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Abdominal Bloating: Pathophysiology and Treatment


Abstract and Figures

Abdominal bloating is a very common and troublesome symptom of all ages, but it has not been fully understood to date. Bloating is usually associated with functional gastrointestinal disorders or organic diseases, but it may also appear alone. The pathophysiology of bloating remains ambiguous, although some evidences support the potential mechanisms, including gut hypersensitivity, impaired gas handling, altered gut microbiota, and abnormal abdominal-phrenic reflexes. Owing to the insufficient understanding of these mechanisms, the available therapeutic options are limited. However, medical treatment with some prokinetics, rifaximin, lubiprostone and linaclotide could be considered in the treatment of bloating. In addition, dietary intervention is important in relieving symptom in patients with bloating.
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Journal of Neurogastroenterology and Motility
2013 The Korean Society of Neurogastroenterology and Motility
J Neurogastroenterol Motil, Vol. 19 No. 4 October, 2013
J Neurogastroenterol Motil, Vol. 19 No. 4 October, 2013
pISSN: 2093-0879 eISSN: 2093-0887
Abdominal Bloating: Pathophysiology and
A Young Seo,
Nayoung Kim
and Dong Hyun Oh
Department of Internal Medicine, Seoul National University, Bundang Hospital, Seongnam, Gyeonggi-do, Korea; and
Department of Internal
Medicine and Liver Research Institute, Seoul National University College of Medicine, Seoul, Korea
Abdominal bloating is a very common and troublesome symptom of all ages, but it has not been fully understood to date.
Bloating is usually associated with functional gastrointestinal disorders or organic diseases, but it may also appear alone. The
pathophysiology of bloating remains ambiguous, although some evidences support the potential mechanisms, including gut
hypersensitivity, impaired gas handling, altered gut microbiota, and abnormal abdominal-phrenic reflexes. Owing to the in-
sufficient understanding of these mechanisms, the available therapeutic options are limited. However, medical treatment with
some prokinetics, rifaximin, lubiprostone and linaclotide could be considered in the treatment of bloating. In addition, dietary
intervention is important in relieving symptom in patients with bloating.
(J Neurogastroenterol Motil 2013;19:433-453)
Key Words
Bloating; Pathophysiology; Rifaximin; Therapy
Received: September 3, 2013 Revised: September 10, 2013 Accepted: September 16, 2013
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.
org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work
is properly cited.
*Correspondence: Nayoung Kim, MD
Department of Internal Medicine, Seoul National University Bundang Hospital, 82 Gumi-ro, 173 Beon-gil, Bundang-gu,
Seongnam, Gyeonggi-do 463-707, Korea
Tel: +82-31-787-7008, Fax: +82-31-787-4051, E-mail:
Financial support: This work was supported by the National Research Foundation of Korea (NRF) grant (No. 2011-0030001) for the Global Core
Research Center (GCRC) funded by the Korea government (MSIP).
Conflicts of interest: None.
Author contributions: A Young Seo analyzed the references and wrote a manuscript. Dong Hyun Oh collected references and adapted the figures.
Nayoung Kim provided ideas, designed and supervised the manuscript.
Bloating is one of the most common gastrointestinal (GI)
symptoms, which is a frequent complaint in the patients of all
ages. This symptom is very common in patients with irritable
bowel syndrome (IBS) and other functional gastrointestinal dis-
orders (FGIDs) as well as in patients with organic disorders.
Many clinicians encounter the patients’ complaints such as “too
much gas in abdomen,” “heavy and uncomfortable feeling in ab-
domen” and “full belly.” The severity of bloating is varied from
mild discomfort to severe, and it is one of the bothersome symp-
toms of the patients, affecting their quality of life. Despite being
one of the frequent and bothersome complaints, bloating remains
incompletely understood of all the symptoms. Therefore clini-
cians need to be more considerate when evaluating patients with
abdominal bloating.
The possible causes of bloating are various and complicated,
thus intestinal gas production and transit, gut microflora and hy-
persensitivity of the patient’s gut might be the factors for the
symptom generation. As the underlying mechanism of bloating
remains elusive to date, there are few evidences for diagnostic and
A Young Seo, et al
Journal of Neurogastroenterology and Motility
therapeutic options available. In addition, patients who complain
of bloating tend to have IBS or functional dyspepsia (FD), thus
most of the therapeutic approaches of abdominal bloating are
based on the treatments of IBS and FD.
However bloating
could occur alone without associated diseases and there has been
not enough data of randomized controlled trials for treatment of
bloating alone. The treatments for bloating have not been stand-
ardized and there is no evidence-based algorithm. Although there
have been several comprehensive reviews for pathophysiology or
treatment of abdominal bloating in FGID (Table 1),
clinical trials and systematic reviews regarding functional bloat-
ing (FB) alone are scarce so far. Only one available pilot study
was from Spain, which indicated that sugar intolerance was fre-
quently observed in patients with FB and associated with bloating
symptom. Additionally, a malabsorbed sugar-free diet gave rise
to clinical improvement in high percentage of patients.
Thus, in
the clinical setting, rational treatment for bloating is hard and the
result of treatment is frequently unsatisfactory. Most treatment
options for bloating are similar to treatments for IBS, but as pre-
viously mentioned, FB and IBS are in different disease entities.
Aims and Methods
Our aim was to explain the clinical importance, pathophysio-
logic mechanisms, and management of abdominal bloating, thus
to provide a better understanding of this specific problem. We re-
viewed the literature of mechanisms and treatment interventions
for abdominal bloating based on a PubMed search on the follow-
ing terms; “abdominal bloating,” “intestinal gas and IBS,”
“distension and IBS” and “FGID.” We also quoted important
knowledge from a standard textbook, the chapter “intestinal
Bloating is defined as subjective discomfort by patient’s sen-
sation of intestinal gas; otherwise, abdominal distension is a visi-
ble increase in abdominal girth. In the past, bloating had been
considered to be related to abdominal distension directly, but re-
cent studies have suggested that it is not always accompanied by
abdominal distension.
There have been many studies to evaluate
the relationship between bloating and abdominal distension. One
study has shown that actual abdominal distension only occurred
in about half of the patients suffering from bloating.
In addi-
tion, some patients with both visceral hypersensitivity and FGID
complained of bloating in the absence of visible distension.
Briefly, abdominal bloating is the subjective symptom and dis-
tension is the objective sign, so bloating and distension should be
considered as separate disorders with different mechanisms.
Although bloating has been considered as a supportive symptom
for IBS or FD according to Rome classification, FB is also in-
cluded as an independent entity in Rome criteria.
The diag-
nosis of FB is made in patients who do not meet the diagnostic
criteria of IBS or other FGIDs, but have recurrent symptoms of
bloating. According to Rome III, the diagnostic criteria include
recurrent feeling of bloating or visible distension at least 3 days a
month in the last 3 months with symptom onset at least 6 months
prior to diagnosis. Also it should exclude FD, IBS or other
FGIDs. The name has been changed from functional abdominal
bloating in Rome I and II criteria to functional bloating in Rome
III criteria.
‘Bloating’ has been first described by Alvarez of the Mayo
Clinic in 1949, in a woman patient with psychological problem.
In USA, 15-30% of general population has been reported to ex-
perience bloating.
Also in Asia, similar result has been
shown (15-23%), suggesting that the prevalence of bloating is not
interracially different.
Though the data for FB alone are rela-
tively little, women typically have higher rates of bloating than
men according to the reports of IBS.
This relevance be-
tween female gender and bloating has long been suggested and
the hormonal effect in connection with menstrual cycle is re-
garded as one of the possible explanation.
Besides, there are
some reports of obese people experiencing more GI symptoms
such as abdominal pain or bloating.
Bloating is the second most common reported symptom in
patients with IBS following abdominal pain.
In a study from
USA which assessed bloating in 542 IBS patients, 76% of the pa-
tients reported that they experienced bloating.
Other study re-
vealed that more than 90% of patients with IBS suffered from
In addition, on comparing constipation dominant IBS
(IBS-C) with diarrhea dominant IBS (IBS-D), the prevalence of
bloating was higher in IBS-C.
A survey from the USA suggested that more than 65% of pa-
tients with bloating rated their symptom as moderate to severe,
and 54% of patients complained of decreased daily activity due to
bloating. Furthermore, 43% of patients took medication for
bloating or needed medication.
Abdominal Bloating: Pathophysiology and Treatment
Vol. 19, No. 4 October, 2013 (433-453)
Table 1. Summary of the Comprehensive Reviews for Abdominal Bloating
Author (yr) Study aim (method) Suggested mechanisms of bloating Treatment strategy
Zar et al
Pathophysiology and treatment for bloating
in functional bowel disorders
1. Abnormal gas trapping
2. Fluid retension
3. Food intolerance
4. Altered gut microflora
altered abdominal muscle tone, altered mucosal
sensitivity, colonic motor abnormalities
1. Limited efficacy; dietary intervention, activated charcoal, sime-
thicone, hypnotherapy
2. No efficacy; antibiotics, probiotics, prokinetics
Houghton et al
Pathophysiology and treatment for bloating
in FGIDs
1. Gas accumulation
2. Visceral hypersensitivity
3. Fluid retension
motor dysfunction, abnormal gut flora, weak
abdominal musculature
1. Some benefit; tegaserod, non-absorbable antibiotics, hypnothe-
rapy, surfactant
2. No efficacy; probiotics, activated charcoal, exercise, weight loss,
Azpiroz et al
Clinical importance, pathophysiology and
management of abdominal bloating (lite-
rature review from January 1989 to
September 2004, based on a PubMed
1. Altered abdominal wall activity
2. Abnormal perception
3. Intraluminal contents
4. Impaired gut and gas handling
Intraluminal gas volume
1. Some benefit; hypnosis, antidepressant
2. Undetermined; prokinetics, spasmolytics, peppermint oil, gas-re-
ducing substances, exclusion diet, exercise
Agrawal et al
Epidemiology and pathophysiology of ab-
dominal bloating in FGIDs (literature
review up to 2006, based on a Medline
1. Abnormal gas handling
2. Visceral hypersensitivity
3. Abnormal anterior wall muscular activity
carbohydrate intolerance, altered gut flora, small
bowel bacterial overgrowth
gas excess, altered intestinal transit
1. Effective; prokinetics (tegaserod, neostigmine), antibiotcs (neo-
mycin, rifiximin)
2. Worth trying; dietary intervention
3. Little evidence; simethicone, charcoal, antispasmodics, probiotics
Schmulson et al
Treatmentfor abdominal bloating and dis-
tension (literature review up to February
2010 in Medline)
Not available 1. Some efficacy; 5-HT
agonist (cisapride, tegaserod), lubipro-
stone, rifaximin, some probiotics (B. infantis 35624 and B.
animalis), antifoaming agents
2. New suggestion; low FODMAPs diet
3. Undetermined; antispasmodics, SSRIs, dopamine antagonist
4. No efficacy; bulking agents, laxatives
Lacy et al
Pathophysiology, evaluation, and treatment
of bloating and distension
1. Altered gut flora
2. Impaired gas transit
3. Impaired evacuation
4. Abnormal abdominal-diaphragmatic reflexes
5. Abnormal perception
psychosocial aspects
1. Some efficacy; exercise, rifaximin, cisapride, neostigmine, tegase-
rod, lubiprostone, linaclotide
2. New suggestion; diet (low FODMAPs)
3. Undetermined; simethicone, probiotics, TCAs, dopamine anta-
4. No efficacy; antispasmodics
possible mechanisms,
little or no evidence,
FGIDs, functional gastrointestinal disorders; 5-HT, 5-hydroxytryptamine; FODMAPs, fermentable oligo-, di- and mono-saccharides and polyols; SSRIs, selective serotonin reuptake inhibitors; TCAs, Tricyclic
A Young Seo, et al
Journal of Neurogastroenterology and Motility
Figure 1. Luminal and mucosal colonic microbiota and their roles in
gut homeostasis. Modified from Parkes et al.
Abnormal Gut Microbiota
The GI tract microbiota play an important role in host im-
mune system, and there are more than 500 different species of GI
microbiota in adult, which mostly are obligate anaerobes.
a fraction of these organisms can be cultured; therefore, the un-
derstanding of the functions of various microbes in the GI tract is
still limited. However, researches over the past decades have
shown that altered colonic flora were found in stool samples of
patients with IBS.
Parkes et al
suggested that the GI micro-
biota can be divided into 2 ecosystems; the luminal bacteria and
the mucosa-associated bacteria (Fig. 1). Luminal microbiota
form the majority of the GI tract flora, and they play a key role in
bloating and flatulence in IBS through carbohydrate fermenta-
tion and gas production.
One comprehensive study of the luminal microbiota in IBS
examined the fecal samples of IBS subgroups (diarrhea predom-
inant, constipation predominant and mixed subtype) and the con-
trols using 16S ribosomal RNA (rRNA) sequencing. It has been
shown that fecal microbiota are significantly altered in IBS. That
is, some patients with IBS seem to have different patterns of colo-
nization with coliforms, such as lactobacillus and bifidobacterium
compared to the controls.
Similar study from Korea using 16S
rRNA gene signatures also has demonstrated significant differ-
ences in diversity and dominance between IBS and non-IBS fecal
In addition, these microbial changes altered protein
and carbohydrate metabolism in the gut.
A study from Japan al-
so showed higher counts of Veillonella (P = 0.046) and Lactoba-
cillus (P = 0.031) in IBS patients than in controls. Besides, they
expressed significantly higher levels of acetic acid (P = 0.049),
propionic acid (P = 0.025) and total organic acids (P = 0.014)
than controls, which is related to symptoms such as abdominal
pain, bloating and changes in bowel habits.
Another study dem-
onstrated that the patients with IBS produced more H
but the
total gas excretion was similar in both IBS patients and controls.
This may be associated with alteration in colonic fermentation by
hydrogen-consuming bacteria, which may be an important factor
in the pathogenesis of IBS.
Collins et al
have proposed that disruption of the balance
between the host and intestinal microbiota produces changes in
the mucosal immune system from microscopic to overt in-
flammation and this also results in changes in gut sensory-motor
function and immune activity. Besides, these altered microflora
may produce differences in fermented gas type and volume,
which may be the causes of symptom in patients with bloa-
There have been some reports to verify the relationship be-
tween the types of gas produced by colonic microflora and
bloating. The low producers of methane reported significantly in-
creased bloating and cramping after ingestion of sorbitol and fi-
ber, and the high producers of methane revealed lower prevalence
of severe lactulose intolerance than low producers. Hence, the
role of methanogenic flora may be important in the pathogenesis
of bloating.
Small Intestinal Bacterial Overgrowth
The patients with IBS who specifically complain of bloating
have been reported to have increased gas production from bacte-
rial fermentation caused by small intestinal bacterial overgrowth
(SIBO). Pimentel and colleagues had established the concept
that SIBO might be a major pathogenesis of IBS.
several studies found significant improvement of symptoms such
as abdominal pain or bloating, when they were treated with
These findings, however, have not been sup-
ported by other studies;
they found mildly increased counts of
small intestinal bacteria by culture to be more common in IBS,
but the breath H
concentration was not significantly different
between IBS patients and controls.
Also, there was no correla-
tion between bacterial alteration and symptom pattern, and even
lactulose breath test was considered as an unreliable method to
detect an association between bacterial overgrowth and IBS.
Abdominal Bloating: Pathophysiology and Treatment
Vol. 19, No. 4 October, 2013 (433-453)
In another study, breath hydrogen concentration was similar in
IBS group and control group, and did not correlate with pain rat-
ings in IBS patients, owing to the lack of objective diagnostic
measures and inconsistent data.
It is unclear whether changes in small bowel bacterial flora
could contribute to bloating in IBS patients, thus further studies
are required to confirm these observations.
Intestinal Gas Accumulation
In the fasting state, the healthy GI tract contains only about
100 mL of gas distributed almost equally among 6 compartments
- stomach, small intestine, ascending colon, transverse colon, de-
scending colon and distal (pelvic) colon. Postprandial volume of
gas increases by about 65%, primarily in the pelvic colon.
excessive volume of intestinal gas has been proposed as the likely
cause of bloating and distension, and many researchers have at-
tempted to determine this view. A few studies using plain ab-
dominal radiography demonstrated that intestinal gas volume was
greater in patients with IBS than in controls (54% vs. 118%),
however, the correlation between intra-abdominal gas contents
and bloating was poor.
The vast majority of studies do not
support that excessive gas induces bloating or abdominal pain.
Lasser et al
conducted a study using argon washout technique,
which demonstrated no differences in the accumulation of in-
testinal gas between patients with bloating and healthy subjects.
More recent studies using CT scans combined with modern
imaging analysis software have also shown that excess gas was not
associated with abdominal bloating in most patients.
Thus, these
observations suggest that increased volume of gas may not be the
main mechanism of bloating, but rather impaired gas transit or
distribution are more often the sources of problem.
Altered Gut Motility and Impaired Gas
Various abnormal motility patterns have been described in
IBS patients, but none of those parameters can be used as diag-
nostic markers.
Some authors have suggested that slow transit
of food representing alteration in gut motility is related to bloat-
ing in IBS-C patients.
Also in a traditional experiment, normal
volunteers being made constipated with loperamide, an agent
known to slow transit, experienced bloating.
Recently, IBS-C
patients with delayed orocecal and colonic transits have shown ab-
dominal distension rather than bloating.
Although delayed gas-
tric emptying and slow intestinal transit in IBS-C patients were
reported in many Asian studies, there are still controversies to de-
fine these motor disturbances as unique features in Asian IBS
patients. Besides, the association between altered gut motility and
IBS symptoms is pretty obscure.
A recent study has also sug-
gested that altered colon transit is of no or minor importance for
IBS symptoms such as bloating or pain.
However, there are some different points with respect to the
intestinal gas handling or transit. In a study by Serra et al,
have shown that infused gas into the jejunum resulted in dis-
tension and abdominal bloating in most of the IBS patients (18 of
20), while only 20% (4 of 20) of control subjects developed symp-
toms like that. Another study using gas challenge technique has
demonstrated that small intestinal gas transit (especially, jeju-
num) was more prolonged in patients with bloating than in con-
trols, whereas colonic transit was normal.
These data support
that impaired small intestinal gas handling could be a mechanism
of IBS or gas-bloating. Furthermore, a gas challenge test in
healthy subjects during blocked rectal gas outflow showed that
abdominal distension by girth measurement was similar in the je-
junal and rectal infusion experiments, whereas abdominal symp-
toms including bloating were more significant in jejunal group.
These data indicate that gas related symptom perception is de-
termined by intraluminal gas distribution, whereas abdominal
distension depends on the volume of intestinal gas. Besides, the
patients with IBS or FB are considered to evacuate intestinal gas
less effectively, so that they are more likely to have symptoms of
abdominal distension.
This aspect of bloating’s mechanism
has not been considered to be very relevant, but some researchers
are interested in this view owing to the observations of anorectal
function, especially in patients with constipation. Constipated pa-
tients with bloating plus distension exhibited a greater degree of
anorectal dysfunction than those without distension. Moreover,
self-restrained anal evacuation also increased symptom percep-
tion, while impaired gut propulsion caused by intravenous gluca-
gon did not.
Taken together, ineffective anorectal evacuation as well as
impaired gas handling may be possible mechanisms of abdominal
distension and bloating. However, the data on the link between
altered food transit of gut and bloating are not consistent, al-
though they probably account for bloating in some of the IBS
Abnormal Abdominal-diaphragmatic Reflexes
The abdominal cavity is determined by the placement of the
walls of abdominal cavity including diaphragm, vertebral column
and abdominal wall musculature. Even if there is no increase in
A Young Seo, et al
Journal of Neurogastroenterology and Motility
intra-abdominal volume, a change of the position of abdominal
cavity components may produce abdominal distension.
there have been some efforts to evaluate the relationship between
bloating and lumbar lordosis or weakened abdominal muscles. In
one classic report, Sullivan suggested that the patients with bloat-
ing have weak abdominal muscles and frequently had recently
gained weight than controls.
But another study measuring up-
per and lower abdominal wall activities using surface electro-
myography has suggested that there were no differences in ab-
dominal muscle activities between the patients and the controls.
Moreover, in an early CT study, some IBS patients showed a ten-
dency of lumbar lordosis but not consistent, and a change in lum-
bar lordosis did not correlate in any way with the changes in ab-
dominal girth. Also, there were no noticeable changes in position
of the diaphragm.
Tremolaterra et al
reported that intestinal gas load was asso-
ciated with a significant increment in abdominal wall muscle ac-
tivity in healthy subjects. In contrast, the response to gas infusion
was impaired in patients with bloating, and rather a paradoxical
relaxation of the internal oblique muscles was noted.
study using modern CT analysis with electromyography from
Barcelona group has provided a novel concept of abnormal ab-
domino-phrenic reflexes for abdominal bloating and distension.
Since then, several studies have demonstrated that abdomi-
no-phrenic dyssynergia is one of main factors for abdominal dis-
tension and bloating. In healthy adults, colonic gas infusion in-
creases anterior wall tone and relaxes the diaphragm at the same
time. On the contrary, patients with bloating have shown dia-
phragmatic contraction (descent) and relaxation of the internal
oblique muscle with the same gas load.
Visceral Hypersensitivity
The sensation of bloating may originate from abdominal vis-
cera in patients with FGIDs, in whom normal stimuli or small
variations of gas content within the gut may be perceived as
bloating. Indeed, it has been well recognized that the patients
with IBS have lower visceral perception threshold than healthy
and it has been speculated that this process might be
associated with the sensation of bloating. Kellow et al
that threshold for perception of small bowel contraction was lower
than normal in some patients with IBS. Also, altered rectal per-
ception assessed by phasic balloon distension has been reported in
IBS patients.
In addition, a gas challenge test proved a role of
sensory disturbances in IBS patients,
and recent clinical experi-
ment has demonstrated that bloating without visible distension is
associated with visceral hypersensitivity.
The autonomic nervous system may also contribute to modu-
lation of the visceral sensitivity. Sympathetic activation is known
to increase the perception of intestinal distention in FD patients;
likewise, autonomic dysfunction could affect the visceral sensi-
tivity in IBS patients.
This mechanism may play a role in
bloating. Moreover, it has been proposed that visceral perception
may be influenced by cognitive mechanism. That is, IBS patients
with bloating pay more attention to their abdominal symptoms,
which is a kind of hyper-vigilance.
Also, a report indicated that
female patients with IBS had worsening of abdominal pain and
bloating during their peri-menstrual phase, at which time height-
ened rectal sensitivity might have contributed to bloating, but not
to distension.
Taken together, altered sensory threshold com-
bined with altered conscious perception may explain the mecha-
nism of bloating.
Food Intolerance and Carbohydrate
It is well recognized that dietary habits may be responsible for
abdominal symptoms, and there have been efforts to prove the re-
lationship between diet and IBS symptoms. Fiber overload has
long been regarded as worsening factor of IBS symptoms
through decreased small bowel motility or intraluminal bulking.
In addition, lactose intolerance may contribute to symptom devel-
opment in IBS patients. In the small intestine, disaccharides are
split by intestinal enzymes into monosaccharides which are then
absorbed. If this process is not carried out, the disaccharide
reaches the colon, in turn is split by bacterial enzymes into short
chain carbonic acids and gases. Hence, malabsorption of lactose
may produce the symptom of bloating in patients with IBS or
Additionally, a new hypothesis is proposed, by which
excessive delivery of highly fermentable but poorly absorbed
short chain carbohydrates and polyols (collectively termed
FODMAPs; fermentable oligo-, di- and mono-saccharides and
polyols) to the small intestine and colon may contribute to the de-
velopment of GI symptoms. FODMAPs are small molecules
that are osmotically active and very rapidly fermentable compared
with long-chain carbohydrates. These molecules induce relatively
selective bacterial proliferation, especially of bifidobacterium, and it
has been demonstrated indirectly that these can lead to expansion
of bacterial populations in distal small intestine.
Thus, high
FODMAP diet has demonstrated prolonged hydrogen pro-
duction in the intestine, colonic distension by fermentation, in-
creased colonic fluid delivery by osmotic load within the bowel lu-
Abdominal Bloating: Pathophysiology and Treatment
Vol. 19, No. 4 October, 2013 (433-453)
men, and GI symptom generation.
Intraluminal Contents
Levitt et al
suggested that abdominal bloating might devel-
op without gas retention, but by other gut contents. They had un-
dertaken randomized, double-blind, crossover study of gaseous
symptoms by observing the responses of healthy subjects to diet-
ary supplement with lactulose or 2 types of fibers (psyllium or
methylcellulose). In lactulose group, gas passages, subjective per-
ception of rectal gas and breath hydrogen excretion were sig-
nificantly increased, but not in fiber groups. However, the sensa-
tion of bloating was increased in all 3 groups. Thus, it has been
proposed that increased intra-abdominal bulk, not gaseous fill-
ing, might be a cause of abdominal bloating.
In another study,
bran accelerated small bowel transit and ascending colon clear-
ance without causing symptom in controls, but small bowel trans-
it has not further been accelerated in IBS patients with bloating.
Thus, they speculated that bran might cause increased bulking
effect in the colon, which led to the exacerbation of bloating in
IBS patients.
Francis and Whorwell
even proposed that use of
the bran in IBS should be reconsidered, because excessive con-
sumption of bran might give rise to symptoms such as bloating in
IBS patients. Although more studies are needed for further un-
derstanding of their relationship, it could be possible that intra-
luminal bulking aggravates the bloating in some IBS patients.
Hard stool/Constipation
Many constipated patients complain of bloating.
Also there
is a tendency of its being more common in IBS-C patients than
IBS-D patients, though it is not statistically significant in some
Distension of the rectum by retained feces slows
small intestinal transit as well as colonic transit, probably explain-
ing the aggravated bloating in constipated patients.
Thus it
seems reasonable that constipation or hard/lumpy stool induces
alteration of gut motility and thus maybe increases bacterial
fermentation. In addition, constipation may accelerate bloating by
intraluminal bulking effect in the same manner as bran.
Psychological Aspects
Bloating is a frequent complaint of women with IBS. Park et
proposed that there was a tendency to increase the index of
psychological distress when the bloating was more severe. Also,
patients with bloating revealed increased anxiety and depression,
which allows the hypothesis that psychological distress may con-
tribute to the perceived severity of bloating.
Additionally, in
large population surveys, bloating was significantly related with
psychiatric dysfunction such as major depressive disorder, panic
disorder and sleeping difficulties.
Nevertheless, other studies
have failed to demonstrate the relationships between psycho-
logical distress and either bloating or distension.
However, it
is unclear whether or not there is an actual relationship between
bloating and psychosocial distress, and further studies are needed
to demonstrate it.
Gender and Sex Hormones
In a population based study in USA, female gender was sig-
nificantly associated with increased symptoms of bloating and
distension in IBS, and similar findings have been reported so
Although the question of the gender role in IBS has
been raised from many studies, the mechanisms of gender differ-
ences in bloating and distension are unclear. Some studies have
suggested that bloating is one of the frequent symptoms of men-
struation as aforementioned.
Hormonal effect has also been
speculated, that is, the variation of reproductive hormones
throughout the menstrual cycle and after the menopause may in-
fluence the gut motility and visceral perception.
nally, difference in symptom expression by gender is presented as
a potential explanation.
Although more investigations regarding
the underlying mechanisms for these disparities remain to be de-
termined, it seems to be possible to speculate that the hormonal
fluctuation may contribute to bloating in female IBS patients.
There has been an increasing acceptance of the use of the an-
tibiotics to treat IBS symptoms, and it is plausible based on the
presumption that altered gut flora or SIBO may contribute to
gaseous distension or bloating symptom.
Although some questions have been raised regarding the
validity of the lactulose breath test in diagnosis of SIBO and the
possibility of overdiagnosis,
much more data support the clin-
ical use of antibiotics in this condition. Specifically, rifaximin, a
rifamycin derivative, has largely been studied, and it showed su-
periority to placebo in relieving bloating in IBS or in patients who
were diagnosed as SIBO (Table 2). As rifaximin is a non-absorb-
able antimicrobial agent, the risk of side effects or emergence of
resistant organisms is expected to be low; therefore it is suitable
for chronic administration.
Recently, a phase 3 multi-
A Young Seo, et al
Journal of Neurogastroenterology and Motility
Table 2. Studies for Rifaximin Treatment in Irritable Bowel Syndrome Patients
Author (yr) Study design
IBS subtypes
Mean age /
Female ratio (n)
rifaximin vs. placebo
Drug dosage
RR for global
(rifaximin, %)
RR for bloating
Sharara et al
single center
70 met
Rome II
All (IBS-D 20.0%, IBS-C
38.3%, IBS-M 41.7%)
42.2/52.4% (63) vs.
38.9/57.4% (61)
400 mg b.i.d. 10 41.3 NA (bloating score;
24.4 20.8)
(P = 0.001)
Pimentel et al
Rome II Excluded IBS-C 46.2/76.1% (309) vs.
45.5/70.7% (314)
550 mg t.i.d. 14 40.8 39.5%
Pimentel et al
Rome II Excluded IBS-C 45.9/72.1% (315) vs.
46.3/70.3% (320)
550 mg t.i.d. 14 40.6 41.0%
Peralta et al
analysis, single arm,
single center
Rome II All (IBS-D 35.2%, IBS-C
20.4%, IBS-M 44.4%)
NA (54) 1,200 mg/day 7 NA NA (symptom
score; 2.3 0.8)
(P = 0.003)
Yang et al
Retrospective study,
single center
Rome I NA NA (84) 1,200 mg/day NA (follow-up
duration; median
11 months)
69.0 (other
Pimentel et al
study, 2 centers
Rome I All (%; NA) 39.1/67.4% (43) vs.
38.2/65.9% (44)
400 mg t.i.d. 10 36.40 NA
Jolley et al
Retrospective study,
single center
Rome III All (IBS-D 28.0%, IBS-C
20.0%, IBS-M 15.0%,
not reported in 37.0%;
1,200 mg/d group)
(30.0%, 20.0%, 14.0%
and 37.0% respectively;
high dose group)
58.0/77.2% (162) vs.
60.0/72.8% (81)
(high dose group)
1,200 mg/day vs.
2,400 mg/day
(high dose group)
10 49.0 vs. 47.0
(high dose
IBS, irritable bowel syndrome; RR, response rate; NA, not available; IBS-D, IBS with diarrhea; IBS-C, IBS with constipation; IBS-M, mixed IBS.
Abdominal Bloating: Pathophysiology and Treatment
Vol. 19, No. 4 October, 2013 (433-453)
center trial proved that rifaximin provided significant improve-
ment of IBS symptoms including abdominal pain and bloating in
non-constipated IBS patients.
Pimentel et al
also suggested
that neomycin normalized lactulose breath test and it contributed
to the reduction of bloating in IBS patients. Besides, there have
been several retrospective or observational studies, which support
the efficacy of rifaximin treatment in IBS patients. Specifically, ri-
faximin turned the lactulose breath test to negative and sig-
nificantly reduced the overall symptom scores.
Also, high dose
rifaximin treatment (2,400 mg/day) was proved to be effective in
patients who had incomplete response to usual dose of rifaxi-
Another retrospective study has revealed that rifaximin is
superior to other antibiotics, such as neomycin, doxycycline,
amoxicillin/clavulanate and ciprofloxacin in patients with IBS.
Therefore, antibiotics like rifaximin could be considered as a
short course therapeutic regimen for bloating, mainly in IBS
without constipation. Further studies are needed to determine
how long these antibiotics should be given and whether drug re-
sistance will be a problem.
Alteration in gut microbiota may produce or perpetuate the
symptoms of bloating or distension, therefore many researchers
postulated that modification of the gut microflora could improve
gas related symptoms.
One placebo-controlled study conducted
in IBS patients revealed a beneficial effect of Bifidobacterium in-
fantis and they suggested immune-modulating role of that
Another multicenter, clinical trial in women with
IBS also showed that B. infantis relieved many of the symptoms of
IBS, but just at a specific dosage (1 × 10
In addi-
tion, more recent experiments have shown that some probiotic
strains significantly alleviate the bloating as well as overall symp-
One study from Korea has shown that multi-species
probiotics given to IBS patients are effective in the relief of bloat-
ing, albeit not statistically significant over placebo.
In the most
recent meta-analysis of probiotics for lower GI symptoms, specif-
ic probiotics are recommended in the management of bloating in
IBS patients as moderate grade of evidence along with 70% level
of agreement.
On the contrary, many other studies have failed to prove fa-
vorable effects of the probiotics. Kim et al
evaluated the effec-
tiveness of VSL#3, a composite probiotic containing Bifidobacte-
rium, Lactobacillus and Streptococcus in IBS patients. VSL#3 re-
duced flatulence scores and retarded colonic transit without alter-
ing bowel function, but there was no significant reduction in
bloating score with VSL#3.
Some experimental studies from
Korea showed a trend towards amelioration of bloating, but failed
to prove beneficial effect over placebo.
In addition, several
other studies using lactobacillus strains reported unfavorable effect
on bloating in IBS (Table 3).
Most of the studies were
relatively small and there have been inconsistent results regarding
the efficacy of probiotics on bloating. Hence, larger and well-de-
signed trials are needed to prove whether the probiotics are rea-
sonable to treat patients with bloating.
Prokinetics have been used in the treatment of bloating in
FD traditionally, in spite of the weak evidence for correlation be-
tween symptoms and underlying pathophysiological mechanisms.
A number of studies have shown the beneficial effect of proki-
netics such as dopamine antagonist, muscarinic antagonist, and
serotonergic agents in FD, but studies conducted in IBS patients
are relatively rare (Table 4). Several studies have suggested that
cisapride, a 5-hydroxytryptamine 4 (5-HT
) receptor agonist,
significantly improves postprandial bloating in FD patients.
Levosulpiride turned out to be as effective as cisapride in the
treatment of FD symptoms, such as bloating.
Acotiamide, a
novel prokinetic agent, also provided relief of bloating in FD pa-
tients in a small study.
Some researchers tried to investigate the efficacy of tegaser-
od, a selective 5-HT
partial agonist, in patients with IBS-C
whose main symptom was not diarrhea, and they suggested sig-
nificant relief in bloating with tegaserod.
However, tegaser-
od was withdrawn from the market in 2007 due to possible ad-
verse cardiovascular effects. Additionally, neostigmine, a potent
prokinetic drug, also exhibited significant effect in reducing ob-
jective abdominal distension as well as bloating in IBS or FB
On the other hand, some other studies do not agree
with the favorable action of prokinetics in IBS. One double-blind
trial suggested that cisapride was not superior to placebo in the
treatment of bloating and other abdominal symptoms of IBS, but
it reduced difficulty of stool passage.
However, cisapride was
also removed from the market due to the side effect. Another
study conducted in IBS patients to evaluate the efficacy of dom-
peridone showed no significant improvement of bloating.
In a
small experimental study, pyridostigmine reduced the severity of
bloating, but it did not reach the statistical difference across
Although there are conflicting evidences regarding the
effect of prokinetics on bloating, some of the prokinetics could be
a treatment option for bloating.
A Young Seo, et al
Journal of Neurogastroenterology and Motility
Table 3. Summary of Studies for Probiotics in Irritable Bowel Syndrome
Author (yr)
Criteria IBS subtypes
Probiotic strains
(daily dose)
Nobaek et al
RCT Rome I All (IBS-C,
60 L. plantarum DSM 9843 (299V)
(5 × 10
4 Flatulence; improved in test group (P 0.05)
Pain, bloating; no benefit over placebo
O’Mahony et al
RCT Rome II All 75 L. salivarius UCC 4331 or
B. infantis 35624
8 Abdominal pain, bowel movement difficulty; significantly
improved in B. infantis group (all P 0.05)
Bloating; improved in B. infantis group (P 0.05)
No benefit in L. salivarius group
Whorwell et al
RCT Rome II All 362 B. infantis 35624 (3 groups; 1 × 10
, 1 × 10
or 1 × 10
4 Abdominal pain, bloating, incomplete evacuation, straining,
passage of gas; improved only in 1 × 10
(all P 0.05)
Kim et al
RCT Rome II All 48 VSL#3 4-8 Flatulence; improved in test group (P 0.01)
Failed to show improvement in bloating
Niv et al
RCT Rome II All 54 L. reuteri ATCC 55730
(1 × 10
CFU/tablet, twice a day)
26 Abdominal pain, bloating, gases, visible abdominal swelling,
GSS; improved, but no benefit over placebo
et al
RCT Rome III All 122 B. bifidum MIMBb75
(1× 10
CFU/capsule, once a day)
4 Pain, distension/bloating, GSS; significantly reduced in test
group (all P 0.0001)
Choi et al
RCT Rome II IBS-D, IBS-M 67 S. boulardii
(2 × 10
4 Quality of life; significant improvement in test group
(P 0.05)
Bloating; no benefit over placebo
Kicha et al
RCT Rome III IBS-D 50 A mixture of L. acidophilus, L. plantarum, L.
rhamnosus, B. breve, B. lactis, B. longum and S.
thermophilus (1 × 10
8 Adequate relief of overall IBS symptoms in test group
(P 0.05)
Bloating; no benefit over placebo
Ducrotté et al
RCT Rome III All 214 L. plantarum DSM 9843 (299V)
(1 × 10
4 Abdominal pain, bloating; improved in test group
(all P 0.05)
Yoon et al
RCT Rome III All 49 A mixture of B. longum, B. bifidum, B. lactis, L.
acidophilus, L.rhamnosus and S. thermophilus
(5 × 10
cells/capsule, twice daily)
4 GSS; significantly relieved in test group (P = 0.03)
Abdominal pain, bloating; improved, but no statistical
significance over placebo
IBS, irritable bowel syndrome; RCT, randomized controlled trial; IBS-C, IBS with constipation; IBS-D, IBS with diarrhea; IBS-M, mixed IBS; L. plantarum, Lactobacillus plantarum; L. salivarius;
alivarius; B. infantis; Bifidobacterium infantis; L. reuteri, Lactobacillus reuteri; B. bifidum; Bifidobacterium bifidum; S. boulardii, Saccharomyces bouladii; L. acidophilus, Lactobacillus acidophilus; L. rhamnosus,
hamnosus; B. lactis, Bifidobacterium lactis; B. longum, Bifidobacterium longum, S. thermophilus, Streptococcus thermophilus; GSS, global symptom score.
Abdominal Bloating: Pathophysiology and Treatment
Vol. 19, No. 4 October, 2013 (433-453)
Table 4. Summary of Studies for Prokinetics in Irritable Bowel Syndome
Author (yr)
Prokinetics used
(daily dose)
Schütze et al
RCT Rome I IBS-C 96 Cisapride (5 mg t.i.d., titrated to
10 mg t.i.d. if no response
after 4 wk)
12 Bloating, GSS; not superior to placebo
Difficulty of stool passage; significant improvement in test group
(P 0.05)
et al
RCT Rome I All (IBS-D,
881 Tegaserod (2 mg or 6 mg b.i.d.) 12 Abdominal pain/discomfort; improved in both test groups (P 0.05),
more consistent efficacyover time in higher dose group
Bloating; favorable trend in reduction in both test groups
Novick et al
RCT Rome I All 1,519
(all female)
Tegaserod (6 mg b.i.d.) 12 Abdominal pain, bloating, stool consistency, GSS; improved in test group
(all P 0.05)
Kellow et al
RCT Rome II Excluded
520 Tegaserod (6 mg b.i.d.) 12 GSS; improved in test group (P 0.0001)
Abdominal pain, bloating, hard stools; improved in test group (all P 0.05
Tack et al
RCT Rome II IBS-C 2,660
(all female)
Tegaserod (6 mg b.i.d.) 4 Abdominal pain, bloating, constipation; improved in test group
(all P 0.0001)
Chey et al
(all female)
Tegaserod (6 mg b.i.d.) 4 Overall symptom; relieved in test group (P 0.001)
Bloating; no benefit over placebo
George et al
RCT Rome II IBS-C 510 Renzapride (1 mg, 2 mg or 4 mg
12 Stool frequency, stool consistency; improved in 2 mg and 4 mg o.d. groups
(all P 0.05)
Bloating; reduction in 1mg o.d. group (P = 0.01)
RCT, randomized controlled trial; GSS, global symptom score; IBS, irritable bowel syndrome; IBS-D, IBS with diarrhea; IBS-C, IBS with constipation; IBS-M, mixed IBS.
Table 5. Summary of Studies for Spamolytics in Irritable Bowel Syndrome
Author (yr)
IBS subtypes
Spasmolytics used
(daily dose)
Battaglia et al
RCT Drossman’s
criteria for IBS
NA 325 Otilonium bromide (40 mg t.i.d.) 15 Abdominal pain, distension; significant reduction (all P 0.05)
Dobrilla et al
RCT Clinical diagnosis and
NA 70 Cimetropium (50 mg t.i.d.) 12 Severity and frequency of abdominal pain; significantly decreased
(P = 0.0005 and 0.001, respectively)
Abdominal distension; decreased, but not statistically significant
(P = 0.055)
Glende et al
RCT Rome I All (IBS-D,
378 Otilonium bromide (40 mg t.i.d) 15 Abdominal pain, distension; improved in test group
(all P 0.05)
Mitchel et al
RCT Rome II All 107 Alverine (150 mg t.i.d.) 12 Abdominal pain, bloating, general well-being; failed to show
benefit over placebo
Clave et al
RCT Rome II All 356 Otilonium bromide (40 mg t.i.d.) 15 Abdominal pain (P = 0.03), bloating (P = 0.02), global efficacy
(P = 0.047); significant benefit over placebo
Chang et al
RCT Rome II All 117 Otilonium bromide (40 mg t.i.d.)
Ormebeverine (100 mg t.i.d.)
8 Abdominal pain, flatulence, bloating, global assessment; relieved
in both treatment group (all P 0.05)
NA, not available; RCT, randomized controlled trial; IBS, irritable bowel syndrome; IBS-D, IBS with diarrhea; IBS-C, IBS with constipation; IBS-M, mixed IBS.
A Young Seo, et al
Journal of Neurogastroenterology and Motility
Various types of antispasmodics have been commonly used to
relieve the symptoms of IBS, given the presumption that altered GI
motility and smooth muscle spasm may give rise to the IBS
Several studies have shown the efficacy of these drugs
in IBS symptoms such as bloating, but some do not (Table 5).
Also data are limited since many of these agents (e.g., mebever-
ine, otilonium and trimebutine) are not licensed in the USA.
There have been several reports that support the beneficial effect
of otilonium.
Besides, in a few studies, peppermint oil, con-
sidered as a natural spasmolytic agent due to its calcium influx
blocking effect, was also superior to placebo in reduction of ab-
dominal distension and bloating.
One systematic review
evaluated the efficacy and tolerability of mebeverine. In the
meta-analysis, it was effective in the clinical improvement of ab-
dominal pain or distension, but it did not reach a statistical
Taken together, antispasmodics have shown some
efficacy in the treatment of bloating, but the study results were in-
consistent and it is difficult to draw definite conclusion about
these conflicting views. Thus, larger studies are needed.
Dietary Interventions
Food intake may play a key role in perpetuating symptoms in
IBS patients, so a careful history taking for diet should be taken.
Many retrospective observational studies have shown that the re-
duced intake of large amounts of highly fermentable, poorly ab-
sorbed short chain carbohydrates (FODMAPs) may reduce
bloating in IBS patients.
Finally, the low FODMAP diet
was developed at Monash University in Melbourne,
and re-
cently, the first prospective study confirming the efficacy of low
FODMAP diet for IBS patients was reported. Besides, patients
with IBS who had also fructose malabsorption were significantly
more likely to respond to the low FODMAP diet than those
without fructose malabsorption (Table 6).
Gas Reducing Substances
One of the earliest pharmachological modalities used in treat-
ing distension and bloating was antifoaming agent, and a silicone
derivative with surfactant, officially designated as “simethicone”
is known as a traditional antifoaming agent, by which gases are
evacuated and absorbed from the gut.
As most of the studies
which investigated the therapeutic benefit of those agents were
carried out in the subset of patients who have FD, their efficacy in
IBS patients seems questionable. Bernstein et al
reported that
Table 6. Summary of Studies for Dietary Interventions in Irritable Bowel Syndrome
Author (yr) Study design Subjects included
Dietary interventions Results
Choi et al
Prospective study, single
arm, single center
IBS (Rome II) 26 Fructose-restricted diet
(mean follow-up of 13 mo)
Abdominal pain, belching, fullness, bloating; significant
relief (all P 0.02)
Shepherd et al
RCT IBS (Rome II) 25 Low FODMAP diet before trial
(median 24 mo)
Fructan, fructose, fructan-fructose mix, or glu-
cose drinks (for 2 wk)
Abdominal pain, bloating; significantly increased in fructan,
fructose, and mix group compared with glucose group
(all P 0.01)
Ong et al
Single-blind, crossover
intervention trial
IBS (Rome III) vs.
healthy subjects
15 vs. 15 Low (9 g/day) or high (50 g/day) in FODMAPs
for 2 days
Abdominal pain, bloating, excessive flatus; increased with
HFD in IBS patients (all P 0.01)
de Roest et al
Prospective study, single
IBS 90 low FODMAP diet
(mean follow-up of 15.7 mo)
Abdominal pain, bloating, flatulence, diarrhea; significantly
improved compared to baseline (all P 0.001)
RCT, randomized controlled study; IBS, irritable bowel syndrome; FODMAPs, fermentable oligo-, di-, and mono-saccharides and polyols HFD, high FODMAP diet.
Abdominal Bloating: Pathophysiology and Treatment
Vol. 19, No. 4 October, 2013 (433-453)
simethicone significantly relieved the frequency and severity of
gas-related symptoms in patients with FGID. Holtmann
conducted a randomized, placebo-controlled trial of simethicone,
and suggested that simethicone was significantly better than pla-
cebo for overall symptom control in FD patients, in spite of un-
favorable effect for bloating. More recently, prospective, multi-
center trial to demonstrate a favorable action of activated char-
coal-simethicone combination therapy revealed that the severity
of fullness and bloating was significantly decreased in the therapy
group compared with placebo (Table 7).
Stimulants of Fluid Secretion
Lubiprostone and linaclotide are novel agents recently ap-
proved by the USA Food and Drug Administration, that en-
hance fluid secretion into the gut lumen and accelerate intestinal
transit. These properties are considered to play a role in treatment
of constipation, thus a number of clinical trials focusing in the
chronic constipation or IBS-C have been conducted (Table 8). In
2 phase III trials, lubiprostone significantly improved the overall
IBS symptoms including bloating in IBS-C.
Several multi-
center, randomized trials of linaclotide in chronic constipation or
IBS-C also demonstrated the beneficial effect in relieving ab-
dominal bloating.
Thus so far, these 2 novel drugs offer a
reasonable therapeutic approach for bloating mainly in IBS-C
and functional constipation patients.
Antidepressants such as selective serotonin reuptake in-
hibitor (SSRI) or tricyclic antidepressant (TCA) are believed to
alleviate symptoms in FGIDs on the basis of their visceral an-
algesic properties as well as psychological aspects. However, one
small study conducted in IBS patients with visceral hyper-
sensitivity revealed that fluoxetine, one of the SSRI, was effective
only in abdominal pain, not in other symptoms such as bloa-
Paroxetine was also evaluated in IBS patients who did not
respond to high fiber diet. Overall well-being sensation was im-
proved more with paroxetine than with placebo, but abdominal
bloating was not.
However, there were also some positive
results. That is, the SSRI, citalopram significantly improved ab-
dominal bloating compared with placebo, though the therapeutic
effect was independent of the effect on anxiety, depression and
colonic sensitivity (Table 9).
Taken together, the results for the
treatment of bloating and distension with antidepressants are
partly contradictory, and there were few studies which explained
the effect of TCA on bloating. Hence, larger, well-designed trials
Table 7. Summary of Studies for Gas-reducing Substances in Functional Gastrointestinal Disorder
Author (yr) Study design Subjects included Sample size Drugs used (daily dose) Duration Results
Bernstein et al
RCT FGID 41 Simethicone
(50 mg, number of tablets unclear)
10 days Fullness, bloating, distension; significant improvement in test
group (all P 0.005)
Holtmann et al
RCT FD 185 Simethicone (105 mg t.i.d.) or
cisapride (10 mg t.i.d.)
8 wk Overall symptom, fullness, pain; improved in both test groups
Bloating; no benefit
Lecuyer et al
RCT Patients with fullness,
bloating, nausea or slow
132 Simethicone and activated charcoal
3 mo Overall complaints; no improvement over placebo
Fullness, bloating; significant improvement in test group
(all P 0.05)
Wittmann et al
RCT IBS (Rome III) 412 Alverine citrate/Simethicone
(60 mg/300 mg t.i.d.)
4 wk Abdominal pain, discomfort; superior efficacy in test group
(P = 0.047)
Bloating; no evidence
RCT,randomized controlled study; FGID, functional gastrointestinal disorder; FD, functional dyspepsia; IBS, irritable bowel syndrome.
A Young Seo, et al
Journal of Neurogastroenterology and Motility
Table 8. Summary of Studies for Stimulants of Fluid Secrection in Functional Gastrointestinal Disorder
Author (yr) Study design Subjects included Sample size Drug used (daily dose) Duration (wk) Results
Johanson et al
RCT Chronic constipation 129 Lubiprostone
(24 μg/day, 48 μg/day,
or 72 μg/day)
3 Bloating; significant relief in all test groups (P = 0.035)
SBM frequency; improved in a dose-dependent manner
Drossman et al
RCT IBS-C (by Rome II) 1,171 Lubiprostone
(8 μg twice daily)
12 Overall response rate; higher in test group (P = 0.001)
Abdominal pain, bloating, constipation severity; significant relief only in
Lembo et al
RCT Chronic constipation 1,276 Linaclotide
(145 μg or 290 μg once
12 CSBM; improved in both trials (all P 0.001)
Abdominal discomfort, bloating, constipation severity; improved in both
trials (all P 0.05)
Quigley et al
RCT IBS-C 1,608 Linaclotide
(290 μg once daily)
12 or 26 Abdominal discomfort, bloating, stool consistency; significant improvements
in both trials (all P 0.0001)
RCT, randomized controlled trial; SBM, spontaneous bowel movement; IBS-C, IBS with constipation; CSBM, complete SBM.
Table 9. Summary of Studies for Antidepressants in Functional Gastointestinal Disorder
Author (yr) Study design Subjects included Sample size Antidepressant used (daily dose) Duration Results
Kuiken et al
RCT IBS 40 Fluoxetine (20 mg/day) 6 wk Threshold for abdominal pain, bloating; no significant changes
Tabas et al
RCT IBS, not responding to
high fiber diet
81 Paroxetine (10 mg/day) 12 wk Overall well-being; significantly improved (P = 0.01)
Abdominal pain, bloating; no benefit over placebo
Vahedi et al
RCT IBS-C (Rome II) 44 Fluoxetine (20 mg/day) 12 wk Abdominal discomfort, stool consistency, bloating; significant relief
in test group (all P 0.05)
Tack et al
RCT IBS (Rome II) 23 Citalopram (20 mg/day for 3 wk,
then 40 mg/d for 3 wk)
6 wk Abdominal pain, bloating, overall well-being; significant relief in
test group (all P 0.05)
Vahedi et al
RCT IBS-D (Rome II) 54 Amitriptyline (10 mg/day) 2 mo Abdominal pain, loose stools, diarrhea; significant improvement in
test group (all P 0.05)
Flatulence; no benefit over placebo
Bloating; not evaluated
RCT, randomized controlled study; IBS, irritable bowel syndrome; IBS-C, IBS with constipation; IBS-D, IBS with diarrhea.
Abdominal Bloating: Pathophysiology and Treatment
Vol. 19, No. 4 October, 2013 (433-453)
with SSRIs and TCAs are warranted to identify the efficacy of
these drugs on bloating and distension.
Opioid Agents
There have been a few reports that propose the usefulness of
opioid agents in IBS patients (Table 10). The kappa receptor ag-
onist, fedotozine has been shown to increase the threshold of per-
ception to colonic distension and reduce visceral sensation.
has also demonstrated its superiority to placebo in relieving post-
prandial fullness and bloating in FD patients.
In a phase II tri-
al, asimadoline, a novel kappa-opioid agonist, has yielded ex-
cellent efficacy results on pain and bloating in IBS-D patients.
A small study has suggested that naloxone is beneficial in re-
ducing the bloating score in IBS-C or IBS-M patients, but there
were no significant differences in the results with naloxone and
Though a recent review also makes a suggestion of the
use of opioid agonists in IBS-D patients,
their role in bloating
is uncertain to date.
Abdominal bloating is a frequent and bothersome, but poorly
understood clinical problem. The terms of bloating and dis-
tension are often confused, but these 2 symptoms should be con-
sidered to be separate, as they probably have different pathophy-
siological mechanisms. The possible mechanisms of bloating are
complex and maybe various mechanisms are combined in symp-
tom generation. Important mechanisms of bloating are impaired
gas handling and hypersensitivity. Also, recent evidences are be-
ginning to emphasize that patients with bloating may have an al-
tered bacterial flora, SIBO, and abdomino-phrenic dyssynergia.
Other less-established factors for bloating are food intolerance,
intraluminal bulking and psychological factors (Fig. 2).
On approaching to the treatment of abdominal bloating,
clinicians should consider a heterogeneous condition produced
by a combination of various mechanisms. Currently, there is no
treatment which has indisputably proven to be effective for
bloating. Treatment strategy for bloating may include pharmaco-
logic approach, dietary modification, and psychological therapy.
Taken together, 5-HT
agonists, antibiotics such as rifaximin,
some probiotics, and also novel agents, lubiprostone and linaclo-
tide are substantiated to be effective in some degree in the treat-
ment of bloating. Dietary intervention with low FODMAP is al-
so newly qualified treatment option. Though the evidence is
weak, antifoaming agents and antidepressants could be consid-
Table 10. Summary of Studies for Opioid Agents in Functional Gastrointestinal Disorder
Author (yr) Study design Subjects included Sample size Drug used (daily dose) Duration (wk) Results
Fraitag et al
RCT NUD 146 Fedotozine (10, 30 or 70 mg
6 Postprandial fullness, bloating, abdominal pain and nausea; significant
relief in 30 mg and 70 mg groups
Read et al
RCT FD 271 Fedotozine (30 mg t.i.d.) 6 Epigastric pain, postprandial fullness, nausea; significant improvement
in test group
Bloating; not evaluated
Hawkes et al
(Rome II)
28 Naloxone (10 mg b.i.d.) 8 Abdominal pain, bloating, straining, urgency to defecate; improved, but
no significant differences over placebo
Mangel et al
RCT IBS (Rome II) 596 Asimadoline (0.15, 0.5 or 1.0 mg
12 Abdominal pain, bloating; improved only in IBS-D with both 0.5 mg
and 1.0 mg dose
Szarka et al
RCT IBS (Rome II) 100 Asimadoline (on demand/up to
1.0 mg q.i.d.)
4 Abdominal pain/discomfort, frequency of bowel movements; not
Bloating; not evaluated
RCT, randomized controlled trial; NUD, nonulcer dyspepsia; FD, functional dyspepsia; IBS-C, IBS with constipation; IBS-M, mixed IBS; IBS-D, IBS with diarrhea.
A Young Seo, et al
Journal of Neurogastroenterology and Motility
Figure 2. Potential mechanisms behind
bloating and visible distension in func-
tional gastrointestinal disorders. Modi-
fied from Simrén.
CNS, central ner-
vous system; ENS, enteric nervous sys-
tem; GI, gastrointestinal.
ered in some patients. Of course a careful history and physical ex-
amination should be the first step and reassurance and education
are likewise important.
Though the whole mechanism and treatment strategies are
yet to be fully elucidated, this article proposes a framework for as-
sessing and managing the patients with bloating.
1. Bradette M, Delvaux M, Staumont G, Fioramonti J, Bueno L,
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... Patients with FGIDs such as irritable bowel syndrome (IBS), functional bloating, functional dyspepsia, and functional constipation commonly have abdominal bloating with a prevalence of 40-76%, which may affect their quality of life. 1 Various mechanisms of abdominal bloating in FGID have been proposed, 2 including increased gas production from colonic bacterial fermentation, visceral hypersensitivity, gut dysmotility, or carbohydrate malabsorption. 3 Diets rich in fermentable oligo-, di-, mono-saccharides, and polyols (FODMAPs) can contribute to bloating symptoms by increasing intestinal gas production, osmotic load and increased intestinal transit time, causing abnormal intestinal contractions and intestinal hypersensitivity. 4 The low FODMAP diet is one of the effective non-pharmacological treatments for patients with IBS, which can relieve bloating symptoms and improve overall gastrointestinal (GI) symptoms. ...
... The overall GI symptoms and abdominal pain severity in both IBS and non-IBS subgroups were lower than baseline but did not reach statistical significance. The number of high FODMAPs diet items in both IBS and non-IBS subgroups significantly decreased from baseline and was not different between groups (IBS patients: 11 [7][8][9][10][11][12][13][14] items to 5 [3][4][5][6][7][8] items; non-IBS patients: 10 [6][7][8][9][10][11][12][13][14][15] items to 5 [4][5][6][7] items; both P < 0.05). ...
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Background/Aims An increase in postprandial intestinal gas plays a role in bloating symptoms. We aim to study the utility of spot breath hydrogen (H2) level in predicting the response to a low fermentable oligo-, di-, mono-saccharides, and polyols (FODMAPs) diet. Methods Patients with functional gastrointestinal disorders diagnosed by Rome IV criteria with bothersome bloating for > 6 months were prospectively enrolled. Patients completed 7-day food diaries and collected a breath sample 2 hours after their usual lunch at baseline and 4 weeks after low FODMAPs dietary advice by a dietitian. The responder was defined as an improvement of ≥ 30% bloating scores in the fourth week. Results Thirty-eight patients (32 female, 52.6 ± 13.8 years; 22 irritable bowel syndrome) completed the study. Twenty-one patients (55%) were classified as responders. Baseline global gastrointestinal symptoms, bloating, abdominal pain scores, and numbers of high FODMAPs items were similar between responders and non-responders. Both groups significantly decreased high FODMAPs items intake with similar numbers at the follow-up. The area under the curve for predicting low FODMAPs responsiveness using baseline H2 levels was 0.692 (95%CI, 0.51-0.86; P < 0.05), with the best cutoff at 8 parts per million (sensitivity 66.7%, specificity 82.4%). 66% of responders had baseline H2 level > 8 parts per million vs 17% of non-responders (P < 0.05). The baseline spot hydrogen level in responders was 9.5 (3.3-17.3) vs 4.5 (3.3-6.3) in non-responders (P < 0.05). Conclusions A higher baseline breath hydrogen level was associated with bloating improvement after low FODMAPs dietary advice. A spot breath test after lunch, a simple point-of-care test, is possibly helpful in managing patients with bloating.
... Gastroesophageal reflux disease (GERD) is an increasingly prevalent chronic gastrointestinal disease that affects between 18% and 28% of Americans. 1,2 Abdominal bloating (AB), defined as the subjective sensation of trapped gas in the upper abdomen accompanied by increased abdominal pressure, [3][4][5] is commonly reported by patients with GERD. It has been associated with significantly lower patient quality of life (QoL). ...
... Currently, there is no reliable objective measurement for AB. This is likely due to the significant role of visceral hypersensitivity in the patient-reported sensation of AB. 5 Physical measurements, primarily abdominal distension, have been proposed as an objective measurement of AB, but abdominal distension is noted in as few as 48% of patients reporting AB. 19 The measurement of outcomes in terms of AB is also limited because there is no standardization of the routine application of tools, such as clinical questionnaires, that can quantify the severity of the symptom and its impact on the patient's QoL. In most of the studies presented, the severity of AB and its prevalence is reported; however, the patient's general satisfaction concerning AB before and after ARS is not specifically addressed. ...
Abdominal bloating (AB) is a common symptom among patients with gastroesophageal reflux disease (GERD); however, in clinical practice, its prevalence is likely underestimated due to the lack of objective tools to measure its frequency and severity. It is associated with dissatisfaction and worse quality of life, but data on its prevalence before and after mechanical control of GERD (i.e. fundoplication, magnetic sphincter augmentation, and antireflux mucosectomy) are lacking. To assess and determine the pre-and postoperative prevalence and severity of AB among patients with GERD, we conducted a structured literature search using MeSH and free-text terms in MEDLINE (via Pubmed), EMBASE, and Taylor & Francis Online between January 1977 and October 2022. Fifteen articles reporting the prevalence or severity of AB using quality-of-life questionnaires before or after antireflux surgery (ARS) were included. Overall, a high prevalence of AB before ARS was found. A decline in the prevalence and severity of AB was documented postoperatively in most cases independent of the surgical approach. Among surgical approaches, a complete fundoplication had the highest reported postoperative AB. Overall, patients reported less severe and less frequent AB after ARS than before. The traditional belief that postoperative bloating is a sequela of ARS should be reevaluated.
... FODMAPs are small molecules that induce relatively selective bacterial proliferation, especially of Bifidobacterium, that lead to expansion of bacterial populations in distal small intestine. The high FODMAP diet has demonstrated prolonged hydrogen production in the intestine, colonic distension by fermentation, increased colonic fluid delivery by osmotic load within the bowel lumen, and GI symptom generation [2][3][4]. ...
... it has been observed that increased intra-abdominal bulk, not gaseous filling, might be a cause of abdominal bloating for example consumption of bran might give rise to symptoms such as bloating in IBS patients [3,4]. ...
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associated with functional gastrointestinal disorders or organic diseases, but it may also appear with no specific reasons. Studies have revealed that 15–30% of the general United States (US) population experiences bloating symptoms, compared with about 15% reported in the Asian population. Tummy bloating every day, unless you have eaten too much or are menstruating, is not okay, and it amounts to a gut disorder. The pathophysiology of bloating remains ambiguous, although some evidence supports the potential mechanisms, like gut hypersensitivity, impaired gas handling, altered gut microbiota, and abnormal abdominal-phrenic reflexes have been put forth. No treatment is unequivocally beneficial to all. Dietary intervention is important in relieving symptoms in patients with bloating. Medical treatment with some prokinetics, Rifaximin, lubiprostone, and linaclotide could be considered in the treatment of bloating. In this manuscript, I have tried to analyze 5 cases of abdominal bloating including autobiographical cases in the last 2 decades and their medical management. GI system pathological causes are kept out of the purview of this article.
... An independent review committee determined that the overall response rate (ORR) was the most important efficacy outcome measure in both studies. The most common side effects were bladder discomfort [15,16], bloating [17], or swelling of the face, arms, hands, lower legs, or feet, bloody or cloudy urine [18], body aches or pain, chest pain or tightness, coughing up blood [19,20], and decreased urination [21,22]. Figures 1 and 2 depict the chemical structures of zanubrutinib impurities and degradation products. ...
A new reverse phase ultra performance liquid chromatography method was developed and validated for the separation and analysis of impurities and zanubrutinib degradation products were characterized using liquid chromatography mass spectrometry. The chromatographic method was optimized using specimens generated by stress degradation and impurities spiked with the sample solution. On a 150´4.6 mm X-Bridge C 18 column with a particle size of 3.5 mm connected to a PDA detector, and by using a linear mobile phase gradient prepared from trifluoroacetic acid (0.1%) in water and acetonitrile, with a flow rate of 1.0 mL/min and detection at 216 nm, good resolution of the analyte peak was obtained from peaks belonging to impurities and degradation products. Excellent accuracy, precision, and linearity results were obtained for zanubrutinbin and its impurities. When the forced test solutions were analyzed by comparison with the zanubrutinib working standard the mass balance was always close to 99.4%, indicating that the method was well stabilized and validation was performed under International Council for Harmonization requirements. Limit of detection and limit of quantification were well established, and the correlation coefficient of zanubrutinib and related compounds was 0.999.
... Constipation or diarrhoea can be a burdensome FGID issue that occurs in many individuals and whose treatment remains challenging. Similarly, bloating is a subjective abdominal discomfort that is associated with abdominal inflation due to the accumulation of excessive gas (flatulence) and may not necessarily be Nutrients 2023, 15, 4490 2 of 12 accompanied by abdominal distension [4][5][6]. Whereas constipation and diarrhoea can be classified using the Bristol Stool Form Scale, bloating symptoms are generally subjective in nature, and therefore, assigning an objective score is fraught with inter-and intra-subject variations. However, the severity of bloating-related abdominal discomfort experienced by individuals can range from mild to severe, and the discomfort can negatively impact health and mental health [2]. ...
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Background: Functional gastrointestinal disorders (FGIDs) are common, difficult-to-manage conditions. Probiotics are emerging as a dietary component that influence gastrointestinal (GI) health. We conducted a double-blinded randomised controlled trial of a proprietary strain of deactivated Bacillus subtilis (BG01-4™) high in branched-chain fatty acids (BCFA) to treat self-reported FGID. Methods: Participants (n = 67) completed a four-week intervention of BG01-4™ (n = 34) or placebo (n = 33). The Gastrointestinal Symptom Rating Scale (GSRS) served as the outcome measure, collected prior to, at two weeks, and at four weeks after completion of the intervention. Results: At four weeks, one of three primary outcomes, constipation in the experimental group, was improved by 33% compared to placebo (15%); both other primary outcomes, Total GSRS and diarrhoea, were significantly improved in both the experimental and placebo groups (32%/26% and 20%/22%, respectively). The pre-planned secondary outcome, indigestion, was improved at four weeks (32%) but compared to the placebo (21%) was not significant (p = 0.079). Exploratory analysis, however, revealed that clusters for constipation (18% improvement, p < 0.001), indigestion (11% improvement, p = 0.04), and dyspepsia (10% improvement, p = 0.04) were significantly improved in the intervention group compared to the placebo. Conclusions: These initial findings suggest that in people with self-reported FGID, BG01-4™ improves specific symptoms of constipation and related GI dysfunction. Longer-term confirmatory studies for this intervention are warranted. Trial registration: This study was registered prospectively (25 October 2021) at the Australian New Zealand Clinical Trials Registry (ACTRN12621001441808p).
... Lawsonibacter asaccharolyticus, Ruminococcus bicirculans, Odoribacter splanchnicus and Ruminococcus callidus, which may in part explain the beneficial effect of FMT in abdominal bloating and serve as promising candidates for next-generation probiotic development.Bloating has been a challenging problem in IBS and the underlying causes include gut hypersensitivity, impaired gas handling, altered gut microbiota and abnormal abdominal-phrenic reflexes.8 Microbiota modulation has been shown to be effective in improvingbloating in IBS. ...
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LINKED CONTENT This article is linked to Yau et al papers. To view these articles, visit and
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Background Functional Abdominal Bloating and Distension (FABD) is a multifaceted condition related in part to trapped gas, with changes in the intestinal barrier and small intestinal bacterial overgrowth (SIBO), which lead to gas production. Currently, there are no treatments targeting the etiology of FABD. Methods This double-blind, multicenter, randomized study evaluated the safety and efficacy of a product containing xyloglucan and pea proteins (XG + PP) compared with simethicone, both administered orally (three times daily) for 20 consecutive days. Eighty-eight patients with FABD were randomly assigned to the two groups in a 1:1 ratio. Primary outcome was safety; secondary outcomes were (i) efficacy in alleviating the symptoms of FABD and (ii) efficacy in reducing SIBO, as assessed by hydrogen breath test (HBT). Results No Adverse Events or Serious Unexpected Adverse Reactions were reported during the study. XG + PP showed a faster onset of action and a significant reduction in bloating and abdominal pain compared with simethicone. At Day 20, XG + PP drastically reduced abdominal girth when compared with simethicone, with an average reduction of 4.7 cm versus 1.8 cm. At Day 20, the XG + PP arm showed a significant reduction in HBT compared to baseline. Conclusions This study supports the evidence that FABD patients may benefit from a XG + PP-based treatment that acts on etiology and not just the symptoms.
The development of novel prebiotics, which could regulate the intestinal microbiota, may help prevent and treat intestinal diseases. Here, we studied a homogeneous polysaccharide, LPE-2, produced by Lactobacillus pentosus YY-112 during fermentation. Methylation and gas chromatography-mass spectrometry analysis, combined with nuclear magnetic resonance results, suggested that the structural unit of LPE-2 comprises a branched mannan moiety and a linear glucan moiety. In vitro simulated intestinal fermentation showed that LPE-2 reduced harmful intestinal gas production and promoted short-chain fatty acid production (especially propionic acid). Moreover, it reduced the relative abundance of Escherichia-Shigella, increased that of Bifidobacterium and Lactobacillus, and had a stronger regulatory effect on intestinal flora in women than in men. The potential sex-specific prebiotic effects of LPE-2 on human intestinal health, were possibly related to its mannan branch with (1→2) and (1→3) linkages and backbones with flexible α configurations, which are sheared and degraded/utilized easier by Bifidobacterium and Lactobacillus.
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Background: Functional gastrointestinal disorders (FGIDs) are a common, difficult to manage condition. Branched chain fatty acids are emerging as a dietary component that influence gastrointestinal (GI) health. We conducted a double blinded randomized controlled trial of a proprietary strain of deactivated Bacillus subtilis (BG01-4™) that produce branched change fatty acids (BCFA) in the lower GI tract to treat self-reported FGID. Methods: Participants (n = 67) completed a four-week intervention of BG01-4™ (n = 34) or placebo (n = 33). The Gastrointestinal Symptom Rating Scale (GSRS) served as the outcome measure, collected prior to, at two-weeks, and at the four-week completion of the intervention. Results: At four weeks one of three primary outcomes, constipation in the experimental group, was improved compared to placebo; both other primary outcomes Total GCRS and diarrhoea, were significantly improved in both experimental and placebo groups. The pre-planned secondary outcome indigestion was improved at four weeks compared to entry with trend to significance compared to placebo (p = 0.079). Exploratory analysis revealed clusters for constipation (18% improvement, p < 0.001), indigestion (11% improvement, p = 0.04), and dyspepsia (10% improvement, p = 0.04), were significantly improved in the intervention group compared to the placebo. Conclusions: These initial findings suggest that in people with self-reported FGID, BG01-4™ improves specific symptoms of constipation and related GI dysfunction, potentially mediated via synthesis of BCFA. Longer term confirmatory studies for this intervention are warranted. Trial registration:: This study was registered prospectively (25/10/2021) at the Australian New Zealand Clinical Trials Registry (ACTRN12621001441808).
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Geğirme, yutulan mide havasının dışarı atılmasını sağlayan fizyolojik bir olaydır. Aşırı geğirme, gastroenteroloji klinikle-rinde sık görülen bir durumdur ve izole bir şikayet olabilir veya diğer gastrointestinal problemlerle de ilişkilendirilebilir (2). Hastanın aşırı gaz ile neyi belirttiğinin net olarak bilinmesi önem taşır. Çünkü fonksiyonel veya organik nedenler bu şekilde ayırt edilebilir. Ayrıca ileri tetkik gerekliliği ve teda-AEROFAJİ ve GEĞİRME Aerofaji, aşırı hava yutulmasıdır ve tekrarlayan geğirme ile so-nuçlanır. Çocuklarda ve her yaşta ortaya çıkabilir. Hava hasta tarafından bilinçsizce yutulabilir. Başlangıcı akut olabilir, an-cak dikkatli bir öykü, genellikle gelişiminin yavaş olduğunu, hasta tıbbi yardım isteyene kadar şiddetinin arttığını gösterir. Hastalar genellikle aşırı gaz yakınması ile başvururlar. Yapılan çalışmalarda bu oranın %20 ila %40 arasında olduğu bildiril-mektedir (1). Abstract • Today, 20-40% of patients apply to the outpatient clinic with the complaint of excessive gas. Supragastric belching can be behavioral and psychological, or is seen in conditions affecting the esophagus, such as reflux, motility disorder. Aerophagia is the most common cause. The air that passes into the stomach by swallowing may return to the esophagus due to lowering the pressure of the lower esophageal sphincter and may be expelled by belching. This is called gastric belching. Ambulatory impedance and pH monitoring are used in diagnosis. If there are alarming symptoms such as dysphagia, abdominal pain, weight loss and reflux, further technique are needed. In daily practice, 15-30% of patients may apply to the outpatient clinic with a feeling of bloating and fullness in the abdomen. Half of these have distension and measurable volume increase. It may occur for functional reasons such as irritable bowel syndrome. Further investigations are needed in the presence of organomegaly, ascites, weight loss, inflammatory bowel diseases, parasites, food intolerance and malabsorption. Özet • Günümüzde %20-40 hasta aşırı gaz yakınması ile polikliniğe başvurmaktadır. Supragastrik geğirme, davranışsal ve psikolojik olabilir veya özofagusu etkileyen reflü, motilite bozukluğu gibi durumlarda görülür. Aerofaji en sık nedendir. Yutularak mideye geçen hava alt özofagus sifinkter basıncını düşüren nedenlerle özofagusa geri dönebilir ve geğirme ile atılabilir. Buna gastrik geğirme denir. Ambulatuvar empedans ve pH izleme tanıda kullanılır. Disfaji, karın ağrısı, kilo kaybı ve reflü gibi alarme edici semptomlar varsa ileri tetkike gerek vardır. Günlük pratikte %15-30 hasta karında şişkinlik ve dolgunluk hissi ile polikliniğe başvurabilir. Bunların yarısında distansiyon ve ölçülebilir volüm artışı vardır. İrritabl barsak sendromu gibi fonksiyonel nedenlerle oluşabilir. Organomegali, assit, kilo kaybı, inflamatuvar barsak hastalıkları, parazitler, besin intoleransı ve malabsorbsiyon varlığında ileri tetkiklere ihtiyaç vardır.
The objective of this study was to determine if gender differences exist when using the Manning criteria for diagnosis of irritable bowel syndrome. In an outpatient setting, 61 women and 36 men with entry complaints of abdominal pain, altered bowel habits, or both underwent full evaluation by board-certified/eligible gastroenterologists who also systematically rated the presence or absence of the six Manning criteria. Irritable bowel syndrome was defined as the absence of an organic disease explanation for the entry complaints. This determination was made by two other board-certified gastroenterologists after patients had been in the study for 9 months. These raters were independent of the study and rated the transcripts of patients' clinic visits, all other available clinical data from this and other clinics, all laboratory data obtained during the 9-month study period, and the results of a 9-month telephone follow-up to patients and their physicians. Sixty-five percent of the study population had no organic disease explanation for the entry symptoms, thereby representing irritable bowel syndrome for this study. A similar proportion and type of organic disease and irritable bowel syndrome were experienced by men and women. For the total sample of 97 subjects, the correlation of the Manning criteria with irritable bowel syndrome was 0.22 ( P r = 0.47; P r = −0.16). It was concluded that significant gender differences exist when using the Manning criteria for the diagnosis of irritable bowel syndrome and that the Manning criteria were not of diagnostic value in men.
Objective: To determine the effect of fibre, antispasmodics, and peppermint oil in the treatment of irritable bowel syndrome. Design: Systematic review and meta-analysis of randomised controlled trials. Data sources: Medline, Embase, and the Cochrane controlled trials register up to April 2008. Review methods: Randomised controlled trials comparing fibre, antispasmodics, and peppermint oil with placebo or no treatment in adults with irritable bowel syndrome were eligible for inclusion. The minimum duration of therapy considered was one week, and studies had to report either a global assessment of cure or improvement in symptoms, or cure of or improvement in abdominal pain, after treatment. A random effects model was used to pool data on symptoms, and the effect of therapy compared with placebo or no treatment was reported as the relative risk (95% confidence interval) of symptoms persisting. Results: 12 studies compared fibre with placebo or no treatment in 591 patients (relative risk of persistent symptoms 0.87, 95% confidence interval 0.76 to 1.00). This effect was limited to ispaghula (0.78, 0.63 to 0.96). Twenty two trials compared antispasmodics with placebo in 1778 patients (0.68, 0.57 to 0.81). Various antispasmodics were studied, but otilonium (four trials, 435 patients, relative risk of persistent symptoms 0.55, 0.31 to 0.97) and hyoscine (three trials, 426 patients, 0.63, 0.51 to 0.78) showed consistent evidence of efficacy. Four trials compared peppermint oil with placebo in 392 patients (0.43, 0.32 to 0.59). Conclusion: Fibre, antispasmodics, and peppermint oil were all more effective than placebo in the treatment of irritable bowel syndrome.
Food intake plays a key role in triggering or perpetuating symptoms in patients with IBS. Evaluation of the impact of diet in the individual patient requires a precise dietary history and a 7-day prospective dietary analysis, which should include the quality and quantity of food consumed, chronologic sequence and nature of symptoms, and the frequency and consistency of bowel movements. The caloric density of the meal, total fat intake, the quantity and quality of lactose-containing foods, sorbitol, fructose, and the nature and quantity of soluble and insoluble fiber intake must be noted. Patients with reflux esophageal symptoms should eliminate foods that decrease LES pressure, such as chocolate, peppermint, alcohol, and coffee. Direct esophageal mucosal irritants such as tomatoes, citrus juices, sharp condiments, and alcohol should be limited. Gastric emptying is slowed with the ingestion of fats and soluble fiber. Small bowel motility is slowed by soluble fiber and fatty foods. Gaseous syndromes may be reduced by avoidance of smoking, chewing gum, excessive liquid intake, and carbonated drinks. The reduced intake of large amounts of lactose-containing foods, sorbitol, and fructose may limit postprandial bloating. Flatus production can be lowered by reducing fermentable carbohydrates such as beans, cabbage, lentils, brussel sprouts, and legumes. Soluble and insoluble fiber ingestion will reduce sigmoidal intraluminal pressures and overcome spastic constipation when given in progressive graded doses. Effective dietary manipulations remain a key factor in reducing symptoms in IBS.