FODMAPs or fermentable oligosaccharides, disaccharides, monosaccharides, and polyols [1] are short-chain carbohydrates that are poorly absorbed in the small intestine and ferment in the colon. They include short-chain oligosaccharide polymers of fructose (fructans) and galactooligosaccharides (GOS, stachyose, raffinose), disaccharides (lactose), monosaccharides (fructose), and sugar alcohols (polyols), such as sorbitol, mannitol, xylitol, and maltitol. [1] [2] Most FODMAPs are naturally present in food and the human diet, but the polyols may be added artificially in commercially prepared foods and beverages.
FODMAPs may cause digestive discomfort in some people. The reasons are hypersensitivity to luminal distension and/or a proclivity to excess water retention and gas production and accumulation, but they do not cause intestinal inflammation. Naturally occurring FODMAPs may help avert digestive discomfort for some people because they produce beneficial alterations in the gut flora. [3] [4] [5] [6] They are not the cause of these disorders, [7] but a low-FODMAP diet, restricting FODMAPs, might help to improve digestive symptoms in adults with irritable bowel syndrome (IBS) and other functional gastrointestinal disorders (FGID). [7] [8] [9] [10] [11] Avoiding all FODMAPs long-term may have a detrimental impact on the gut microbiota and metabolome. [2] [9] [11] [12]
FODMAPs, especially fructans, are present in small amounts in gluten-containing grains and have been identified as a possible cause of symptoms in people with non-celiac gluten sensitivity. [13] [14] [15] [16] [3] They are only minor sources of FODMAPs when eaten in the usual standard quantities in the daily diet. [13] As of 2019, reviews conclude that although FODMAPs present in wheat and related grains may play a role in non-celiac gluten sensitivity, they only explain certain gastrointestinal symptoms, such as bloating, but not the extra-digestive symptoms that people with non-celiac gluten sensitivity may develop, such as neurological disorders, fibromyalgia, psychological disturbances, and dermatitis. [3] [17] [13] Consuming a low FODMAP diet without a previous medical evaluation could cause health risks because it can ameliorate and mask digestive symptoms of celiac disease, delaying or avoiding its correct diagnosis and therapy. [18]
Some FODMAPs, such as fructose, are readily absorbed in the small intestine of humans via GLUT receptors. [19] Absorption thus depends on the appropriate expression and delivery of these receptors in the intestinal enterocyte to both the apical surface, contacting the lumen of the intestine (e.g., GLUT5), and to the basal membrane, contacting the blood (e.g., GLUT2). [19] Improper absorption of these FODMAPS in the small intestine leaves them available for absorption by gut flora. The resultant metabolism by the gut flora leads to the production of gas and potentially results in bloating and flatulence. [7]
Although FODMAPs can cause certain digestive discomfort in some people, not only do they not cause intestinal inflammation, but they help prevent it because they produce beneficial alterations in the intestinal flora that contribute to maintaining good colon health. [4] [5] [6]
FODMAPs are not the cause of irritable bowel syndrome or other functional gastrointestinal disorders, but rather a person develops symptoms when the underlying bowel response is exaggerated or abnormal. [7]
Fructose malabsorption and lactose intolerance may produce IBS symptoms through the same mechanism, but unlike other FODMAPs, poor absorption of fructose is found in only a minority of people. Lactose intolerance is found in most adults, except for specific geographic populations, notably those of European descent. [20] Many who benefit from a low FODMAP diet need not restrict fructose or lactose. It is possible to identify these two conditions with hydrogen and methane breath testing, thus eliminating the necessity for dietary compliance. [7]
The significance of sources of FODMAPs varies through differences in dietary groups such as geography, ethnicity, and other factors. [7] Commonly used FODMAPs comprise the following: [21]
Sources of fructans include wheat, rye, barley, onion, garlic, Jerusalem and globe artichoke, beetroot, dandelion leaves, the white part of leeks, the white part of spring onion, brussels sprouts, savoy cabbage, and prebiotics such as fructooligosaccharides (FOS), oligofructose and inulin. [22] [ failed verification ] [7] [23] Asparagus, fennel, red cabbage, and radicchio contain moderate amounts but may be eaten if the advised portion size is observed. [22] [ failed verification ]
Pulses and beans are the main dietary sources (although green beans, canned lentils, sprouted mung beans, tofu (not silken), and tempeh contain comparatively low amounts). [22] [ failed verification ] [23] Supplements of the enzyme alpha-galactosidase may reduce symptoms, [24] assuming the enzyme product does not contain other FODMAPs, such as polyol artificial sweeteners.[ citation needed ]
Polyols are found naturally in mushrooms, some fruit (particularly stone fruits), including apples, apricots, avocados, blackberries, cherries, lychees, nectarines, peaches, pears, plums, prunes, watermelon, and in some vegetables, including cauliflower, snow peas, and mange-tout peas. [25] Cabbage, chicory, and fennel contain moderate amounts, but may be eaten in a low-FODMAP diet if the advised portion size is observed. [26] [ better source needed ][ failed verification ]
Polyols, specifically sugar alcohols, used as artificial sweeteners in commercially prepared food, beverages, and chewing gum, include isomalt, maltitol, mannitol, sorbitol, and xylitol. [7] [23]
People following a low-FODMAP diet may be able to tolerate moderate amounts of fructose and lactose, particularly if they have lactase persistence. [27]
A low-FODMAP diet consists of the global restriction of all fermentable carbohydrates (FODMAPs), [7] and is recommended only for a short time. A low-FODMAP diet is recommended for managing patients with irritable bowel syndrome (IBS) and can reduce digestive symptoms of IBS, including bloating [28] and flatulence. [29]
Several studies have found a low-FODMAP diet to improve digestive symptoms in adults with irritable bowel syndrome, [8] [9] [10] [11] but its long-term use can have negative effects, because it has a detrimental impact on the gut microbiota and metabolome. [2] [9] [11] [12] It should only be used for short periods and under the advice of a specialist. [30] More study is needed to evaluate its effectiveness in children with irritable bowel syndrome. [8] Small studies (which are susceptible to bias) show little evidence of its effectiveness in treating functional symptoms of inflammatory bowel disease (IBD). [31] [32] More study is needed to assess the true impact of this diet on health. [9] [11]
FODMAPs present in gluten-containing grains have been identified as a possible cause of gastrointestinal symptoms in people with non-celiac gluten sensitivity, either by themselves, [33] or in combination effect with gluten and other proteins in gluten-containing cereals, such as amylase-trypsin inhibitors (ATIs). [14] [13] The amount of fructans in these cereals is small. In rye, they account for 3.6–6.6% of dry matter, 0.7–2.9% in wheat, and barley contains only trace amounts. [3] They are only minor sources of FODMAPs when eaten in common dietary amounts. [13] Wheat and rye may comprise a major source of fructans when consumed in large amounts. [7]
In a 2018 double-blind, crossover research study on 59 persons on a gluten-free diet with challenges of gluten, fructans, or placebo, intestinal symptoms (specifically bloating) were (borderline) significantly higher after challenge with fructans, in comparison with gluten proteins (P=0.049). [3] [17] Although the differences between the three interventions were small, the authors concluded that fructans are more likely to cause gastrointestinal symptoms in non-celiac gluten sensitivity than gluten. [3] Fructans used in the study were extracted from chicory root, and the results may or may not apply to wheat fructans. [17]
A 2018 review concluded that although fructan intolerance may play a role in non-celiac gluten sensitivity, it only explains some gastrointestinal symptoms. Fructan intolerance does not explain the extra-digestive symptoms that people with non-celiac gluten sensitivity may develop, such as neurological disorders, fibromyalgia, psychological disturbances, and dermatitis. This review also found that FODMAPs may cause digestive symptoms when the person is hypersensitive to luminal distension. [3]
A 2019 review concluded that wheat fructans could cause certain IBS-like symptoms, such as bloating, but that they are not likely to cause immune activation or extra-digestive symptoms, as many people with non-celiac gluten sensitivity reported resolution of their symptoms after removing gluten-containing cereals. These same participants continued to eat fruits and vegetables with high FODMAP content without issue. [17]
Flatulence is the expulsion of gas from the intestines via the anus, commonly referred to as farting or trumping. "Flatus" is the medical word for gas generated in the stomach or bowels. A proportion of intestinal gas may be swallowed environmental air, and hence flatus is not entirely generated in the stomach or bowels. The scientific study of this area of medicine is termed flatology.
Gluten is a structural protein naturally found in certain cereal grains. The term gluten usually refers to a wheat grain's prolamins, specifically glutelin proteins, that naturally occur in many cereal grains, and which can trigger celiac disease in some people. The types of grains that contain gluten include all species of wheat, and barley, rye, and some cultivars of oat; moreover, cross hybrids of any of these cereal grains also contain gluten, e.g. triticale. Gluten makes up 75–85% of the total protein in bread wheat.
Coeliac disease or celiac disease is a long-term autoimmune disorder, primarily affecting the small intestine, where individuals develop intolerance to gluten, present in foods such as wheat, rye and barley. Classic symptoms include gastrointestinal problems such as chronic diarrhoea, abdominal distention, malabsorption, loss of appetite, and among children failure to grow normally. Non-classic symptoms are more common, especially in people older than two years. There may be mild or absent gastrointestinal symptoms, a wide number of symptoms involving any part of the body, or no obvious symptoms. Coeliac disease was first described in childhood; however, it may develop at any age. It is associated with other autoimmune diseases, such as Type 1 diabetes mellitus and Hashimoto's thyroiditis, among others.
Dietary fiber or roughage is the portion of plant-derived food that cannot be completely broken down by human digestive enzymes. Dietary fibers are diverse in chemical composition, and can be grouped generally by their solubility, viscosity, and fermentability, which affect how fibers are processed in the body. Dietary fiber has two main components: soluble fiber and insoluble fiber, which are components of plant-based foods, such as legumes, whole grains and cereals, vegetables, fruits, and nuts or seeds. A diet high in regular fiber consumption is generally associated with supporting health and lowering the risk of several diseases. Dietary fiber consists of non-starch polysaccharides and other plant components such as cellulose, resistant starch, resistant dextrins, inulin, lignins, chitins, pectins, beta-glucans, and oligosaccharides.
Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel movement. Complications from constipation may include hemorrhoids, anal fissure or fecal impaction. The normal frequency of bowel movements in adults is between three per day and three per week. Babies often have three to four bowel movements per day while young children typically have two to three per day.
Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by a group of symptoms that commonly include abdominal pain, abdominal bloating and changes in the consistency of bowel movements. These symptoms may occur over a long time, sometimes for years. IBS can negatively affect quality of life and may result in missed school or work or reduced productivity at work. Disorders such as anxiety, major depression, and chronic fatigue syndrome are common among people with IBS.
Inulins are a group of naturally occurring polysaccharides produced by many types of plants, industrially most often extracted from chicory. The inulins belong to a class of dietary fibers known as fructans. Inulin is used by some plants as a means of storing energy and is typically found in roots or rhizomes. Most plants that synthesize and store inulin do not store other forms of carbohydrate such as starch. In the United States in 2018, the Food and Drug Administration approved inulin as a dietary fiber ingredient used to improve the nutritional value of manufactured food products. Using inulin to measure kidney function is the "gold standard" for comparison with other means of estimating glomerular filtration rate.
A gluten-free diet (GFD) is a nutritional plan that strictly excludes gluten, which is a mixture of prolamin proteins found in wheat, as well as barley, rye, and oats. The inclusion of oats in a gluten-free diet remains controversial, and may depend on the oat cultivar and the frequent cross-contamination with other gluten-containing cereals.
Fructose malabsorption, formerly named dietary fructose intolerance (DFI), is a digestive disorder in which absorption of fructose is impaired by deficient fructose carriers in the small intestine's enterocytes. This results in an increased concentration of fructose. Intolerance to fructose was first identified and reported in 1956.
Functional gastrointestinal disorders (FGID), also known as disorders of gut–brain interaction, include a number of separate idiopathic disorders which affect different parts of the gastrointestinal tract and involve visceral hypersensitivity and motility disturbances.
Small intestinal bacterial overgrowth (SIBO), also termed bacterial overgrowth, or small bowel bacterial overgrowth syndrome (SBBOS), is a disorder of excessive bacterial growth in the small intestine. Unlike the colon, which is rich with bacteria, the small bowel usually has fewer than 100,000 organisms per millilitre. Patients with bacterial overgrowth typically develop symptoms which may include nausea, bloating, vomiting, diarrhea, malnutrition, weight loss and malabsorption, which is caused by a number of mechanisms.
Prebiotics are compounds in food that foster growth or activity of beneficial microorganisms such as bacteria and fungi. The most common environment considered is the gastrointestinal tract, where prebiotics can alter the composition of organisms in the gut microbiome.
Food intolerance is a detrimental reaction, often delayed, to a food, beverage, food additive, or compound found in foods that produces symptoms in one or more body organs and systems, but generally refers to reactions other than food allergy. Food hypersensitivity is used to refer broadly to both food intolerances and food allergies.
Abdominal bloating is a short-term disease that affects the gastrointestinal tract. Bloating is generally characterized by an excess buildup of gas, air or fluids in the stomach. A person may have feelings of tightness, pressure or fullness in the stomach; it may or may not be accompanied by a visibly distended abdomen. Bloating can affect anyone of any age range and is usually self-diagnosed, in most cases does not require serious medical attention or treatment. Although this term is usually used interchangeably with abdominal distension, these symptoms probably have different pathophysiological processes, which are not fully understood.
The specific carbohydrate diet (SCD) is a restrictive diet originally created to manage celiac disease; it limits the use of complex carbohydrates. Monosaccharides are allowed, and various foods including fish, aged cheese and honey are included. Prohibited foods include cereal grains, potatoes and lactose-containing dairy products. It is a gluten-free diet since no grains are permitted.
Gluten-related disorders is the term for the diseases triggered by gluten, including celiac disease (CD), non-celiac gluten sensitivity (NCGS), gluten ataxia, dermatitis herpetiformis (DH) and wheat allergy. The umbrella category has also been referred to as gluten intolerance, though a multi-disciplinary physician-led study, based in part on the 2011 International Coeliac Disease Symposium, concluded that the use of this term should be avoided due to a lack of specificity.
Non-celiac gluten sensitivity (NCGS) or gluten sensitivity is a controversial disorder which can cause both gastrointestinal and other problems.
The gluten challenge test is a medical test in which gluten-containing foods are consumed and (re-)occurrence of symptoms is observed afterwards to determine whether and how much a person reacts to these foods. The test may be performed in people with suspected gluten-related disorders in very specific occasions and under medical supervision, for example in people who had started a gluten-free diet without performing duodenal biopsy.
Serum-derived bovine immunoglobulin/protein isolate (SBI) is a medical food product derived from bovine serum obtained from adult cows in the United States. It is sold under the name EnteraGam.
A low-FODMAP diet is a person's global restriction of consumption of all fermentable carbohydrates (FODMAPs), recommended only for a short time. A low-FODMAP diet is recommended for managing patients with irritable bowel syndrome (IBS) and can reduce digestive symptoms of IBS including bloating and flatulence.
Although intolerance to fructans and other FODMAPs may contribute to NCGS, they may only explain gastrointestinal symptoms and not the extraintestinal symptoms observed in NCGS patients, such as neurologic dysfunction, psychological disturbances, fibromyalgia, and skin rash.15 Therefore, it is unlikely that they are the sole cause of NCGS.
Wheat is a major source of fructans in the diet. (...) Table 1 Food sources of FODMAPs. (...) Oligosaccharides (fructans and/or galactans). Cereals: wheat & rye when eaten in large amounts (e.g. bread, pasta, couscous, crackers, biscuits)
An emerging body of research now demonstrates the efficacy of fermentable carbohydrate restriction in IBS. [...] However, further work is urgently needed both to confirm clinical efficacy of fermentable carbohydrate restriction in a variety of clinical subgroups and to fully characterize the effect on the gut microbiota and the colonic environ¬ment. Whether the effect on luminal bifidobacteria is clinically relevant, preventable, or long lasting, needs to be investigated. The influence on nutrient intake, dietary diversity that might also affect the gut microbiota, and quality of life also requires further exploration as does the possible economic effects due to reduced physician contact and need for medication. Although further work is required to confirm its place in IBS and functional bowel disorder clinical pathways, fermentable carbohydrate restriction is an important consideration for future national and international IBS guidelines.
Cereals such as wheat and rye, when consumed in normal quantities, are only minor sources of FODMAPs in the daily diet. (...) Table 1. Sources of FODMAPs (...) Oligosaccharides (fructans and/or galactans). Cereals: wheat and rye when eaten in large amounts (eg, bread, pasta, couscous, crackers, biscuits)
Furthermore, a role for the FODMAP (eg, fructans) component of wheat as the sole trigger for symptoms is somewhat doubtful, because many patients with NCWS report resolution of symptoms after the withdrawal of wheat and related cereals, while continuing to ingest vegetables and fruits with high FODMAP content in their diets.59 On the whole, it is conceivable that more than one culprit may be involved in symptoms of NCWS (as they are currently defined), including gluten, other wheat proteins, and FODMAPs.60–62
Common symptoms of IBS are bloating, abdominal pain, excessive flatus, constipation, diarrhea, or alternating bowel habit. These symptoms, however, are also common in the presentation of coeliac disease, inflammatory bowel disease, defecatory disorders, and colon cancer. Confirming the diagnosis is crucial so that appropriate therapy can be undertaken. Unfortunately, even in these alternate diagnoses, a change in diet restricting FODMAPs may improve symptoms and mask the fact that the correct diagnosis has not been made. This is the case with coeliac disease where a low-FODMAP diet can concurrently reduce dietary gluten, improving symptoms, and also affecting coeliac diagnostic indices. Misdiagnosis of intestinal diseases can lead to secondary problems such as nutritional deficiencies, cancer risk, or even mortality in the case of colon cancer.
the impact of a lactose-restricted diet in patients with IBS is debated. Lactose is a component of the FODMAPs (highly fermentable oligo-, di-, monosaccharides and polyols) diet. Several studies confirmed the positive impact of a low FODMAP diet (LFD) in improving digestive symptoms in IBS. On the other hand, a lactose BT should be performed before an LFD in populations with a low prevalence of LM, avoiding an inappropriate exclusion of lactose in lactase-persistent IBS patients. Apart from FODMAPs, a lactose-restricted diet should be reserved for hypolactasic IBS patients. In conclusion, a restriction of lactose should be not systematically recommended in patients with IBS
Even less evidence exists for the efficacy of the SCD, FODMAP, or Paleo diet. Furthermore, the practicality of maintaining these interventions over long periods of time is doubtful. At a practical level, adherence to defined diets may result in an unnecessary financial burden or reduction in overall caloric intake in patients who are already at risk for protein-calorie malnutrition.
The literature suggests that FODMAPs and not gluten per se are the triggers of gastrointestinal symptoms in patients that fit most of the proposed NCGS definitions
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