Approaching Therapy for IBS: Diet Modification

Starting their conversation on therapeutic options for irritable bowel syndrome [IBS], key opinion leaders consider diet’s role in management.

Mark Pimentel, MD: OK, now the rubber meets the road, because the patient really doesn’t care that they have IBS [irritable bowel syndrome]. They care that you have something to make them better. And so we’re going to move on to the management part of this. Tony, when you decide on therapy, what are the factors? We talked about the symptoms, but tell me with more granularity how you manage these patients when they show up in your office.

Anthony J. Lembo, MD: Sure. In the absence of a biomarker to direct therapy, in most patients, it’s based on symptoms. I look for their predominant symptom, and I direct my therapy at that symptom. We also like to determine if they have more constipation or diarrhea or if they’re mixed because a lot of the therapies will affect bowel function. You wouldn’t want to give somebody a drug that increases bowel frequency if they already have diarrhea. And so we put them in little buckets. I also look at how severe their symptoms are. That is kind of a vague term, but it really is determined by the patient.

And the more severe the patient, the more comorbid conditions that are associated with IBS. For example, if they have psychosocial factors or if they have other chronic pain syndromes, I will direct my therapy that way, differently, and direct it toward more centrally acting products. And of course I take the patient’s view as well—how they want to be treated. We see a lot of people who aren’t interested in taking drugs that have adverse effects and are more interested in lifestyle factors and psychosocial factors. We have a discussion regarding that. I don’t just give them an algorithm. It really does vary based on the patient’s presentation.

Mark Pimentel, MD: Brennan, I’ve heard you talk about how you manage patients, and I think it’s a slight modification of that. Can you give me an example of your clinic and how you do it?

Brennan Spiegel, MD: Yeah. People often ask, “Is there an algorithm?” Or, “What do you use first? What do you use second? What do you use third?” I can never answer that question because every patient has some slight variation. But I think for me, a starting point is, first, is pain a predominant feature or not? Abdominal pain as opposed to discomfort and bloat often is a really important symptom. And if pain is an important symptom, I want to understand that a bit more.

Buddha described things as, “the 2 arrows of pain.” So the first arrow, he said, is the injury itself. When you get struck by the arrow, the archer hits you and it hurts. It’s a sensory experience. But the second arrow is the self-inflicted arrow. This is when you look at the first arrow and you think, “Am I going to die? What does this mean about my life? What do I need to do about it?” You know, catastrophizing and the psychological and emotional fallout of having pain.

They are 2 components of pain. As a clinician, this means that I want to tamp down the sensory experience of pain, and there are ways of doing that. But I also need to think about the emotional response to that pain too. And so I’ll often wonder, do I need to add, as Tony called, a centrally acting agent—something like a tricyclic antidepressant, which can probably help with the sensory experience of pain and, maybe to some degree, that second arrow; or add an SNRI [serotonin-norepinephrine reuptake inhibitors], or whatever the case may be?

We all probably have our own go-to medicine, but that’s just a very big umbrella. Then we start to need to get funneled down. OK, what about the bowel symptoms? The frequency of the form? And is there a single agent that I can use to address all this, or do I need to use combination therapy? And again, we probably all have our own combinations. I’d be interested to see what my colleagues think.

Mark Pimentel, MD: We’re going to get to antidepressants, or that category, and maybe that’s not the right word for that category considering the use in this particular instance. We’ll debate that. But diet. Diet is all the rage right now. There are more diets out there than there are patients, I sometimes think. There are so many trends and patterns and fads, and Paleo versus SCD [specific carbohydrate diet]. But the 1 that’s sort of been framed around IBS is the low-FODMAP [fermentable oligo-, di-, mono-saccharides and polyols] diet. You’ve done some really good work, Bill, on really guiding people on it. You can’t be on it forever, and it may not be safe forever. Can you comment on what you think of the low-FODMAP diet?

William D. Chey, MD: I think our jobs as physicians, whether you’re talking about primary care or gastroenterologists, is to help shepherd patients through that maze of different options. There are a lot of options, but there aren’t very many evidence-based options. That’s really the key thing to understand. And right now, low FODMAP is probably the only evidence-based option in terms of diet interventions for IBS. That’s not to say that other ones won’t turn out to be beneficial. It’s just to say that, right now, the only evidence-based option is the low-FODMAP diet, which excludes short-chain sugars that tend to be difficult to absorb and, for that reason, get to the distal small bowel, the ilium, and [the] colon, where they’re fomented to produce short-chain fatty acids and gases, which are important triggers for symptoms in some IBS patients.

One other thing I’ll just say, as you alluded to, Mark, is to please remember that it’s not just an elimination diet. There’s an elimination diet for 2 to 6 weeks, which is really a diagnostic test to figure out if somebody is sensitive to FODMAP or not. But then they have to go through an introduction phase where they receive foods containing individual FODMAPs, and that information is used to personalize and liberalize a person’s diet. In my clinic, of the patients who start a low FODMAP diet, within a few months, 85% are on a modification of the diet. They’re no longer on the full exclusion. That’s really important because we don’t want to leave people on that full exclusion indefinitely.