Irritable bowel syndrome From Wikipedia, the free encyclopedia This article is about a functional disorder. For bowel inflammation, see Inflammatory bowel disease. Irritable bowel syndrome Classification and external resources ICD-10 K58 ICD-9 564.1 DiseasesDB 30638 MedlinePlus 000246 eMedicine med/1190 Patient UK Irritable bowel syndrome MeSH D043183 Irritable bowel syndrome (IBS) or spastic colon is a symptom-based diagnosis. It is characterized by chronic abdominal pain, discomfort, bloating, and alteration of bowel habits. Diarrhea or constipation[1] may predominate, or they may alternate (classified as IBS-D, IBS-C, or IBS-A, respectively). As a functional gastrointestinal disorder (FGID), IBS has no known organic cause.[2] Onset of IBS is more likely to occur after an infection (postinfectious IBS-PI),[3] or a stressful life event,[4] but varies little with age.[5] The most common theory is that IBS is a disorder of the interaction between the brain and the gastrointestinal tract.[6] For at least some individuals, abnormalities in the gut flora occur, and it has been theorised that these abnormalities result in inflammation and altered bowel function.[7] A diagnosis of IBS may be made on the basis of symptoms, in the absence of worrisome features such as age of onset greater than 50 years, weight loss, bloody stool, signs of infection or colitis, or family history of inflammatory bowel disease.[8][9] Routine testing yields no abnormalities, although the bowels may be more sensitive to certain stimuli, such as balloon insufflation testing. Several conditions may present similarly, including coeliac disease, fructose malabsorption,[10] mild infections, parasitic infections like giardiasis,[11] inflammatory bowel disease, bile acid malabsorption, functional chronic constipation, small intestinal bacterial overgrowth, and chronic functional abdominal pain. Although no cure for IBS is known, treatments to relieve symptoms exist. This including dietary adjustments, medication, and psychological interventions. Patient education and good doctor–patient relationships are also important.[12] Dietary measures that have been found to be effective include increasing soluble fiber intake.[13] IBS has no direct effect on life expectancy. It is, however, a source of chronic pain, fatigue, and other symptoms, and contributes to work absenteeism.[14][15] It is common[16][17][18] and its effects on quality of life make it a disease with a high social cost.[19][20] Psychiatric disorders such as anxiety and major depression are common in IBS.[21] Contents 1 Classification 2 Signs and symptoms 3 Causes 3.1 Risk factors 4 Mechanism 5 Diagnosis 5.1 Differential diagnosis 5.2 Investigations 5.3 Misdiagnosis 5.4 Comorbidities 6 Management 6.1 Diet 6.2 Medication 6.3 Psychological therapies 6.4 Stress relief 7 Epidemiology 7.1 Gender 8 History 9 Economics 9.1 In the US 10 Research 11 See also 12 References 13 External links Classification IBS can be classified as either diarrhea-predominant (IBS-D), constipation-predominant (IBS-C), or with alternating stool pattern (IBS-A) or pain-predominant.[22] In some individuals, IBS may have an acute onset and develop after an infectious illness characterized by two or more of: fever, vomiting, diarrhea, or positive stool culture. This postinfective syndrome has consequently been termed "postinfectious IBS" (IBS-PI). Signs and symptoms The primary symptoms of IBS are abdominal pain or discomfort in association with frequent diarrhea or constipation and a change in bowel habits.[23] There may also be urgency for bowel movements, a feeling of incomplete evacuation (tenesmus), bloating, or abdominal distension.[24] In some cases, the symptoms are relieved by bowel movements.[12] People with IBS, more commonly than others, have gastroesophageal reflux, symptoms relating to the genitourinary system, chronic fatigue syndrome, fibromyalgia, headache, backache, and psychiatric symptoms such as depression and anxiety.[21][24] About a third of men and women who have IBS also report sexual dysfunction typically in the form of a reduction in libido.[25] Some studies indicate up to 60% of people with IBS also have a psychological disorder, typically anxiety or depression.[26] Causes While the cause of IBS is unknown, a disruption of the brain-gut axis and small intestinal bacterial overgrowth are thought to be important factors.[27][28] The risk of developing IBS increases six-fold after acute gastrointestinal infection. Postinfection, further risk factors are young age, prolonged fever, anxiety, and depression.[29] Antibiotic usage also appears to increase the risk of developing IBS.[30] Risk factors Research has found that genetic defects in innate immunity and epithelial homeostasis increase the risk of developing both post-infectious as well as other forms of IBS.[31] Post-infectious Approximately 10 percent of IBS cases are triggered by an acute gastroenteritis infection. Genetic defects relating to the innate immune system and epithelial barrier as well as high stress and anxiety levels appear from evidence to increase the risk of developing post-infectious IBS. Post-infectious IBS usually manifests itself as the diarrhea predominant subtype. Evidence has demonstrated that the release of high levels of proinflammatory cytokines during acute enteric infection causes increased gut permeability leading to translocation of the commensal bacteria across the epithelial barrier resulting in significant damage to local tissues which is likely to result in chronic gut abnormalities in sensitive individuals. However, increased gut permeability is strongly associated with IBS regardless of whether IBS was initiated by an infection or not.[31] Stress Publications suggesting the role of brain-gut "axis" appeared in the 1990s[32] and childhood physical and psychological abuse is often associated with the development of IBS.[33] Given the high levels of anxiety seen in IBS patients and the overlap with conditions such as fibromyalgia and chronic fatigue syndrome, a potential model of IBS involves a disruption of the stress system. The stress response in the body involves the HPA axis and the sympathetic nervous system, both of which have been shown to operate abnormally in IBS patients. Psychiatric illness or anxiety precedes IBS symptoms in two-thirds of patients, and psychological traits predispose previously healthy people to developing IBS after gastroenteritis.[34][35] Small intestinal bacterial overgrowth Small intestinal bacterial overgrowth occurs with greater frequency in patients who have been diagnosed with IBS compared to healthy controls. SIBO is most common in diarrhea predominate IBS but also occurs in constipation predominant IBS more frequently than healthy controls. Symptoms of SIBO include bloating, abdominal pain, diarrhea or constipation among others. IBS may be the result of the immune system interacting abnormally with gut microbiota resulting in an abnormal cytokine signalling profile.[36] Active infections Prevalence of protozoal infections in industrialized countries (United States and Canada) in the 21st century[37][38] Other researchers have focused on a possible unrecognized protozoal infection such as blastocystosis as a cause of IBS[6] as certain protozoal infections occur more frequently in IBS patients.[39][40] Dientamoeba fragilis has also been considered a possible organism to study, though it is also found in people without IBS.[41] Mechanism There is evidence that abnormalities occur in the gut flora of individuals who suffer from IBS such a loss of diversity with a decrease in Bacteroidetes.[7] The changes in gut flora are most profound in individuals who have diarrhoea predominant IBS. Antibodies against common components (namely flagellin) of the commensal gut flora are a common occurrence in IBS affected individuals.[42] Chronic low-grade inflammation commonly occurs in IBS affected individuals with abnormalities found including increased enterochromaffin cells, intraepithelial lymphocytes, and mast cells resulting in chronic immune mediated inflammation of the gut mucosa.[43] Genetic, environmental, and psychological factors seem to be important in the development of IBS. Studies have shown that IBS has a genetic component even though there is a predominant influence of environmental factors.[44] IBS has been reported in greater quantities in multigenerational families with IBS than in the regular population.[45] This suggests a heritability factor. This factor does not follow classic Mendelian but is of the complex/multifactorial variety. 286 genes have been identified that are variably expressed in IBS-D patients.[46] Some research suggests the consumption of spicy foods is directly associated with IBS, especially in women.[47] Changes in serotonin metabolisms are thought to play a role in IBS development. One study found increased levels of serotonin transporter in the ileum of patients suffering from IBS.[48] Another study suggested that an increased expression of apoptotic genes in IBS can lead to an increase in mast cells in the intestine. This may lead to internalization of cellular adhesion proteins such as ZO-1 and occludin.[46] Diagnosis No specific laboratory or imaging test can be performed to diagnose irritable bowel syndrome. Diagnosis involves excluding conditions that produce IBS-like symptoms, and then following a procedure to categorize the patient's symptoms. Ruling out parasitic infections, lactose intolerance, small intestinal bacterial overgrowth, and celiac disease is recommended for all patients before a diagnosis of irritable bowel syndrome is made. In patients over 50 years old, they are recommended to undergo a screening colonoscopy.[49] IBS sufferers are at increased risk of being given inappropriate surgeries such as appendectomy, cholecystectomy, and hysterectomy due to their IBS symptoms being misdiagnosed as medical conditions.[50] Differential diagnosis Colon cancer, inflammatory bowel disease, thyroid disorders, and giardiasis can all feature abnormal defecation and abdominal pain. Less common causes of this symptom profile are carcinoid syndrome, microscopic colitis, bacterial overgrowth, and eosinophilic gastroenteritis; IBS is, however, a common presentation, and testing for these conditions would yield low numbers of positive results, so it is considered difficult to justify the expense.[51] Because many causes of diarrhea give IBS-like symptoms, the American Gastroenterological Association published a set of guidelines for tests to be performed to rule out other causes for these symptoms. These include gastrointestinal infections, lactose intolerance, and coeliac disease. Research has suggested these guidelines are not always followed.[49] Once other causes have been excluded, the diagnosis of IBS is performed using a diagnostic algorithm. Well-known algorithms include the Manning criteria, the obsolete Rome I and II criteria, and the Kruis criteria, and studies have compared their reliability.[52] The more recent Rome III process was published in 2006. Physicians may choose to use one of these guidelines or may simply choose to rely on their own anecdotal experience with past patients. The algorithm may include additional tests to guard against misdiagnosis of other diseases as IBS. Such "red flag" symptoms may include weight loss, gastrointestinal bleeding, anemia, or nocturnal symptoms. However, red flag conditions may not always contribute to accuracy in diagnosis; for instance, as many as 31% of IBS patients have blood in their stool, many possibly from hemorrhoidal bleeding.[52] The diagnostic algorithm identifies a name that can be applied to the patient's condition based on the combination of the patient's symptoms of diarrhea, abdominal pain, and constipation. For example, the statement "50% of returning travelers had developed functional diarrhea while 25% had developed IBS" would mean half the travelers had diarrhea while a quarter had diarrhea with abdominal pain. While some researchers believe this categorization system will help physicians understand IBS, others have questioned the value of the system and suggested all IBS patients have the same underlying disease but with different symptoms.[53] Investigations Investigations are performed to exclude other conditions: Stool microscopy and culture (to exclude infectious conditions) Blood tests: Full blood examination, liver function tests, erythrocyte sedimentation rate, and serological testing for coeliac disease Abdominal ultrasound (to exclude gallstones and other biliary tract diseases) Endoscopy and biopsies (to exclude peptic ulcer disease, coeliac disease, inflammatory bowel disease, and malignancies) Hydrogen breath testing (to exclude fructose and lactose malabsorption) Misdiagnosis Some common examples of misdiagnosis include infectious diseases, coeliac disease,[54] Helicobacter pylori,[55][56] parasites.[6][57][58] Coeliac disease in particular is often misdiagnosed as IBS. The American College of Gastroenterology recommends all patients with symptoms of IBS be tested for coeliac disease.[59] Bile acid malabsorption is also sometimes missed in patients with diarrhea-predominant IBS. SeHCAT tests suggest around 30% of D-IBS patients have this condition, and most respond to bile acid sequestrants.[60] Chronic use of certain sedative-hypnotic drugs, especially the benzodiazepines, may cause irritable bowel-like symptoms that can lead to a misdiagnosis of irritable bowel syndrome.[61] Comorbidities Several medical conditions, or comorbidities, appear with greater frequency in patients diagnosed with IBS. Neurological/Psychiatric: A study of 97,593 individuals with IBS identified comorbidities such as headache, fibromyalgia, and depression.[62] IBS occurs in 51% of chronic fatigue syndrome patients and 49% of fibromyalgia patients, and psychiatric disorders occur in 94% of IBS patients.[21] Inflammatory bowel disease: IBS may be a type of low-grade inflammatory bowel disease.[63] Researchers have suggested IBS and IBD are interrelated diseases,[64] noting that patients with IBD experience IBS-like symptoms when their IBD is in remission.[65][66] A three-year study found that patients diagnosed with IBS were 16.3 times more likely to be diagnosed with IBD during the study period.[67] Serum markers associated with inflammation have also been found in patients with IBS. Abdominal surgery: IBS patients were at increased risk of having unnecessary gall bladder removal surgery not due to an increased risk of gallstones, but rather to abdominal pain, awareness of having gallstones, and inappropriate surgical indications.[68] These patients also are 87% more likely to undergo abdominal and pelvic surgery and three times more likely to undergo gallbladder surgery.[69] Also, IBS patients were twice as likely to undergo hysterectomy.[70] Endometriosis: One study reported a statistically significant link between migraine headaches, IBS, and endometriosis.[71] Other chronic disorders: Interstitial cystitis may be associated with other chronic pain syndromes, such as irritable bowel syndrome and fibromyalgia. The connection between these syndromes is unknown.[72] Management A number of treatments have been found to be effective including: fiber, talk therapy antispasmodic and antidepressant medication, and peppermint oil.[73][74] Diet Studies have shown that up to 70% of IBS patients benefited from eating a low FODMAP diet. Symptoms most likely to improve from such a diet include urgency, flatulence, bloating, abdominal pain, and altered stool output. One national guideline advises a low FODMAP diet for managing IBS when other dietary and lifestyle measures have been unsuccessful.[75] This diet restricts various carbohydrates which are poorly absorbed in the small intestine, as well as fructose and lactose, which are similarly poorly absorbed in those with intolerances to them. Reduction of fructose and fructan has been shown to reduce IBS symptoms in a dose-dependent manner in patients with fructose malabsorption and IBS.[76] Many[quantify] individuals with IBS are lactose intolerant and a trial of a lactose-free diet is often recommended.[77] Alternatively, an over-the-counter remedy containing lactase enzyme can be taken before consuming milk products. Allergy to milk products also causes diarrhea and other symptoms, and this will not be improved by a lactase enzyme supplement. Many who benefit from a low-FODMAP diet need not restrict fructose or lactose. Some IBS patients believe they have some form of dietary intolerance; however, tests attempting to predict food sensitivity in IBS have proven disappointing. A small study reported that an IgG antibody test was somewhat effective in determining food sensitivity in IBS patients, with patients on the elimination diet experiencing 10% greater symptom-reduction than those on a sham diet.[78] However, more research is necessary before IgG testing can be recommended.[79] No evidence indicates digestion of food or absorption of nutrients is problematic for those with IBS at rates different from those without IBS. However, the very act of eating or drinking can provoke an overreaction of the gastrocolic response in some patients with IBS owing to their heightened visceral sensitivity, and this may lead to abdominal pain, diarrhea, and/or constipation.[80] FODMAPs diet A diet restricted in fermentable oligo- di- and monosaccharides and polyols (FODMAPs) now has an evidence base sufficiently strong to recommend its widespread application in conditions such as IBS and IBD.[81] They also state the restriction of FODMAPs globally, rather than individually, controls the symptoms of functional gut disorders (e.g., IBS), and the majority of IBD patients respond just as well. It is more successful than restricting only fructose and fructans, which are also FODMAPs, as is recommended for those with fructose malabsorption. Longer-term compliance with the diet was high. Fiber Some evidence suggests soluble fiber supplementation (e.g., psyllium/ispagula husk) is effective.[13] It acts as a bulking agent, and for many IBS-D patients, allows for a more consistent stool. For IBS-C patients, it seems to allow for a softer, moister, more easily passable stool. However, insoluble fiber (e.g., bran) has not been found to be effective for IBS.[82][83] In some people, insoluble fiber supplementation may aggravate symptoms.[84][85] Fiber might be beneficial in those who have a predominance of constipation. In people who have IBS-C, soluble fiber can reduce overall symptoms, but will not reduce pain. The research supporting dietary fiber contains conflicting, small studies complicated by the heterogeneity of types of fiber and doses used.[86] One meta-analysis found only soluble fiber improved global symptoms of irritable bowel, but neither type of fiber reduced pain.[86] An updated meta-analysis by the same authors also found soluble fiber reduced symptoms, while insoluble fiber worsened symptoms in some cases.[87] Positive studies have used 10–30 grams per day of psyllium.[88][89] One study specifically examined the effect of dose, and found 20 g of ispaghula husk were better than 10 g and equivalent to 30 g per day.[90] Medication Medications may consist of stool softeners and laxatives in IBS-C and antidiarrheals (e.g., opiate, opioid, or opioid analogs such as loperamide, codeine, diphenoxylate) in IBS-D for mild symptoms and stronger opiates such as morphine and oxycodone for severe cases.[91][92][93] Drugs affecting serotonin (5-HT) in the intestines can help reduce symptoms.[94] On the other hand, many IBS-D patients report that SSRI type medications exacerbate spasms and diarrhea. This is thought to be due to the large number of serotonin receptors in the gut. 5HT3 antagonists such as ondansetron are effective in postinfectious IBS and diarrhoea-dominant IBS due to their blockade of serotonin on 5HT3 receptors in the gut; the reason for their benefit is believed to be that excessive serotonin in the gut is thought to play a role in the pathogenesis of some subtypes of IBS. Certain atypical antipsychotic medications, such as clozapine and olanzapine, may also provide relief due to serotonergic properties these agents possess, acting on the same receptors as other medications in this specific category.[95] Benefits may include reduced diarrhoea, reduced abdominal cramps, and improved general well-being. Any nausea present may also respond to 5HT3 antagonists owing to their antiemetic properties.[96] Serotonin stimulates the gut motility and so agonists can help constipation-predominate irritable bowel, while antagonists can help diarrhea-predominant irritable bowel. Selective serotonin reuptake inhibitors, SSRIs, frequently prescribed for panic and/or anxiety disorder and depression, affect serotonin in the gut, as well as the brain. The bowels are highly dependent on serotonin for neural communication. "Selective serotonin reuptake inhibitor antidepressants seem to promote global well-being in some patients with irritable bowel syndrome and, possibly, some improvement in abdominal pain and bowel symptoms, but this effect appears to be independent of improved depression. Further research is required."[97] Laxatives For patients who do not adequately respond to dietary fiber, osmotic laxatives such as polyethylene glycol, sorbitol, and lactulose can help avoid "cathartic colon" which has been associated with stimulant laxatives.[98] Among the osmotic laxatives, doses of 17–26 g/d of polyethylene glycol have been well studied. Lubiprostone (Amitiza) is a gastrointestinal agent used for the treatment of idiopathic chronic constipation and constipation-predominant IBS. It is well tolerated in adults, including elderly patients. As of July 20, 2006, lubiprostone had not been studied in pediatric patients. Lubiprostone is a bicyclic fatty acid (prostaglandin E1 derivative) that acts by specifically activating ClC-2 chloride channels on the apical aspect of gastrointestinal epithelial cells, producing a chloride-rich fluid secretion. These secretions soften the stool, increase motility, and promote spontaneous bowel movements. Unlike many laxative products, lubiprostone does not show signs of tolerance, dependency, or altered serum electrolyte concentration. Antispasmodics The use of antispasmodic drugs (e.g., anticholinergics such as hyoscyamine or dicyclomine) may help patients, especially those with cramps or diarrhea. A meta-analysis by the Cochrane Collaboration concludes if seven patients are treated with antispasmodics, one patient will benefit.[91] Antispasmodics can be divided in two groups: neurotropics and musculotropics. Neurotropics — for example, phenobarbitals such as Donnatal or atropine — act at the nerve fibre of the parasympathicus, but also affect other nerves, causing side effects in many patients. Musculotropics, such as mebeverine, act directly at the smooth muscle of the gastrointestinal tract, relieving spasm without affecting normal gut motility.[citation needed] Since this action is not mediated by the autonomic nervous system, the usual anticholinergic side effects are absent.[citation needed] Discontinuation of proton pump inhibitors Proton pump inhibitors (PPIs) used to suppress stomach acid production may cause bacterial overgrowth leading to IBS symptoms. Discontinuation of PPIs in selected individuals has been recommended as it may lead to an improvement or resolution of IBS symptoms.[99] Tricyclic antidepressants Strong evidence indicates low doses of tricyclic antidepressants can be effective for IBS. However, the evidence is less robust as to the effectiveness of other antidepressant classes such as SSRIs.[83][85] Serotonin agonists Tegaserod (Zelnorm), a selective 5-HT4 agonist for IBS-C, is available for relieving IBS constipation in women and chronic idiopathic constipation in men and women. On March 30, 2007, the FDA requested Novartis Pharmaceuticals to voluntarily discontinue marketing of tegaserod based on the recently identified finding of an increased risk of serious cardiovascular adverse events (heart problems) associated with use of the drug. Novartis agreed to voluntarily suspend marketing of the drug in the United States and in many other countries. On July 27, 2007, the FDA approved a limited-treatment IND program for tegaserod in the US to allow restricted access to the medication for patients in need if no comparable alternative drug or therapy is available to treat the disease. The FDA had issued two previous warnings about the serious consequences of tegaserod. In 2005, it was rejected as an IBS medication by the European Union. Tegaserod, marketed as Zelnorm in the United States, was the only agent approved to treat the multiple symptoms of IBS (in women only), including constipation, abdominal pain, and bloating. Selective serotonin reuptake inhibitor antidepressants (SSRIs), because of their serotonergic effect, would seem to help IBS, especially patients who are constipation predominant. Initial crossover studies[100] and randomized controlled trials[101][102][103] support this role. Serotonin antagonists Alosetron, a selective 5-HT3 antagonist for IBS-D and cilansetron (also a selective 5-HT3 antagonist) were trialed for IBS. Due to severe adverse effects, namely ischemic colitis and severe constipation, they are not available or recommended.[85] Other agents Magnesium aluminum silicates and alverine citrate drugs can be effective for IBS.[85] Evidence is conflicting about the benefit of antidepressants in IBS. Some meta-analyses have found a benefit, while others have not.[104] A meta-analysis of randomized controlled trials of mainly TCAs found three patients have to be treated with TCAs for one patient to improve.[105] A separate randomized controlled trial found TCAs are best for patients with IBS-D.[106] Rifaximin can be used as an effective treatment for abdominal bloating and flatulence,[107][108] giving more credibility to the potential role of bacterial overgrowth in some patients with IBS.[109] Domperidone, a dopamine receptor blocker and a parasympathomimetic, has been shown to reduce bloating and abdominal pain as a result of an accelerated colon transit time and reduced faecal load, that is, a relief from 'hidden constipation'; defecation was similarly improved.[110] The use of opioids is controversial due to the potential risk of tolerance, physical dependence, and addiction, but can be the only relief for some diarrhea-predominant cases when other treatment has been ineffective.[111] SIBO therapy Statistically significant reduction in IBS symptoms occurs following antibiotic therapy for small intestinal bacterial overgrowth.[28] However, recent research has shown that the lactulose hydrogen breath test does not actually measure SIBO, and that SIBO is unlikely to be the cause of IBS.[112] Psychological therapies The mind-body or brain-gut interactions has been proposed for IBS, and is gaining increasing research attention.[83] Hypnosis can improve mental well-being, and cognitive behavioural therapy can provide psychological coping strategies for dealing with distressing symptoms, as well as help suppress thoughts and behaviours that increase the symptoms of IBS,[83][85] although the evidence base for effectiveness of psychotherapy and hypnosis is weak and such therapies are in general not recommended.[50] However, in treatment resistant cases where pharmacological therapies over a period of at least 12 months have failed to give relief, NICE clinical guidelines recommend that consideration should be given to psychological treatment strategies such as cognitive behavioural therapy [CBT], hypnotherapy and/or psychological therapy.[113] Stress relief Reducing stress may reduce the frequency and severity of IBS symptoms. Techniques that may be helpful include: Relaxation techniques such as meditation Physical activities such as yoga or tai chi Regular exercise such as swimming, walking, or running[114] Probiotics Probiotics can be beneficial in the treatment of IBS; taking 10 billion to 100 billion beneficial bacteria per day is recommended for beneficial results. However, further research is needed on individual strains of beneficial bacteria for more refined recommendations.[83][115] Probiotics have positive effects such as enhancing the intestinal mucosal barrier, providing a physical barrier, bacteriocin production (resulting in reduced numbers of pathogenic and gas-producing bacteria), reducing intestinal permeability and bacterial translocation, and regulating the immune system both locally and systemically among other beneficial effects.[50] Probiotics may also have positive effects on the gut-brain axis by their positive effects countering the effects of stress on gut immunity and gut function.[116] A number of probiotics have been found to be effective, including Lactobacillus plantarum,[50] and Bifidobacteria infantis;[117] but one review found only Bifidobacteria infantis showed efficacy.[118] B. infantis may have effects beyond the gut via it causing a reduction of proinflammatory cytokine activity and elevation of blood tryptophan levels, which may cause an improvement in symptoms of depression.[119] Some yogurt is made using probiotics that may help ease symptoms of IBS.[120] A probiotic yeast called Saccharomyces boulardii has some evidence of effectiveness in the treatment of irritable bowel syndrome.[121] Certain probiotics have different effects on certain symptoms of IBS. For example, Bifidobacterium breve, B. longum, and Lactobacillus acidophilus have been found to alleviate abdominal pain. B. breve, B. infantis, L. casei, or L. plantarum species alleviated distension symptoms. B. breve, B. infantis, L. casei, L. plantarum, B. longum, L. acidophilus, L. bulgaricus, and Streptococcus salivarius ssp. thermophilus have all been found to affect flatulence levels. Most clinical studies show probiotics do not improve straining, sense of incomplete evacuation, stool consistency, fecal urgency, or stool frequency, although a few clinical studies did find some benefit of probiotic therapy. The evidence is conflicting for whether probiotics improve overall quality of life scores.[122] Probiotics may exert their beneficial effects on IBS symptoms via preserving the gut microbiota, normalisation of cytokine blood levels, improving the intestinal transit time, decreasing small intestine permeability, and by treating small intestinal bacterial overgrowth of fermenting bacteria.[122] Herbal remedies Peppermint oil appears useful.[123] Safety during pregnancy has not been established, however, and caution is required not to chew or break the enteric coating; otherwise, gastroesophageal reflux may occur as a result of lower esophageal sphincter relaxation. Occasionally, nausea and perianal burning occur as side effects.[83] Iberogast: The multi-herbal extract was found to be superior to placebo.[124] Commiphora mukul and Plantago ovata[125] Only limited evidence exists for the effectiveness of other herbal remedies for IBS. As with all herbs, it is wise to be aware of possible drug interactions and adverse effects.[83] Yoga Yoga may be effective for some IBS patients, especially poses which exercise the lower abdomen.[85] Acupuncture Acupuncture might be beneficial for some patients with IBS, but current evidence does not support its use.[83] A meta-analysis found no benefits of acupuncture relative to placebo for IBS symptom severity or IBS-related quality of life.[126] Epidemiology.
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