December 08, 2017
7 min read

Diet in IBD: An important component to stabilize the microbiome

You've successfully added to your alerts. You will receive an email when new content is published.

Click Here to Manage Email Alerts

We were unable to process your request. Please try again later. If you continue to have this issue please contact

In patients with inflammatory bowel disease, diet significantly impacts the fecal microbiome, which is believed to be involved in triggering and maintaining inflammation. In particular, diets high in sugar and fat have been implicated in the pathogenesis of IBD.

The most commonly recommended diet for IBD patients is the Specific Carbohydrate Diet (SCD), which involves the elimination of grains, dairy products, most sugars and many starches. In pediatric patients, an exclusive enteral nutrition (EEN) helps patients achieve clinical and biochemical remission. While diet may be used as primary or adjunctive therapy, it is an important part of addressing almost any disease process, according to David L. Suskind, MD, professor of pediatrics and director of clinical gastroenterology at Seattle Children’s Hospital.

“In the world of medicine, we really have to focus on how diet affects our patients,” Suskind told Healio Gastroenterology and Liver Disease. “We know from the studies in cancer, in heart disease, in many chronic conditions, that diet is a central player. We are now realizing that this is the case too in IBD.”

Suskind spoke with Healio Gastroenterology and Liver Disease about the diets that show benefit in IBD, the role of the fecal microbiome in the disease, and the challenges in predicting which patients will benefit from dietary intervention.

Healio: It seems as though diet can make a big difference in patients with IBD. Is diet usually done in addition to medication, or is it used instead of medication?

Suskind: We use diet as both primary and adjunctive therapy; it all depends on the clinical situation that is occurring, and the patient’s desires. But we do have many individuals who are on diet and diet therapy alone, who have done extremely well clinically, and we’ve had resolution of inflammation within their GI tract. We also use diet in conjunction with medications. When medication is not working as well as we want it to, or is helping only somewhat in terms of symptoms and inflammation, we’ll bring in the Specific Carbohydrates diet or other dietary therapy to get that patient into clinical remission. We use it in both areas.

Healio: If a patient is going to do diet alone, would they need to be very adherent?

Suskind: Absolutely. I should emphasize that diet is important for everyone — it doesn’t matter if you’re on the SCD or not. We know that diet has an impact on how people do from a GI perspective, but also just in terms of life overall. For individuals who want dietary therapy, like SCD, as their primary therapy, compliance is paramount; making sure a patient stays on the diet and maintains it long-term is going to be important. We know that the fecal microbiome as a major impact in terms of IBD, as a likely trigger of the inflammation and of the continuation of the inflammation. So, it makes perfect sense that diet should have an impact on how patients do from a disease perspective.


Healio: What is the role of the fecal microbiome in IBD?

Suskind: Both of our initial studies, as well as our prospective studies looking at the fecal microbiome, have shown that diet has a major impact on how people do clinically.
 That’s when it was first described, and the term was coined. Its impact in IBD has been known over the past 20 or 30 years. We continue to learn more about the impact of the fecal microbiome because our scientific studies and our assays, which can tell you what’s in the microbiome, have continually improved over the last few decades.

Now, we’re able to literally tell an individual what the constituents are of those 100 trillion bacteria within the bowels. But it’s a fairly complex area. There are 1,000 different species that hypothetically could live in there. It’s a very complex ecosystem and we know that diet impacts it, but we don’t know fully who will respond to dietary therapy, who won’t be, and how it’s going to affect an individual’s fecal microbiome. We will get that knowledge; it’s just about time, energy and money.

Healio: Currently, how do you predict whether a patient will respond to dietary therapy? Do you just have to try it and see?

Suskind: At this stage, that’s exactly what we do. If someone is interested in dietary therapy, we educate them, we teach them, and then when they bring it into their life, we see how they respond. Even though we’ve had success with dietary therapy, it’s not 100%, and we don’t know why it’s not 100%. It may be that some people just won’t respond. It may be a question of compliance. It may be other factors that we’re just not knowledgeable about yet.

Healio: There has been a lot written about the impact of high-fat and high-sugar diets on IBD. What are the roles of sugar and fat in the IBD disease process?

Suskind: Well, especially in our animal models of IBD, we are able to really see what occurs in the GI tract with these high-fat, high-sugar diets. They not only change the type of bacteria in the GI tract to bacteria we think are pro-inflammatory, but it also actually breaks down the mucus layer, which is a very thin mucus layer, about 9 microns thick, which actually is able to keep out the vast majority of bacteria. It breaks it down, which allows the bacteria to get much closer to the immune system and have the immune system respond. Food additives and emulsifiers also affect the lining of the GI tract. Those bacteria are there for a reason, but the immune system and the mucus layer are there for a reason, too, and when we break that down, you’re much more likely to develop inflammation and IBD if you’re predisposed to it.


Healio: But eliminating these foods and food additives would not necessarily result in remission?

Suskind: This hasn’t yet been studied well. We actually have an ongoing study right now, where we are putting individuals with active Crohn’s disease on one of three diets, and one of the diets is the strict SCD, one is the SCD with some rice, and the third diet is a whole foods diet, meaning we’re just taking away those additives and seeing what happens to the patients. As it is ongoing, I can’t yet tell you the result.

Healio: What are the current uses of an EEN diet in IBD patients?

Suskind: Exclusive enteral nutrition is a therapy that has actually been around for 40 or 50 years. It’s been a primary therapy for pediatric Crohn’s disease and it’s been really well studied, which adds to the literature on the impact of diet on IBD. We know that if someone goes onto formula and formula alone, that is equal to steroids in terms of getting the patient into clinical and biochemical remission. It works equal to steroids, but actually heals the bowels better than steroids, which, again, points to the impact of the microbiome: the impact of diet’s effect on the microbiome and on IBD itself.

It’s actually recommended for pediatric Crohn’s disease. My parent organization, the North American Society of Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN), recommends EEN as a primary therapy for pediatric Crohn’s disease. Diet has been integrated in the form of EEN in IBD therapy, but we’re now pushing the envelope forward and saying, a whole foods diet can have a significant positive impact as well.

Healio: But EEN is not recommended for adult patients with Crohn’s?

Suskind: There have been studies done in adults. The studies done in adults have not been as successful with use of EEN, but there are actually two studies that have been very successful with EEN, equal to the results seen in the pediatric population. In those studies, the individuals received nasogastric tubes, meaning that they didn’t have to drink formula, they just put it down the NG tube. Those studies were equal to the pediatric studies, which means that adults are less compliant. They don’t follow the diet.


Healio: Adults are more likely to do the Specific Carbohydrate Diet. Can you describe that diet?

Suskind: The SCD was a diet that was started about 80 years ago. It was started by a pediatrician named Sidney V. Haas, MD. He treated patients with celiac with it, and because it’s a diet that removes all grains, these patients did phenomenally well. He then treated a patient with ulcerative colitis, and that individual’s mother wrote a book. Dr. Haas passed away, and the diet stayed in the world based on this book.

We had a patient come to us and say, “This diet works.” That’s where our research started, because once we verified what was going on through this patient, we pushed forward the research. The diet itself is a diet that removes grains. It removes sugars, except for honey. It removes milk products except for yogurt fermented 24 hours and some hard cheeses. Because of that, it actually removes the vast majority of food additives, and people make a kind of whole foods diet from the general guidelines of the SCD.

Healio: It does seem like a difficult diet to adhere to. How much of an issue is compliance?

Suskind: The diet is not for everyone, absolutely. I would say probably about 5% to 10% of our patient population is on the diet. The key is, it has to be right for the patient, meaning that they have to want to do it. They have to want to maintain it. If they can, and they continue to want that, we support them 100%. It’s not as hard as you would imagine it to be. I think it is hard in the beginning, but it eventually becomes their lifestyle, it becomes what they do, and it gets a lot easier with time.

I also think if you look at medicine 30 years ago, being on a gluten free celiac diet was extremely difficult, because you couldn’t get gluten-free products, but today, there’s gluten-free food everywhere. We’re seeing a similar trend with the SCD and Paleo diets; these types of diets are all very similar.

Healio: What advice would you give to physicians and/or patients regarding diet therapy for IBD?

Suskind: I would refer them to our website, Our goal is to further research, but also to develop support for physicians and patients who are interested in dietary therapy. Our site includes all of our protocols, as well as patient resources.


I think another interesting thing to be aware of is that there are currently two large, multicenter studies underway. One doing in pediatrics, the PRODUCE study. The other is an adult study called DINE. They’re just beginning. These are going to further our knowledge in terms of efficacy and the effect of diet on the fecal microbiome.

I would add that whether or not a practitioner prescribes dietary therapy such as the SCD, I think all of us are obligated to discuss healthy diet with our patients. We want to make sure they do well from a GI standpoint, but also from an overall health standpoint. – by Jennifer Byrne

For m ore information:

David L. Suskind, MD can be reached at 4800 Sandpoint Way, Seattle, Washington, 98105; email:

Disclosure: Suskind reports a prior speaking engagement for Imedex.