of proton pump inhibitors proton-pump inhibitors (ppis) used to suppress stomach acid production may cause small intestinal bacterial overgrowth (sibo) 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. antidepressants evidence is conflicting about the benefit of antidepressants in ibs. some meta-analyses have found a benefit, while others have not. there is good evidence that low doses of tricyclic antidepressants (tcas) can be effective for ibs. with tcas, about one in three people improve. however, the evidence is less robust for the effectiveness of other antidepressant classes such as selective serotonin reuptake inhibitor antidepressants (ssris). because of their serotonergic effect, ssris have been studied in ibs, especially for people who are constipation predominant. as of 2015, the evidence indicates that ssris do not help. antidepressants are not effective for ibs in people with depression, possibly because lower doses of antidepressants than the doses used to treat depression are required for relief of ibs. other agents magnesium aluminum silicates and alverine citrate drugs can be effective for ibs. rifaximin may be useful as a treatment for ibs symptoms, including abdominal bloating and flatulence, although relief of abdominal distension is delayed. it is especially useful where small intestinal bacterial overgrowth is involved. in individuals with ibs and low levels of vitamin d supplementation is recommended. some evidence suggests that vitamin d supplementation may improve symptoms of ibs, but further research is needed before it can be recommended as a specific treatment for ibs. psychological therapies there is low quality evidence from studies with poor methodological quality that psychological therapies can be effective in the treatment of ibs. reducing stress may reduce the frequency and severity of ibs symptoms. techniques that may be helpful include regular exercise, such as swimming, walking, or running. vagus nerve stimulation vagus nerve stimulation has anti-inflammatory effects and its potential for the treatment of ibs is actively researched. alternative medicine a meta-analysis found no benefits of acupuncture relative to placebo for ibs symptom severity or ibs-related quality of life. 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. 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. 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. a number of probiotics have been found to be effective, including lactobacillus plantarum, and bifidobacteria infantis; but one review found only bifidobacteria infantis showed efficacy. 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. some yogurt is made using probiotics that may help ease symptoms of ibs. a probiotic yeast called saccharomyces boulardii has some evidence of effectiveness in the treatment of irritable bowel syndrome. 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. 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. a fecal transplant does not appear useful as of 2019. the most clinically researched multi-strain probiotic is the de simone formulation. developed by a gastroenterologist medical doctor, the formulation has been studied in over 70 human clinical trials since the 1990s including for dysbiosis factors relating to irritable bowel syndrome in children and adults. herbal remedies peppermint oil appears useful. in a meta-analysis it was found to be superior to placebo for improvement of ibs symptoms, at least in the short term. an earlier meta-analysis suggested the results of peppermint oil were tentative as the number of people studied was small and blinding of those receiving treatment was unclear. 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. iberogast, a multi-herbal extract, was found to be superior in efficacy to placebo. a comprehensive meta-analysis using twelve random trials resulted that the use of peppermint oil is an effective therapy for adults with irritable bowel syndrome. research into cannabinoids as treatment for ibs is limited. gi propulsion, secretion, and inflammation in the gut are all modulated by the ecs (endocannabinoid system), providing a rationale for cannabinoids as treatment candidates for ibs. 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. epidemiology percentage of population with ibs reported in various studies in different countries (see sources in the table) the prevalence of ibs varies by country and by age range examined. the bar graph at right shows the percentage of the population reporting symptoms of ibs in studies from various geographic regions (see table below for references). the following table contains a list of studies performed in different countries that measured the prevalence of ibs and ibs-like symptoms: percentage of population reporting symptoms of ibs in various studies from various geographic areas location prevalence author/year notes canada 6% boivin, 2001 japan 10% quigley, 2006 study measured prevalence of gi abdominal pain/cramping united kingdom 8.2% 10.5% ehlin, 2003 wilson, 2004 prevalence increased substantially 1970–2004 united states 14.1% hungin, 2005 most undiagnosed united states 15% boivin, 2001 estimate pakistan 14% jafri, 2007 much more common in 16–30 age range. 56% male, 44% female pakistan 34% jafri, 2005 college students mexico city 35% schmulson, 2006 n=324. also measured functional diarrhea and functional vomiting. high rates attributed to "stress of living in a populated city." brazil 43% quigley, 2006 study measured prevalence of gi abdominal pain/cramping mexico 46% quigley, 2006 study measured prevalence of gi abdominal pain/cramping gender in western countries, women are around two to three times more likely to be diagnosed with ibs and four to five times more likely to seek specialty care for it than men. however, women in east asian countries are not more likely than men to have irritable bowel syndrome, and there are conflicting reports about the female predominance of the disease in africa and other parts of asia. people diagnosed with ibs are usually younger than 45 years old. studies of females with ibs show symptom severity often fluctuates with the menstrual cycle, suggesting hormonal differences may play a role. endorsement of gender-related traits has been associated with quality of life and psychological adjustment in ibs. the increase in gastrointestinal symptoms during menses or early menopause may be related to declining or low estrogen and progesterone, suggesting that estrogen withdrawal may play a role in ibs. gender differences in healthcare-seeking may also play a role. gender differences in trait anxiety may contribute to lower pain thresholds in women, putting them at greater risk for a number of chronic pain disorders. finally, sexual trauma is a major risk factor for ibs, as are other forms of abuse. because women are at higher risk of sexual abuse than men, sex-related risk of abuse may contribute to the higher rate of ibs in women. history the concept of an "irritable bowel" was introduced by p.w. brown, first in the journal of the kansas medical society in 1947 and later in the rocky mountain medical journal in 1950. the term was used to categorize people who developed symptoms of diarrhea, abdominal pain, and constipation, but where no well-recognized infective cause could be found. early theories suggested the irritable bowel was caused by a psychosomatic or mental disorder. society and culture economics united states the aggregate cost of irritable bowel syndrome in the united states has been estimated at $1.7–10 billion in direct medical costs, with an additional $20 billion in indirect costs, for a total of $21.7–30 billion. a study by a managed care company comparing medical costs for people with ibs to non-ibs controls identified a 49% annual increase in medical costs associated with a diagnosis of ibs. people with ibs incurred average annual direct costs of $5,049 and $406 in out-of-pocket expenses in 2007. a study of workers with ibs found that they reported a 34.6% loss in productivity, corresponding to 13.8 hours lost per 40 hour week. a study of employer-related health costs from a fortune 100 company conducted with data from the 1990s found people with ibs incurred us$4527 in claims costs vs. $3276 for controls. a study on medicaid costs conducted in 2003 by the university of georgia college of pharmacy and novartis found ibs was associated in an increase of $962 in medicaid costs in california, and $2191 in north carolina. people with ibs had higher costs for physician visits, outpatients visits, and prescription drugs. the study suggested the costs associated with ibs were comparable to those found for people with asthma. research individuals with ibs have been found to have decreased diversity and numbers of bacteroidota microbiota. preliminary research into the effectiveness of fecal microbiota transplant in the treatment of ibs has been very favourable with a 'cure' rate of between 36 percent and 60 percent with remission of core ibs symptoms persisting at 9 and 19 months follow up. treatment with probiotic strains of bacteria has shown to be effective, though not all strains of microorganisms confer the same benefit and adverse side effects have been documented in a minority of cases. there is increasing evidence for the effectiveness of mesalazine (5-aminosalicylic acid) in the treatment of ibs. mesalazine is a drug with anti-inflammatory properties that has been reported to significantly reduce immune mediated inflammation in the gut of ibs affected individuals with mesalazine therapy resulting in improved ibs symptoms as well as feelings of general wellness in ibs affected people. it has also been observed that mesalazine therapy helps to normalise the gut flora which is often abnormal in people who have ibs. the therapeutic benefits of mesalazine may be the result of improvements to the epithelial barrier function. treatment based on "abnormally" high igg antibodies cannot be recommended. differences in visceral sensitivity and intestinal physiology have been noted in ibs. mucosal barrier reinforcement in response to oral 5-htp was absent in ibs compared to controls. ibs/ibd individuals are less often hla dq2/8 positive than in upper functional gastrointestinal disease and healthy populations. in other species a similar syndrome is found in rats (rattus spp.). in rats a short-chain fatty acid receptor is involved. karaki et al., 2006 finds a free fatty acid receptor 2 subtype – gpr43 – that is expressed in both enteroendocrine cells and mucosal mast cells. these cells then respond in an exaggerated way to the ibs rat's own large quantity of maldigestion products. notes the cited review is based on sources ranging from 1988 to 2001 and is probably biased relative to a more recent research.