Jacqueline S. Barrett

Gluten Causes Gastrointestinal Symptoms in Subjects Without Celiac Disease: A Double-Blind Randomized Placebo-Controlled Trial

OBJECTIVES:Despite increased prescription of a gluten-free diet for gastrointestinal symptoms in individuals who do not have celiac disease, there is minimal evidence that suggests that gluten is a trigger. The aims of this study were to determine whether gluten ingestion can induce symptoms in non-celiac individuals and to examine the mechanism.METHODS:A double-blind, randomized, placebo-controlled rechallenge trial was undertaken in patients with irritable bowel syndrome in whom celiac disease was excluded and who were symptomatically controlled on a gluten-free diet. Participants received either gluten or placebo in the form of two bread slices plus one muffin per day with a gluten-free diet for up to 6 weeks. Symptoms were evaluated using a visual analog scale and markers of intestinal inflammation, injury, and immune activation were monitored.RESULTS:A total of 34 patients (aged 29–59 years, 4 men) completed the study as per protocol. Overall, 56% had human leukocyte antigen (HLA)-DQ2 and/or HLA-DQ8. Adherence to diet and supplements was very high. Of 19 patients (68%) in the gluten group, 13 reported that symptoms were not adequately controlled compared with 6 of 15 (40%) on placebo (P=0.0001; generalized estimating equation). On a visual analog scale, patients were significantly worse with gluten within 1 week for overall symptoms (P=0.047), pain (P=0.016), bloating (P=0.031), satisfaction with stool consistency (P=0.024), and tiredness (P=0.001). Anti-gliadin antibodies were not induced. There were no significant changes in fecal lactoferrin, levels of celiac antibodies, highly sensitive C-reactive protein, or intestinal permeability. There were no differences in any end point in individuals with or without DQ2/DQ8.CONCLUSIONS:“Non-celiac gluten intolerance” may exist, but no clues to the mechanism were elucidated.

Manipulation of dietary short chain carbohydrates alters the pattern of gas production and genesis of symptoms in irritable bowel syndrome.

Background and Aim:  Reduction of short‐chain poorly absorbed carbohydrates (FODMAPs) in the diet reduces symptoms of irritable bowel syndrome (IBS). In the present study, we aimed to compare the patterns of breath hydrogen and methane and symptoms produced in response to diets that differed only in FODMAP content.

Fermentable Carbohydrate Restriction Reduces Luminal Bifidobacteria and Gastrointestinal Symptoms in Patients with Irritable Bowel Syndrome

Preliminary studies indicate that dietary restriction of fermentable short-chain carbohydrates improves symptoms in irritable bowel syndrome (IBS). Prebiotic fructo-oligosaccharides and galacto-oligosaccharides stimulate colonic bifidobacteria. However, the effect of restricting fermentable short-chain carbohydrates on the gastrointestinal (GI) microbiota has never been examined. This randomized controlled trial aimed to investigate the effects of fermentable carbohydrate restriction on luminal microbiota, SCFA, and GI symptoms in patients with IBS. Patients with IBS were randomized to the intervention diet or habitual diet for 4 wk. The incidence and severity of symptoms and stool output were recorded for 7 d at baseline and follow-up. A stool sample was collected and analyzed for bacterial groups using fluorescent in situ hybridization. Of 41 patients randomized, 6 were withdrawn. At follow-up, there was lower intake of total short-chain fermentable carbohydrates in the intervention group compared with controls (P = 0.001). The total luminal bacteria at follow-up did not differ between groups; however, there were lower concentrations (P < 0.001) and proportions (P < 0.001) of bifidobacteria in the intervention group compared with controls when adjusted for baseline. In the intention-to-treat analysis, more patients in the intervention group reported adequate control of symptoms (13/19, 68%) compared with controls (5/22, 23%; P = 0.005). This randomized controlled trial demonstrated a reduction in concentration and proportion of luminal bifidobacteria after 4 wk of fermentable carbohydrate restriction. Although the intervention was effective in managing IBS symptoms, the implications of its effect on the GI microbiota are still to be determined.

Dietary poorly absorbed, short‐chain carbohydrates increase delivery of water and fermentable substrates to the proximal colon

Background  Functional gut symptoms are induced by inclusion and reduced by dietary restriction of poorly absorbed short‐chain carbohydrates (FODMAPs), but the mechanisms of action remain untested.

Reduction of dietary poorly absorbed short-chain carbohydrates (FODMAPs) improves abdominal symptoms in patients with inflammatory bowel disease—a pilot study

OBJECTIVE Functional gut symptoms are common in patients with inflammatory bowel disease (IBD). Since poorly absorbed, short-chain carbohydrates (FODMAPs) appear to play an important role in the induction of functional gut symptoms, we aimed to determine the effect of their dietary restriction on abdominal symptoms in patients with stable IBD and to examine factors associated with success of and adherence to the diet. MATERIAL AND METHOD 52 consecutive patients with Crohns disease and 20 with ulcerative colitis who received dietary advice at least 3 months prior at a gastrointestinal dietetic service in Victoria, Australia, underwent a retrospective telephone questionnaire. Information gathered included patient demographics, recall of dietary advice, dietary adherence, and change in gastrointestinal symptoms. RESULTS Up to 70% of patients were adherent to the diet. Approximately one in two patients responded (defined as improvement of at least 5 out of 10 in overall symptoms). Overall abdominal symptoms, abdominal pain, bloating, wind and diarrhoea improved in patients with Crohns disease and ulcerative colitis (p<0.02 for all), but constipation did not. For Crohns disease, efficacy was associated with dietary adherence (p= 0.033) and inefficacy with non-adherence (p=0.013). Sustained response was associated with post-secondary education and working 35 h per week or less (p<0.03). CONCLUSIONS These data suggest that reduction of FODMAP intake offers an efficacious strategy for patients with IBD who have concurrent functional gut symptoms. A controlled dietary intervention trial is indicated.

Review article: fructose malabsorption and the bigger picture.

Fructose is found widely in the diet as a free hexose, as the disaccharide, sucrose and in a polymerized form (fructans). Free fructose has limited absorption in the small intestine, with up to one half of the population unable to completely absorb a load of 25 g. Average daily intake of fructose varies from 11 to 54 g around the world. Fructans are not hydrolysed or absorbed in the small intestine.

Measurement of short-chain carbohydrates in common Australian vegetables and fruits by High-Performance Liquid Chromatography (HPLC)

Fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs) are short-chain carbohydrates that can be poorly absorbed by the small intestine and may have a wide range of effects on gastrointestinal processes. FODMAPs include lactose, fructose in excess of glucose, fructans and fructooligosaccharides (FOS, nystose, kestose), galactooligosaccharides (GOS, raffinose, stachyose), and sugar polyols (sorbitol, mannitol). This paper describes an analytical approach based on HPLC with ELSD that quantifies the major FODMAPs in 45 vegetables and 41 fruits. Sorbitol and/or mannitol were measured in 18 vegetables (range = 0.09-2.96 g/100 g of fw), raffinose and/or stachyose in 7 vegetables (0.08-0.68 g/100 g of fw), and nystose and/or kestose in 19 vegetables (0.02-0.71 g/100 g of fw). Apple, pear, mango, clingstone peach, and watermelon all contained fructose in excess of glucose. Sorbitol was measured in 15 fruits (0.53-5.99 g/100 g of fw), mannitol was found in 2 fruits, and nystose or kestose was measured in 8 fruits. Understanding the importance of dietary FODMAPs will be greatly assisted by comprehensive food composition data.

Quantification of fructans, galacto-oligosacharides and other short-chain carbohydrates in processed grains and cereals

BACKGROUND Wholegrain grains and cereals contain a wide range of potentially protective factors that are relevant to gastrointestinal health. The prebiotics best studied are fructans [fructooligosaccharides (FOS), inulin] and galactooligosaccharides (GOS). These and other short-chain carbohydrates can also be poorly absorbed in the small intestine (named fermentable oligo-, di- and monosaccharides and polyols; FODMAPs) and may have important implications for the health of the gut. METHODS In the present study, FODMAPs, including fructose in excess of glucose, FOS (nystose, kestose), GOS (raffinose, stachyose) and sugar polyols (sorbitol, mannitol), were quantified using high-performance liquid chromatography with an evaporative light scattering detector. Total fructan was quantified using an enzymic hydrolysis method. RESULTS Fifty-five commonly consumed grains, breakfast cereals, breads, pulses and biscuits were analysed. Total fructan were the most common short-chain carbohydrate present in cereal grain products and ranged (g per portion as eaten) from 1.12 g in couscous to 0 g in rice; 0.6 g in dark rye bread to 0.07 g in spelt bread; 0.96 g in wheat-free muesli to 0.11 g in oats; and 0.81 g in muesli fruit bar to 0.05 g in potato chips. Raffinose and stachyose were most common in pulses. CONCLUSIONS   Composition tables including FODMAPs and prebiotics (FOS and GOS) that are naturally present in food will greatly assist research aimed at understanding their physiological role in the gut.

Comparison of the prevalence of fructose and lactose malabsorption across chronic intestinal disorders

Background  Fructose malabsorption, lactose malabsorption and an early rise in breath hydrogen after lactulose (ERBHAL) may play roles in induction of symptoms in gastrointestinal conditions.

Fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) and nonallergic food intolerance: FODMAPs or food chemicals?

Food intolerance in irritable bowel syndrome (IBS) is increasingly being recognized, with patients convinced that diet plays a role in symptom induction. Evidence is building to implicate fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) in the onset of abdominal pain, bloating, wind and altered bowel habit through their fermentation and osmotic effects. Hypersensitivity to normal levels of luminal distension is known to occur in patients with IBS, with consideration of food chemical intolerance likely to answer many questions about this physiological process. This paper summarizes the evidence and application of the most common approaches to managing food intolerance in IBS: the low-FODMAP diet, the elimination diet for food chemical sensitivity and others including possible noncoeliac gluten intolerance.