Effects of varying dietary content of fermentable short-chain carbohydrates on symptoms, fecal microenvironment, and cytokine profiles in patients with irritable bowel syndrome.

BACKGROUND: A diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) is increasingly recommended for patients with irritable bowel syndrome (IBS). We aimed to investigate the effects of a blinded low-FODMAP vs high-fructo-oligosaccharides (FOS) diet on symptoms, immune activation, gut microbiota composition, and short-chain fatty acids (SCFAs). METHODS: Twenty patients with diarrhea-predominant or mixed IBS were instructed to follow a low-FODMAP diet (LFD) throughout a 9-week study period. After 3 weeks, they were randomized and double-blindly assigned to receive a supplement of either FOS (FODMAP) or maltodextrin (placebo) for the next 10 days, followed by a 3-week washout period before crossover. Irritable bowel syndrome severity scoring system (IBS-SSS) was used to evaluate symptoms. Cytokines (interleukin [IL]-6, IL-8, and tumor necrosis factor alpha) were analyzed in blood samples, and gut microbiota composition (16S rRNA) and SCFAs were analyzed in fecal samples. KEY RESULTS: Irritable bowel syndrome symptoms consistently improved after 3 weeks of LFD, and significantly more participants reported symptom relief in response to placebo (80%) than FOS (30%). Serum levels of proinflammatory IL-6 and IL-8, as well as levels of fecal bacteria (Actinobacteria, Bifidobacterium, and Faecalibacterium prausnitzii), total SCFAs, and n-butyric acid, decreased significantly on the LFD as compared to baseline. Ten days of FOS supplementation increased the level of these bacteria, whereas levels of cytokines and SCFAs remained unchanged. CONCLUSIONS AND INFERENCES: Our findings support the efficacy of a LFD in alleviating IBS symptoms, and show changes in inflammatory cytokines, microbiota profile, and SCFAs, which may have consequences for gut health.

Abnormal accumulation of intestinal fluid following ingestion of an unabsorbable carbohydrate in patients with irritable bowel syndrome: an MRI study.

BACKGROUND: Postprandial discomfort following intake of poorly absorbable, but fermentable carbohydrates is a common complaint in patients with irritable bowel syndrome (IBS). We used lactulose as a model substance for this group of symptom triggering carbohydrates, aiming to visualize the intestinal response in IBS patients compared to healthy controls. METHODS: Patients with IBS according to Rome III criteria (n = 52) and healthy controls (n = 16) underwent a lactulose challenge test. By using magnetic resonance imaging, we measured small bowel water content (SBWC), and distension (diameter) of the distal ileum and the colon, both in fasting state and 1 h after ingestion of 10 g lactulose. We recorded symptoms after lactulose ingestion. KEY RESULTS: Lactulose provoked significantly more symptoms in IBS patients than in healthy controls (p < 0.0001). SBWC increased more in the patient group compared to the control group (p = 0.0005). The postprandial diameter of the terminal ileum was larger in patients with IBS and the postprandial diameter of the ascending colon was smaller in patients with diarrhea-predominant phenotype (IBS-D). Symptoms were not correlated with change in SBWC (r = 0.05; p = 0.11), nor to the diameters of the terminal ileum or the colon. CONCLUSIONS & INFERENCES: Compared to healthy controls, IBS patients developed more symptoms and had an abnormal accumulation of fluid in the small bowel in response to ingestion of the unabsorbable carbohydrate lactulose. This may be due to impaired motor activity of the small intestine or impaired function of the ileocecal segment.

Intestinal B cell-activating factor: an indicator of non-IgE-mediated hypersensitivity reactions to food?

BACKGROUND: Medically confirmed hypersensitivity reactions to food are usually IgE-mediated. Non-IgE-mediated reactions are not only seldom recognized but also more difficult to diagnose. AIM: To examine B cell-activating factor (BAFF) in serum and gut lavage fluid of patients with self-reported food hypersensitivity, and to study its relationship to atopic disease. METHODS: Gut lavage fluid was obtained from 60 and serum from another 17 patients with self-reported food hypersensitivity. Twenty healthy volunteers served as controls, gut lavage fluid was obtained in all, serum from 11 of 20. The patients were divided into atopic and non-atopic subgroups. BAFF was measured by ELISA in both serum and gut lavage fluid. RESULTS: B cell-activating factor levels in serum and gut lavage fluid were significantly higher in patients than in controls (P < 0.03 and P < 0.002 respectively). Non-atopic patients had significantly higher levels of BAFF in serum than both atopic patients (P < 0.05) and controls (P < 0.05). There was no significant correlation between serum levels of BAFF and IgE. CONCLUSIONS: The results suggest that BAFF might be a new mediating mechanism in food hypersensitivity reactions. Significantly higher levels in non-atopic compared with atopic patients, and no correlation between BAFF and IgE, suggest that BAFF might be involved particularly in non-IgE-mediated reactions.

Indications of 'atopic bowel' in patients with self-reported food hypersensitivity.

BACKGROUND: An association between atopic disease and gastrointestinal complaints has been suggested. AIM: To explore the association between atopic disease, gastrointestinal symptoms, and possible gastrointestinal manifestations of atopic disease in patients with self-reported food hypersensitivity. METHODS: Symptoms, skin prick tests, serum markers of allergy and intestinal permeability were recorded in 71 adult patients. Eosinophils, tryptase- and IgE-positive cells were counted in duodenal biopsies. RESULTS: Sixty-six (93%) patients had irritable bowel syndrome (IBS) and 43 (61%) had atopic disease, predominantly rhinoconjunctivitis. All 43 were sensitized to inhalant allergens, 29 (41%) to food allergens, but food challenges were negative. Serum total IgE and duodenal IgE-positive cell counts were significantly correlated (P < 0.0001) and both were significantly higher in atopic than in non-atopic patients (P < 0.0001 and P = 0.003 respectively). IgE-positive cells appeared to be 'armed' mast cells. Intestinal permeability was significantly elevated in atopic compared with non-atopic patients (P = 0.02). Gastrointestinal symptoms and numbers of tryptase-positive mast cells and eosinophils did not differ between groups. CONCLUSIONS: Patients with self-reported food hypersensitivity had a high prevalence of IBS and atopic disease. Atopic patients had increased intestinal permeability and density of IgE-bearing cells compared with non-atopic patients, but gastrointestinal symptoms did not differ between groups.

Sedimentological research as a basis for environmental management: the Oresund fixed link.

A fixed 16 km link (immersed tunnel, artificial island and peninsula, bridges) to connect the Scandinavian countries of Denmark and Sweden is being constructed during the period 1995-2000. The link crosses Oresund, one of the three sounds connecting the brackish Baltic Sea to the oceanic North Sea. Dredging of approximately 8 x 10(6) m3 of limestone bedrock and clay till is being carried out during the construction phase. Environmental planning and management when constructing the fixed link were heavily dependent on extensive sedimentological and biological research prior to construction. Base-line turbidity and seabed sediments were investigated, and sediment spill parameters were measured during test dredging and test reclamation, in addition to the environmental impact. Now, when dredging and reclamation have been finalised in Oresund, it is clear that the environmental management approach used during construction of the fixed link has safeguarded the marine environment in Oresund. At the same time it has allowed the dredging and reclamation works to be carried out within the planned time period and expenses. A detailed base-line monitoring of the regional turbidity regime and the regional sedimentation regime in Oresund made post-dredging evaluation of the regional effects possible. The measurements in Oresund showed that the construction caused no permanent regional change in turbidity and sedimentation, as the base-line conditions did not change.