The low FODMAP diet in clinical practice: where are we and what are the long-term considerations?

A diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) improves functional bowel symptoms and is a second-line dietary management strategy for the treatment of irritable bowel syndrome (IBS). The diet is complex and involves three stages: restriction, reintroduction and personalisation and clinical effectiveness is achieved with dietitian-led education; however, this is not always available. The aim of this review is to provide an update on the evidence for using the low FODMAP diet, with a focus on the impact of FODMAP restriction and reintroduction considering long-term management of IBS in a clinical setting. Randomised controlled trials have assessed symptom response, quality of life, dietary intake and changes to the gut microbiota during FODMAP restriction. Systematic reviews and meta-analyses consistently report that FODMAP restriction has a better symptom response compared with control diets and a network analysis reports the low FODMAP diet is superior to other dietary treatments for IBS. Research focused on FODMAP reintroduction and personalisation is limited and of lower quality, however common dietary triggers include wheat, onion, garlic, pulses and milk. Dietitian-led delivery of the low FODMAP diet is not always available and alternative education delivery methods, e.g. webinars, apps and leaflets, are available but remove the personalised approach and may be less acceptable to patients and may introduce safety concerns in terms of nutritional adequacy. Predicting response to the low FODMAP diet using symptom severity or a biomarker is of great interest. More evidence on less restrictive approaches and non-dietitian-led education delivery methods are needed.

Optimizing educational methods for the low FODMAP diet in disorders of gut-brain interaction: A feasibility randomized controlled trial.

BACKGROUND: A diet low in fermentable oligo-saccharides, di-saccharides, mono-saccharides and polyols (low FODMAP diet) is complex and clinical effectiveness is achieved with dietitian-led education, although dietitian availability in clinical practice varies. This study aimed to assess the feasibility of undertaking a trial to investigate the clinical and cost-effectiveness of different education delivery methods of the low FODMAP diet in patients with disorders of gut-brain interaction (DGBI). METHODS: In this feasibility randomized controlled trial, patients with DGBI requiring the low FODMAP diet were randomized to receive one of the following education delivery methods: booklet, app, or dietitian. Recruitment and retention rates, acceptability, symptoms, stool output, quality of life, and dietary intake were assessed. KEY RESULTS: Fifty-one patients were randomized with a recruitment rate of 2.4 patients/month and retention of 48 of 51 (94%). Nobody in the booklet group strongly agreed that this education delivery method enabled them to self-manage symptoms without further support, compared to 7 of 14 (50%) in the dietitian group (p = 0.013). More patients reported adequate relief of symptoms in the dietitian group (12, 80%) compared with the booklet group (7, 39%; p = 0.026), but not when compared to the app group (10, 63%, p > 0.05). There was a greater decrease in the IBS-SSS score in the dietitian group (mean -153, SD 90) compared with the booklet group (mean -90, SD 56; p = 0.043), but not when compared with the app group (mean -120, SD 62; p = 0.595). CONCLUSIONS & INFERENCES: Booklets were the least acceptable education delivery methods. Dietitian-led consultations led to high levels of clinical effectiveness, followed by the app, while the dietitian was superior to booklets alone. However, an adequately powered clinical trial is needed to confirm clinical effectiveness of these education delivery methods.

Gut Symptoms during FODMAP Restriction and Symptom Response to Food Challenges during FODMAP Reintroduction: A Real-World Evaluation in 21,462 Participants Using a Mobile Application.

BACKGROUND: There is limited evidence regarding the use of low FODMAP diet apps. This study aimed to evaluate the effectiveness of an app intended to reduce symptoms in FODMAP restriction and symptoms and tolerance of high FODMAP food challenges during FODMAP reintroduction and personalisation. METHODS: Data were collected from 21,462 users of a low FODMAP diet app. Self-reported gut symptoms during FODMAP restriction, reintroduction, and personalisation and dietary triggers were identified from symptom response data for FODMAP food challenges. RESULTS: Compared with baseline, at the end of FODMAP restriction, participants (n = 20,553) reported significantly less overall symptoms (11,689 (57%) versus 9105 (44%)), abdominal pain (8196 (40%) versus 6822 (33%)), bloating (11,265 (55%) versus 9146 (44%)), flatulence (10,318 (50%) 8272 (40%)), and diarrhoea (6284 (31%) versus 4961 (24%)) and significantly more constipation (5448 (27%) versus 5923 (29%)) (p < 0.001 for all). During FODMAP reintroduction, participants (n = 2053) completed 8760 food challenges; the five most frequent challenges and n/N (%) of dietary triggers identified were wheat bread 474/1146 (41%), onion 359/918 (39%), garlic 245/699 (35%), milk 274/687 (40%), and wheat pasta 222/548 (41%). The most frequently reported symptoms during food challenges were overall symptoms, abdominal pain, bloating, and flatulence. CONCLUSIONS: In a real-world setting, a low FODMAP diet app can help users improve gut symptoms and detect dietary triggers for long-term self-management.

Development and validation of an inflammatory bowel disease nutrition self-screening tool (IBD-NST) for digital use.

Background and aim: The identification of, and timely intervention for, patients with impaired nutritional status may reduce inflammatory bowel disease (IBD) complications. This study aimed to develop and validate an IBD-specific nutrition self-screening tool (IBD-NST) that identifies patients at nutrition risk. Methods: An expert IBD panel was consulted to support development of an IBD-NST. The tool was assessed in different cohorts of patients attending IBD outpatient clinics for face, content and convergent validity and repeat reliability. The tool was compared with (i) the malnutrition universal screening tool to assess face validity and (ii) subjective global assessment (SGA), hand-grip strength (HGS) and mid-arm muscle circumference to assess convergent validity. Tool content was informed by agreement between assessment tools, sensitivity analysis and chi-squared tests. The IBD-NST was completed electronically twice, 1 week apart to assess repeat reliability using observed agreement and kappa statistic. Statistical significance assumed at p < 0.05. Results: In total, 282 IBD patients (175 with Crohn's disease) were recruited to validate the IBD-NST. The final validated IBD-NST includes body mass index (BMI), weight loss and IBD-specific nutrition-focussed questions which were acceptable to patients. It identified patients at risk of malnutrition, moderately or severely malnourished patients and patients at nutritional risk. The IBD-NST identified 54/179 (30%) patients at moderate or high nutrition risk and had excellent repeat reliability in 85 patients [r = 0.77 (95% CI 0.669 to 0.746)]. Conclusion: The IBD-NST is a self-screening tool, validated for use as either a paper or e-health version, that identifies patients at nutrition risk who are likely to benefit from dietetic assessment and intervention. Furthermore, patients with IBD symptoms who are concerned about their dietary intake can potentially access dietetic care more easily therefore encouraging greater self-management of IBD-related symptoms. The routine use of the IBD-NST as a self-screening tool would enable patient-led care in the outpatient setting and may facilitate timely access to dietetic care.

British Dietetic Association consensus guidelines on the nutritional assessment and dietary management of patients with inflammatory bowel disease.

BACKGROUND: Despite increased awareness of diet and nutrition being integral to the management of patients with inflammatory bowel disease (IBD), there are gaps in the knowledge of IBD healthcare providers regarding nutrition. Furthermore, high quality evidence on nutritional assessment and dietary management of IBD is limited. A Delphi consensus from a panel of experts allows for best-practice guidelines to be developed, especially where high quality evidence is limited. The aim was to develop guidelines for the nutritional assessment and dietary management of IBD using an eDelphi online consensus agreement platform. METHODS: Seventeen research topics related to IBD and nutrition were systematically reviewed. Searches in Cochrane, Embase®, Medline® and Scopus® electronic databases were performed. GRADE was used to develop recommendations. Experts from the IBD community (healthcare professionals and patients with IBD) were invited to vote anonymously on the recommendations in a custom-built online platform. Three rounds of voting were carried out with updated iterations of the recommendations and evaluative text based on feedback from the previous round. RESULTS: From 23,824 non-duplicated papers, 167 were critically appraised. Fifty-five participants completed three rounds of voting and 14 GRADE statements and 42 practice statements achieved 80% consensus. Comprehensive guidance related to nutrition assessment, nutrition screening and dietary management is provided. CONCLUSIONS: Guidelines on the nutritional assessment and dietary management of IBD have been developed using evidence-based consensus to improve equality of care. The statements and practice statements developed demonstrate the level of agreement and the quality and strength of the guidelines.

Long-term personalized low FODMAP diet improves symptoms and maintains luminal Bifidobacteria abundance in irritable bowel syndrome.

BACKGROUND: Short-term trials demonstrate the low FODMAP diet improves symptoms of irritable bowel syndrome (IBS) but impacts nutrient intake and the gastrointestinal microbiota. The aim of this study was to investigate clinical symptoms, nutrient intake, and microbiota of patients with IBS 12 months after starting a low FODMAP diet. METHODS: Participants enrolled in a previous short-term clinical trial and who had been through structured FODMAP restriction, reintroduction, and personalization were invited to participate in a follow-up study at one time point at 12 months. Gastrointestinal symptoms, stool output, dietary intake, and quality of life were recorded. Stool samples were collected and analyzed for microbiota (qPCR) and short-chain fatty acids (SCFA). Data were compared with baseline (prior to any intervention in the original clinical trial) using non-parametric statistics. KEY RESULTS: Eighteen participants were included in the study. Adequate relief of symptoms occurred in 5/18 (28%) at baseline and increased to 12/18 (67%) following long-term personalized low FODMAP diet (p = 0.039). There was a reduction in IBS-SSS total score between baseline (median 227, IQR 99) and long term (154, 89; p < 0.001). Bifidobacteria abundance was not different between baseline (median 9.29 log10 rRNA genes/g, IQR 1.45) and long term (9.20 log10 rRNA genes/g, 1.41; p = 0.766, q = 0.906); however, there were lower concentrations of total SCFA, acetate, propionate, and butyrate. CONCLUSIONS: In this long-term analysis, two thirds of patients reported adequate relief of symptoms after 12 months of personalized low FODMAP diet that did not result in differences from baseline in Bifidobacteria. FODMAP reintroduction and personalization may normalize some of the effects of short-term FODMAP restriction.

Food-related quality of life is impaired in inflammatory bowel disease and associated with reduced intake of key nutrients.

BACKGROUND: Inflammatory bowel disease (IBD) may impact the extent to which food, eating, and drinking bring satisfaction and enjoyment to peoples' lives, and this may impact dietary intake. The prevalence of an impaired food-related quality of life (FR-QoL), its associated factors, and its impact on diet have not been explored. OBJECTIVES: To measure the prevalence and nature of the burden of impaired FR-QoL in people with IBD, the factors associated with these, and their associations with nutrient intake. METHODS: We recruited 1576 outpatients with IBD (≥16 years old) in person from 7 IBD centers across the United Kingdom. Patients completed validated questionnaires to measure their FR-QoL, quality of life (QoL), distress, fatigue, anxiety, and depression. Dietary intake was recorded using the European Prospective Investigation into Cancer FFQ. A health professional recorded disease activity, Montreal classification, blood results, BMI, and malnutrition risk. FR-QoL was regressed onto explanatory variables using univariable and multivariable analyses. RESULTS: Data from 1221 patients were available (77.4% response; Crohn's disease, 65%; ulcerative colitis, 35%). The FR-QoL mean (± SD) score was 80.8 ± 26.9, with wide ranges (minimum, 29; maximum, 145). Following multivariable regression, the strongest associations with FR-QoL were the number of recent disease flares (5 flares ß = -12.7; P < 0.001), the IBD-specific QoL (ß = 0.33; P < 0.001), and IBD-related distress (ß = -0.26; P < 0.001). Patients with poorer FR-QoL had lower intakes of fiber (nonstarch polysaccharide; Q1 to Q5 difference = 2.1 g/d; 95% CI: 0.4-3.8; P = 0.048), calcium (192.6 mg/d; 95% CI: 112.5-272.6; P < 0.001), phosphorus (167 mg/d; 95% CI: 58-276; P = 0.041), and magnesium (34.4 mg/d; 95% CI: 9.3-59.4; P = 0.041). CONCLUSIONS: Impaired FR-QoL is prevalent in IBD and is associated with recurrent disease flares, a reduced IBD-specific QoL, and greater IBD-related distress. A poorer FR-QoL was associated with lower intakes of key nutrients of importance to IBD, including those relating to gut health and bone mineralization.

Nutrient Intake, Diet Quality, and Diet Diversity in Irritable Bowel Syndrome and the Impact of the Low FODMAP Diet.

BACKGROUND: Individuals with irritable bowel syndrome (IBS) may modify their diet, which may pose nutritional risk. Further, some dietary approaches, such as a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs), are restrictive and may contribute to nutritional inadequacy. OBJECTIVE: Our aim was to evaluate habitual nutrient intake, diet quality, and diversity in IBS and the effect of a 4-week low FODMAP diet on these parameters compared with controls. DESIGN: Data from two randomized controlled trials were included for this secondary analysis. Participants were randomized to low FODMAP diet (n=63) or control diet (sham diet n=48, habitual diet n=19). PARTICIPANTS/SETTING: Participants included 130 individuals with IBS referred to a tertiary center in London, UK between January 2010 to June 2011 and January 2013 to November 2014. INTERVENTION: Participants in one trial were randomized to receive either low FODMAP dietary counseling or sham control dietary counseling. In the other, they were randomized to receive low FODMAP dietary counseling or to continue habitual diet. All advice was provided by a specialist dietitian. MAIN OUTCOME MEASURES: Habitual (usual) dietary intake at baseline (n=130) and after a 4-week intervention period was measured using 7-day food records. STATISTICAL ANALYSES PERFORMED: Analysis of covariance and χ2 tests evaluated differences across groups at 4 weeks. RESULTS: When examining habitual intake of individuals with IBS, fiber intake was low, with only 6 (5%) achieving the target (30 g/day). In those receiving low FODMAP advice, there was no difference in intake of most nutrients compared with controls. However, there was lower intake of starch (109 g/day) vs habitual control diet (128 g/day; P=0.030), and higher intake of vitamin B-12 (6.1 µg/day) vs habitual (3.9 µg/day) and sham control diets (4.7 µg/day; P<0.01). Overall scores for diet quality were lower after low FODMAP advice vs habitual control diet (P<0.01). CONCLUSION: This study demonstrates many individuals with IBS fail to meet dietary reference values for multiple nutrients. A 4-week low FODMAP diet, when delivered by a specialist dietitian, does not impact on intake of most nutrients or diet diversity but decreases diet quality compared with control diets.

Nutrition Assessment in Crohn's Disease using Anthropometric, Biochemical, and Dietary Indexes: A Narrative Review.

Malnutrition is common in patients with Crohn's disease and negatively influences immunity and quality of life. The optimal tools for nutrition assessment in patients with Crohn's disease are not clearly defined and lead to variations in practice. With this review, we aimed to appraise the existing evidence for nutrition assessment of patients with Crohn's disease compared with healthy controls and provide a comprehensive guide with relevant measures applicable to clinical practice. A literature search using Medline, Embase, and Scopus from inception to October 1, 2018, was conducted. Forty-one articles that assessed body composition, muscle strength, micronutrient status and/or dietary intake in adults with Crohn's disease compared with an age- and sex-matched healthy individuals were included. There were heterogeneous findings on nutritional status in patients with Crohn's disease compared with healthy controls. Only one article reported a clinically significant difference for body mass index; however, significant deficits in fat mass, fat-free mass, and muscle strength were observed in patients with Crohn's disease compared with healthy controls, with more pronounced differences with increasing disease activity and length of diagnosis. Most research reported significantly lower serum micronutrients in patients with Crohn's disease compared with healthy controls. Half of studies measuring micronutrient intake reported lower intakes in patients with Crohn's disease compared with healthy controls. Fruit and vegetable intake was also lower in patients with Crohn's disease. Difficulties characterizing the type and prevalence of malnutrition exist due to the heterogeneous nature of Crohn's disease and warrants continued investigation. As a result of this review, we advocate that a nutrition assessment should include more parameters than weight and body mass index.

British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults.

Ulcerative colitis and Crohn's disease are the principal forms of inflammatory bowel disease. Both represent chronic inflammation of the gastrointestinal tract, which displays heterogeneity in inflammatory and symptomatic burden between patients and within individuals over time. Optimal management relies on understanding and tailoring evidence-based interventions by clinicians in partnership with patients. This guideline for management of inflammatory bowel disease in adults over 16 years of age was developed by Stakeholders representing UK physicians (British Society of Gastroenterology), surgeons (Association of Coloproctology of Great Britain and Ireland), specialist nurses (Royal College of Nursing), paediatricians (British Society of Paediatric Gastroenterology, Hepatology and Nutrition), dietitians (British Dietetic Association), radiologists (British Society of Gastrointestinal and Abdominal Radiology), general practitioners (Primary Care Society for Gastroenterology) and patients (Crohn's and Colitis UK). A systematic review of 88 247 publications and a Delphi consensus process involving 81 multidisciplinary clinicians and patients was undertaken to develop 168 evidence- and expert opinion-based recommendations for pharmacological, non-pharmacological and surgical interventions, as well as optimal service delivery in the management of both ulcerative colitis and Crohn's disease. Comprehensive up-to-date guidance is provided regarding indications for, initiation and monitoring of immunosuppressive therapies, nutrition interventions, pre-, peri- and postoperative management, as well as structure and function of the multidisciplinary team and integration between primary and secondary care. Twenty research priorities to inform future clinical management are presented, alongside objective measurement of priority importance, determined by 2379 electronic survey responses from individuals living with ulcerative colitis and Crohn's disease, including patients, their families and friends.

A multicentre Study of Nutrition Risk Assessment in Adult Patients with Inflammatory Bowel Disease Attending Outpatient Clinics.

BACKGROUND: Overnutrition and undernutrition can affect patients with inflammatory bowel disease (IBD). Although all IBD outpatients should be screened for nutrition risk, screening is not routinely performed, potentially leading to reduced identification and treatment. This study aimed to estimate the prevalence of nutrition risk in adult IBD outpatients and the proportion of cases who discussed diet and/or nutrition during their routine clinical appointment. METHODS: Adults with IBD attending outpatient clinics at 4 hospitals in Greece and in UK were recruited. Demographic and anthropometric data were collected using face-to-face patient interviews and clinical records. Patients were classified as high (i.e., body mass index [BMI] < 18.5 or 18.5-20 kg/m2 and weight loss > 5%), moderate (i.e., BMI 20-25 kg/m2 and weight loss > 5%) or low risk of undernutrition and high risk of obesity (i.e., BMI 25-30% and weight gain > 5%). The proportion of patients who discussed diet and/or nutrition during their clinical appointment was calculated. RESULTS: In total, 390 IBD patients participated. Sixteen (4%) patients were underweight, 113 (29%) were overweight and 71 (18%) were obese. Twenty-one (5%) patients were at high risk of undernutrition; of these 4 (19%) were under dietetic care. Of those at high risk of undernutrition, 11 (52%) had discussed diet and/or nutrition during their routine clinical appointment. Fifty-six (14%) patients had gained more than 5% weight since their last recorded/reported weight and 19 (5%) were at high risk of obesity. CONCLUSIONS: Few patients were identified to be at high risk of undernutrition and less than a fifth of these were under dietetic care. Overnutrition is a growing problem in IBD with almost half of adult patients being overweight or obese. Diet and/or nutrition were not routinely discussed in this group of IBD outpatients.

A low FODMAP diet is associated with changes in the microbiota and reduction in breath hydrogen but not colonic volume in healthy subjects.

BACKGROUND & AIMS: Ingestion of poorly digested, fermentable carbohydrates (fermentable oligo-, di-, mono-saccharides and polyols; FODMAPs) have been implicated in exacerbating intestinal symptoms and the reduction of intake with symptom alleviation. Restricting FODMAP intake is believed to relieve colonic distension by reducing colonic fermentation but this has not been previously directly assessed. We performed a randomised controlled trial comparing the effect of a low FODMAP diet combined with either maltodextrin or oligofructose on colonic contents, metabolites and microbiota. METHODS: A parallel randomised controlled trial in healthy adults (n = 37). All subjects followed a low FODMAP diet for a week and supplemented their diet with either maltodextrin (MD) or oligofructose (OF) 7g twice daily. Fasted assessments performed pre- and post-diet included MRI to assess colonic volume, breath testing for hydrogen and methane, and stool collection for microbiota analysis. RESULTS: The low FODMAP diet was associated with a reduction in Bifidobacterium and breath hydrogen, which was reversed by oligofructose supplementation. The difference in breath hydrogen between groups post-intervention was 27ppm (95% CI 7 to 50, P<0.01). Colonic volume increased significantly from baseline in both groups (OF increased 110ml (19.6%), 95% CI 30ml to 190ml, P = 0.01; MD increased 90ml (15.5%), 95% CI 6ml to 175ml, P = 0.04) with no significant difference between them. Colonic volumes correlated with total breath hydrogen + methane. A divergence in Clostridiales abundance was observed with increased abundance of Ruminococcaceae in the maltodextrin group, while in the oligofructose group, Lachnospiraceae decreased. Subjects in either group with high methane production also tended to have high microbial diversity, high colonic volume and greater abundance of methanogens. CONCLUSION: A low FODMAP diet reduces total bacterial count and gas production with little effect on colonic volume.

A Diet Low in FODMAPs Reduces Symptoms in Patients With Irritable Bowel Syndrome and A Probiotic Restores Bifidobacterium Species: A Randomized Controlled Trial.

BACKGROUND & AIMS: Dietary restriction of fermentable carbohydrates (a low FODMAP diet) has been reported to reduce symptoms in some patients with irritable bowel syndrome (IBS). We performed a randomized, placebo-controlled study to determine its effects on symptoms and the fecal microbiota in patients with IBS. METHODS: We performed a 2×2 factorial trial of 104 patients with IBS (18-65 years old), based on the Rome III criteria, at 2 hospitals in the United Kingdom. Patients were randomly assigned (blinded) to groups given counselling to follow a sham diet or diet low in FODMAPs for 4 weeks, along with a placebo or multistrain probiotic formulation, resulting in 4 groups (27 receiving sham diet/placebo, 26 receiving sham diet/probiotic, 24 receiving low FODMAP diet /placebo, and 27 receiving low FODMAP diet/probiotic). The sham diet restricted a similar number of staple and non-staple foods as the low FODMAP diet; the diets had similar degrees of difficulty to follow. Dietary counselling was given to patients in all groups and data on foods eaten and compliance were collected. The incidence and severity of 15 gastrointestinal symptoms and overall symptoms were measured daily for 7 days before the study period; along with stool frequency and consistency. At baseline, global and individual symptoms were measured, along with generic and disease-specific health-related quality of life, using standard scoring systems. All data were collected again at 4 weeks, and patients answered questions about adequate symptom relief. Fecal samples were collected at baseline and after 4 weeks and analyzed by quantitative PCR and 16S rRNA sequencing. The co-primary endpoints were adequate relief of symptoms and stool Bifidobacterium species abundance at 4 weeks. RESULTS: There was no significant interaction between the interventions in adequate relief of symptoms (P = .52) or Bifidobacterium species (P = .68). In the intention-to-treat analysis, a higher proportion of patients in the low FODMAP diet had adequate symptom relief (57%) than in the sham diet group (38%), although the difference was not statistically significant (P = .051). In the per-protocol analysis, a significantly higher proportion of patients on the low FODMAP diet had adequate symptom relief (61%) than in the sham diet group (39%) (P = .042). Total mean IBS-Severity Scoring System score was significantly lower for patients on the low FODMAP diet (173 ± 95) than the sham diet (224 ± 89) (P = .001), but not different between those given probiotic (207 ± 98) or placebo (192 ± 93) (P = .721) Abundance of Bifidobacterium species was lower in fecal samples from patients on the low FODMAP diet (8.8 rRNA genes/g) than patients on the sham diet (9.2 rRNA genes/g) (P = .008), but higher in patients given probiotic (9.1 rRNA genes/g) than patients given placebo (8.8 rRNA genes/g) (P = .019). There was no effect of the low FODMAP diet on microbiota diversity in fecal samples. CONCLUSIONS: In a placebo-controlled study of patients with IBS, a low FODMAP diet associates with adequate symptom relief and significantly reduced symptom scores compared with placebo. It is not clear whether changes resulted from collective FODMAP restriction or removal of a single component, such as lactose. Co-administration of the multistrain probiotic increased numbers of Bifidobacterium species, compared with placebo, and might be given to restore these bacteria to patients on a low FODMAP diet. Trial registration no: ISRCTN02275221.

The challenges of control groups, placebos and blinding in clinical trials of dietary interventions.

High-quality placebo-controlled evidence for food, nutrient or dietary advice interventions is vital for verifying the role of diet in optimising health or for the management of disease. This could be argued to be especially important where the benefits of dietary intervention are coupled with potential risks such as compromising nutrient intake, particularly in the case of exclusion diets. The objective of the present paper is to explore the challenges associated with clinical trials in dietary research, review the types of controls used and present the advantages and disadvantages of each, including issues regarding placebos and blinding. Placebo-controlled trials in nutrient interventions are relatively straightforward, as in general placebos can be easily produced. However, the challenges associated with conducting placebo-controlled food interventions and dietary advice interventions are protean, and this has led to a paucity of placebo-controlled food and dietary advice trials compared with drug trials. This review appraises the types of controls used in dietary intervention trials and provides recommendations and nine essential criteria for the design and development of sham diets for use in studies evaluating the effect of dietary advice, along with practical guidance regarding their evaluation. The rationale for these criteria predominantly relate to avoiding altering the outcome of interest in those delivered the sham intervention in these types of studies, while not compromising blinding.

Variable access to quality nutrition information regarding inflammatory bowel disease: a survey of patients and health professionals and objective examination of written information.

BACKGROUND: Patients with inflammatory bowel disease (IBD) report a range of nutritional and dietary problems and high-quality written information should be available on these. There is little research investigating the availability and quality of such information for patients with IBD. OBJECTIVE: This study assessed the type and quality of written information on nutrition and diet available to patients with IBD and the opinions of patients and health professionals. SETTING AND PARTICIPANTS: Seventy-two patients with IBD were recruited from a large gastroenterology outpatient centre in England. One hundred dietitians from across the United Kingdom were also recruited. METHODS: Face-to-face surveys were conducted with patients with IBD. Questions regarding the use, format and usefulness of dietary information received were probed. Dietitians were surveyed regarding written dietary information used in clinical practice. Samples of IBD-specific dietary information used across the UK were objectively assessed using two validated tools. MAIN RESULTS: The majority of patients rated written information as 'good' or 'very good', with the most useful information relating to 'general diet and IBD'. Forty-nine (49%) dietitians reported gaps in written information available for patients with IBD. Fifty-three different samples of IBD-specific information sheets were returned, with widely variable objective quality ratings. Commercially produced written information scored greater than locally produced information (BMA tool, P < 0.05). CONCLUSIONS: Patient access to high-quality, written, IBD-specific dietary information is variable. IBD-specific written nutrition information needs to be developed in accordance with validated tools to empower patients, encourage self-management and overcome nutritional implications of IBD.

A rapid, simple questionnaire to assess gastrointestinal symptoms after oral ferrous sulphate supplementation.

BACKGROUND: Oral iron supplementation is often associated with rapid onset of gastrointestinal side-effects. The aim of this study was to develop and trial a short, simple questionnaire to capture these early side-effects and to determine which symptoms are more discriminating. METHODS: The study was a double-blind placebo-controlled randomized parallel trial with one week treatment followed by one week wash-out. Subjects were randomized into two treatment groups (n = 10/group) to receive either ferrous sulphate (200 mg capsules containing 65 mg of iron) or placebo, both to be taken at mealtimes twice daily during the treatment period. Subjects completed the questionnaires daily for 14 days. The questionnaire included gastrointestinal symptoms commonly reported to be associated with the oral intake of ferrous iron salts (i.e. nausea, vomiting, heartburn, abdominal pain, diarrhoea, and constipation). RESULTS: Seventy five per cent of participants reporting the presence of one or more symptoms in the first week of the study were in the ferrous sulphate group. In the second week of the study (i.e. wash-out), 67% of the participants reporting one or more symptom(s) were in the ferrous sulphate group. In the first week of the study (treatment) the number of symptoms reported by participants in the ferrous sulphate group (mean ± SEM = 6.7 ± 1.7) was significantly higher than that for participants in the placebo group (1.2 ± 0.5) (p = 0.01). In the second week of the study (wash-out) the number of symptoms reported by participants in the ferrous sulphate group (4.6 ± 2.0) appeared higher than for participants in the placebo group (1.0 ± 0.7) although this did not reach significance (p = 0.12). Events for which the gastrointestinal symptom questionnaire was most discriminatory between ferrous sulphate and placebo groups were: heartburn, abdominal pain and the presence of black stools (all p ≤ 0.03). CONCLUSIONS: A tool for the detection of commonly-occurring side effects should not require large study numbers to be effective. With just 10 subjects per group (iron or placebo), this simple questionnaire measures gastrointestinal side-effects associated with oral iron (ferrous sulphate) supplementation, and would be appropriate for use in intervention studies or clinical trials. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02146053 (21/05/2014).

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.

Short-chain carbohydrates and functional gastrointestinal disorders.

Carbohydrates occur across a range of foods regularly consumed including grains such as wheat and rye, vegetables, fruits, and legumes. Short-chain carbohydrates with chains of up to 10 sugars vary in their digestibility and subsequent absorption. Those that are poorly absorbed exert osmotic effects in the intestinal lumen increasing its water volume, and are rapidly fermented by bacteria with consequent gas production. These two effects alone may underlie most of the induction of gastrointestinal symptoms after they are ingested in moderate amounts via luminal distension in patients with visceral hypersensitivity. This has been the basis of the use of lactose-free diets in those with lactose malabsorption and of fructose-reduced diets for fructose malabsorption. However, application of such dietary approaches in patients with functional bowel disorders has been restricted to observational studies with uncertain efficacy. As all dietary poorly absorbed short-chain carbohydrates have similar and additive effects in the intestine, a concept has been developed to regard them collectively as FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) and to evaluate a dietary approach that restricts them all. In patients with irritable bowel syndrome, there is now an accumulating body of evidence, based on observational and comparative studies, and on randomized-controlled trials that supports the notion that FODMAPs trigger gastrointestinal symptoms in patients with functional bowel disorders, and that a diet low in FODMAPs offers considerable symptom relief in the majority of patients who use it.