future Randomized Controlled Trials

Probiotic supplementation, traditionally used for the prevention or treatment of a variety of disease indications, is now recognized in a variety of population groups including athletes and those physically active for improving general health and performance. However, experimental and clinical trials with probiotics commonly suffer from design flaws and different outcome measures, making comparison and synthesis of conclusions difficult. Here we review current randomized controlled trials (RCTs) using probiotics for performance improvement, prevention of common illnesses, or general health, in a specific target population (athletes and those physically active). Future RCTs should address the key elements of (1) properly defining and characterizing a probiotic intervention, (2) study design factors, (3) study population characteristics, and (4) outcome measures, that will allow valid conclusions to be drawn. Careful evaluation and implementation of these elements should yield improved trials, which will better facilitate the generation of evidence-based probiotic supplementation recommendations for athletes and physically active individuals.

Consumer's acceptability and health consciousness of probiotic and prebiotic of non-dairy products

Human gut microbiota is a protective agent of intestinal and systemic health, and its modulation is of great interest for human wellbeing. In the world of biotics, besides probiotics, prebiotics, and synbiotics, also appears the denomination of "postbiotics" and "psychobiotics". Fermented dairy products are, traditionally, the major source of probiotics. Nevertheless, due to the increasing number of lactose-intolerant individuals and strict vegetarians, there is a need for innovative non-dairy products. Non-dairy biotics are being included in the normal diet and due to technological advances, many products are created using non-conventional food matrices like kombucha tea, herbal tea, baking mix, and cereal-based products. The microorganisms most used as probiotics in many of the non-dairy products are strains belonging to the genera Bifidobacterium, Enterococcus, Lactobacillus, Lactococcus, Streptococcus, and Bacillus, and some yeast strains namely Saccharomyces cerevisiae var. boulardii. Recently, several other yeasts have been described as having probiotic properties. This review describes gut-derived effects in humans of possible microorganisms, such as yeasts, and bacteria, isolated from non-dairy fermented and non-fermented foods and beverages. The microorganisms responsible for the processing of these non-dairy fermented products, together with the prebiotics, form a class of nutrients that have been proven to be beneficial for our gut health.

Prebiotic fructans have greater impact on luminal microbiology and CD3+ T cells in healthy siblings than patients with Crohn's disease: A pilot study investigating the potential for primary prevention of inflammatory bowel disease

BACKGROUND & AIMS

Siblings of people with Crohn's disease (CD) share aspects of the disease phenotype (raised faecal calprotectin, altered microbiota), which are markers of risk for their own development of CD. The aim was to determine whether supplementation with prebiotic oligofructose/inulin induces a prebiotic response and impacts the risk phenotype in CD patients and siblings.

METHODS

Patients with inactive CD (n = 19, CD activity index <150) and 12 of their unaffected siblings (with calprotectin >50 μg/g) ingested oligofructose/inulin (15 g/day) for three weeks. Faecal microbiota (qPCR), intestinal permeability (lactulose-rhamnose test), blood T cells (flow-cytometry) and calprotectin (ELISA) were measured at baseline and follow-up.

RESULTS

Following oligofructose/inulin, calprotectin did not significantly change in patients (baseline mean 537 SD 535 μg/g; follow-up mean 974 SD 1318 μg/g, p = 0.08) or siblings (baseline mean 73 SD 90 μg/g: follow up mean 58 SD 72 μg/g, p = 0.62). Faecal Bifidobacteria and Bifidobacterium longum increased in patients and siblings; Bifidobacterium adolescentis and Roseburia spp. increased only in siblings. Compared with patients, siblings had a greater magnitude change in Bifidobacteria (+14.6% vs +0.4%, p = 0.028), B. adolescentis (+1.1% vs 0.0% p = 0.006) and Roseburia spp. (+1.5% vs -0.1% p = 0.004). Intestinal permeability decreased significantly in patients after oligofructose/inulin to a level that was similar to siblings. Blood T cell abundance reduced in siblings but not patients following oligofructose/inulin.

CONCLUSIONS

Oligofructose/inulin supplementation did not significantly impact calprotectin, but the prebiotic effect was more marked in healthy siblings compared with patients with inactive CD and was associated with alterations in other CD risk markers. Future research should focus on dietary intervention, including with prebiotics, in the primary prevention of CD.

Conducting research on diet-microbiome interactions: A review of current challenges, essential methodological principles, and recommendations for best practice in study design

Diet is one of the strongest modulators of the gut microbiome. However, the complexity of the interactions between diet and the microbial community emphasises the need for a robust study design and continued methodological development. This review aims to summarise considerations for conducting high-quality diet-microbiome research, outline key challenges unique to the field, and provide advice for addressing these in a practical manner useful to dietitians, microbiologists, gastroenterologists and other diet-microbiome researchers. Searches of databases and references from relevant articles were conducted using the primary search terms 'diet', 'diet intervention', 'dietary analysis', 'microbiome' and 'microbiota', alone or in combination. Publications were considered relevant if they addressed methods for diet and/or microbiome research, or were a human study relevant to diet-microbiome interactions. Best-practice design in diet-microbiome research requires appropriate consideration of the study population and careful choice of trial design and data collection methodology. Ongoing challenges include the collection of dietary data that accurately reflects intake at a timescale relevant to microbial community structure and metabolism, measurement of nutrients in foods pertinent to microbes, improving ability to measure and understand microbial metabolic and functional properties, adequately powering studies, and the considered analysis of multivariate compositional datasets. Collaboration across the disciplines of nutrition science and microbiology is crucial for high-quality diet-microbiome research. Improvements in our understanding of the interaction between nutrient intake and microbial metabolism, as well as continued methodological innovation, will facilitate development of effective evidence-based personalised dietary treatments.

Development of a Repertoire and a Food Frequency Questionnaire for Estimating Dietary Fiber Intake Considering Prebiotics: Input from the FiberTAG Project

Most official food composition tables and food questionnaires do not provide enough data to assess fermentable dietary fibers (DF) that can exert a health effect through their interaction with the gut microbiota. The aim of this study was to develop a database and a food frequency questionnaire (FFQ) allowing detailed DF intake estimation including prebiotic (oligo)saccharides. A repertoire of DF detailing total, soluble DF, insoluble DF and prebiotic (oligo)saccharides (inulin-type fructans, fructo-oligosaccharides and galacto-oligosaccharides) in food products consumed in Europe has been established. A 12 month FFQ was developed and submitted to 15 healthy volunteers from the FiberTAG study. Our data report a total DF intake of 38 g/day in the tested population. Fructan and fructo-oligosaccharides intake, linked notably to condiments (garlic and onions) ingestion, reached 5 and 2 g/day, respectively, galacto-oligosaccharides intake level being lower (1 g/day). We conclude that the FiberTAG repertoire and FFQ are major tools for the evaluation of the total amount of DF including prebiotics. Their use can be helpful in intervention or observational studies devoted to analyze microbiota–nutrient interactions in different pathological contexts, as well as to revisit DF intake recommendations as part of healthy lifestyles considering specific DF.

A systematic review of reviews identifying UK validated dietary assessment tools for inclusion on an interactive guided website for researchers: www.nutritools.org

Background: Health researchers may struggle to choose suitable validated dietary assessment tools (DATs) for their target population. The aim of this review was to identify and collate information on validated UK DATs and validation studies for inclusion on a website to support researchers to choose appropriate DATs.Design: A systematic review of reviews of DATs was undertaken. DATs validated in UK populations were extracted from the studies identified. A searchable website was designed to display these data. Additionally, mean differences and limits of agreement between test and comparison methods were summarized by a method, weighting by sample size.Results: Over 900 validation results covering 5 life stages, 18 nutrients, 6 dietary assessment methods, and 9 validation method types were extracted from 63 validated DATs which were identified from 68 reviews. These were incorporated into www.nutritools.org. Limits of agreement were determined for about half of validations. Thirty four DATs were FFQs. Only 17 DATs were validated against biomarkers, and only 19 DATs were validated in infant/children/adolescents.Conclusions: The interactive www.nutritools.org website holds extensive validation data identified from this review and can be used to guide researchers to critically compare and choose a suitable DAT for their research question, leading to improvement of nutritional epidemiology research.

Relative Validity and Reproducibility of a Food Frequency Questionnaire to Assess Nutrients and Food Groups of Relevance to the Gut Microbiota in Young Children

Dietary fiber is an important nutrient for the gut microbiota, with different fiber fractions having different effects. The aim of this study was to determine the relative validity and reproducibility of a food frequency questionnaire (EAT5 FFQ) for measuring intake of fiber, and low and high fiber foods, in studies examining diet and gut microbiota in young children. One hundred parents of 5-year old children completed the 123-item EAT5 FFQ on two occasions four weeks apart. A 3-day weighed diet record (WDR) was completed on non-consecutive days between FFQ appointments. Mean correlations between the (randomly chosen) FFQ and WDR were acceptable for nutrient and food group intakes (r = 0.34 and r = 0.41 respectively). Gross misclassification was below chance (12.5%) for quartiles of nutrient (mean 5.7%) and food group (mean 5.1%) intake. ‘Absolute values for surrogate categories’ suggested the FFQ clearly differentiated between highest and lowest quartiles for all nutrients and food groups tested. Mean correlations between repeat administrations of the FFQ suggested very good reproducibility for nutrients (r = 0.83) and food groups (r = 0.80). The EAT5 FFQ appears to be an appropriate tool for investigating the intake of nutrients and food groups of relevance to the gut microbiota, and is the first FFQ validated to measure total, soluble and insoluble non-starch polysaccharide intakes in young children.

Habitual dietary fibre intake influences gut microbiota response to an inulin-type fructan prebiotic: a randomised, double-blind, placebo-controlled, cross-over, human intervention study

Dysbiotic gut microbiota have been implicated in human disease. Diet-based therapeutic strategies have been used to manipulate the gut microbiota towards a more favourable profile. However, it has been demonstrated that large inter-individual variability exists in gut microbiota response to a dietary intervention. The primary objective of this study was to investigate whether habitually low dietary fibre (LDF)v. high dietary fibre (HDF) intakes influence gut microbiota response to an inulin-type fructan prebiotic. In this randomised, double-blind, placebo-controlled, cross-over study, thirty-four healthy participants were classified as LDF or HDF consumers. Gut microbiota composition (16S rRNA bacterial gene sequencing) and SCFA concentrations were assessed following 3 weeks of daily prebiotic supplementation (Orafti®Synergy 1; 16 g/d) or placebo (Glucidex®29 Premium; 16 g/d), as well as after 3 weeks of the alternative intervention, following a 3-week washout period. In the LDF group, the prebiotic intervention led to an increase inBifidobacterium(P=0·001). In the HDF group, the prebiotic intervention led to an increase inBifidobacterium(P<0·001) andFaecalibacterium(P=0·010) and decreases inCoprococcus(P=0·010), Dorea(P=0·043) andRuminococcus(Lachnospiraceae family) (P=0·032). This study demonstrates that those with HDF intakes have a greater gut microbiota response and are therefore more likely to benefit from an inulin-type fructan prebiotic than those with LDF intakes. Future studies aiming to modulate the gut microbiota and improve host health, using an inulin-type fructan prebiotic, should take habitual dietary fibre intake into account.

Long-term impact of the low-FODMAP diet on gastrointestinal symptoms, dietary intake, patient acceptability, and healthcare utilization in irritable bowel syndrome

BACKGROUND

The low-FODMAP diet is a frequently used treatment for irritable bowel syndrome (IBS). Most research has focused on short-term FODMAP restriction; however, guidelines recommend that high-FODMAP foods are reintroduced to individual tolerance. This study aimed to assess the long-term effectiveness of the low-FODMAP diet following FODMAP reintroduction in IBS patients.

METHODS

Patients with IBS were prospectively recruited to a questionnaire study following completion of dietitian-led low-FODMAP education. At baseline and following FODMAP restriction (short term) only, gastrointestinal symptoms were measured as part of routine clinical care. Following FODMAP reintroduction, (long term), symptoms, dietary intake, acceptability, food-related quality of life (QOL), and healthcare utilization were assessed. Data were reported for patients who continued long-term FODMAP restriction (adapted FODMAP) and/or returned to a habitual diet (habitual).

KEY RESULTS

Of 103 patients, satisfactory relief of symptoms was reported in 12% at baseline, 61% at short-term follow-up, and 57% at long-term follow-up. At long-term follow-up, 84 (82%) patients continued an 'adapted FODMAP' diet (total FODMAP intake mean 20.6, SD 14.9 g/d) compared with 19 (18%) of patients following a 'habitual' diet (29.4, SD 22.9 g/d, P=.039). Nutritional adequacy was not compromised for either group. The 'adapted FODMAP' group reported the diet cost significantly more than the 'habitual' group (P<.001) and affected social eating (P<.01) but there was no effect on food-related QOL. Healthcare utilization was similar between both groups.

CONCLUSION AND INFERENCES

Low-FODMAP education is effective for long-term IBS management, enables a nutritionally adequate diet, and is broadly acceptable to patients.

Fermentable Carbohydrates [FODMAPs] Exacerbate Functional Gastrointestinal Symptoms in Patients With Inflammatory Bowel Disease: A Randomised, Double-blind, Placebo-controlled, Cross-over, Re-challenge Trial

BACKGROUND AND AIMS

Preliminary evidence suggests that fermentable carbohydrate restriction might ameliorate functional gastrointestinal symptoms [FGS] in inflammatory bowel disease [IBD]. Our aim was to determine whether fermentable carbohydrates exacerbate FGS in IBD using a randomised, double-blinded, placebo-controlled, re-challenge trial.

METHODS

Patients with quiescent IBD and FGS responsive to a low FODMAP diet were allocated to a series of 3-day [d] fermentable carbohydrate challenges in random order [fructan, 12 g/d; galacto-oligosaccharides [GOS] 6 g/d; sorbitol, 6 g/d; and glucose placebo, 12 g/d], each separated by a washout period. Symptoms and stool output were measured daily during the challenges.

RESULTS

Thirty-two patients with IBD, fulfilling criteria for irritable bowel syndrome, functional bloating, or functional diarrhoea, were recruited and data were available for 29 patients completing all arms [12 Crohn's disease, 17 ulcerative colitis]. Significantly fewer patients reported adequate relief of FGS on the final day day of the fructan challenge [18/29, 62.1%] compared with glucose [26/29, 89.7%] [p = 0.033]. There was greater severity of pain [1.1 vs 0.5, p = 0.004], bloating [1.3 vs 0.6, p = 0.002], flatulence [1.5 vs 0.7, p = 0.004], and faecal urgency [0.9 vs 0.4, p = 0.014] on the final day of fructan challenge compared with glucose.

CONCLUSIONS

At the relatively high doses used, fructans, but not GOS or sorbitol, exacerbated FGS in quiescent IBD. Further research is required to determine whether a low FODMAP diet reduces FGS in IBD and the degree of FODMAP restriction required for symptom improvement.

Functional and therapeutic potential of inulin: A comprehensive review

Inulin as a heterogeneous blend of fructose polymers is diversely found in nature primarily as storage carbohydrates in plants. Besides, inulin is believed to induce certain techno-functional and associated properties in food systems. Inulin owing to its foam forming ability has been successfully used as fat replacer in quite a wide range of products as dairy and baked products. Furthermore, it is known to impart certain nutritional and therapeutic benefits that extend apart to improve health and reduce the risk of many lifestyle related diseases. Additionally, as a functional ingredient, Inulin has been adopted in various efficacy studies involving animal and human studies to function as a prebiotic, in promoting good digestive health, influencing lipid metabolism and has some beneficial roles in ensuring optimum levels of glucose and insulin. This review article is an attempt to present a comprehensive overview on both techno-functional and therapeutic potential of inulin.

Role of microbiota in the pathogenesis of functional disorders of the lower GI tract: Work in progress

Functional bowel disorders affect a significant proportion of people word wide. Patients suffer from longstanding symptoms of abdominal pain or discomfort in combination with abnormal bowel habits. The evidence for role of microbiota is currently contradictory and descriptive. This review aims to summarize the reasons which include methodological differences in DNA extraction and sample handling along with other factors such as diet, prior antibiotic use and transit, all important major determinants of microbiota which are difficult to control. Randomized studies of specific intervention in which such factors are varied may improve reproducibility and consistency of findings in future research.

Validation and reproducibility of an Australian caffeine food frequency questionnaire

The aim of this study was to measure validity and reproducibility of a caffeine food frequency questionnaire (C-FFQ) developed for the Australian population. The C-FFQ was designed to assess average daily caffeine consumption using four categories of food and beverages including; energy drinks; soft drinks/soda; coffee and tea and chocolate (food and drink). Participants completed a seven-day food diary immediately followed by the C-FFQ on two consecutive days. The questionnaire was first piloted in 20 adults, and then, a validity/reproducibility study was conducted (n = 90 adults). The C-FFQ showed moderate correlations (r = .60), fair agreement (mean difference 63 mg) and reasonable quintile rankings indicating fair to moderate agreement with the seven-day food diary. To test reproducibility, the C-FFQ was compared to itself and showed strong correlations (r = .90), good quintile rankings and strong kappa values (κ = 0.65), indicating strong reproducibility. The C-FFQ shows adequate validity and reproducibility and will aid researchers in Australia to quantify caffeine consumption.

Influence of habitual dietary fibre intake on the responsiveness of the gut microbiota to a prebiotic: protocol for a randomised, double-blind, placebo-controlled, cross-over, single-centre study

INTRODUCTION

The commensal gut microbiota have been shown to have an impact on human health as aberrant gut microbiota have been linked to disease. Dietary constituents are influential in shaping the gut microbiota. Diet-specific therapeutic strategies may therefore play a role in optimising human health via beneficial manipulation of the gut microbiota. Research has suggested that an individual's baseline gut microbiota composition may influence how the gut microbiota respond to a dietary intervention and individuals with differing habitual dietary intakes appear to have distinct baseline gut microbiota compositions. The responsiveness of the gut microbiota may therefore be influenced by habitual dietary intakes. This study aims to investigate what influence differing habitual dietary fibre intakes have on the responsiveness of the gut microbiota to a prebiotic intervention.

METHODS AND ANALYSIS

In this randomised, double-blind, placebo-controlled, cross-over, single-centre study, 20 low dietary fibre (dietary fibre intake <18 g/day for females and <22 g/day for males) and 20 high dietary fibre (dietary fibre intake ≥25 g/day for females and ≥30 g/day for males) consumers will be recruited. Participants will be randomised to a placebo (Glucidex 29 Premium) or a prebiotic (Synergy 1) intervention for 3 weeks with a 3-week washout followed by 3 weeks of the alternative intervention. Outcome measures of gut microbiota composition (using 16S rRNA gene sequencing) and functional capacity (faecal short chain fatty acid concentrations and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt)) as well as appetite (visual analogue scale appetite questionnaire) will be assessed at the beginning and end of each intervention phase.

ETHICS AND DISSEMINATION

The Massey University Human Ethics Committee approved this study (Massey University HEC: Southern A application-15/34). Results will be disseminated through peer-review journal publications, conference presentations and a summary of findings will be distributed to participants.

TRIAL REGISTRATION NUMBER

ACTRN12615000922572; Pre-results.

Altered gastrointestinal microbiota in irritable bowel syndrome and its modification by diet: probiotics, prebiotics and the low FODMAP diet

Irritable bowel syndrome (IBS) is a functional bowel disorder characterised by abdominal pain or discomfort with disordered defecation. This review describes the role of the gastrointestinal (GI) microbiota in the pathogenesis of IBS and how dietary strategies to manage symptoms impact on the microbial community. Evidence suggests a dysbiosis of the luminal and mucosal colonic microbiota in IBS, frequently characterised by a reduction in species of Bifidobacteria which has been associated with worse symptom profile. Probiotic supplementation trials suggest intentional modulation of the GI microbiota may be effective in treating IBS. A smaller number of prebiotic supplementation studies have also demonstrated effectiveness in IBS whilst increasing Bifidobacteria. In contrast, a novel method of managing IBS symptoms is the restriction of short-chain fermentable carbohydrates (low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet). Studies consistently demonstrate clinical effectiveness of the low FODMAP diet in patients with IBS. However, one unintentional consequence of this dietary intervention is its impact on the microbiota. This leads to an interesting paradox; namely, increasing luminal Bifidobacteria through probiotic supplementation is associated with a reduction in IBS symptoms while in direct conflict to this, the low FODMAP diet has clinical efficacy but markedly reduces luminal Bifidobacteria concentration. Given the multifactorial aetiology of IBS, the heterogeneity of symptoms and the complex and diverse nature of the microbiome, it is probable that both interventions are effective in patient subgroups. However combination treatment has never been explored and as such, presents an exciting opportunity for optimising clinical management, whilst preventing potentially deleterious effects on the GI microbiota.

Dietary intake of inulin-type fructans in active and inactive Crohn's disease and healthy controls: a case-control study

BACKGROUND AND AIMS

Prebiotic inulin-type fructans are widely consumed in the diet and may have contrasting effects in Crohn's disease by stimulating gut microbiota and/or by generating functional gastrointestinal symptoms. The aim of this study was to measure fructan and oligofructose intakes in patients with active and inactive Crohn's disease compared with healthy controls.

METHODS

Patients with active Crohn's disease (n = 98), inactive Crohn's (n = 99) and healthy controls (n = 106) were recruited to a case-control study. Dietary intake of inulin-type fructans was measured using a specific food frequency questionnaire and was compared between the three groups and between patients with different disease phenotypes (Montreal classification). Associations between intakes and disease activity (Harvey-Bradshaw Index, HBI) were also undertaken.

RESULTS

Patients with active Crohn's disease had lower fructan intakes (median 2.9 g/d, interquartile range [IQR] 1.8) than those with inactive Crohn's (3.6 g/d, 2.1, p = 0.036) or controls (3.9 g/d, 2.1, p = 0.003) and lower oligofructose intakes (2.8 g/d, 1.8) than those with inactive Crohn's (3.5 g/d, 2.2, p = 0.048) or controls (3.8 g/d, 2.1, p = 0.003). There were no differences in intakes related to disease site or behaviour. There were negative correlations between HBI well-being score and fructan intake (ρ = -0.154, p = 0.03) and oligofructose intake (ρ = -0.156, p = 0.028) and for the HBI abdominal pain score and fructan (ρ = -0.164, p = 0.021) and oligofructose intake (ρ = -0.157, p = 0.027).

CONCLUSIONS

Patients with active Crohn's disease consume lower quantities of fructans and oligofructose than their inactive counterparts and healthy controls. The impact of lower intakes of prebiotic fructans on gut microbiota is unknown and warrants further research.

Review article: the aetiology, diagnosis, mechanisms and clinical evidence for food intolerance

BACKGROUND

Food intolerance is non-immunological and is often associated with gastrointestinal symptoms.

AIM

To focus on food intolerance associated with gastrointestinal symptoms and critically appraise the literature in relation to aetiology, diagnosis, mechanisms and clinical evidence.

METHODS

A search using the terms and variants of food intolerance, lactose, FODMAP, gluten, food chemicals within Pubmed, Embase and Scopus was carried out and restricted to human studies published in English. Additionally, references from relevant papers were hand searched for other appropriate studies.

RESULTS

Food intolerance affects 15-20% of the population and may be due to pharmacological effects of food components, noncoeliac gluten sensitivity or enzyme and transport defects. There have been significant advances in understanding the scientific basis of gastrointestinal food intolerance due to short-chain fermentable carbohydrates (FODMAPs). The most helpful diagnostic test for food intolerance is food exclusion to achieve symptom improvement followed by gradual food reintroduction. A low FODMAP diet is effective, however, it affects the gastrointestinal microbiota and FODMAP reintroduction to tolerance is part of the management strategy.

CONCLUSIONS

There is increasing evidence for using a low FODMAP diet in the management of functional gastrointestinal symptoms where food intolerance is suspected. Exclusion diets should be used for as short a time as possible to induce symptom improvement, and should be followed by gradual food reintroduction to establish individual tolerance. This will increase dietary variety, ensure nutritional adequacy and minimise impact on the gastrointestinal microbiota.

Mechanisms and efficacy of dietary FODMAP restriction in IBS

IBS is a debilitating condition that markedly affects quality of life. The chronic nature, high prevalence and associated comorbidities contribute to the considerable economic burden of IBS. The pathophysiology of IBS is not completely understood and evidence to guide management is variable. Interest in dietary intervention continues to grow rapidly. Ileostomy and MRI studies have demonstrated that some fermentable carbohydrates increase ileal luminal water content and breath hydrogen testing studies have demonstrated that some carbohydrates also increase colonic hydrogen production. The effects of fermentable carbohydrates on gastrointestinal symptoms have also been well described in blinded, controlled trials. Dietary restriction of fermentable carbohydrates (popularly termed the 'low FODMAP diet') has received considerable attention. An emerging body of research now demonstrates the efficacy of fermentable carbohydrate restriction in IBS; however, limitations still exist with this approach owing to a limited number of randomized trials, in part due to the fundamental difficulty of placebo control in dietary trials. Evidence also indicates that the diet can influence the gut microbiota and nutrient intake. Fermentable carbohydrate restriction in people with IBS is promising, but the effects on gastrointestinal health require further investigation.

Validation of an FFQ to assess short-term antioxidant intake against 30 d food records and plasma biomarkers

OBJECTIVE

To validate a brief FFQ developed for capturing short-term antioxidant intake in a sample of US college students.

DESIGN

A seventy-four-item antioxidant FFQ was developed based on major antioxidant sources in the American diet. The FFQ was validated against 30 d food records (FR) and plasma antioxidant concentrations. The reliability of the FFQ was evaluated by two FFQ administered at a 1-month interval. Settings University of Connecticut, CT, USA.

SUBJECTS

Sixty healthy college students.

RESULTS

Estimates of dietary antioxidants from the FFQ were moderately to highly correlated with those estimated from the 30 d FR (r = 0·29-0·80; P < 0·05) except for γ-tocopherol and β-cryptoxanthin. Total antioxidant capacity from diet only or from diet and supplements estimated by the 30 d FR and FFQ were highly correlated (r = 0·67 and 0·71, respectively; P < 0·0001). The FFQ categorized 91 % of participants into the same or adjacent tertiles of antioxidant intake as the 30 d FR. Most dietary carotenoids estimated from the FFQ were correlated with plasma levels (P < 0·05). Correlation coefficients for test-retest reliability ranged from 0·39 to 0·86. More than 94 % of the participants were classified in the same or adjacent tertiles between the two administrations of the FFQ.

CONCLUSIONS

The brief FFQ demonstrated reasonable validity for capturing a comprehensive antioxidant intake profile. This FFQ is applicable in epidemiological or clinical studies to capture short-term antioxidant intake or to simply document the variations of antioxidant intake in intervention trials. Cross-validation studies are warranted in other target populations.

Mechanisms and effectiveness of prebiotics in modifying the gastrointestinal microbiota for the management of digestive disorders

The gastrointestinal microbiota is a complex ecosystem with each human individual hosting at least 160 different bacterial strains. Our understanding of its role is rapidly expanding as a result of the molecular microbiological techniques that can accurately characterise its composition and 'omics' technologies that measure its metabolic activity. Since 1995, extensive research has investigated the prebiotic concept, which describes how supplementation of some non-digestible oligosaccharides can stimulate the growth and/or activity of specific genera including bifidobacteria. However, the vast majority of studies are in healthy human subjects, with few undertaken in patients with disorders relevant to clinical nutrition. Marked alterations of the luminal microbiota have been demonstrated in patients with digestive disorders, highlighting mechanisms through which they might be involved in their pathogenesis, including higher clostridia in patients who develop diarrhoea during enteral nutrition and the influence of bifidobacteria on intestinal dendritic cell phenotype in Crohn's disease. The impact of prebiotics on the intestinal microbiota of healthy people has not been consistently replicated in patients with digestive disorders. For example, a number of studies show that inulin/oligofructose do not increase bifidobacteria in enteral nutrition and Crohn's disease. Indeed, in Crohn's disease and irritable bowel syndrome there is evidence that some prebiotics in high doses worsen functional symptoms. Unlike healthy human subjects, patients experience a number of issues that may alter their gastrointestinal microbiota (disease, antibiotics and inflammation) and the use of microbiota modifying therapies, such as prebiotics, do not always elicit the same effects in patients as they do in healthy people.