The importance of the gut-brain axis in maintaining homeostasis has long been appreciated. However, the past 15 yr have seen the emergence of the microbiota (the trillions of microorganisms within ...

The Microbiota-Gut-Brain Axis

Recent studies have suggested that the intestinal microbiome plays an important role in modulating risk of several chronic diseases, including inflammatory bowel disease, obesity, type 2 diabetes, cardiovascular disease, and cancer. At the same time, it is now understood that diet plays a significant role in shaping the microbiome, with experiments showing that dietary alterations can induce large, temporary microbial shifts within 24 h. Given this association, there may be significant therapeutic utility in altering microbial composition through diet. This review systematically evaluates current data regarding the effects of several common dietary components on intestinal microbiota. We show that consumption of particular types of food produces predictable shifts in existing host bacterial genera. Furthermore, the identity of these bacteria affects host immune and metabolic parameters, with broad implications for human health. Familiarity with these associations will be of tremendous use to the practitioner as well as the patient.

/pdf/influence-of-diet-on-the-gut-microbiome-and-implications-for-4i0trq9u9q.pdf

Influence of diet on the gut microbiome and implications for human health.

Functional Gastrointestinal Disorders: History, Pathophysiology, Clinical Features and Rome IV.

https://www.spg.pt/wp-content/uploads/2015/11/2013-ACG_Guideline_CeliacDisease_May_2013.pdf

ACG Clinical Guidelines: Diagnosis and Management of Celiac Disease

The colon is inhabited by a dense population of microorganisms, the so-called “gut microbiota”, able to ferment carbohydrates and proteins that escape absorption in the small intestine during digestion. This microbiota produces a wide range of metabolites, including short chain fatty acids (SCFA). These compounds are absorbed in the large bowel and are defined as 1-6 carbon volatile fatty acids which can present straight or branched-chain conformation. Their production is influenced by the pattern of food intake and diet-mediated changes in the gut microbiota. SCFA have distinct physiological effects: they contribute to shaping the gut environment, influence the physiology of the colon, they can be used as energy sources by host cells and the intestinal microbiota and they also participate in different host-signalling mechanisms. We summarize the current knowledge about the production of SCFA, including bacterial cross-feedings interactions, and the biological properties of these metabolites with impact on the human health

Intestinal Short Chain Fatty Acids and their Link with Diet and Human Health.

http://www.fodmapdieet.nl/pdf/a%20diet%20low%20in%20FODMAPs%20reduces%20symptoms%20of%20IBS.pdf

A Diet Low in FODMAPs Reduces Symptoms of Irritable Bowel Syndrome

https://wellspringofhealth.com/wp-content/uploads/2015/08/Gluten-Causes-Gastrointestinal-Symptoms-in-Subjects-Without-Celiac-Disease-2011.pdf

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

Objective A low FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols) diet reduces symptoms of IBS, but reduction of potential prebiotic and fermentative effects might adversely affect the colonic microenvironment. The effects of a low FODMAP diet with a typical Australian diet on biomarkers of colonic health were compared in a single-blinded, randomised, cross-over trial. Design Twenty-seven IBS and six healthy subjects were randomly allocated one of two 21-day provided diets, differing only in FODMAP content (mean (95% CI) low 3.05 (1.86 to 4.25) g/day vs Australian 23.7 (16.9 to 30.6) g/day), and then crossed over to the other diet with ≥21-day washout period. Faeces passed over a 5-day run-in on their habitual diet and from day 17 to day 21 of the interventional diets were pooled, and pH, short-chain fatty acid concentrations and bacterial abundance and diversity were assessed. Results Faecal indices were similar in IBS and healthy subjects during habitual diets. The low FODMAP diet was associated with higher faecal pH (7.37 (7.23 to 7.51) vs 7.16 (7.02 to 7.30); p=0.001), similar short-chain fatty acid concentrations, greater microbial diversity and reduced total bacterial abundance (9.63 (9.53 to 9.73) vs 9.83 (9.72 to 9.93) log 10 copies/g; p Clostridium cluster XIVa (median ratio 6.62; p Akkermansia muciniphila (19.3; p Ruminococcus torques . Conclusions Diets differing in FODMAP content have marked effects on gut microbiota composition. The implications of long-term reduction of intake of FODMAPs require elucidation. Trial registration number ACTRN12612001185853.

https://gut.bmj.com/content/gutjnl/64/1/93.full.pdf

Diets that differ in their FODMAP content alter the colonic luminal microenvironment

Background and Aim: Functional gastrointestinal symptoms are common and their management is often a difficult clinical problem. The link between food intake and symptom induction is recognized. This review aims to describe the evidence base for restricting rapidly fermentable, short-chain carbohydrates (FODMAPs) in controlling such symptoms. Methods: The nature of FODMAPs, their mode of action in symptom induction, results of clinical trials and the implementation of the diet are described. Results: FODMAPs are widespread in the diet and comprise a monosaccharide (fructose), a disaccharide (lactose), oligosaccharides (fructans and galactans), and polyols. Their ingestion increases delivery of readily fermentable substrate and water to the distal small intestine and proximal colon, which are likely to induce luminal distension and induction of functional gut symptoms. The restriction of their intake globally (as opposed to individually) reduces functional gut symptoms, an effect that is durable and can be reversed by their reintroduction into the diet (as shown by a randomized placebo-controlled trial). The diet has a high compliance rate. However it requires expert delivery by a dietitian trained in the diet. Breath hydrogen tests are useful to identify individuals who can completely absorb a load of fructose and lactose so that dietary restriction can be less stringent. Conclusions: The low FODMAP diet provides an effective approach to the management of patients with functional gut symptoms. The evidence base is now sufficiently strong to recommend its widespread application.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1440-1746.2009.06149.x

Evidence-based dietary management of functional gastrointestinal symptoms: the FODMAP approach.

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. Methods: Fifteen healthy subjects and 15 with IBS (Rome III criteria) undertook a single-blind, crossover intervention trial involving consuming provided diets that were either low (9 g/day) or high (50 g/day) in FODMAPs for 2 days. Food and gastrointestinal symptom diaries were kept and breath samples collected hourly over 14 h on day 2 of each diet. Results: Higher levels of breath hydrogen were produced over the entire day with the high FODMAP diet for healthy volunteers (181 77 ppm.14 h vs 43 18; mean SD P < 0.0001) and patients with IBS (242 79 vs 62 23; P < 0.0001), who had higher levels during each dietary period than the controls (P < 0.05). Breath methane, produced by 10 subjects within each group, was reduced with the high FODMAP intake in healthy subjects (47 29 vs 109 77; P = 0.043), but was not different in patients with IBS (126 153 vs 86 72). Gastrointestinal symptoms and lethargy were significantly induced by the high FODMAP diet in patients with IBS, while only increased flatus production was reported by healthy volunteers. Conclusions: Dietary FODMAPs induce prolonged hydrogen production in the intestine that is greater in IBS, influence the amount of methane produced, and induce gastrointes- tinal and systemic symptoms experienced by patients with IBS. The results offer mecha- nisms underlying the efficacy of the low FODMAP diet in IBS.

/pdf/manipulation-of-dietary-short-chain-carbohydrates-alters-the-1vi1ne4g7r.pdf

Susan Joy Shepherd

Papers

A Diet Low in FODMAPs Reduces Symptoms of Irritable Bowel Syndrome

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

Diets that differ in their FODMAP content alter the colonic luminal microenvironment

Evidence-based dietary management of functional gastrointestinal symptoms: the FODMAP approach.

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