Review article: the impact of diet on ileoanal pouch function and on the pathogenesis of pouchitis.

BACKGROUND: There is expanding interest in the role that diet plays in ileoanal pouch function and in the pathogenesis of pouchitis. AIMS: To present a narrative review of published literature regarding the relationship of diet with pouch function and the pathogenesis of pouchitis, and to provide potentially beneficial dietary strategies. METHODS: Current relevant literature was summarised and critically examined. RESULTS: Dietary components influence pouch function via their effect on upper gastrointestinal transit, small bowel water content and the structure and fermentative activity of the pouch microbiota. FODMAPs in fruits and vegetables appear to affect pouch function the most, with intake positively associated with increased stool frequency and reduced consistency. Dietary factors that influence the pathogenesis of pouchitis appear different and, at times, opposite to those better for optimising function. For example, risk of pouchitis appears to be inversely associated with intake of fruits. The food components mechanistically responsible for this observation are not known, but a rich supply of fermentable fibres and micronutrients in such foods might play a beneficial role via modulation of microbial community structure (such as increasing diversity and/or changing microbial communities to favour 'protective' over 'pathogenic' bacteria) and function and/or anti-inflammatory effects. CONCLUSION: Available data are weak but suggest tailoring dietary recommendations according to pouch phenotype/behaviour and pouchitis risk might improve outcomes. More sophisticated dietary strategies that utilise the physiological and pathophysiological effects of dietary components on ileoanal pouches have potential to further improve outcomes. Well designed, adequately powered studies are required.

Adherence to the Mediterranean diet is associated with decreased fecal calprotectin in patients with ulcerative colitis after pouch surgery.

BACKGROUND: Mediterranean diet (MED) is associated with health benefits, yet scarce data exist regarding the role of MED in inflammatory bowel diseases (IBD). Herein, we aimed to evaluate the association between MED and inflammatory markers in patients with IBD after pouch surgery. METHODS: Consecutive patients after pouch surgery due to ulcerative colitis (UC) were recruited at a comprehensive pouch clinic. Adherence to MED was calculated according to MED score, ranging from 0 (low adherence) to 9 (high adherence), based on food-frequency questionnaires. Pouch behavior was defined as normal pouch (NP) or pouchitis based on Pouchitis Disease Activity Index (PDAI) and disease activity was defined as active or inactive. C-reactive protein (CRP) and fecal calprotectin were assessed. RESULTS: Overall 153 patients were enrolled (male gender 47%; mean age 46 ± 14 years; mean pouch age 9.5 ± 7 years). MED scores were higher in patients with normal vs. elevated CRP and calprotectin levels (4.6 ± 1.8 vs. 4.4 ± 1.6, p = 0.28; 4.8 ± 1.8 vs. 4.07 ± 1.7, p < 0.05, respectively). In a multivariate regression, MED score was associated with decreased calprotectin levels (OR = 0.74 [0.56-0.99]). Adherence to MED was associated with dietary fiber and antioxidants intake. Finally, in a subgroup of patients with NP followed up for 8 years, higher adherence to MED trended to be inversely associated with the onset of pouchitis (log rank = 0.17). CONCLUSIONS: In patients with UC after pouch surgery, adherence to MED is associated with decreased calprotectin levels. Thus, MED may have a role in modifying intestinal inflammation in IBD.

Exclusive elemental diet impacts on the gastrointestinal microbiota and improves symptoms in patients with chronic pouchitis.

BACKGROUND: Treatment resistant chronic pouchitis causes significant morbidity. Elemental diet is effective treatment for Crohn's disease. Since pouchitis shares some similarities to Crohn's disease we hypothesised that elemental diet may be an effective treatment. METHOD: Seven pouchitis patients (with ulcerative colitis) were studied. All had active pouchitis with a pouch disease activity index (PDAI) ≥7. Exclusion criteria were recent NSAIDs, antibiotics or probiotics. Sufficient elemental diet to achieve energy requirements was provided. Flexible-pouchoscopy was performed, and the Cleveland Global Quality of Life score (CGQoL), Pouch Disease Activity Index (PDAI) and BMI were recorded at baseline and following 28 days of elemental diet. Faecal samples were also collected at these time points and analysed for major bacterial groups using culture independent fluorescence in situ hybridisation. Data were analysed using Wilcoxon's signed-rank test. RESULTS: Following 28 days of exclusive elemental diet, median stool frequency decreased from 12 to 6 per day (p=0.028), median clinical PDAI decreased from 4 to 1 (p=0.039). There was no significant difference in quality of life scores or PDAI before and following treatment. There was a trend towards an increase in the concentration of Clostridium coccoides-Eubacterium rectale (median 7.9 to 8.5 log10/g, p=0.08) following exclusive elemental diet. CONCLUSION: Treatment with four weeks elemental diet appeared to improve the symptoms of chronic pouchitis in some patients but is not an effective strategy for inducing remission. Although a potential symptom modifier, elemental diet cannot be recommended for the routine treatment of active pouchitis.

Discrepancy between clinical and histological effects of DHA supplementation in a rat model of pouchitis.

Docosahexaenoic acid (DHA) potentially modulates inflammatory processes. Therefore, the aim of this study was to determine the influence of DHA supplementation on the expression of intestinal inflammation and nutritional status in rats which have undergone restorative proctocolectomy. Twenty-four Wistar rats were operated. After the induction of pouchitis, animals were randomly divided into a control group (CG) and supplementation groups receiving respectively a semi-synthetic diet without or with DHA (in a lower or higher dose, respectively known as the lower dose, LD, and higher dose, HD, groups) for six weeks. Selected nutritional parameters were assessed. Histopathological and immunohistochemical analysis of pouch mucosa specimens was also performed. The effectiveness of feeding and quality of stools were significantly better in the HD group than in the CG. The intensity of inflammation (Moskovitz scale) was higher in HD and LD than in CG (p = 0.03 and p = 0.0006, respectively). Nevertheless, pouch adaptation (Laumonier scale) was more significant in LD than in CG (p = 0.007). On the other hand, tissue expression of IL-1α and IL-10 was higher in HD and LD than in CG (IL-1α, p = 0.009 and p = 0.05, respectively; IL-10, p = 0.04 for both). DHA supplementation has no impact on body weight gain. Yet it seems that it may improve the effectiveness of nutrition and stool quality in rats which have undergone restorative proctocolectomy. Simultaneously, it increases the intensity of pouch adaptation and inflammation. The specificity of observed changes is not clear. However, it may imply potential modulation of inflammatory processes of pouch mucosa.

Do probiotics have a role in the management of inflammatory bowel disease?

Inflammatory bowel disease treatments have generally revolved around immunological manipulations to reduce inflammation of the gastrointestinal tract. Bacterial interactions with the gastrointestinal epithelium may be a trigger for inflammatory changes which occur in the gut. Antibiotics have been shown to alter disease activity in Crohn's disease. Probiotics (live microorganisms) administered for therapeutic purposes have been proposed due to the possibility of their altering the interaction of the gut mucosa with enteric bacteria. Extensive randomized trials are lacking in this area at this time. Current trials indicate the possibility of maintaining remission in pouchitis (non-specific inflammation) and the potential for inducing and maintaining remission in ulcerative colitis. Trials in Crohn's disease have shown mixed results.

Place of probiotics.

PURPOSE OF REVIEW: This review reports on the recent progress understanding mechanisms of action and clinical applications of probiotics. RECENT FINDINGS: New insights on regulating mechanisms of intestinal commensal bacteria to prevent and treat different gastrointestinal diseases have been reported. Some probiotics, though not all, exert beneficial effects by modulating the mucosal barrier function and immune activity. It seems that a combination of different probiotics is more effective than a single strain. It was demonstrated that not only viable bacteria administered to the intestinal tract but also isolated probiotic DNA is active, even if injected subcutaneously. There is reasonable evidence to recommend probiotics in infectious diarrhoea for prevention and treatment (mainly in children) and to prevent antibiotic-induced gastrointestinal side effects. Furthermore, probiotics are effective in maintaining remission in ulcerative colitis and preventing and treating pouchitis. Promising positive effects were published in major surgery patients (gastric resection, pancreatic resection, liver transplantation) and in severe necrotising acute pancreatitis. SUMMARY: Increasing knowledge on probiotics is exciting, but in the near future it must be defined which probiotics (single strains or a combination) are most effective in specific diseases. Well-designed, randomized clinical trials are still required to further define the role of probiotics as preventive and therapeutic agents.