Effects of Low FODMAP Diet on Colonic Epithelial Physiology in Diarrhea-predominant Irritable Bowel Syndrome
Phase: NA
Conditions: Irritable Bowel Syndrome
Sponsor: University of Michigan

Study Title:  Effect of Low FODMAP Diet on Colonic Epithelial Physiology in Diarrhea-
predominant Irritable Bowel Syndrome
PI: Prashant Singh, MBBS
Study ID:  HUM00166423
NCT#:  NCT04542018
Protocol Version IRB Update: 8/8/2022

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Version Date: 4/6/2022 
PART B 
STUDY DESCRIPTION 
TITLE OF PROTOCOL 
Effects of low FODMAP diet on leaky gut and mucosal immune cell 
abundance in diarrhea-predominant irritable bowel syndrome 
Principal Investigator 
Prashant Singh 
1.
PURPOSE OF PROTOCOL
The pathophysiology of Irritable bowel syndrome (IBS) is multifactorial involving complex interplay of 
altered intestinal permeability, mucosal immune activation, visceral hypersensitivity and gut dysbiosis. 
Although the exact triggers for these pathological changes in IBS are not clear but diet might play an 
important role. In-fact, the majority of patients with IBS report dietary factors as triggers for 
gastrointestinal symptoms. Fermentable, oligosaccharides, disaccharides, monosaccharides, and 
polyols (FODMAPs) have been shown to induce IBS symptoms. Several studies have reported 
improvement in gastrointestinal symptoms on a diet low in FODMAPs (LFD) in patients with IBS, 
specifically in diarrhea predominant IBS (IBS-D). However, the mechanism of action of LFD is not 
well understood. Recent data from rodent studies have suggested an increase in colonic permeability 
and visceral hypersensitivity in response to high FODMAP diet which are reversed on a LFD. 
However, no human study has investigated the effect of LFD on colonic intestinal permeability. 
Although a few human studies have investigated the effect of LFD on serum cytokines and fecal 
microbiome, no study to date has systematically looked into the effect of LFD on mucosal immune 
cell abundance or mucosal microbiome. We hypothesize that LFD alters mucosal microbiome which, 
in turn, causes improvement in mucosal immune activation as well as intestinal permeability. In this 
study, we aim to evaluate the following effects of LFD in patients with IBS-D- i) colonic permeability 
ii) abundance of colonic mucosal T-cells and mast cell abundance iii) colonic mucosal and fecal
microbiome.
2.
SIGNIFICANCE AND BACKGROUND FOR THE STUDY
Irritable bowel syndrome (IBS) is a gastrointestinal disorder characterized by abdominal pain and altered 
bowel habits which affects up to 11% of world population.1 There is overwhelming evidence that 
pathophysiology of IBS is multifaceted involving intestinal permeability, mucosal inflammation, mast cell 
activation, and visceral hypersensitivity.2,3 The exact triggers for these physiological changes in IBS are 
not clear but likely factors include diet and microbial dysbiosis.2,3 
Dietary factors are known triggers of IBS related symptoms up to 65% of IBS patients report 
symptoms attributed to food.4 In double-blind, randomized, placebo-controlled trials; fructose and 
fructans have been shown to induce IBS symptoms in a dose-dependent manner.5 In fact, a diet low 
in fermentable, oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) is the 
most extensively investigated dietary intervention in IBS.6–8 A recent meta-analysis of seven 
randomized controlled trials comparing a low FODMAP diet (LFD) with various control interventions in 
397 participants suggested a 31% greater likelihood in improvement of global IBS symptoms.9 In 
patients with diarrhea-predominant IBS (IBS-D), Eswaran et al showed that those randomized to LFD 
had greater reductions in daily scores of abdominal pain, bloating, stool frequency, stool consistency, 
and urgency than the modified National Institute for Health and Care Excellence (NICE) diet.10 Others 
have also shown objective improvement in stool consistency of IBS-D patients with LFD using King’s 
stool chart.6  
Despite the clinical efficacy of LFD in improving symptoms of IBS-D, its mechanism of action 
is not clear. Recently, Zhou et al have shown FODMAPs induce colonic tight junction dysfunction and 
visceral hypersensitivity in rat models, both of which are reversible when rats were fed an LFD.11 
They further showed that this effect of FODMAPs is mediated by microbial dysbiosis and elevated 
fecal lipopolysaccharide level.11 However, studies evaluating the effect of LFD on colonic permeability 
of humans are lacking. Halmos et al have shown that LFD significantly decreases butyrate producing 

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bacteria and fecal butyrate levels in humans, a short chain fatty acid known to improve tight junction 
assembly.12 Other studies have evaluated the effect of LFD on fecal microbiome. No studies have 
evaluated the effect of LFD on the luminal microbiome in IBS.13,14 Studies have shown significant 
differences in intra-individual luminal and mucosal microbiome of patients with functional 
gastrointestinal disorders.15 Thus, the exact effect of FODMAP on intestinal permeability and mucosal 
microbiome in humans is not clear and needs further evaluation.  
Several studies have also shown an increase in the number of mucosal T-cells and mast cells 
in the colonic mucosa of IBS patients.16 Mucosal inflammation has been associated with altered 
gastrointestinal motor function, and visceral hypersensitivity.3 These sensorimotor abnormalities can 
occur even when inflammation is minimal and restricted to the mucosa.3 Although diet is perceived as 
an important trigger for mucosal mast cell increase and activation reported in IBS-D, it has been 
poorly investigated. The above reported study by Zhou et al also reported increase in colonic mast 
cell and mononuclear cell abundance in rats fed on high FODMAP diet.11 However, their study was 
limited to the colon and lacked detailed phenotyping of immune cells.11 The effect of LFD on human 
colonic mucosal immune cell abundance has not been reported. 
 
Given the gaps in knowledge, we aim to evaluate the following in patients with IBS-D 
1. The effect of LFD on colonic permeability 
2. The effect of LFD on abundance of colonic mucosal immune cells specifically T-cell and 
mast cell abundance 
3. The effect of LFD on colonic mucosal and fecal microbiome  
 
 
 
3. 
DESCRIPTION OF RESEARCH PROTOCOL 
A. 
Study Design – Overview, Methods, Procedures 
 
Study Design 
Forty consenting IBS-D patients and twenty consenting IBS-C patients will undergo a 7-day screening 
period beginning with the baseline visit. Patients fulfilling the inclusion and exclusion criteria will 
undergo a i) flexible sigmoidoscopy to obtain colonic mucosal samples from the recto-sigmoid 
junction for assessment of intestinal permeability, mucosal immune cell abundance, and mucosal 
microbiome ii) stool collection for microbiome analysis iii) serological markers of intestinal 
permeability and iv) saccharide excretion assay. They will then go on a 4-week low FODMAP diet 
followed by a repeat flexible sigmoidoscopy with biopsies, stool collection, serological markers of 
intestinal permeability and saccharide excretion assay.  
 
Baseline Visit  
• 
Informed consent will be obtained from the subjects 
• 
Medical history including IBS history will be obtained from the subjects 
• 
Blood samples will be obtained 
• 
Subjects will be instructed on the online questionnaires (described below) to be completed for 
the duration of the study. 
• 
Subjects will be given a stool collection kit for collection prior to their next visit. The stool will 
be collected from the subjects’ home and brought with frozen icepacks to their next visit. 
• 
Subjects will be given the lactulose-mannitol standard solution and be instructed on urine 
collection for the test. Subjects will drink the solution first thing in the morning on a day of his 
or her choice prior to the Initiation Visit and collect of all their urine in a jug for the next 24 
hours. 
 
Initiation Visit (7 days post-baseline visit +/- 7 day) 
• 
Subjects will undergo a flexible sigmoidoscopy in MCRU. The flexible sigmoidoscopy will only 
be performed up to the rectum. Subjects are not required to prep for the procedure (e.g. no 
diet restrictions or laxatives). Sedation will not be given to the subjects. 

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• 
Twelve biopsies will be obtained from the recto-sigmoid junction. 
• 
Subjects will be given the low FODMAP diet instructions.  Subjects will be instructed to stay 
on the low FODMAP diet for 4 weeks. 
• 
Subjects will be given the lactulose-mannitol standard solution and be instructed on urine 
collection for the test. Subjects will drink the solution first thing in the morning on a day of his 
or her choice in the week prior to the Post-Diet Visit and collect of all their urine in a jug for the 
next 24 hours.  
• 
Subjects will be given a stool collection kit for collection prior to their next visit. The stool will 
be collected at the subject’s home in the week prior to the Post-Diet Visit and brought with 
frozen icepacks to the Post-Diet Visit. 
 
Post-Diet Visit (28 days post-Initiation Visit +/- 5 days) 
• 
Subjects will undergo a flexible sigmoidoscopy in the MCRU. The flexible sigmoidoscopy will 
only be performed up to the rectum. Subjects are not required to prep for the procedure (e.g. 
no diet restrictions or laxatives). Sedation will not be given to the subjects. 
• 
Twelve biopsies will be obtained from the recto-sigmoid junction. 
• 
Subjects will return the urine collection container.  
• 
Blood samples will be obtained 
 
Low FODMAP diet 
Subjects who consent to participate in the study will be given low FODMAP meals delivered to their 
home by Epicured at no charge to the subject. Epicured is a meal delivery service that provides 
ready-to-eat low FODMAP meals. Subjects will be required to provide their home address and name 
to Epicured in order to receive the delivery 2-3x/week. Epicured will provide 3 meals, 2 snacks and 1 
non-water beverage to subjects for each day of the 4 week low FODMAP period. Vegetarian, vegan, 
and omnivore meals will be provided. Subjects will be told to only ingest Epicured provided items 
(excluding water).     
 
Healthy Control Arm 
The stool of healthy subjects will be collected to compare to the IBS subjects’ stool (details of analysis 
below). These subjects will be recruited from UMHealthResearch.org. Their medical records will be 
used to ascertain eligibility and to collect demographic information. The study team will consent and 
give the subject a stool collection kit. The subjects will return the stool to the study team and their 
participation in the study will end at that time. 
 
IBS-C Arm 
Like IBS-D, the physiological effects of a low FODMAP diet are unclear in patients with IBS-C. The 
relationship between the physiology of IBS-C and IBS-D, if there any, is also unclear. Thus, as a 
disease comparison group, 20 patients with IBS-C will be enrolled in the study in order to better 
understand how a low FODMAP diet effects and changes the microbiome and intestinal permeability 
of IBS-C patients.  
 
In vivo Intestinal Permeability:  
Saccharide excretion assay (Lactulose-Mannitol assay): The test is based on timed urine 
collection after ingestion of an oral load of two saccharide probes, lactulose and mannitol. In brief, 
subjects will be required to refrain from ingestion of alcohol, aspirin and NSAIDs for at least 7 days 
prior to the test. They will also be asked not to consume artificial sweeteners, lactulose, mannitol (2 
days prior to the testing) and during the 24-hour testing period. A standard oligosaccharide solution of 
lactulose (1000 mg), mannitol (100 mg) and flavored rink crystals (1.5 gram) in 250 mL of bottled or 
tap water, followed by 500 cc of bottled or tap water after 30 minutes, will be ingested. Urine 
collections will be performed in containers with 5 mL of thymol solution for 0-2, 2-8 and 8-24h 
following the administration of test sugars and returned to the study center. The total urine volume will 
be measured, and urinary concentrations of lactulose and mannitol will be measured using high 
pressure liquid chromatography. The fractional excretion of lactulose and mannitol will be calculated 

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as the ratio of the total urinary excretion of the respective saccharide probe to the total oral dose of 
the probe. For each subject, the lactulose–mannitol ratio (LacMan ratio) will be calculated as the 
fractional excretion of lactulose divided by that of mannitol.  
 
mRNA quantitation  
We will use real-time PCR to quantitate mRNA expression of TJ proteins [ZO-1, occludin, claudin-1, 
3, 8, 15] and glyceraldehyde 3-phosphate dehydrogenase (GAPDH, control) in colonic biopsies from 
IBS-D patients. 
Colonic biopsies will be submerged in RNAlater Solution (Ambion, Austin, TX) and stored at −80°C. 
RNA extraction will be performed as in the manufacturer’s instructions (RNeasy Mini Kit, Qiagen, 
Valencia, CA). cDNA synthesis will be performed using 0.2 µg of total RNA with the High Capacity 
Reverse Transcription Kit (Applied Biosystems, Foster City, CA). Taqman gene expression assays for 
ZO-1, occludin, claudin-1, 3, 8, 15 and GADPH will be carried out in duplicate for each gene on an 
ABI Prism 7900HT Real-time PCR System (Applied Biosystems) according to manufacturer's 
instructions using the comparative ΔΔCT method for relative quantification. The expression of each 
gene will be normalized to the endogenous control, GAPDH. This will be performed at the Owyang 
Lab at U of M.  
 
Immunofluorescence for tight junction proteins contract lab 
Colonic biopsies obtained pre- and post-dietary intervention will be used for this study. Formalin-fixed 
tissues will be embedded in paraffin and assembled into tissue microarrays before staining. After de-
paraffinization, 5 µm sections will be rehydrated, and antigens will be unmasked by boiling in 0.01 M 
Tris/EDTA (pH 9.0). Slides will be stained with mouse anti-human ZO-1 monoclonal antibodies 
(catalog# 33-9100, Thermo Fisher Scientific), occludin polyclonal antibody (catalog# 71-1500, 
Thermo Fisher Scientific), rabbit polyclonal anti-claudin-1 (catalog# 51-9000, Thermo Fisher 
Scientific), rabbit polyclonal anti-claudin-3 (NBP1-48526, Novus Biologicals, Littleton, CO), rabbit 
polyclonal anti-claudin-8 (NBP1-59157, Novus Biologicals, Littleton, CO), rabbit polyclonal anti-
claudin-15 (NBP2-13842, Novus Biologicals, Littleton, CO) primary antibodies. Primary antibodies will 
be detected using Alexa Fluor 594 or 488 conjugated secondary antibodies or highly purified 
secondary Fab’2 fragments (Jackson Immunoresearch). Nuclei will be labeled with Hoechst 33342 
(H3570, Thermo Fisher Scientific). Stained sections will be mounted in Prolong Diamond 
(Thermofisher Scientific). Tiled images will be collected on a DM4000 microscope equipped with 
Chroma filter sets (as above), a 20× HC PLAN APO NA 0.7 objective, CoolSNAP HQ2 grayscale 
CCD (for fluorescence) and Jenoptik ProgRes C10 Plus color CCD (for transmitted light, i.e., 
hematoxylin and eosin-stained sections) cameras, and a motorized xyz-stage (Ludl) controlled with 
custom MetaMorph 7 journals. Post-acquisition processing, including stitching of tiled images and 
quantitative analysis of signal intensity, will be performed using Metamorph 7 (Molecular Devices 
Sunnyvale, CA). The samples for this testing will be sent out coded without patient identifiers to tge 
Owyang Lab at U of M.  
Serological tests for intestinal permeability  
Following 
serological 
markers 
for 
intestinal 
permeability 
will 
be 
assessed: 
serum 
lipopolysaccharide (LPS) activity measured with the Limulus Amebocyte Lysate assay (LAL, Hycult 
Biotechnology, the Netherlands), and serum zonulin levels (Catalog number 30-ZONSHU-E01; 
ALPCO, Salem, NH).  This will be performed at the Owyang Lab at U of M.  
 
Intra-epithelial and lamina propria mononuclear cell isolation 
Mononuclear cells will be obtained from colonic intra-epithelial and lamina propria fractions. Intra-
epithelial (IELs) and lamina propria lymphocytes (LPs) will be isolated following incubation in 
dissociation buffer (HBSS Ca2+ and Mg2+ free containing 2% FBS, 5mM EDTA, 10 mM HEPES) and 
digestion buffer (HBSS with Ca2+ and Mg2+, 10% FBS, 0.5 mg/ml DNase I and 0.5 mg/ml collagenase 
type IV), resuspension in 40% and layering on 80% Percoll Plus. IELs and LPs viability will be 
checked by Trypan blue exclusion. 
 
Flow cytometry staining 

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Cell phenotype will be assessed by flow cytometry following cell incubation with fluorochrome-
conjugated anti-human antibodies to: CD3, CD4, CD8, CD45RO, CD45RA, CD25, CD39, CD73, 
CD56 and CD117 (or c-KIT, marker of mast cell). Frequency of cells positive for FOXP3, RORC, T-
bet and GATA-3 - transcription factors of Tregs, Th17, Th1 and Th2 lymphocytes will be assessed by 
intracellular staining following cell fixation and permeabilization with Cytofix/Cytoperm and incubation 
with fluorochrome-conjugated anti-human FOXP3, RORC, T-bet and GATA-3. Frequency of cytokine-
producing cells will be determined after exposure to phorbol 12-myristate 13-acetate (PMA, 10ng/ml) 
and Ionomycin (500ng/ml) for 60 minutes and to Brefeldin A (20μg/ml) for additional 5 hours. Cells will 
be acquired on a BD LSRII and analyzed using BD FACSDiva software. 3-5×104 events will be 
acquired for each sample. Positively stained cell populations will be gated based on unstained, single 
stained and isotype stained controls. This will be performed at the Owyang Lab at U of M.  
 
Immunohistochemistry for immune cells  
For immunohistochemistry, 5µm colon biopsy sections will be stained for human CD3, CD4, CD8, 
CD56, CD39, FOXP3, RORC, T-bet, GATA-3 and CD117 (or c-KIT). Endogenous peroxidase 
blocking with 3% H2O2 will be carried out. Sections will be incubated overnight at 4°C with primary 
antibodies to the above antigens and subsequently exposed to avidin/biotin complex with HRP 
(Vector Laboratories, Burlingame, CA). ImmPACT DAB (Vector Laboratories) was then applied and 
sections examined by light microscopy. This will be performed at the Owyang Lab at U of M.  
 
Mucosal and fecal microbiome  
Two colonic mucosal biopsies and stool samples obtained before and after the dietary intervention 
would be used for this analysis. Once obtained, each biopsy will be washed using Sterile PBS to 
remove non-adherent luminal/fecal material. The biopsy samples will be weighed, flash frozen in 
liquid nitrogen and stored at -80C for DNA extraction and microbiological analysis. DNA extraction will 
be done using a QIAamp DNA Mini Kit (Qiagen, Crawley, UK) per manufacturer’s instructions. 
Bacterial community composition in isolate DNA samples will be characterized by amplification of the 
V1-V3 variable regions of the 16sRNA gene by polymerase chain reaction for both mucosal and fecal 
samples. 16S rRNA PCR products will be quantified, pooled and purified for the sequencing reaction. 
454 GS FLX Titanium sequencing will be performed on a 454 Life Science Genome Sequencer FLX 
machine for both mucosal and fecal samples. Sequencing data generated will be processed by the 
Quantitative Insights into Microbial Ecology Pipeline (QIIME). Sequences will be screened for 
chimeras using the ChimeraSlayer algorithm, and all potential chimeras will be excluded from 
downstream analysis. Sequences less than 200 bp or greater than 1000 bp in length, those with 
average quality scores <20, incorrect primer sequences, or more than 1 ambiguous base will be 
excluded from downstream analysis. The quality filtered sequences will be assigned to operational 
taxonomic units (OTUs; sequences that share ≥97% similarity) using a closed reference approach in 
QIIME with the UCLUST algorithm and the Greengenes reference database. According to the results 
of OTUs analysis, α diversity analysis including Simpson, Shannon, Chao 1, ACE and Good's 
Coverage will be carried out by QIIME. β diversity metrics, including (UniFrac weighed or unweighed) 
will also be calculated.   
 
Stool samples will also be obtained from 30 healthy controls aged 18-65 years without any known 
gastrointestinal history and who do not report any abnormal bowel movements or abdominal pain. 
Stool samples from healthy controls will be utilized for analyzing fecal microbiome using the 
methodology described above. Their microbiome will be compared with microbiome of IBS-D patients 
pre and post LFD.  
 
Clinical variables 
Data will be collected and stored via Research Electronic Data Capture (REDCap), a HIPAA 
compliant, free, secure, web-based application. Patients will be automatically emailed a link daily (via 
REDCap) with a REDCap link to the questionnaires listed below. 
 
Patients will be asked to complete the IBS-SSS and record their most common stool consistency of 

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the day (measured using Bristol stool form scale) every day during the baseline period and the last 
week of 4-week LFD. In addition, following questionnaires will be administered at the end of the 
baseline period as well as the end of the 4-week LFD.  
 
Patient Reported Outcomes Measurement Information System (PROMIS) 
The Patient Reported Outcomes Measurement Information System (PROMIS) is a National Institutes 
of Health (NIH) set of tools used to provide information on patient outcomes in a variety of fields.  
 
Gastrointestinal PROMIS scales:  PROMIS scales of Belly pain and diarrhea will be administered to 
assess the severity of belly pain and diarrhea in our patients.  PROMIS Belly pain questionnaire and 
PROMIS diarrhea questionnaire have five and six questions, respectively, which assess symptom 
severity on a 5 point Likert scale. Higher T-scores on these questionnaires refer to more severe 
gastrointestinal symptoms.  
PROMIS belly pain asks how often did you have belly pain, severity of belly pain, interference with 
activities, bothersomeness and discomfort. 
PROMIS diarrhea asks how many days did you have loose stools, interference with activities, 
bothersomeness, and how often you experience urgency.  
 
Irritable Bowel Syndrome Severity Scoring System (IBS-SSS):  (IBS-SSS) is a validated scale for 
assessing overall IBS symptom severity.22 It includes 5 questions of equal weight concerning 
symptoms over the past 10 days: average severity of abdominal pain, number of days with abdominal 
pain, average severity of abdominal distension or bloating, satisfaction with bowel habits, and the 
overall interference in their quality of life from these symptoms. All questions are scored on a 0-100 
scale. The scores for all five questions are summed to a total IBS-SSS score between 0-500. Lower 
scores indicate lower symptom severity. 
 
Diet compliance: Patients will also be asked to record their day’s food and drink intake and record 
whether they were compliant with the FODMAP diet.  Prior to the baseline flexible sigmoidoscopy, 
patients will be asked to record the previous 3 days’ food and drink intake 
 
B. 
Statistical Considerations 
 
Sample Size Justification:  Statistical analysis  
All continuous variables will be tested for normality using the Shapiro-Wilk test. Normally distributed 
continuous data will be presented as mean (± SD) and will be compared pre-and post-dietary 
interventions using paired Student’s t-test. Continuous data which are not normally distributed will be 
presented as median (range) and compared using Wilcoxon signed-rank test. Proportions will be 
expressed as percentages and compared using chi-square test or fisher exact test as appropriate. 
Since we anticipate that most of our tests will involve continuous data that is normally distributed, we 
based our power analysis on pre-post comparisons using paired t-tests. Assuming two-tailed tests, 
with alpha set at 5%, a sample size of 20 will provide 80% power to detect a medium effect size (i.e., 
Cohen’s d=.5) when the pre-post correlation is r=.7. 
 
 

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C. 
Subject Selection 
Inclusion criteria for IBS subjects 
Patients with IBS-D or IBS-C diagnosed per Rome IV questionnaire and without any alarm features 
(rectal bleeding, weight loss, nocturnal symptoms, family history of inflammatory bowel disease or 
celiac disease) will be considered for the study if they had: 
i) 
Aged 18-65 years at the time of screening 
ii) 
Normal serum studies including serum tissue-transglutaminase antibodies, thyroid stimulating 
hormone levels, C-reactive protein, complete blood count since the onset of symptoms  
iii) 
Normal stool studies including, ova and parasites since the onset of symptoms  
iv) 
IBS-SSS score of ≥175 at the end of the 7-day screening period  
 
In case of presence of any alarm features and/or elevated inflammatory markers (C-reactive 
protein or fecal calprotectin), patients will be eligible if they have been excluded for 
inflammatory bowel disease with upper endoscopy, and colonoscopy in the last one year. 
 
 
 
Exclusion criteria for IBS subjects 
i) individuals already on a LFD or other dietary restriction such as gluten free diet within the past 
6 months  
ii) individuals with any known food allergy or insulin-dependent diabetes 
iii) known history of celiac disease, inflammatory bowel disease or microscopic colitis  
iv) prior small bowel or colonic surgery or cholecystectomy  
v) pregnant patients  
vi) Antibiotics in the past 3 months  
vii) Those who regularly use mast cell stabilizers or anti-histaminic or non-steroidal anti  
inflammatory agents (NSAIDs) excluding daily baby aspirin or steroids or bile-acid binder.  
 
Inclusion criteria for healthy volunteers 
Aged 18-65 years 
 
Exclusion criteria for healthy volunteers 
1. History of gastrointestinal illness 
2. Self-reported constipation, diarrhea, or abdominal pain 
3. Antibiotics in the past 3 months 
4. Gastroenteritis in the past 3 months 
 
  
 
4. 
POSSIBLE BENEFITS 
No direct benefit to subjects is expected, although there may be some relief from IBS symptoms.  
However, this will help understand the pathophysiology of IBS-D and investigate the effect of low 
FODMAP diet on various physiologic parameters and even identify the predictors for response to this 
dietary intervention.   
 
 
 

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5. 
POSSIBLE RISKS AND ANALYSIS OF RISK/BENEFIT RATIO 
The possible risks for the study include flexible endoscopy related complications such as bleeding or 
perforation. These are very unlikely to occur as we will be examining and taking biopsies from the last 
20 cm of colon (and not performing polypectomies). These complications are very rare and unlikely to 
happen.  
 
Blood Drawing 
The risks and discomforts of blood drawing from a vein include the possibility of pain or bruising at the 
site of the blood draw; occasional feeling of lightheadedness; and rarely, infection at the site of the 
blood draw. 
 
The benefit of this study is to help us understand how low FODMAP diet impacts the various gut 
functions- permeability, immune activation and microbiome. This will help us identify the patients who 
might benefit from this dietary intervention (as the diet is cumbersome to follow). Will also shed light on 
how diet interacts with gut physiology.  
 
 
6. 
RECRUITMENT AND CONSENT PROCEDURES 
Recruitment 
Patients will be identified in the following ways:  
• 
Clinical practice at Michigan Medicine 
• 
GI referrals 
• 
Review of medical records and appointment logs 
• 
Advertisements 
• 
UMHealthResearch.org 
• 
Data Direct screens 
• 
EMERSE screens 
 
Potential study participants (obtained from the means listed above) will be approached or contacted by 
phone or email. A brief screening will be initiated to assess subject’s eligibility before scheduling the 
office visit. Patients identified through clinical screening will be called using a phone script. Patients 
identified through a data direct / EMERSE screen will be re-screened and called by study staff to judge 
their eligibility and interest. Patients will be contacted three times before study team will cease contact. 
 
Consent 
During the Baseline Visit, a member of the study team will fully explain the purpose of the study to the 
patient and all questions and concerns regarding the study will be addressed as well (informed 
consent process). This will take place in a private area. 
 
Subject Protection 
None of the subjects in this study will be vulnerable to coercion or undue influence 
 
 
7. 
STUDY LOCATION and DATA SECURITY 
Privacy  
All data will be kept in a password protected folder on the shared drive.  All serum, urine and biopsy 
samples will be coded without patient identifiers and stored in restricted-access research areas at U 
of M. When the mucosal samples will be sent to a contract lab, they will not have any PHI labeled.  
 
Physical Setting 
All samples will be stored in freezers in restricted-access areas. All data generated from this study will 
also be stored in a password protected folder or in locked cabinets in locked offices.  
 

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8 
Dissemination of Research Results 
Patients will not be informed about the results of the study. Results might be presented/published.