Brian Lacy, MD, and Kate Scarlata, RDN, on Dietary Management for IBS

In this podcast, Dr Brian Lacy and Registered Dietitian Kate Scarlata discuss dietary approaches to the management of irritable bowel syndrome.
 

Brian Lacy, MD, is a professor of medicine at the Mayo Clinic in Jacksonville, Florida. Kate Scarlata, RDN, is a gut health and nutrition expert and specialist in management of irritable bowel syndrome based in Boston, Massachusetts.

TRANSCRIPT:

Dr. Brian Lacy:  Welcome to this "Gastroenterology Learning Network" podcast. My name is Brian Lacy. I'm a professor of medicine at the Mayo Clinic in Jacksonville, Florida.

I'm absolutely delighted today to be speaking with Kate Scarlata, a registered dietitian, who also has a master's in public health and has extensive experience in the field of dietary therapies and nutrition for GI conditions. She runs a nutrition consulting business outside of Boston, Massachusetts.

Our topic today is one that is important for every health care provider, regardless of specialty, and that's dietary therapies for IBS. Kate, welcome. Irritable bowel syndrome, or IBS, it's a common medical condition that leads to referrals to healthcare providers of all specialties. Why would dietary therapy help IBS symptoms?

Kate Scarlata:  First, thank you so much for having me on. I'm happy to be here. Patients with IBS, it's very common for them to perceive eating any food to triggering GI distress. In fact, up to 84% of people living with IBS note food as a trigger.

It's possible, because IBS presents with visceral hypersensitivity and exaggerated gastric colic response to food consumption. These could all play a role. We also know that food intolerance may be common in disorders where the gut microbiome is altered. Additionally, in IBS, the messaging between the gut and the brain is so heightened. That may also play a role.

I will say that food intolerance in IBS is in its infancy, understanding it. It's exciting times. It's a new frontier in IBS treatments. We have a long way to go to fully understand what's going on.

Dr. Lacy:  I like that point. We are in the infancy here. This is why it's such an important topic to discuss. In the big picture here, when you think about diets for IBS, do you think there's one patient population most likely to benefit?

Maybe patients with IBS and diarrhea, or maybe those with IBS and bloating-predominant. Is it just too variable and too hard to predict?

Kate:  A little bit of all of that. I do think it can be a little bit difficult to predict. From the FODMAP science, it's been mostly done in irritable bowel syndrome with diarrhea predominance. I know we'll talk about FODMAPs in a little bit.

We know that those patients respond to diet therapy. Additionally, the FODMAP science has also elucidated that individuals with bloating and pain seem to respond well to this diet therapy. We also know, in patients that have constipation predominance, that bloating is often a side effect.

I found, in clinical practice, that patients can benefit when bloating is present with their constipation. I think it is important to note that food intolerance is very much portion-driven. When we're working with our patients, it's important...It's not an all or nothing approach here.

We need to understand the patient's background diet, because that can tell us a lot about why they're experiencing symptoms. Dietitians are good at doing that detective work behind the scenes to figure, is this just an overabundance of fiber that's beyond what anyone should be consuming? Is this a need to do an elimination diet? There's a wide range here.

Dr. Lacy:  I like many of the points you just made. One, you need to be a great detective. Dietitians are wonderful detectives who can sort through the wheat from the chaff. Also, sometimes it's portions. I know we're going to get into that.

I want to focus a little bit more and home in on maybe predictors of response. I think this will help our listeners and providers who may be in clinic this afternoon. Do you think that there are specific patient characteristics that might help with one dietary intervention as opposed to another?

For an example, maybe older patients are much more likely to respond, in general, than younger patients, or maybe women as opposed to men.

Kate:  To be honest, I'm not aware of any specific data that suggests women or men are more likely to benefit from diet change, or that age would make a difference. It might be out there. I'm not familiar with it. I would say that most of the data that we have is in women, because IBS impacts more women than men.

In my clinical experience, I've been surprised to see a wide range, from adolescents to the elderly, respond to dietary change. Again, that diet change is specific to their symptoms. If the dietitian's in tune to what diet can precipitate a symptom and make that change, they can have a better positive yield in the therapy.

Dr. Lacy:  Kate, you've contributed so much to the field of dietary interventions for IBS. Thank you for that. Can you review some of the most common diets that are used for IBS?

Kate:  Absolutely. Lactose-free or reduced-lactose diet is common. High fiber or adjusting fiber intake. Gluten-free. Low fat is sometimes utilized. This may be in the setting of a patient with bacterial overgrowth, which can contribute to fat malabsorption, or something else, a comorbid condition. Then also, low FODMAP.

There was a GI survey done by Leonhardt, Dr. Chey's group from UMichigan. They looked specifically at what diets GI practitioners are recommending. They found the most frequently recommended diet was the low FODMAP diet—77% of the physicians recommended low FODMAP.

That was followed by high fiber, lactose-reduced, and lastly, gluten-free. I think we're seeing gluten-free getting kicked to the curb a little bit for IBS. When you look at patient surveys, what are some common dietary triggers?

It's interesting that a good majority of them, it comes out, carbohydrates are the triggers. Whether it's breads and cereals as one group, or just collectively. There was a study out of Sweden looking at diet, 70% of that cohort, it was about 200 IBS patients, suggested that any carbohydrate triggered symptoms.

Dr. Lacy:  What a great review. That was a nice article by Bill Chey and colleagues from Michigan, who surveyed GI providers about some of the diets that they routinely use in practice. I like one of those points you made about carbohydrates.

As you well know, there was an older study from the University of North Carolina, published in about 2009, from Austin and colleagues. This focused on a very low carbohydrate diet for patients with IBS and diarrhea, that subgroup. Why would that work?

Kate:  Again, carbohydrates are, one, the gut microbiota's favorite fuel. Our gut microbes have digestive enzymes, and can create a lot of gas, which is problematic for our patients with IBS. When we're adjusting this particular diet, it was a very low carbohydrate diet of 20 grams, which is...Typical diet would have 175 grams per day, maybe.

You're adjusting down fiber and FODMAPs. Possibly, insoluble fiber as part of that fiber drop, which we know can be a trigger in IBS patients. It does make sense to me that that would work. Is it taking the diet needs far? Probably.

I will say, I started in dietetics 30 years ago. We had nothing for our patients. It's nice to see this onslaught of interest in diet as a way to help our patients. Not all patients, but many patients with IBS.

Dr. Lacy:  Kate, you mentioned gluten earlier. We know that in the United States, a conservative estimate is that about 7 billion dollars a year are spent on low- or no-gluten products. Most of those patients consuming that do not have celiac disease. Low-gluten diets are now used by a number of IBS patients. Why might this work? What's the data to support its use?

Kate:  It's crazy. There's a couple things I want to say here: 2.7 million people are adhering to the gluten-free diet without a celiac diagnosis. This is a real big problem. I blame the Internet and the social media outlets that are villainizing gluten out there.

As far as data supporting a gluten-free diet in IBS, it's lacking overall. I think Jasper Sikorsky, who is a friend of mine, did a great study. It was a placebo-controlled crossover intervention looking at gluten, and whether it was driving IBS symptoms.

In this particular study, they put patients that were habitually consuming a gluten-free diet on a low FODMAP diet. They got better on the low FODMAP diet. Then when they added back gluten, there was no specific or dose-dependent reaction with gluten. That was a telltale study.

There's been other studies that have dismissed gluten as being an issue. That being said, there probably, in my opinion, is a subset of IBS patients that are gluten-sensitive. It's possible that going gluten-free, some patients feel better just simply because of the placebo effect. Remember, that's pretty high in IBS patients.

Also, when we go gluten-free, we're reducing other foods. We're removing wheat, barley, and rye, which also contain FODMAP carbohydrates. It may be that we're just getting better because of that adjustment in the diet alone.

Dr. Lacy:  All great points. As you mentioned, fructans act like high fructose corn syrup, and can worsen symptoms. That's a great segue to talk about the low FODMAP diet. Unless you've been stranded on a desert island without any form of communication in the last 8 to 10 years, you've probably been bombarded with information about the low FODMAP diet.

For the few listeners who may not be quite as comfortable with this topic as you are, what is the low FODMAP diet?

Kate:  We'll start with FODMAPs. They're a certain group of small carbohydrates that are commonly maldigested. Because they're small, they have a high osmotic capacity, so they can draw water in. They're also fast food for our gut microbiota. They create a lot of gas. This can stretch the lumen.

We'll talk a little bit more about the bio, what's going on in the body. The diet itself is a 3-phase nutritional approach. It has 3 phases: the elimination phase, which is typically undertaken 2 to 6 weeks, where all high FODMAP foods are removed.

Followed by the reintroduction phase, which is a systematic reintroduction of FODMAPs back into the diet to identify which FODMAPs are triggering symptoms. Then lastly, a personalization phase, where the tolerable FODMAPs are added back in. The full elimination phase, it's a full 3-phase process.

Dr. Lacy:  I love the way you phrase that about FODMAPs, which as everybody knows, stands for fermentable, oligosaccharides, disaccharides, monosaccharides, and polyols. You call them fast food for our gut microbiota. That's wonderful.

You mentioned it, but there is some biologic basis for why the FODMAP diet might help. You mention the osmolar load, this osmotic load. Why else might it help?

Kate:  Exactly. It's interesting, and it's, again, not fully elucidated. We're learning more about how FODMAPs interact with our gut microbiota and our immune system in our gut. We know that because of the osmotic effects, it increases small bowel water.

There is also a high production of colonic gas with the breakdown of FODMAPs, malabsorbed FODMAPs in the colon, and the production of short-chain fatty acids. The short-chain fatty acids can act on our intestinal motility, water, and sodium absorption.

There's also some effects on the mast cell and mast cell activity that we're learning, and even histamine release, that may increase this real hypersensitivity. A lot of the stat has been in animal studies. We're starting to do more studies specifically on humans, which is exciting.

The luminal distention, the water, the short-chain fatty acids, and gas are part of the picture. Then there's all this additional information that's starting to build on the story.

Dr. Lacy:  Kate, I know that you practice data-driven medicine for your patients. I know our listeners do as well. Can you provide us with a little bit of data that supports the use of the low FODMAP diet for our IBS patients?

Kate:  Absolutely. The low FODMAP diet has been done in a number of studies throughout the globe. Now we have even a few systematic reviews and meta-analyses done, looking at its efficacy. Compared to comparator diets, the low FODMAP diet does offer greater benefit to global symptoms.

Dr. Chey's group at Michigan noted a reduction in abdominal pain and bloating when they looked at that specifically. That seems to be consistent across the board. There are some limitations in the research. There's a lot of heterogeneity between studies, and a high risk of bias in the studies. We have enough data to say it's working. It's working on a subset of patients.

Dr. Lacy:  Now, a couple of focus questions about the low FODMAP diet, now that you've given us this global view. One question that comes up a lot from patients and providers is, what is an adequate trial to assess response? Is it 2 weeks? Is it 4 weeks? Is it even longer?

Kate:  What we know from the research setting, Monash University did a study, it was published in 2014 in Gastroenterology, where they provided all of the food to their patients. They noted the maximum symptom benefit by 7 days, improved beyond that 7 days.

That's not the real world, though. We are educating patients. They're taking on this diet on their own. UMichigan study was that type of study, where they're educated, and patients adapted the diet on their own. It took 4 weeks on the diet to note maximum symptom benefit.

In the real world setting, it's probably closer to the 4-week mark. That being said, and I've seen thousands of patients applying this diet in my practice, most patients that respond, we do notice some level of response before 48 hours. It's relatively quick. You may see, still, improvement up to a month.

Dr. Lacy:  Very useful. Teaching point there is don't give up too early. Conversely, I've had some patients who I see as a third or fourth opinion, where they've been on it for a year without any benefit, and they're still on it. You don't need to drag this out.

Going back to some of our earlier questions, Kate, we're talking about maybe predictors of response. Thinking about the low FODMAP diet specifically, is it appropriate for all patients with IBS, all comers?

Kate:  No, it isn't. A quick screening question off the top would be, does eating exacerbate your symptoms? That's a good clinical question, a good starting point. You definitely want to be thinking about eating disorder risk in your patients, which we're learning and seeing more data being processed in this area in the GI patient population.

One systematic review and meta-analysis showed that over 23% of GI patients had some level of disordered eating. We've definitely seen disordered eating in IBS, as well as celiac disease, and a number of other conditions.

A low FODMAP diet is a restrictive elimination diet, which would trigger restrictive eating. Which is not what we would want to do in a patient with this history, or one that appears to be at increased risk. We want to be very judicious about how we apply the diet.

I would also say kids that are just developing their eating habits and good relationship with food, we want to be careful with the way we apply the diet. We want to be careful to apply a restrictive diet in someone that's malnourished or underweight.

Then we also want to think about people that have limited control over what they eat, or even cooking ability. If you're asking them to do a specialized diet, we want to make sure they can actually employ it appropriately.

Going back to the eating disorder piece, we need to, one, bear in mind that eating disorder tools are not validated in the GI population. That some level of fear associated with eating when eating causes pain is a normal adaptive behavior.

If you had foodborne illness, or gastroenteritis after eating something, you're not rushing out to eat that food again, and if food is constantly tripping up your symptoms. We have to be careful and judicious when we're slapping on an eat disorder diagnosis in this patient population. I will say that. Lastly, I will tell you that even in an elderly patient, I was able to use the FODMAP science to employ a lighter version of the diet.

After looking at the diet recall, she was a patient with fecal incontinence and IBS-D, just removing apple-based products, which were a source of polyols as well as excess fructose, that was enough to get her to a level that she was more in control of her bowel movements and felt like she could get out of the house again.

There's a lot of leeway and application with this diet in the right hands, that we can make a difference without going full blown elimination.

Dr. Lacy:  Wonderful. All great teaching points, Kate. Thank you. Can you remind our listeners, please, about concerns over long-term use of the low FODMAP diet?

Kate:  Absolutely. We do know that in the elimination phase of the diet, when they've looked at the stool microbiome, that there has been a reduction in Bifidobacteria abundance. We want to be very careful about changing the gut microbiome. We really don't know the long-term implications of these changes. We do want to be careful.

If you're constantly on a restricted diet, and hyper vigilant with your diet, that may prompt even more disordered eating behaviors, which may prompt, then, an eating disorder. Also, long-term low FODMAP diet could lead to nutritional deficiencies. We want to be careful about that as well.

I think it's also important for your listeners to know that we are seeing an uptick in eating disorders as a general rule prior to the pandemic. Now, we're seeing a noted escalation of inpatient visits during the pandemic. The thought is that food is something we can control. When our life is out of control, people hone in on to diet.

I think we're going to be seeing more and more of this in our practice. It's important that gastroenterologists, if they suspect it, that they get these patients in the right hands.

Dr. Lacy:  Thank you, Kate. Great points. You've made this seem so easy and so logical. Starting a patient on a low FODMAP diet should be really easy. You just send them to a website, you give them a list of foods, or you have some Xerox sheet of paper. You and I know this is a lot more complicated than that. Can you tell us how you start the process with a patient? Remind our listeners how long it takes to do a great job.

Kate:  I'll tell you, initially, when I started educating patients, it took me a good hour and a half. I had a private practice. I could allow that amount of time to get it down. Then as I went, and I developed the handouts that were missing, I could do this in an hour. You need a good hour, for sure.

You do need good teaching tools. Not just a high and low FODMAP checklist. Grocery list. What foods to buy. Tips to help patients read a label. Menu planning. How do they put these foods to their meal planning for the week?

After a thorough nutrition and medical history review, typically, what I would do is explain the pathophysiology of FODMAPs in the gut, and why eliminating them could be helpful. You always want to stress in that first visit that it's a 3-phase approach, and that they have to undergo all 3 phases.

You don't want to just hand them a handout and say, "Bye-bye," because they will stay on it for a year or more. Once you go through all of those practical application features, and handouts to support those types of things, the patients do well.

Typically, I usually do 3 visits. One for the elimination phase, one when they're ready for reintroduction, and the last phase to get them to personalize the diet. Three visits is ideal, if possible.

I do recommend that most GI patients, if possible, see a GI dietitian once a year. Food intolerances can change over time. If they can liberalize the diet, we want to get them to do that.

Dr. Lacy:  Thank you very much. Kate, what resources, other than yourself, since you're the resource, are the best for the low FODMAP diet? Can you help point our listeners in the right direction?

Kate:  Absolutely. I appreciate Monash University's low FODMAP diet app. It provides up to date, in real-time, as they're doing food analysis, appropriate portions, as well as which items would be low FODMAP versus high FODMAP. They also add filters in. If you do not need to eliminate lactose, because you know lactose is not a problem, you can do that.

They also have a science-based blog at monashfodmap.com. Those are my 2 go-tos. I will do a little plug. I have a low FODMAP diet step by step, which also walks patients through all 3 phases, and could be done and read even when they're working with the dietitian or gastroenterologist, as an adjunct to that.

Additionally, I have articles that I've written. "The Low FODMAP Diet, What Your Patients Need to Know," I wrote in The American Journal of Gastroenterology, in February of 2019. Then another article in Clinical Gastro and Hepatology was titled, "From A Dietician's Perspective, Diets for Irritable Bowel Syndrome are Not One Size Fits All."

In this particular article, we really address the disordered eating piece, and how to deal with that in a gastro practice. Those are 2 articles that can also support clinicians as they work through patients that might require diet change.

Dr. Lacy:  Kate, thank you. For our listeners, there is a small fee for the Monash app for your smartphone. All that money goes to research. The inventors of the diet do not get any money from that. That's important to understand.

Your 2 articles, one in the red journal, The American Journal of Gastroenterology, and one in the blue journal, CGH, were both wonderful. Thank you. Kate, this really has been a wonderful conversation. I can't thank you enough for educating our listeners. Any last thoughts?

Kate:  No. If you can work with a dietitian, I think it'll make life a lot easier when applying a diet. That there's risk factors for eating disorders out there, and other issues that would contraindicate doing a low FODMAP diet. Using the diet judiciously, and the right patient.

Dr. Lacy:  Wonderful. Kate, once again, thank you so much for lending us your wonderful expertise and great number of years of experience. I know I learned something today. I'm sure all of our listeners did as well. Thank you so much.

Kate:  My pleasure. Thanks for having me on.