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Objective: This systematic review aims to synthesise existing literature to examine the relationship between natural food chemical components and reported symptoms., Design: A systematic literature review was completed. Databases CINAHL (Ebscohost), Medline (Ovid), Scopus, Informit Health and Google Scholar were searched to identify relevant articles. The population included human studies of adults (≥17 years) and excluded those with IgE-mediate food allergies. Studies examining food chemical components or 'food chemical elimination diets' and symptoms were included. Data was synthesised based on clinical conditions and specific food chemical components examined. The risk of bias was assessed using the Academy of Nutrition and Dietetics 'Quality Criteria Checklist: Primary Research'., Results: Of the 1659 articles retrieved, 21 met inclusion criteria. This included eight randomised controlled trials, four non-randomised controlled trials, four cohort studies with placebo-controlled challenge, one prospective cohort study, three cross sectional cohort studies, one case-controlled study. Available studies support the role of a low-histamine diet for symptoms in chronic urticaria and low-salicylate diet for reducing sino-nasal symptoms in aspirin exacerbated respiratory disease and chronic rhinosinusitis and/or asthma. While further evidence is needed to verify the role of glutamate in respiratory, pain, asthma and gastrointestinal symptoms., Conclusions: Food chemical elimination diets may improve condition-specific symptoms across the adult cohorts outlined within this review, with the strongest evidence to support the role of a low-histamine diet for management of symptoms in chronic urticaria and a low-salicylate diet in aspirin exacerbated respiratory disease and/or asthma. Further well-designed trials are needed to elucidate the effect of specific natural food chemical components on symptoms., Trial Registration: Systematic review number: CRD42022322511., (© 2024 The Author(s). Clinical & Experimental Allergy published by John Wiley & Sons Ltd.)

Introduction: Orthorexia, a harmful obsession with eating healthily, may develop from illnesses characterized by dietary restriction, including irritable bowel syndrome (IBS) and eating disorders (ED). Evidence of disordered eating in IBS exists, but orthorexia has not been assessed. This cross-sectional study in adults (≥18 years) assessed presence and characteristics of disordered eating and orthorexia in IBS, compared to control subjects (CS) and ED., Methods: IBS participants met Rome IV, and ED participants met DSM-5 criteria. Disordered eating was assessed using "sick, control, one-stone, fat, food" (SCOFF, ≥2 indicating disordered eating), and orthorexia by the eating habits questionnaire (EHQ). Secondary measures included stress (PSS); anxiety (HADS-A); food-related quality of life (Fr-QoL), and dietary intake (CNAQ)., Key Results: In 202 IBS (192 female), 34 ED (34 female), and 109 CS (90 female), more IBS (33%) and ED (47%) scored SCOFF≥2 compared to CS (16%, p < 0.001, chi-square). IBS and ED had higher orthorexia symptom severity compared to CS (EHQ IBS 82.9 ± 18.1, ED 90.1 ± 19.6, and CS 73.5 ± 16.9, p < 0.001, one-way ANOVA). IBS and ED did not differ for SCOFF or EHQ (p > 0.05). Those with IBS and disordered eating had higher orthorexia symptom severity (EHQ 78.2 ± 16.6 vs. 92.4 ± 17.5, p < 0.001, independent t-test), worse symptoms (IBS-SSS 211.0 ± 78.4 vs. 244.4 ± 62.5, p = 0.008, Mann-Whitney U test), higher stress (p < 0.001, independent t-test), higher anxiety (p = 0.002, independent t-test), and worse FR-QoL (p < 0.001, independent t-test)., Conclusions and Inferences: Disordered eating and orthorexia symptoms occur frequently in IBS, particularly in those with worse gastrointestinal symptoms, higher stress, and anxiety. Clinicians could consider these characteristics when prescribing dietary therapies., (© 2024 The Authors. Neurogastroenterology & Motility published by John Wiley & Sons Ltd.)

Background: Evidence-based dietary management approaches for symptoms of dyspepsia are lacking. This study aimed to compare dietary factors, symptoms, quality of life (QOL) and salivary cortisol in dyspepsia participants and healthy controls., Methods: A cross-sectional survey was completed by adults with dyspepsia (n = 121) meeting Rome IV criteria and healthy controls (n = 52). Outcome measures included self-reported questionnaires about dietary habits, triggers, restrictions, dietary management approaches, nutritional intake, psychological variables, QOL, gastrointestinal symptoms, and optional cortisol awakening response (CAR) via saliva samples. Data were analyzed using Chi-square or Mann-Whitney U. Cortisol awakening response data was analyzed using moderated regression controlling for age, gender and distress., Key Results: Fermentable carbohydrates (FODMAPs) (55%) were the most reported trigger in adults with dyspepsia. The dyspepsia group (88%) followed special diets more than controls (47%; p < 0.001), with a low FODMAP diet being most common (69%). The dyspepsia group consumed less fiber (p = 0.014), calcium (p = 0.015), and total FODMAPs (p < 0.001) than controls. There was a greater prevalence of comorbid anxiety (41%) and depression (31%) in dyspepsia compared to controls (15% and 12%, respectively, p < 0.001 and p = 0.006). The dyspepsia group had poorer QOL and greater gastrointestinal symptom severity than controls (p < 0.001). There was a negative association between anxiety and CAR (p = 0.001) in dyspepsia but not in controls., Conclusions & Inferences: Adults with dyspepsia follow special diets more than controls and perceive FODMAPs as a key dietary trigger. These findings highlight the importance of monitoring nutritional adequacy and QOL, and emphasize mechanisms of depleted stress response in dyspepsia, warranting further exploration., (© 2023 The Authors. Neurogastroenterology & Motility published by John Wiley & Sons Ltd.)

Background: Monosodium glutamate (MSG) has been identified as a trigger of abdominal pain in irritable bowel syndrome (IBS), but the mechanism is unknown. This study examined whether MSG causes visceral hypersensitivity using a water-avoidance stress (WAS) mouse model of visceral pain., Methods: Mice were divided into four groups receiving treatment for 6 days: WAS + MSG gavage, WAS + saline gavage, sham-WAS + MSG gavage, and sham-WAS + saline gavage. The acute effects of intraluminal administration of 10 μM MSG on jejunal extrinsic afferent nerve sensitivity to distension (0-60 mmHg) were examined using ex vivo extracellular recordings. MSG was also applied directly to jejunal afferents from untreated mice. Glutamate concentration was measured in serum, and in the serosal compartment of Ussing chambers following apical administration., Key Results: Acute intraluminal MSG application increased distension responses of jejunal afferent nerves from mice exposed to WAS + MSG. This effect was mediated by wide dynamic range and high-threshold units at both physiologic and noxious pressures (10-60 mmHg, p < 0.05). No effect of MSG was observed in the other groups, or when applied directly to the jejunal afferent nerves. Serum glutamate was increased in mice exposed to WAS + MSG compared to sham-WAS + saline, and serosal glutamate increased using WAS tissue (p = 0.0433)., Conclusions and Inferences: These findings demonstrate that repeated exposure to MSG in mice leads to sensitization of jejunal afferent nerves to acute ex vivo exposure to MSG. This may contribute to visceral hypersensitivity reported in response to MSG in patients with IBS., (© 2023 The Authors. Neurogastroenterology & Motility published by John Wiley & Sons Ltd.)

There is concern that use of restrictive therapeutic diets, such as those used in disorders of the gut-brain interaction (DGBI), may increase disordered eating. In this issue of Neurogastroenterology and Motility, Burton Murray et al. and Peters et al. both demonstrate a high prevalence of disordered eating in patients with gastrointestinal conditions, particularly those with DGBI. Given these findings, it is likely that orthorexia is common in this patient group, although this was not directly examined in these studies. Orthorexia nervosa is described as an obsessive and unsafe focus on eating foods perceived as healthy. This mini-review therefore focuses on orthorexia by conducting a scoping review, as per the PRISMA extension for scoping reviews, aimed to assess the prevalence of orthorexia, and associations between orthorexia and restrictive eating practices. While a wide range of orthorexia prevalence has been reported (0%-97%) across the 57 studies included, no studies assessed prevalence specifically in gastrointestinal conditions. Four of eight studies describing diseases associated with specific dietary patterns suggested that participants who followed a diet for "digestive issues" or "food intolerances" were at higher orthorexia risk. These results suggest that dietary modifications may be a factor contributing to orthorexia. Additionally, we provide a commentary on the clinical implications of the findings for gastrointestinal conditions including a clinical flow chart. Clinicians should consider if a restrictive diet is appropriate for individuals with DGBI and include screening for disordered eating prior to implementation of dietary modifications. Future prospective studies should evaluate orthorexia within this patient group., (© 2022 The Authors. Neurogastroenterology & Motility published by John Wiley & Sons Ltd.)

Background: The low FODMAP (fermentable oligo-, di-, monosaccharides, and polyols) diet reduces functional gastrointestinal symptoms (FGID) when implemented by dietitian-delivered education in clinical trials, but it is unknown how well the diet is followed in routine clinical care and if differences exist when implemented by physician or dietitian. This study aimed to evaluate the real-world experience of patients recommended the diet., Methods: This case-series interviewed FGID patients attending a gastroenterology clinic with previous recommendation to trial the low FODMAP diet, examining who recommended the diet and what their percentage improvement was. To evaluate implementation of the diet's 3 phases, questions were constructed based on current literature and clinical guidelines regarding length of initial restriction and food knowledge (Phase-1), number of foods re-challenged (Phase-2) and food re-introduction as tolerated (Phase-3). The comprehensive nutrition assessment questionnaire provided daily FODMAP intake. Data were analyzed using chi-squared tests., Key Results: In 80 patients (21 male), the diet was recommended by the gastroenterologist in 53%, general practitioner 22%, dietitian 9% and other 15%. 30% saw a dietitian for guidance. 55% reported a ≥50% symptom improvement. The diet was followed appropriately during Phase-1 by 78% (with vs without a dietitian, 96% vs 71%; P = .02), Phase-2 by 48% (70% vs 39%; P = .02) and Phase-3 by 40% (65% vs 29%; P < .01). A FODMAP intake of <12 g/d (considered therapeutic) was achieved by 44% (72% vs 31%; P < .01)., Conclusions & Inferences: Symptom improvement was reported in half of patients, but many did not reach the therapeutic FODMAP intake target, especially without dietitian education. Compliance was poor in Phase-2 and Phase-3 but improved with dietitian guidance., (© 2019 John Wiley & Sons Ltd.)

Background: A low fermentable carbohydrate (FODMAP) diet is used in quiescent inflammatory bowel disease when irritable bowel syndrome-like symptoms occur. There is concern that the diet could exacerbate inflammation by modifying microbiota and short-chain fatty acid (SCFA) production. We examined the effect of altering dietary FODMAP content on inflammation in preclinical inflammatory models., Methods: C57BL/6 mice were given 3% dextran sodium sulfate (DSS) in drinking water for 5 days and recovered for 3 weeks (postinflammatory, n = 12), or 5 days (positive-control, n = 12). Following recovery, DSS-treated or control mice (negative-control, n = 12) were randomized to 2-week low- (0.51 g/100 g total FODMAP) or high-FODMAP (4.10 g) diets. Diets mimicked human consumption containing fructose, sorbitol, galacto-oligosaccharide, and fructan. Colons were assessed for myeloperoxidase (MPO) activity and histological damage. Supernatants were generated for perforated patch-clamp recordings and cytokine measurement. Cecum contents were analyzed for microbiota, SCFA, and branched-chain fatty acids (BCFA). Data were analyzed by two-way ANOVA with Bonferroni., Key Results: Inflammatory markers were higher in the positive-control compared with negative-control and postinflammatory groups, but no differences occurred between the two diets within each treatment (MPO P > .99, histological scores P > .99, cytokines P > .05), or the perforated patch-clamp recordings (P > .05). Microbiota clustered mainly based on DSS exposure. No difference in SCFA content occurred. Higher total BCFA occurred with the low-FODMAP diet in positive-control (P < .01) and postinflammatory groups (P < .01)., Conclusions and Inferences: In this preclinical study, reducing dietary FODMAPs did not exacerbate nor mitigate inflammation. Microbiota profile changes were largely driven by inflammation rather than diet. Low FODMAP intake caused a shift toward proteolytic fermentation following inflammation., (© 2019 John Wiley & Sons Ltd.)

Breath hydrogen testing for assessing the presence of carbohydrate malabsorption is frequently applied to refine dietary restrictions on a low fermentable carbohydrate (FODMAP) diet. Its application has also been extended for the detection of small intestinal bacterial overgrowth. Recently, several caveats of its methodology and interpretation have emerged. A review of the evidence surrounding its application in the management of patients with a functional bowel disorder was performed. Studies were examined to assess limitations of testing methodology, interpretation of results, reproducibility, and how this relates to clinical symptoms. A wide heterogeneity in testing parameters, definition of positive/negative response, and the use of clinically irrelevant doses of test carbohydrate were common methodological limitations. These factors can subsequently impact the sensitivity, specificity, and false positive or negative detection rates. Evidence is also increasing on the poor intra-individual reproducibility in breath responses with repeated testing for fructose and lactulose. On the basis of these limitations, it is not surprising that the diagnosis of small intestinal bacterial overgrowth based on a lactulose breath test yields a wide prevalence rate and is unreliable. Finally, symptom induction during a breath test has been found to correlate poorly with the presence of carbohydrate malabsorption. The evidence suggests that breath hydrogen tests have limited clinical value in guiding clinical decision for the patient with a functional bowel disorder., (© 2017 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.)

The low fermentable, oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet has good evidence for use in the treatment of patients with irritable bowel syndrome. Importantly, patients are encouraged not to remain on a strict low FODMAP diet long-term, and many patients maintain symptom improvement with a relaxed, moderate FODMAP restriction. The re-challenge phase is crucial to assist patients in identifying specific dietary triggers, reduce the level of dietary restriction required, and increase prebiotic intake. Limited evidence is available to guide best practice, but, in practice, beneficial outcomes can be seen through strategic food reintroductions. Here, we set out some practical recommendations based on clinical experience. Dietitians should tailor the challenge process to the individual patient and their needs. Food challenges should aim to improve dietary variety and nutritional adequacy while considering specific food preferences and usual dietary habits. Identifying FODMAP subgroups that are well tolerated is helpful, allowing the reintroduction of some moderate to high FODMAP foods back into the diet without symptom induction. FODMAP subtypes that are less well tolerated may also be reintroduced, but dosage and frequency of consumption need to be individualized. Additional challenges that face dietitians include consideration of patients with multiple dietary restrictions such as in vegetarians or patients with diabetes who are simultaneously following a low FODMAP diet. Ensuring nutritional adequacy is essential. The outcome of the re-challenge process aims to find a balance between good symptom control and expansion of the diet., (© 2017 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.)