Treating IBS-C: Expert Roundtable Part 2

In part 2 of this roundtable series, Drs Anthony Lembo, Megan Riehl, and Brooks Cash review the varieties of treatments available for irritable bowel syndrome-constipation, including diet, lifestyle modifications, and medication.

Anthony Lembo, MD, is a professor of medicine at the Lerner School of Medicine at Case Western Reserve at Cleveland Clinic in Cleveland, Ohio. Brooks Cash, MD, is a professor of medicine at Texas A &M School of Medicine and the medical director of the Functional Bowel Center at Baylor Scott & White at Baylor University Medical Center in Dallas, Texas. Megan Riehl, PsyD, is a GI psychologist and an associate professor of medicine and the clinical director of the GI Behavioral Health Program at the University of Michigan in Ann Arbor, Michigan.

CLINICAL PRACTICE SUMMARY:

Irritable Bowel Syndrome With Constipation (IBS-C): Lifestyle- and Diet-First Management Insights From Expert Panel Discussion

• IBS-C clinical management begins with a confident diagnosis and structured assessment of lifestyle, diet, and prior therapies before escalating treatment. Clinicians emphasized taking a focused history on diet, physical activity, meal patterns, prior constipation treatments, symptom drivers (frequency vs incomplete evacuation), and red flags such as pelvic surgery or radiation, with initial therapy often starting with soluble fiber plus osmotic laxatives (e.g., PEG 3350) before escalation to FDA-approved agents.

• Diet quality and eating patterns meaningfully affect IBS-C symptoms, with evidence supporting soluble fiber, regular meals, and less restrictive approaches. Data discussed linked higher intake of ultraprocessed foods and alcohol to IBS, noted widespread fiber deficiency in the US (~10% meeting goals), and supported soluble fiber (e.g., psyllium) over insoluble fiber, along with three regular meals daily to leverage the gastrocolic reflex; Mediterranean-style and NICE-based “traditional IBS” diets showed benefit.

• Restrictive diets require caution due to high rates of avoidant restrictive food intake disorder (ARFID) in IBS populations. Screening identified ARFID in ~25–33% of patients in a functional bowel clinic, and panelists cautioned against low-FODMAP diets in these patients due to risk of harm, highlighting multidisciplinary care with GI dietitians, GI psychology, CBT, and gut-directed hypnotherapy, and emerging pilot data on simplified FODMAP approaches targeting fewer trigger groups.

TRANSCRIPT

Dr Lembo:

So let's switch gears and talk a little bit about treatment. So Megan, you're already introduced the fact we make it a confident diagnosis, which we all need to do. And then what would be the next thing that you would do? Like Brooks, do you have a checklist that you go down and say, tell me about your diet or what do you do for the, let's talk about lifestyle. Do you go through the lifestyle factors and how do you approach your patients?

Dr Cash:

Yeah, I'll often, I typically will start with that in my clinical visits, which tend to be a little bit longer, but I'm certainly cognizant of the fact that a lot of my colleagues don't necessarily have that luxury. It is too short of time to take a full dietary history. But I will ask patients about their diet and about their lifestyle, how active they are if they have a regular exercise program. I think it's really important to ask them what they've tried or what's been tried for their constipation symptoms in the past. I also ask them about what the most bothersome symptoms are. Is it a frequency issue, is it a completeness issue? Do they have to use digital manipulations, have they had prior surgeries or other interventions of their abdomen or their pelvis? Have they ever had radiation and that sort of thing. So I'll ask about a complete medical history including lifestyle and then figuring out if there are exacerbating factors with regards to their constipation.

Often we get that history of travel that patients will get worse when they travel and we all change our behavior when we travel, but that's sometimes a key feature for a lot of my patients. And then we kind of gauge our initial therapies on their prior experience. I often will see patients in a referral setting, so they've seen two or three other providers and they may have tried four or five other things in those patients. I'm often going to send them for pelvic floor testing right away because they've tried a lot of the therapies and they've not been satisfactorily treated. On the other hand, if I have somebody who's really not tried very much at all, perhaps they tried an over the counter stool softener, well then I'm going to start them on generally some medications as well as alter their lifestyle if we can increase their activity level. But I generally start with osmotic laxatives as well as bulking agents. So fiber plus something like PEG 3350 over-the-counter therapies, we see how that works. Not a lot of great data for irritable bowel syndrome because there's conflicting data and not convincing evidence that the abdominal symptoms get a lot better but still may be worthwhile to try. And then I'll escalate therapy to the FDA approved pharmacology.

Dr Lembo:

Before we jump into those therapies. I'll say that in my practice what's changed over the last few years is that I spend a lot more time with diet

There I think I'd like to dive a little bit deeper into that because we now know and there's now been a lot of studies looking at the role of diet, the impact of diet on the physiology and the pathophysiology perhaps of IBS. So I do a pretty thorough dive and I was intrigued by studies that show that patients or people that took in more ultraprocessed foods were more likely to develop IBS. Now the rates weren't that high and it was an older population, but it's intriguing that something like that might contribute to IBS. We've seen studies over and over again show that ingestion of alcohol is a predictor as well. We don't think of that necessarily, but alcohol can affect the microbiome, not only the effects directly of the content of it. So we've seen, so I go spend a bit of time on that, making sure that they eat not just fiber.

Dr Riehl:

I was going to say fiber's another one. We're living in a fiber deficit. Only about 10% of Americans are getting enough fiber and even our general guidelines of about 20 to 25 grams of fiber for women and aiming for about 35 for men are the basics. They actually want us getting a lot more. So fiber can be a good one.

Dr Lembo:

Yeah, there are studies, there's some interesting studies years ago looking at the difference between soluble and insoluble fiber, A study looking at psyllium versus bran versus placebo and the psyllium seemed to be better tolerated at least initially in the first couple months of treatment. And so that's become one of the recommendations a soluble fiber. The studies looking at various fruits, I mean for example, both in constipation as well as in IBS, which it can have soluble type fibers. So I generally recommend that for patients, particularly we're talking about IBS with constipation, because you're right, Megan, that most people don't. Invariably when I talk to them about they just get a sample, their diet, everybody says they eat well and lots of fiber and then you find out that you calculate it in your mind it's probably about 10, 12 grams. I mean it's not that much. It's hard.

Dr Riehl:

So many of our patients with constipation are restricting food and so that food restriction and altering the patterns of their eating are going to impact their motility. And so even again those lifestyle questions of are you eating breakfast, lunch, and dinner, educating on the gastrocolic reflex, and how getting up in the morning and having some breakfast and maybe even that coffee is a natural laxative to kind of get things going. You'll find that so many of our patients are like, Nope, I skipped breakfast or I have a bagel at some point and then I'm too busy for lunch or it causes me to bloat and have gas and abdominal pain. So I wait till the end of the day and then they overeat and then they lay down and go to sleep and then the cycle starts all over again. So sometimes those subtle encouragement of, let's get something nutritious in you in the beginning of the day, midday, end of day, can help get that body going. And that motility stimulated.

Dr Lembo:

I was intrigued by a study where they called it the traditional IBS diet, which is based after the NICE diet from the UK, but they basically just told people, do what you said, eat 3 meals a day, don't snack all day long, eat smaller portions, eat fruits and vegetables, et cetera, avoid sodas and things like that. So really it's sort of a basic somewhat healthy diet. And now there's even studies like with the Mediterranean diet one that was just published showing overall efficacy, which again is not surprising. So we do know that that's all important. I guess I wanted to ask you, I've seen reports of ARFID being particularly common in IBS at the Cleveland Clinic. We see a lot of these type of patients. I was wondering if you could sort of walk us through some of the data and how you would approach these type of patients.

Dr Riehl:

So the screening for it can be difficult. There's the NI, which is a 9-item screening measure and I wish there were better measures, but it's kind of the best that we have right now if we're looking for screening. But I think just asking about how is your relationship with food? And so often we'll find that patients say, I want to eat but it hurts. And so I've started to restrict and I can eat these 5 things and they don't hurt. And so slowly their relationship has become so restrictive that you can develop avoidant restrictive food intake disorder, which is different from traditional eating disorders where you are restricting food based on a desire to lower or impact your body image. ARFID is a different kind of beast where it kind of makes sense that if something hurts you're going to stay away from it, but it becomes a very slippery slope in terms of we have to eat, we have to fuel the body. And if patients are then sticking with a very limited number of foods, they're not adequately getting nutrition.

And so what our gastroenterologists and our program kind of focus on is are asking those questions, they are starting to educate patients on the importance of the dietary side of their treatment and then connecting them with whether it be a registered dietitian who's expert in GI as well as potentially somebody like myself, a GI psychologist ,where depending on the level of severity of the food restriction in that relationship, we can utilize cognitive behavioral therapy and some education and coaching around gentle foods to kind of get them opening up their palate and their diet again. And I typically will pair that nutritional work with relaxation strategies, anxiety management to combat the way the body responds with tension and physical arousal and fear right before a meal. That's really counterproductive to a nice gentle digestive process. So we can certainly address it and I think the sooner we can catch it in clinics, the better for the patient.

Dr Lembo:

And one of the things I want to emphasize, and I see this happen periodically, which is that a patient has limited their diet and yet the recommendation is to go on the low FODMAP diet, which is really a recipe making it for worsening or making ARFID in patients where you could really do harm to patients. There is the most data on the low FODMAP diet, but it's very restrictive, a very difficult to follow and best done with a nutritionist, but that's rarely done because it's expensive and time intensive. There's lots of resources, but we often find patients don't follow it.

A recent study looked at what they call the FODMAP simple, which is akin to with EoE with a 6-food, 4-food, now 2-food, 1-food, right? So this is looking the FODMAPs are 5 different groups. This eliminates 2 of the groups, fructans and oligosaccharides, and showed that in a very pilot small study that it seemed to be similar in efficacy and certainly a lot easier for patients. So we will wait and see for more data on that, but we do want to be cognizant of it, I think for patients' sake. Did you have anything else, Megan, you want to add on that?

Dr Riehl:

Yeah, we did some screening work in our clinic looking at prevalence of ARFID in our patients in our functional bowel program. And it was between one-fourth and one-third of patients that were at least screening positive for ARFID. And so we certainly don't want to prescribe a restrictive diet for those patients. We know that eating disorders can be prevalent and I guess a plug for what we do as GI psychologists is that hypnosis, gut-directed hypnotherapy, can be a really profound technique for those patients. Taking the emphasis completely off food and really getting at the brain-gut connection that's at play with irritable bowel syndrome.

Dr Lembo:

Whenever I'm speaking on this, I always feel awkward telling doctors and clinicians lifestyle factors, exercise, eat right, because of course we should all do, we should be doing that for ourselves and almost for all of our patients. But I do want to emphasize that, I mean there's data showing exercise which has lots of different benefits including relaxation, cardiovascular, et cetera, as good, improving sleep quality is important. Diet as we've already alluded to, and we started with the confident diagnosis and the doctor patient relationship. Again, that's not unique to IBS with constipation and it's important. I just want to just highlight that. That's obviously something I spend time with my patients making sure that they do that and know to do that.