8 WORLD GASTROENTEROLOGY NEWS JANUARY 2016 Gastro 2015: AGW-WGO | Expert Point of View | Gastro 2016: EGHS-WGO | WDHD News | WGO & WGOF News | WGO Global Guidelines | Calendar of Events ferent compositions of the microbiota with animal fat and protein-based diets versus vegetable-based diets. A recent study investigated the role of the Mediterranean Diet on gut micro-biota. In this study, 153 individuals habitually following omnivore, veg-etarian, or vegan diets were included. They detected significant associations between consumption of vegetable-based diets and increased levels of fecal short-chain fatty acids, Prevotella, and some fiber-degrading Firmicutes, whose role in human gut warrants further research. Conversely, they de-tected higher urinary trimethylamine oxide levels in individuals with lower adherence to the Mediterranean Diet. Diet influences microbiota, but gut microbiota richness also changes the re-sponse to diet. Studies investigating the gut microbiota (gene) richness showed differential response to calorie-restrict-ed diets between these two populations (high-gene versus low-gene content). In particular, the two groups differed in terms of short-chain fatty acid (SCFA) production and mucus degradation potential, hydrogen/methane/hydro-gen sulphide production potential, oxidative stress management potential, and Campylobacter/Shigella abundance, suggesting that low gene content indi-viduals harbor inflammation-associated microbiota. In another study, the impact of an energy-restricted high-protein diet on the gut microbiome was investigated. After consuming an energy-restricted diet, gene richness significantly increased in the low gene content group, while in the high gene content group no significant change in gene richness or diversity was found over the course of the study. Increases in gene richness were significantly asso-ciated with decreases in total fat mass, hip circumference, total cholesterol, and LDL cholesterol, supporting the hypothesis that correcting microbial richness may result in improvements in metabolic derangements 13. There are specific diets which are popular in weight reduction and irritable bowel syndrome (IBS). How-ever, there are limited data on diets for IBD for reducing inflammation in the gut 14. Low fiber diet is thought to reduce inflammation via reduc-tion of passage of stool antigens to inflamed bowel as well as reduce the bulk and frequency of stools. Patients have traditionally been instructed to reduce fiber while in an active flare or with intestinal strictures. Limited studies do not clarify current practice of fiber restriction during active flares or in the presence of CD stenosis. There is also no data in UC. As for high-fiber diets, the inclusion of high-fiber foods in the diet would promote production of short-chain fatty acids to modulate intestinal inflammation. The studies failed to demonstrate a benefit in clinical outcomes in active CD. To our knowledge, there are no studies of the use of the diet in quiescent CD. Although the stud-ies showed more promising results in UC than with CD, the overall evidence is weak. Vegetarian diet is another popular diet. One study found possible efficacy as maintenance therapy, but the study was limited by its small sample size and lack of endoscopic or histologic endpoints. There are very few studies at this time to support its use. Lactose-free diet is frequently advised by physicians for IBD patients, especially in the active phase. However, in lactose malabsorp-tion, there is no need to completely restrict lactose; instead, reduce lactose intake as tolerated. IBD patients may report lactose intolerance, but this may not necessarily be due to lactose malabsorption. There are so far no studies that have evaluated the effect of lactose on IBD activity. Specific carbohydrate diet (SCD) is novel diet mainly in studies in patients with IBS. The logic behind eliminating poorly digested carbohydrates is that bacterial fermentation might result in gut inflammation. Few small uncon-trolled studies in CD showed some improvement in symptoms but with inconsistent changes in inflammatory markers. There is no study in UC. Low-FODMAP diet is also studied in IBS. A reduced intake of fermentable carbohydrates (excess fructose, lactose, fructans, galactans, and polyols) in the diet would help reduce symptoms, similar to its effects on IBS. There is evidence to suggest that the diet may help reduce functional symptoms in CD. Studies are needed to assess its effect on intestinal inflammation. There is no study in UC. Paleolithic diet was practiced by hunter-gatherer societies of the Paleolithic era and may reduce the risk of chronic diseases that were uncommon in primitive societ-ies. There are websites and blogs now promoting the diet for the treatment of IBD. However, there are no studies in CD or UC. Gluten-free diet is the elimination of all gluten containing foods. It is suggested that it would help to reduce intestinal inflammation and symptoms in non-celiac IBD, as seen in celiac disease. There currently limited data in CD and UC patients and it is premature to advice in clini-cal practice 14. In conclusion, gut microbiota is the next frontier in the diagnosis, prophylaxis, and treatment of IBD. Diet and antibiotic exposure are the main elements of Western life style. Developing countries might keep some of their beneficial cultural life-style components (diet, environmental factors, etc.) during “Westernization” to keep their healthy microbiome and minimize the risk of IBD-related disorders. References 1. Bamias G, Pizarro TT, Cominelli F. Pathway-based approaches to the treatment of inflammatory bowel disease. Transl Res. 2015 pii: S1931-5244(15)00300-X.
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