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Randomised controlled trial: effects of gluten-free diet on symptoms and the gut microenvironment in irritable bowel syndrome.
Algera, JP, Magnusson, MK, Öhman, L, Störsrud, S, Simrén, M, Törnblom, H
Alimentary pharmacology & therapeutics. 2022;56(9):1318-1327
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The majority of irritable bowel syndrome (IBS) patients relate their symptoms to intake of certain foods. The gut microenvironment, where microbiota, food components and the nervous system interact, is suggested to play a key role in gastrointestinal (GI) symptom generation in a subset of IBS patients. The main aim of this study was to assess and compare the efficacy of the gluten-free and gluten-containing diets in terms of effects on GI symptoms in IBS patients. Secondary aims where to identify the putative link between gut microenvironment and the diets´ effect on GI symptoms, and to identify potential predictors of clinical response to the gluten-free diet. This study is a single-centre, double-blind, randomised, placebo-controlled, cross-over trial. Adult sex- and age-matched IBS patients (n=20) and healthy controls (HC) (n=21) were recruited, randomised and challenged with gluten (14 g/day) and rice flour, both for 2 weeks, while adhering to a strict gluten-free diet. Results indicate that a gluten-free diet may affect IBS symptoms in general, and bowel habits in a subset of IBS patients. The gluten-free diet has distinct effect on the gut microenvironment in IBS patients who respond favourably to gluten reduction. Authors conclude that the gut microenvironment may be of importance in the clinical response to the gluten-free diet in IBS, and future studies should aim to further assess these factors in relation to clinical response to the gluten-free diet.
Abstract
BACKGROUND A gluten-free diet reduces symptoms in some patients with irritable bowel syndrome (IBS) through unclear mechanisms. AIMS To assess the effects of gluten-free versus gluten-containing diet on symptoms and the gut microenvironment, and to identify predictors of response to the gluten-free diet in IBS METHODS Twenty patients with IBS and 18 healthy controls (HC) followed a gluten-free diet during two 14-day intervention periods where they sprinkled either gluten (14 g/day) or rice flour powder over their meals. Primary outcomes included effects of the interventions on IBS symptoms (IBS-SSS) and bowel habits. Secondary outcomes included effects of gluten-free diet on faecal microbiota and metabolite profile. RESULTS IBS symptoms improved during the gluten-free (p = 0.02), but not the gluten-containing period, with no difference between the interventions. IBS patients reported fewer loose stools during the gluten-free intervention (p = 0.01). Patients with IBS and HC presented distinct metabolite profiles based on the effects of the gluten-free diet (p < 0.001). True responders (reduced IBS-SSS by ≥50 solely after gluten-free period) and non-responders were discriminated based on the effects of the gluten-free diet on the microbiota (p < 0.01) and metabolite profiles (p < 0.001). The response to the gluten-free diet could be predicted by the metabolite profile before the intervention (p < 0.001). CONCLUSIONS A gluten-free diet may influence symptoms in a subset of patients with IBS, with a particular effect on bowel habits. A gluten-free diet seems to impact the gut microenvironment. Responsiveness to the gluten-free diet may be predicted by the metabolite profile. CLINICALTRIALS gov: NCT03869359.
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The effect of gluten in adolescents and young adults with gastrointestinal symptoms: a blinded randomised cross-over trial.
Crawley, C, Savino, N, Halby, C, Sander, SD, Andersen, AN, Arumugam, M, Murray, J, Christensen, R, Husby, S
Alimentary pharmacology & therapeutics. 2022;55(9):1116-1127
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The gluten-free diet (GFD) has gained increasing popularity among healthy people without coeliac disease or wheat allergy. The main reasons for following a GFD are weight control, the perception that a GFD is healthier, and the presence of symptoms after gluten ingestion. The aim of this study was to address the hypothesis that adding gluten to the diet results in a self-reported worsening of gastrointestinal symptoms (primary outcome) and mental health (key secondary outcomes) in a well-characterised group of adolescents. This study was arranged in two phases; the first phase began with 2 weeks of a GFD, and if the participants responded to the GFD, they proceeded to phase 2. Phase 2 was a double-blinded randomised trial with cross-over and consisted of three periods, each lasting 7 days: (1) a challenge with gluten/placebo, (2) wash-out phase, and (3) the second challenge with placebo/gluten. Results show that it was not possible to detect a difference in symptoms between gluten and placebo at a group level. Furthermore, on an individual level, there was a comparable number of gluten responders and placebo responders, underscoring the insignificant difference between gluten and placebo. Authors conclude that adding gluten to the diet does not induce gastrointestinal symptoms or worsened mental health in adolescents.
Abstract
BACKGROUND The popularity of the gluten-free diet and sales of gluten-free products have increased immensely. AIMS To investigate whether gluten induces gastrointestinal symptoms, measured by self-reported questionnaires, as well as mental health symptoms in adolescents from a population-based cohort. METHODS The eligible participants (n = 273) were recruited from a population-based cohort of 1266 adolescents and had at least four different gastrointestinal symptoms. Phase one (n = 54) was a run-in phase where the participants lived gluten-free for 2 weeks. If they improved they continued to phase 2 (n = 33), a blinded randomised cross-over trial. Participants were blindly randomised either to start with 7 days of gluten, eating two granola bars containing 10 g of gluten or to 7 days on placebo, eating two granola bars without gluten, followed by the reverse and separated by a 7-day washout period. The effects of the intervention on gastrointestinal symptoms and mental health symptoms were assessed. RESULTS In total, 54/273 participants entered the run-in phase and 35 were eligible for randomization. A total of 33 were randomised and 32 completed the trial. The median age was 20.3 (IQR 19.2-20.9) and 32/33 participants were females. Compared with a placebo, gluten did not induce gastrointestinal symptoms. The difference in the average VAS was -0.01 (95% confidence interval -2.07 to 2.05). Nor did we find a difference in the outcomes measuring mental health. CONCLUSION Compared with placebo, adding gluten to the diet did not induce gastrointestinal symptoms or worsened mental health in adolescents recruited from a population-based cohort. The trial registration number is NCT04639921.