E. P. Halmos

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

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) log10 copies/g; p<0.001) compared with the Australian diet. To indicate direction of change, in comparison with the habitual diet the low FODMAP diet reduced total bacterial abundance and the typical Australian diet increased relative abundance for butyrate-producing Clostridium cluster XIVa (median ratio 6.62; p<0.001) and mucus-associated Akkermansia muciniphila (19.3; p<0.001), and reduced 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.

Diarrhoea during enteral nutrition is predicted by the poorly absorbed short‐chain carbohydrate (FODMAP) content of the formula

Aliment Pharmacol Ther 2010; 32: 925–933

Consistent Prebiotic Effect on Gut Microbiota With Altered FODMAP Intake in Patients with Crohn’s Disease: A Randomised, Controlled Cross-Over Trial of Well-Defined Diets

Objectives:Altering FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) intake has substantial effects on gut microbiota. This study aimed to investigate effects of altering FODMAP intake on markers of colonic health in patients with Crohn’s disease.Methods:After evaluation of their habitual diet, 9 patients with clinically quiescent Crohn’s disease were randomised to 21 days of provided low or typical (“Australian”) FODMAP diets with ≥21-day washout in between. Five-day fecal samples were collected at the end of each diet and analyzed for calprotectin, pH, short-chain fatty acids (SCFA) and bacterial abundance. Gastrointestinal symptoms were recorded daily.Results:Eight participants collected feces and were adherent to the diets. FODMAP intake differed across the three dietary periods with low<habitual<Australian diet. SCFA, pH and total bacterial abundance remained unaltered, but relative abundance was higher for butyrate-producing Clostridium cluster XIVa (P=0.008) and mucus-associated Akkermansia muciniphila (P=0.016), and lower for Ruminococcus torques (P=0.034) during the Australian compared with low FODMAP diet. Results during habitual diet were similar to the low FODMAP intervention, but significantly different to the Australian diet. The diets had no effects on calprotectin, but symptoms doubled in severity with the Australian diet (n=9; P<0.001).Conclusions:In clinically quiescent Crohn’s disease, altering dietary FODMAP intake is associated with marked changes in fecal microbiota, most consistent with a prebiotic effect of increasing FODMAPs as shown in an irritable bowel/healthy cohort. This strategy might be favorable for gut health in Crohn’s disease, but at the cost of inducing symptoms.

Dietary management of IBD—insights and advice

The current general interest in the use of food choice or diet in maintaining good health and in preventing and treating disease also applies to patients with IBD, who often follow poor or nutritionally challenging dietary plans. Unfortunately, dietary advice plays only a minor part in published guidelines for management of IBD, which sends a message that diet is not of great importance. However, a considerable evidence base supports a focused and serious attention to nutrition and diet in patients with IBD. In this Review, a step-wise approach in the evaluation and management of these patients is proposed. First, dietary intake and eating habits as well as current nutritional state should be documented, and corrective measures instituted. Secondly, dietary strategies as primary or adjunctive therapy for the reduction of inflammation and/or prevention of relapse of IBD should be seriously contemplated. Thirdly, use of diet to improve symptoms or lessen the effects of complications should be considered. Finally, dietary advice regarding disease prevention should be discussed when relevant. An increasing need exists for applying improved methodologies into establishing the value of current and new ways of using food choice as a therapeutic and preventive tool in IBD.

Role of FODMAP content in enteral nutrition-associated diarrhea.

Gastrointestinal symptoms including diarrhea are common complications of enteral nutrition (EN); however, the cause is unclear. Mode of EN delivery that alters digestion and possibly absorption is suggested to contribute to the high incidence of diarrhea; however, enteral formula is frequently blamed. Most research has focused on fiber‐supplemented EN, with a meta‐analysis showing that fiber reduces the incidence of diarrhea in non‐intensive care unit studies. Other hypotheses include formula osmolality and FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) content. FODMAPs are poorly absorbed short‐chain carbohydrates that exert an osmotic effect. Dietary FODMAPs have been shown to reduce gastrointestinal symptoms, including diarrhea, in those with irritable bowel syndrome and, given a high‐enough dose, will induce a laxative effect in most people. As FODMAPs are commonly added to enteral formula and EN is frequently used as the main source of nutrition, it is reasonable to hypothesize that EN provides more FODMAPs than usual dietary intake and increases risk for developing diarrhea. This hypothesis was assessed through a retrospective study showing that the standard‐use enteral formula Isosource 1.5 had a protective effect of developing diarrhea. The only characteristic unique to Isosource 1.5 was the lower FODMAP content as determined through methodologies previously validated for food analysis. Methodologies for application to enteral formulas are currently undergoing formal validation. Once confirmed for application in enteral formula, future directions include FODMAP analysis of specific ingredients to increase understanding of potential problems associated with enteral formula and a randomized, controlled trial investigating the role of formula FODMAP content.

The role of FODMAPs in irritable bowel syndrome.

Purpose of reviewIrritable bowel syndrome (IBS) is a condition affecting approximately 10–15% of Western populations. The Rome III criteria are applied to many studies to validate the diagnosis of IBS. The low fermentable oligo, di, monosaccharides and polyol (FODMAP) diet has been the subject of many robust clinical trials and is now used as the primary dietary therapy internationally. This review examines the current evidence for the role of the low FODMAP diet in IBS. Recent findingsDetailed commentary on original research involving FODMAPs and IBS symptoms from 2013 to 2014 is provided. SummaryThe low FODMAP diet has been shown to be an efficacious therapy for reduction of functional gastrointestinal symptoms seen in IBS. Recent publications provide randomized controlled trial and prospective observational evidence in support of the diet for symptom management. The low FODMAP diet appears to be superior to a gluten-free diet in people with self-reported nonceliac gluten sensitivity. Although the low FODMAP diet has not been shown to reduce the prebiotic effect in the colon, total colonic bacterial load was reduced. Further research investigating the potential health implications of both this and the nutritional adequacy of the liberalized low FODMAP diet is required.

Challenges of Quantifying FODMAPs in Enteral Nutrition Formulas Evaluation of Artifacts and Solutions

Background: Diarrhea associated with enteral nutrition has been attributed to excessive FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) content of formulas. This study aimed to readdress their FODMAP content by measuring fermentation-specific effects after a formula load in healthy participants and by defining issues with analytical methods. Methods: Breath hydrogen production expressed as mean area under the curve (AUC) for 12 hours after ingestion of 15 g lactulose or 500 mL of 1 of 2 formulas of seemingly different FODMAP content was evaluated in a double crossover design. Quantification of specified FODMAPs via enzymatic and liquid chromatographic assays was assessed with additional controls to investigate the influence of maltodextrin and sucrose present in the formulas, and alternative assays were applied. Results: In 15 hydrogen-producing participants, AUC following both formulas was minimal (⩽21 ppm/12 h) compared with 15 g lactulose (P < .001). Elevated breath hydrogen was detectable when >2.5 g fructo-oligosaccharide was consumed. Maltodextrin showed dose-dependent interference with enzymatic measurement of fructans and coeluted with raffinose with liquid chromatography. Application of an alternative fructan assay that includes additional enzymes to hydrolyze maltodextrins indicated that fructan content was <15% of that previous reported. Galacto-oligosaccharide (GOS) content could not be estimated by chromatography due to maltodextrins. An enzymatic assay, while overestimating GOS content, showed it to be very low. Conclusion: FODMAPs were not detected in enteral formulas in human bioassays, and their content may be grossly overestimated mainly due to high formula concentrations of maltodextrin. Better estimates of FODMAP content in enteral formulas can be made by alternative assay approaches.

When the low FODMAP diet does not work

Irritable bowel syndrome (IBS) is heterogeneous. Patients need proper assessment and explanation of IBS pathophysiology and appropriate therapies. A low FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diet effectively reduces symptoms in 75% of patients. Best treatment for those nonresponsive will depend on the pathophysiological basis for symptom genesis, with the following possible abnormalities: (i) Visceral hypersensitivity and/or enhanced gut‐brain communication: a low FODMAP diet is mainly targeted for this patient group. A dietitian may also recommend antispasmodic agents, including peppermint oil. Another dietary treatment is a low food chemical diet, although this diet is often extremely limited, and therefore, not suited for some populations. Psychological therapies are also clinically beneficial. (ii) Altered motility: in patients with fast transit, a dietitian may recommend a reduction in all FODMAPs or targeted monosaccharides and disaccharides, which are more osmotic in nature. If not effective, patients may benefit from psyllium, which has an exceptional water‐holding capacity aimed to promote more formed stools. Patients with slow or uncoordinated transit are often more difficult to treat. Dietary interventions have some success and usually comprise a combination of adequate fiber and fluid, osmotic laxatives, and stimulating agents such as caffeine, senna, and exercise. (iii) Altered microbiome: supplementary probiotics and prebiotics have weak evidence of efficacy with some notable exceptions. A dietitian may trial supplementary Bifidobacterium infantis or oligosaccharides, usually as an adjunct therapy. Guidance from a dietitian will encompass dietary methods to treat IBS but additionally identify where dietary treatment is not indicated to ensure that diet is correctly used and patients are not nutritionally or psychologically compromised.

Food knowledge and psychological state predict adherence to a gluten‐free diet in a survey of 5310 Australians and New Zealanders with coeliac disease

A gluten‐free diet treats coeliac disease, but its efficacy depends on strict adherence. A variety of patient factors may influence adherence but have not been well described at a population level.

A low FODMAP diet in patients with Crohn's disease

A low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet is frequently applied to patients with irritable bowel syndrome (IBS) as a treatment to reduce functional gastrointestinal symptoms, with evidence of its efficacy mounting worldwide. The success of the dietary therapy is now frequently applied to patients with inflammatory bowel disease (IBD) and coexisting functional symptoms. Evidence for application of a low FODMAPdiet in the IBD population is limited to a retrospective study of patients with quiescent IBD and IBS-like symptoms, in which more than 50% of patients had a reduction of symptoms. While beneficial for symptom reduction, there is evidence suggesting that a low FODMAP diet also has negative effects on microbiota. This was first suggested in a trial where a dietitiantaught low FODMAP diet reduced relative abundance of fecal Bifidobacteria spp. in IBS subjects compared with parallel cohort of IBS subjects on their habitual diet. A more closely controlled trial that compared fecal bacteria of IBS and healthy subjects after being provided two diets that varied only in FODMAP content showed that a low FODMAP diet was associated with reduction of total fecal bacterial load and specific reduction of the highly butyrate-producing Clostridium cluster XIVa and Akkermansia muciniphila, a likely favorable bacteria that promotes short-chain fatty acid production and an increase in the mucus-degrading Ruminococcus torques. The application of a low FODMAP diet may raise concerns in the IBS population if applied long term; however, risk to an IBD population may be more significant. Literature suggests that the changes in fecal bacterial seen from a reduced FODMAP intake seem to mimic those seen in patients with Crohn’s disease. Patients with Crohn’s disease are more likely to have reduced butyrate-producing bacteria, Bifidobacteria spp. and A. muciniphila and increase R. torques and Ruminococcus gnavus. One bacterium of specific interest in a Crohn’s Disease population is the butyrate-producing Faecalibacterium prausnitzii, as mucosal F. prausnitzii has predicted onset of active disease. Similarly, in vitro and animal models suggest that A. muciniphila may also predict Crohn’s disease activity. A low FODMAP diet may further impact negatively on microbiota of patients with Crohn’s disease, a population already at risk of dysbiosis. With data indicating that caution should be taken in applying a low FODMAP diet, two different approaches may be used in applying an FODMAP restriction for treatment of functional gut symptoms; the ‘top-down’ or the ‘bottom-up’ approach. The more traditional top-down approach involves the patient restricting all or most foods considered to contain FODMAPs for a four-week to eight-week period. Then, if symptom benefit is seen, dietary liberalization is guided through using set food and dose challenges or general recommendations describing FODMAP dosing across restricted foods. This top-down approach is best suited to patients where the success of a low FODMAP diet or the type or amount of FODMAP tolerance is uncertain; in patients who do not normally eat a lot of FODMAPs or who are very symptomatic; or in patients who would prefer this approach. Conversely, the bottomup approach involves reducing specific FODMAPs or a few foods that are very high in FODMAPs for a time period then further restriction of foods if necessary. Arguably, this bottom-up approach should be applied in all patients who are at risk of dysbiosis, including patients with IBD. Other indications for this more gentle restriction include patients at risk of nutritional inadequacy or who have other dietary restrictions, which may again encompass the IBD population. Because of the complex and individual nature of an FODMAP restriction, implementation should be done in guidance with a dietitian well versed in IBD, IBS, and dietary FODMAPs. In addition to appropriate FODMAP manipulation, a dietitian will assess and closely monitor nutritional adequacy with dietary restriction and manage as appropriate, including patients in whom nutrient absorption is impaired or dietary intake is altered.